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Post by Admin on Jun 17, 2015 17:35:53 GMT
Humboldt Bay----Washington clam (Saxidomus) and the soft-shell (Mya). The rock cockle (Paphia) and the gaper (Schizothaerus).
The bay also supports recreationally important bivalve species, particularly in South Bay, including gaper clams, Washington clams, and littleneck clams. DFG annual creel census surveys conducted from 1975 to 1989 reported annual effort and catch estimates as high as 6,639 diggers extracting 188,000 clams in 1982 (Collier 1992). A resumption of that study in 2008 showed sport clamming effort has decreased to an estimated 1,300 diggers extracting a total of 31,189 clams (Brooke McVeigh, DFG, personal communication).
My favorite the Littleneck and Manila clams, (Venerupis staminea & Venerupis japonica) are commonly referred to as steamer clams. Littleneck clams seldom exceeding three inches in length. The shell is distinctly longer in proportion to its height, while the smaller Manila clam often colored bluish on one end and appears as wide as it is long. A ¼ inch plus keyhole shaped show often discloses the presence of the clam 1 to 8 inches under the sand, sandy mud or combination of sand/sandy mud/gravel of the tidal flats in areas of the larger bays exposed during a minus tide. The show of littleneck clams is often confused with shows of other clams. The presence of the clam is confirmed by inserting a bamboo stick into the show but the clam is often located to one side of the show and is easily missed. Littleneck clams are also common to the gravel and cobble substrate associated with rock headlands along the California coast. It is found in much the same areas as the Martha Washington clam and cockles in areas with a substrate composed of firm mud, mixed sand and mud and in mixed gravel with sandy mud and in gravel and rocks mixed with sandy mud. It is usually located nearer the entrances of the bays but higher in the tidal zone in saltwater dominated bay, such as Humboldt Bay and Tomales Bay. It burrows to a depth of from three to eight inches though occasionally it is found at the surface. in accumulated gravel and sand among the rocks in exposed situations. Along the coast it occasionally located in beach areas among boulders with mixed gravel and coarse sand associated with headlands and the rocky shore. It is found in the nearshore subtidal areas in gravel or boulder beaches and live clams are frequently washed ashore on the sandy beaches during large storms.
Distribution and use—The following localities in Northern California contain beds large and well stocked enough to warrant more than casual digging. All were carefully inspected during good tides (W. F. T., 1910) except those in brackets, where the ground seemed favorable and local information reported the presence of the littleneck clams.
Uhlrichs Ranch, near the Oregon Line.
Point St. George to Crescent City.
Nickel Creek (below Crescent City).
Damnation Creek, and between Damnation Creek and Wilsons Creek.
False Klamath Cove.
Patricks Point..
Trinidad, between one-half to one and one-fourth miles east.
Humboldt Bay.
Cape Fortunas.
Mussel Ranch (Cape Mendocino).
Morgans Point.
Shelter Cove, inside Point Delgada.
Abalone Point, near Westport.
Fort Bragg.
Bridgeport Landing, near Point Arena.
Irish Gulch.
Arena Cove.
[Iversons Landing].
[Haven's Neck].
Bowen's Landing.
Gualalla (or Walalla) Point, and Del Mar, two and one-half miles south. [Russian River, both sides a mile distant, a few].
Stewards Point.
Bodega Bay, outside and along northeast side, sparingly.
[Duxberry Reef].
Scotty Creek, near Bodega, 3 miles north.
Between the Estero Del Americano and Estero San Antonio.
Tomales Bay.
Point Reyes, inside southern point.
The distribution of littleneck clams is not, as may be seen from the above remarks, continuous along any portion of the coast, but the beds are of small extent and widely separated. It reaches its greatest abundance in bays such as Humboldt, Bodega and especially Tomales. On the outer coast it exists in very considerable numbers in the beach between Crescent City and Point George, more so toward the point. The remainder of the outer beds are of less importance. In Humboldt Bay the species approaches the Washington clam (Saxidomus) in possible commercial value and is found for the most part coextensive with it in South Humboldt Bay, but also to a lesser degree in North Humboldt Bay. Though used locally it was not found in the markets (F. W. W., 1919). In Bodega Bay it is dug along the northeastern side and is of sufficient importance to warrant digging commercially for shipment to San Francisco.
In Tomales Bay the littleneck clam is found in the greatest abundance and here they are more important commercially than in any other bay on the California coast. The bay is long and narrow and the beaches, not of great width, are composed of boulders, gravel and sand and in some places mud, extending doubtless below low tide level. The clams are found on all these beaches which are gravelly or firm enough to offer suitable ground. On the northern side of the bay the best beds are between Marshals and the Arroya San Antonio, on the southern side they lie opposite these and for two miles towards the head of the bay from Inverness, although digging seems to be carried on elsewhere as well. There are also a few to be found just north of the entrance of the bay. The major part of the supply for the San Francisco market was drawn from Tomales Bay at the time of this survey (W. F. T., 1910; the same held true of the market in the fall of 1919. F. W. W.).
In California south of San Francisco the littleneck clam is also a widely distributed reef and gravel bar species but is found in commercial quantities only at a few points. It was collected at the following points: about the Montara Light, in Elkhorn Slough (Monterey Bay), in numerous very limited beds between Monterey and Point Sur, between Piedras Blancas and San Simeon, between Cambria and Cayucos, the "Pecho" coast between Point Buchon and Point San Luis, along the southern end of the Point Sal reefs north of Casmalia, Purisima Point and on the numerous boulder and gravel bars along the entire mainland coast of the Santa Barbara Channel from Point Conception to middle Ventura County. They are present in the mud flats of Morro Bay, though apparently not abundant, and in El Estero near Carpinteria. At both Playa del Rey and Anaheim Slough they are dug for the market (1919, F. W. W.) as well as used by local residents and campers. The littleneck clam was also found, though less abundantly, in False Bay and San Diego. In these southern points it occurs, as previously stated, in company with the hard-shell cockle (Chione) with which it appears in the Los Angeles markets.
The methods used in collecting the clam are simple. On the beds in Humboldt Bay they are brought to the surface by the hooks that are used for the Washington clam, Saxidomus. Elsewhere they are dug with either spades, forks, hoes or short blades of steel, as happens to be convenient. In the beds open to the ocean the clams congregate in the small depressions or basins in the beds, seemingly because of the presence of water there during ebb tides. A skillful digger watches for such "pot-holes," and observes closely the presence of the material voided by the clam, which is usually to be seen wherever clams are present and sufficient time has elapsed since the disturbance of the water. In such places, a foot or two square, it is possible to collect as many as two dozen good sized clams, lying so close together that their valves touch. In the beds in the bays this distribution is perhaps not so obvious, but is still an aid to the digger. When not to be shipped immediately, the clams are frequently buried until wanted, under gravel in a place on which a slight amount of water stands but which is easily accessible, or they are placed in floating boxes.
The littleneck clam is extensively used in Eureka, being preferred in some cases to any other species (W. F. T., 1910). At Crescent City the Indians occasionally peddle them, and the inhabitants and summer campers frequently gather messes for themselves. All the beds outside of Humboldt Bay are utilized in this fashion by occasional diggers, but at Bodega Bay they are dug for the market to some extent. As noted above, the greater part of the clams of this species in the San Francisco markets are gathered in Tomales Bay. In 1911, as many as fourteen people were employed there, some of them Indian squaws. From a bucket to a half sack was gathered by each during a good low tide, and traded for groceries at the local stores. From these the clams were shipped to market. About ninety sacks, averaging eighty pounds each, were shipped by express each month, a quantity which represented about 75 per cent of the clams taken from Tomales Bay.
The future of the beds is difficult to foresee. If, as seems probable, the species is found extensively below low tide line, the likelihood of exhaustion is lessened. On the outer coast it is unlikely that commercial digging will at any time be carried on in all the beds, and there are so many scattered individuals in small beds as to render their extinction difficult. The importance of these widely scattered small beds as centers of distribution of species is obvious. The temper of the inhabitants of every region is uniformly in favor of protection of the beds as a local attraction, especially those on the outer coast line.
The real danger of depletion is in the bays. Tomales Bay seemed, at the time of the investigation (W. F. T., 1910), to have been exploited to the fullest possible extent. The size of the clams found there was very small, the average length being but three-fifths that of the same species in Humboldt Bay, Bodega Bay and the outer coast line beds. Circumstantial reports as to the former large size of the clams were easily obtainable from storekeepers, diggers and local inhabitants. When an exceptionally low tide occurred, very large clams were to be found at the lowest level reached, indicating that only where they were protected could they grow to full size. Furthermore, the size of the available clams grew steadily all through the season, according to almost universal testimony, and it is a well-known fact that this indicates the dependence of the fishery on the younger classes. If any large stock of clams persisted from year to year, the increase in growth on the average would not be so marked as to attract the attention of the diggers. The small size of the clam, then, would seem to be the result of intensive digging, rather than to be natural to the bay.
It is entirely improbable that a large industry could ever depend solely on the littleneck clam, yet its beds will support a considerable trade in fresh clams; and will yield to the casual diggers on the outer coast, tourist or otherwise, a modicum of a very desirable food. It should add much to the attractiveness of the coast and to the sustenance of the scattered inhabitants.
Saxidomus giganteus
The general appearance of this species is similar to that just described but the shell is somewhat more circular in outline and smaller. The outer surface is much less rough, the growth lines being finer and lower; the white of the interior is without any tinge of purple. The flesh is whiter than that of S. nuttalli.
Habitat and habits—Since essentially similar, the habits of the two species may be described together. The stout shell, the moderately strong foot, and the siphons indicate the ability of this clam to live in diverse localities. The shell varies greatly in strength and thickness according to the locality. Some of the money shells obtained at Bodega Bay were half an inch in thickness, nine inches long, hard, and of great strength and weight for the species. Others from mud flats were sometimes very thin and easily broken. As a rule the shells are of a strength sufficient to stand rough handling, about four or five inches in length, and the valves hold moisture well enough to enable the clam to stand shipment for some distance. The siphons, although small, are long enough to enable the clam to bury itself beyond the reach of the ordinary surface enemies and of the effects of heavy waves, but are not of such bulk as to diminish the value of the clam as food. The species is in many respects intermediate between the surface dwelling cockle (Cardium), with its lack of a siphon and its great foot, and the sedentary, deeply burrowing soft shell (Mya) or gaper (Schizothaerus), with long siphons and small rudimentary foot, but bears some resemblance in habitat and characteristics to Paphia staminea, the rock cockle, or Tomales Bay cockle.
Distribution and use—The localities in which they are most markedly abundant are: Humboldt Bay, Crescent City Beach, Bodega Bay, Wilsons Creek, Tomales Bay, Bolinas Bay, and Drakes Estero.
As it is on the British Columbian and Alaskan beaches, the Washington clam is the most important one present in Humboldt Bay, being so abundant that a digger can gather from eight to twelve buckets full in a good low tide (1911). These are nearly all Saxidomus giganteus, though a small proportion of S. nuttalli are present among those marketed (December, 1919). The beds extend over the northern portion of South Humboldt Bay, between the entrance and Fields Landing. They are also found in North Humboldt Bay, but not as abundantly. The beds are found near low tide line, as a rule, in regions of high salinity, as are those of Schizothaerus. The clams lie about eight inches or less below the surface, and apparently move about in a very limited way, judging from the fact that they are found at the bottom of what the clam diggers term "holes," or softer places among the more viscous surrounding mud. In each of these "holes" are found frequently three or four individuals; these are captured by treading the mud for them and, when discovered, by utilizing a hook to bring them to the surface. Between ten and twenty men were, in 1911, making use of the species extensively for themselves or for the market.
In no other locality on the coast does this species assume a proportionate importance. In Bodega Bay the beds lie in the middle ground exposed by the tides, and along the western shore. In Tomales Bay the beds are neither extensive nor utilized commercially. In Bolinas Bay they are nearly gone, due, it is said, to the deposition of sand. Wilsons Creek, Shelter Cove and Crescent Beach have sparsely inhabited beds open to the ocean, not clearly defined nor of much importance. Judging from the fact that at one time the Indians came annually to camp at Tomales Bay in order to gather the Washington clam, they must have been far more abundant then, than at the time of the survey. At present the use of shells as money is restricted to the older Indians, but formerly it was general, extending along the whole coast beyond Humboldt Bay at least, and inland. A heavy valve without discolorations was recently valued at fifty cents.
It is improbable that any further development of an industry based on this clam is to be expected. It is less hardy and of slower growth than Mya and hence less able to withstand excessive fishing. It is not a species as important to local inhabitants and tourists as it is to the commercial diggers in Humboldt Bay.
Between San Francisco and Santa Cruz occasional Washington clams are found in the sheltered coves but no valuable beds are present. In Elkhorn Slough emptying into Monterey Bay there is a more important bed. Here they are found mixed with the gaper (Schizothaerus) by which they are far outnumbered. No further beds of note occur until Morro Bay is reached when they are found, though less abundantly than the gaper. In both these latter localities as well as farther south only Saxidomus nuttalli was identified.
Shells were obtained from the beaches between Point Conception and Ventura and a single small specimen, apparently the young of this species, was found living on an old pile used as a buoy in Santa Barbara Bay (C. L. H.). Although between Santa Barbara and Santa Monica the beds were largely destroyed by the great storm of 1915, small numbers continue to exist, but at no point do they flourish in sufficient numbers to justify commercial digging. In False Bay, near San Diego, conditions remain unchanged, and the Washington clam is present. The beds, however, are not extensive and the yield is gradually growing less according to the reports of several observers
Heart cockles (clinocardium nuttalli) are common to Humboldt Bay. Often referred to as basket cockles, they are located at the surface to a depth of 3 inches under the sand, sandy mud or muddy substrate in the tidal flats. The cockle show in the photograph is typical of a cockle showing well. The cockle beds show when the outgoing tide exceeds a minus tide, but the most productive raking occurs when the low tide exceeds – 1.0. The most extensive cockle beds are located in Coos Bay, Tillamook Bay, Netarts Bay and Yaquina Bay.
Cockles are raked with a long–handled four pronged cockle rake sold at bait and tackle shops or marine supply stores. The four pronged garden rake used to cultivate plants may also be used to rake cockles. The ends of the prongs on a cockle rake are rounded while the prongs on the four pronged garden rake are pointed and sharp. Consider that cockle rakes are safe to use around children and the rounded prongs will not penetrate your belongings. Either rake works exceptionally well. You can feel the tines of the cockle rake hitting the cockles as the rake is pulled through the sand, sandy mud or muddy substrate. Use a cockle rake with a basket attached to rake cockles in deepwater.
Live cockles are difficult, if not impossible, to open with a knife. To separate the cockle meat from the cockle shell, fill a large pot half full with water. Bring the water to a full boil and carefully drop the cockles into the boiling water. The heat from the boiling water will force the cockle shells to pop open within 40 to 60 seconds. Leaving the cockles in boiling water longer than 60 seconds will cook them making it difficult to clean them. Once the cockles pop open, immediately immerse them in cold tap water to stop them from cooking. Insert the point of a dull butter knife between the shells to open the cockles that did not pop open in the boiling water.
A fork easily separates the cockle meat from the cockle shell. Use a sharp knife to clean the cockles. Split the top half of the cockle’s body with a knife and remove the dark visceral flesh, intestines and gills. Use a small bristle brush to remove the rust colored stain on the cockle’s digger foot. The cockles are ready for cooking or freezing.
Freeze raw cockles for future use by placing them in a freezer storage bag. Add ½ teaspoon of salt and cover them with cold water. The cockles will keep for three months, but are best if served fresh. If the cockles are going to be used immediately boil them for 60 seconds before immersing them in cold water to stop them from overcooking.
Fresh cockles are absolutely delicious when minced and made into cockle fritters, served as cockle chowder or thinly sliced and added to a Caesar salad along with sliced mushrooms topped with graded Romano cheese.
Use—An excellent food mollusk, commanding a good price in the market, it is not handled commercially in California because of its scarcity. For the same reason, there is little local use made of it.
Distribution—Though widely distributed in California it does not appear to reach the importance that it does on the tide flats of Puget Sound and the Gulf of Georgia. It was present in Humboldt Bay, Crescent City, Tomales Bay and on Humboldt Spits and in general where the rock cockle (Paphia) is found, though always in smaller numbers. In Elkhorn Slough emptying into Monterey Bay it is fairly abundant and of good size. Some were found in Morro Bay and between Oso Flaco Lake and Point Sal at the southern end of Oceano Beach, where they were taken with the Pismo clam. In the latter place the sand is coarser and softer than on Pismo Beach and apparently better fitted for rapid burrowing. Shells were obtained at various points south to San Diego and occasional reports of
SMOOTH WASHINGTON CLAM
Saxidomus giganteus (Deshayes 1839)
Description: Shell thick and firm, oval in outline but more rounded than that of the common Washington clam. Outer surface with such finely spaced concentric growth lines as to seem almost smooth. Interior of shell entirely white, never with purple markings near siphonal end of shell. Attains a length of four and one-half inches. Differs from the common Washington clam by lacking purple marks on inside of shell at posterior end and from the thin-shelled littleneck, which is sometimes mistaken for it, by not having radiating ridges.
Range: Sitka, Alaska, to San Francisco Bay, California.
Habits: Lives at depths of 10 to 14 inches or more in mud or sandy mud of bays, lagoons and estuaries in areas which are usually exposed at low tide. In firm mud a narrow slit-like mark about one-quarter inch long indicates the spot where the long siphon tube reaches the surface. This is a more northern species than the common Washington clam and is seldom taken south of Humboldt Bay. In only one locality in California, near Fields Landing, Humboldt Bay, is this species common enough to support a minor fishery.
Use: Highly esteemed for food.
Other names: Butter clam, money shell, giant Saxidomus.
COMMON WASHINGTON CLAM
Saxidomus nuttalli Conrad 1837
Description: Shell thick and firm, oval in outline and roughened on the outer surface by numerous concentric ridges. Shell gapes slightly at siphonal end and siphons though completely retractile can usually be seen through the gape. Inside of shells shiny white with dark purple at posterior (siphonal) end. Attains a length of nearly seven inches. Differs from the smooth Washington clam by having purple markings on inner margin of shell at siphonal end and from the thin-shelled littleneck, which is sometimes mistaken for it, by not having radiating ridges.
Range: Humboldt Bay, California, to San Quintin Bay, Baja California.
Habits: Lives at depths of 12 to 18 or more inches in mud, sandy mud or sand of bays, lagoons and estuaries in areas which are usually exposed at low tide. Siphons joined to form a tube which extends to the surface of the mud. On firm, sandy mud a narrow slit-like mark at the surface, one-half inch or less in length, indicates the presence of this clam. Siphons are seldom withdrawn rapidly enough to squirt water above the surface of the mud. One of the more important clams in the sheltered waters north of Morro Bay, seldom found in the bays to the bays to the south. Best localities in California are Morro Bay, Elkhorn Slough, Bodega Bay, Tomales Bay and Humboldt Bay.
Use: Highly esteemed for food and the object of an extensive fishery in the northern part of the State. Sometimes used for fish bait.
Other names: Butter clam, money shell, giant Saxidomus, sand cockle.
RAZOR CLAMS
Siliqua lucida Conrad
Siliqua patula Dixon
Plate 15, figure 4
Other names—Razor shell; sea clam.
This important form is represented by two closely related species in California, Siliqua lucida, ranging from Monterey south, and Siliqua patula, found from Monterey to Alaska. As there are no important differences one description will do for both.
Description—The razor clam reaches a length of from four to six inches but does not have the bulk of some other species because of its slender form. It is markedly elongated though not to the extent found in Solen and Tagelus, the valves are little arched and very thin and delicate; the periostracum is glossy and varnish-like in appearance. The foot is large and powerful, the siphons rather short and united except at the tip.
Habitat and habits—The razor clam is found in the same locations as is the Pismo clam, the pure sand beaches fully exposed to the ocean and by preference those that are broad and level. Though exposed to the same surf its valves are not massive as are those of the Pismo clam, but the most fragile of all the larger clams. This apparent contradiction finds its explanation in the surprising activity of this clam; its shell is specialized not for strength but for rapid progress through the sand where the heavy and bulky shell would be a hindrance. The method of burrowing, though not different in principle from that of other clams, is so highly developed that an account of it may be given. Some idea of their agility may be gained from the statement that small razor clams placed on wet sand have completely buried themselves by eight or ten movements of the foot in a period as short as seven seconds. That the reaction of digging is a deep seated and fundamental one is shown by the fact that when a small specimen is cut in two by the shovel the foot-bearing end will in some cases bury itself almost if not quite as promptly as the uninjured animal. When first thrown out on the sand the burrowing movements of the foot may readily be seen though they are so rapid that it is hard to make out all the details. The foot is first extended by a series of movements until it projects half the length of the shell. This extension is accomplished by forcing blood into cavities in the foot, thus dilating it. As it is being extended the tip of the foot has a pointed shape; in this way it penetrates the sand readily. Having reached its full extent the tip continues to swell up until its cross section is greater than that of the shell. This crowds against the surrounding sand and when the muscles of the foot contract, pulling the tip nearer the body, the shell moves more readily through the sand than does the foot and hence is drawn after it. Repeated in rapid succession this serves to take the animal out of harm's way. In fact, if the first spade thrust does not cut off the razor clam's retreat and turn it out on the sand it is almost hopeless to follow it. At times the young, at least, move horizontally just below the surface of the sand, burrowing along in the manner just described with the hinge uppermost and leaving a furrow in the sand often a foot in length. How extensively and for what purpose they thus move about is not known.
During its presence at the surface of the sand, the animal holds a vertical position, with the siphons projecting into the water or air above, and the valves usually oriented in a definite manner with relation to the water which flows over it, namely with the hinge toward the open ocean (see pages 31 and 47). The certainty with which its vertical position is assumed evidences the acuteness of its balancing organs. When alarmed, as it easily is by a footstep or tap of a spade in its neighborhood, it digs rapidly downward with its large foot, and unless pursued, comes to rest a short distance below the surface but resumes its motion on being again alarmed. The method of capture illustrates the acute sensitiveness. It is necessary either to discover the clam while its siphons project and to dig it very quickly, or to tap the surface over it with a spade, when it will betray its presence by moving downward and causing a slight pit to appear in the sand over it. Usually two diggers work together, one carrying the sack into which he puts the clams, the other devoting his time entirely to digging.
The clam is able to withstand but little exposure to the air, despite the fact that it will project its siphon from the sand. It requires ground in which the water is retained to a great degree during ebb tides, not merely in order to live, but in order to move with facility. The sensitiveness of the animal probably is of great use to it in serving to warn it of heavy wave action, and its great activity enables it to escape the injurious effect of shifting sand. Thus it is fitted for life on the outer beaches, which must, however, be of pure sand, without pebbles or rocks which would break its shell, or hinder its motion, and deep enough to allow it some scope in its movements, while at the same time level enough to retain a substratum of water. It is not to be found in enclosed waters where the bottom is muddy and tenacious, nor in the slightly brackish water which is so often an accompaniment of such a bottom. Whether it is present in any number in sand banks below low tide level is a moot question, although such a state of affairs is indicated by the presence of shells on the beaches where no clams are to be caught. With these conditions in mind, it should not be hard to understand the peculiarly localized distribution of the species.
Distribution—Northern California: As stated, the form found north of Monterey is Siliqua patula. In accordance with the character of the coast, there are found but three beds of these clams in northern California. The most northerly of these is just above Point St. George, near Crescent City, and extends from the Point proper to near the spit opposite Lake Earl. The clams are more abundant here than in any other locality. The sandy beach south of Crescent City is said to have been at one time abundantly stocked for a distance of about four miles, but it was found to be nearly bare of them; only with great difficulty were specimens obtained. The best known bed, however, is at Little River, but it is subject to a most energetic fishery by the inhabitants of the surrounding country, and hence is less abundantly stocked than the beach near Point St. George. The Little River beach appeared ideal for them, and local report had it that formerly the clams were very abundant. At the time they were examined (1910, W. F. T.) they were to be found from the mouth of Little River a distance of a mile and a half south, becoming progressively less numerous. Elsewhere along the coast cast up shells were to be picked up everywhere, especially along the beaches near Klamath River, Eel River, and the Humboldt Bay spits, and on those of Ten Mile River, near Fort Bragg. Nevertheless, live clams could not be found above low tide line despite earnest search.
SICKLE RAZOR CLAM
Solen sicarius Gould 1850
Description: Thin, flat, elongate, slightly curved valves. Long margins of the shell roughly parallel, anterior end generally flat and posterior margin rounded. Umbos located at extreme anterior end. Shell covered with a heavy, glossy periostracum which gives it a yellowish-brown varnished appearance. Siphons united. Foot frequently darkly pigmented. Siphons or foot or both frequently protrude from the shell. Length to four inches. Differs from the rosy razor clam in having slightly curved shell and from the jackknife clam by having umbo at extreme anterior end.
Range: British Columbia to San Quintin Bay, Baja California.
Habits: Usually found at depths of one foot or more in firm, sandy mud of sheltered bays, sloughs and estuaries. Digs a smooth-lined, permanent burrow in which it moves readily up and down. Most frequently found under the roots of eel grass and is an extremely active digger. Best localities in California are Elkhorn Slough and Humboldt Bay, though it is rare even at these localities.
Use: Taken but incidentally by clam diggers usually seeking other species. More frequently used for fish bait than human consumption.
COCKLE
Cardium corbis Martyn
Plate 5, figure 2
Description—This is the chief of the species of Cardium reaching an important size, and is the bivalve having the best claim to the term cockle. The valves are marked with numerous bold radiating ribs, separated by grooves which are prolonged at the margin to form interlocking points as in the scallop. Viewed from the end, the deeply arched shells give the animal a heart-shaped outline, and they are sometimes known as "heart shells."
Habitat and habits—In the North, this form is found on tide flats in bays or sounds, where it burrows barely beneath the surface, or may be seen lying on top of the sand. In California living specimens were found both in bays and on exposed beaches of coarse loose sand. It is a very active bivalve and corresponding to its habit of shallow burrowing, has a strong, elongated foot and no siphon tubes, the siphon holes being formed by fusion of the mantle margins at two points.
Use—An excellent food mollusk, commanding a good price in the market, it is not handled commercially in California because of its scarcity. For the same reason, there is little local use made of it.
Distribution—Though widely distributed in California it does not appear to reach the importance that it does on the tide flats of Puget Sound and the Gulf of Georgia. It was present in Humboldt Bay, Crescent City, Tomales Bay and on Humboldt Spits and in general where the rock cockle (Paphia) is found, though always in smaller numbers. In Elkhorn Slough emptying into Monterey Bay it is fairly abundant and of good size. Some were found in Morro Bay and between Oso Flaco Lake and Point Sal at the southern end of Oceano Beach, where they were taken with the Pismo clam. In the latter place the sand is coarser and softer than on Pismo Beach and apparently better fitted for rapid burrowing. Shells were obtained at various points south to San Diego and occasional reports of former beds were obtained but these seem to be of little importance.
ROCK COCKLE
Paphia staminea Conrad
Plate 10, figure 2
Other names—Little-neck; hard-shell; Tomales Bay cockle; rock clam.
Description—The rock cockle is a clam of moderate size, seldom exceeding three inches in length, with deeply arched valves so that the whole animal is rounded in form and of fair weight for its size. The shell is marked with bold radiating ribs recalling the true cockle (Cardium) though the shell is distinctly longer in proportion to its height. The foot is flattened and though strong is not as large as the finger-like foot of the cockle. It differs from P. tenerrima in showing comparatively faint growth lines and in having the inner margins of the valves roughened and not smooth.
Habitat and habits—It is not adapted by its form or burrowing powers to loose or rapidly shifting ground such as that occupied by the razor clam, but is still active enough to maintain itself on outer beaches as well as in enclosed waters. In the bays it is found in much the same situations as is the Washington clam (Saxidomus), never in beds of deep soft mud, but nearer the entrances of the bays and as a rule not far distant from low tide line. In firm mud banks it burrows to a depth of from three to eight inches though occasionally it is found at the surface. It does not inhabit pure sand through which its rough shape unfits it to move rapidly, but it is often met with wherever there is room for it to nestle in accumulated gravel and sand among the rocks in exposed situations. Along the outer coast it is therefore possible to judge fairly accurately of its distribution by the presence of firm beaches, such as those of small boulders mixed with gravel or coarse sand. It is capable of living in gravel or boulder beaches below low tide line; from such beaches live clams are frequently washed ashore, as is the case on the pure sand beaches off the Humboldt Bay spits and off Crescent Beach. Naturally, however, clams in such situations are only indirectly of commercial value through forming a source of supply of spawn for the neighboring exposed beaches.
Distribution and use—The following localities in Northern California contain beds large and well stocked enough to warrant more than casual digging. All were carefully inspected during good tides (W. F. T., 1910) except those in brackets, where the ground seemed favorable and local information reported the presence of the rock cockle.
Uhlrichs Ranch, near the Oregon Line.
Point St. George to Crescent City.
Nickel Creek (below Crescent City).
Damnation Creek, and between Damnation Creek and Wilsons Creek.
False Klamath Cove.
Patricks Point..
Trinidad, between one-half to one and one-fourth miles east.
Humboldt Bay.
Cape Fortunas.
Mussel Ranch (Cape Mendocino).
Morgans Point.
Shelter Cove, inside Point Delgada.
Abalone Point, near Westport.
Fort Bragg.
Bridgeport Landing, near Point Arena.
Irish Gulch.
Arena Cove.
[Iversons Landing].
[Haven's Neck].
Bowen's Landing.
Gualalla (or Walalla) Point, and Del Mar, two and one-half miles south. [Russian River, both sides a mile distant, a few].
Stewards Point.
Bodega Bay, outside and along northeast side, sparingly.
[Duxberry Reef].
Scotty Creek, near Bodega, 3 miles north.
Between the Estero Del Americano and Estero San Antonio.
Tomales Bay.
Point Reyes, inside southern point.
The distribution of Paphia is not, as may be seen from the above remarks, continuous along any portion of the coast, but the beds are of small extent and widely separated. It reaches its greatest abundance in bays such as Humboldt, Bodega and especially Tomales. On the outer coast it exists in very considerable numbers in the beach between Crescent City and Point George, more so toward the point. The remainder of the outer beds are of less importance. In Humboldt Bay the species approaches the Washington clam (Saxidomus) in possible commercial value and is found for the most part coextensive with it in South Humboldt Bay, but also to a lesser degree in North Humboldt Bay. Though used locally it was not found in the markets (F. W. W., 1919). In Bodega Bay it is dug along the northeastern side and is of sufficient importance to warrant digging commercially for shipment to San Francisco.
In Tomales Bay the rock cockle is found in the greatest abundance and here they are more important commercially than in any other bay on the California coast. The bay is long and narrow and the beaches, not of great width, are composed of boulders, gravel and sand and in some places mud, extending doubtless below low tide level. The clams are found on all these beaches which are gravelly or firm enough to offer suitable ground. On the northern side of the bay the best beds are between Marshals and the Arroya San Antonio, on the southern side they lie opposite these and for two miles towards the head of the bay from Inverness, although digging seems to be carried on elsewhere as well. There are also a few to be found just north of the entrance of the bay. The major part of the supply for the San Francisco market was drawn from Tomales Bay at the time of this survey (W. F. T., 1910; the same held true of the market in the fall of 1919. F. W. W.).
In California south of San Francisco Paphia is also a widely distributed reef and gravel bar species but is found in commercial quantities only at a few points. It was collected at the following points: about the Montara Light, in Elkhorn Slough (Monterey Bay), in numerous very limited beds between Monterey and Point Sur, between Piedras Blancas and San Simeon, between Cambria and Cayucos, the "Pecho" coast between Point Buchon and Point San Luis, along the southern end of the Point Sal reefs north of Casmalia, Purisima Point and on the numerous boulder and gravel bars along the entire mainland coast of the Santa Barbara Channel from Point Conception to middle Ventura County. They are present in the mud flats of Morro Bay, though apparently not abundant, and in El Estero near Carpinteria. At both Playa del Rey and Anaheim Slough they are dug for the market (1919, F. W. W.) as well as used by local residents and campers. The rock cockle was also found, though less abundantly, in False Bay and San Diego. In these southern points it occurs, as previously stated, in company with the hard-shell cockle (Chione) with which it appears in the Los Angeles markets.
The methods used in collecting the clam are simple. On the beds in Humboldt Bay they are brought to the surface by the hooks that are used for the Washington clam, Saxidomus. Elsewhere they are dug with either spades, forks, hoes or short blades of steel, as happens to be convenient. In the beds open to the ocean the clams congregate in the small depressions or basins in the beds, seemingly because of the presence of water there during ebb tides. A skillful digger watches for such "pot-holes," and observes closely the presence of the material voided by the clam, which is usually to be seen wherever clams are present and sufficient time has elapsed since the disturbance of the water. In such places, a foot or two square, it is possible to collect as many as two dozen good sized clams, lying so close together that their valves touch. In the beds in the bays this distribution is perhaps not so obvious, but is still an aid to the digger. When not to be shipped immediately, the clams are frequently buried until wanted, under gravel in a place on which a slight amount of water stands but which is easily accessible, or they are placed in floating boxes.
The rock cockle is extensively used in Eureka, being preferred in some cases to any other species (W. F. T., 1910). At Crescent City the Indians occasionally peddle them, and the inhabitants and summer campers frequently gather messes for themselves. All the beds outside of Humboldt Bay are utilized in this fashion by occasional diggers, but at Bodega Bay they are dug for the market to some extent. As noted above, the greater part of the clams of this species in the San Francisco markets are gathered in Tomales Bay. In 1911, as many as fourteen people were employed there, some of them Indian squaws. From a bucket to a half sack was gathered by each during a good low tide, and traded for groceries at the local stores. From these the clams were shipped to market. About ninety sacks, averaging eighty pounds each, were shipped by express each month, a quantity which represented about 75 per cent of the clams taken from Tomales Bay.
The future of the beds is difficult to foresee. If, as seems probable, the species is found extensively below low tide line, the likelihood of exhaustion is lessened. On the outer coast it is unlikely that commercial digging will at any time be carried on in all the beds, and there are so many scattered individuals in small beds as to render their extinction difficult. The importance of these widely scattered small beds as centers of distribution of species is obvious. The temper of the inhabitants of every region is uniformly in favor of protection of the beds as a local attraction, especially those on the outer coast line.
The real danger of depletion is in the bays. Tomales Bay seemed, at the time of the investigation (W. F. T., 1910), to have been exploited to the fullest possible extent. The size of the clams found there was very small, the average length being but three-fifths that of the same species in Humboldt Bay, Bodega Bay and the outer coast line beds. Circumstantial reports as to the former large size of the clams were easily obtainable from storekeepers, diggers and local inhabitants. When an exceptionally low tide occurred, very large clams were to be found at the lowest level reached, indicating that only where they were protected could they grow to full size. Furthermore, the size of the available clams grew steadily all through the season, according to almost universal testimony, and it is a well-known fact that this indicates the dependence of the fishery on the younger classes. If any large stock of clams persisted from year to year, the increase in growth on the average would not be so marked as to attract the attention of the diggers. The small size of the clam, then, would seem to be the result of intensive digging, rather than to be natural to the bay.
It is entirely improbable that a large industry could ever depend solely on the rock cockle, yet its beds will support a considerable trade in fresh clams; and will yield to the casual diggers on the outer coast, tourist or otherwise, a modicum of a very desirable food. It should add much to the attractiveness of the coast and to the sustenance of the scattered inhabitants.
QUAHOG
Venus mercenaria Linnaeus 1758
Description: Heavy, compact valves ornamented with prominent concentric ridges, particularly near the anterior and posterior ends and the umbo. Shell covered with a heavy yellowish-brown periostracum and often stained nearly black near the center of each valve. A distinct, heart-shaped lunule. Hinge ligament prominent, external. Ventral margin of shell deeply crenulate. Inside of shell porcellanous white, with deep violet blotches near the muscle scars, and a purple or violet border around the ventral margin. Attains a length of four and one-half inches. Differs from all littleneck clams and chiones by not having apparent radial sculpture.
Range: Humboldt Bay, California.
Habits: There is a small bed of quahogs in Humboldt Bay which possibly resulted from accidental introduction in a shipment of eastern oysters from the Atlantic coast. The clams from this bed in Humboldt Bay may be the supposed native species Venus kennicotti (Dall 1871) but some systematic work must be done before this can be determined. This quahog is found living just beneath the surface in firm sand or sandy mud in the intertidal zone in a restricted area of Humboldt Bay. The species may get started in other bays of California, particularly since shellfish dealers ship it alive from the East Coast and hold it in receivers for long periods of time.
Use: Highly esteemed for food on the Atlantic Coast and the object of a heavy sport and commercial fishery there. Shipped in large quantities to California where it is sold to restaurants and others as quahogs, cherry stone clams, hard shell clams, etc. The shells of this clam were used by the eastern Indians for wampum, cutting small pierced beads of white and purple to string for this purpose.
Other names: Round clam, hard-shell clam, littleneck clam, cherrystone clam
SOFT-SHELL CLAM
Mya arenaria Linnaeus 1758
Description: Valves oval in outline, whitish, sometimes stained grey or black from the mud in which they live. Shell light and brittle with no external sculpturing other than occasional concentric growth lines. Umbos central with a spoon-like projecting tooth or cartilage pit near the umbo on the inside of the left valve. Siphons long and united covered with heavy epidermis, incapable of being completely withdrawn within the valves. Length to five inches.
Range: British Columbia to Elkhorn Slough, California.
Habits: This species was accidentally introduced into California with shipments of Eastern oysters and was first detected in California in 1874. On our coast it is usually found in heavy, black mud in back waters of bays, lagoons and sloughs where there is some mixing of fresh water with sea water. Usually ten or more inches beneath the surface with the siphons extended to the surface. Siphon holes appear slit-like at the surface of the mud flats and once recognized are easily located. Best localities: Elkhorn Slough, San Francisco Bay, Tomales Bay, Bodega Bay, Humboldt Bay in back areas near influx of fresh water.
Use: Highly esteemed for food and the object of extensive sport and commercial fisheries. In years past this species was cultivated to a limited extent in the San Francisco Bay area.
Other names: Soft clam, long clam, mud clam, sand clam.
GEODUCK
Panope generosa (Gould 1850)
Description: Shells whitish, covered with a dull, yellowish-brown periostracum which is often badly eroded in large specimens. Shells sculptured with a number of unevenly spaced, concentric growth lines. Siphons united to form a tube, extremely long and impossible to withdraw into the shells. Valves gape widely on all sides except dorsal (hinge) area. Flesh exposed between the gaping valves covered with a heavy reddish-brown epidermis or skin. Shell attains a length of seven inches, with reputed weights for the entire animal of more than eight pounds. Differs from the gapers for which it is often mistaken by not having cutaneous flaps at siphon tip.
Range: Forrester Island, Alaska, to Scammons Lagoon, Baja California.
Habits: Lives in sandy mud of bays, sloughs and estuaries at depths of four or more feet. Siphons reach the surface through a smooth hole. At low tide these clams may be located on mud flats by columns of water which they squirt several feet into the air. They may be also located by the siphon hole which is an inch or more in diameter at the surface of the mud. When the extended siphon is touched it is seldom withdrawn so rapidly as to squirt water into the air. Not common in California but may be found in some numbers at Morro Bay.
Use: One of the finest food clams in California but due to its comparative rarity and the difficulty involved in excavating for a single clam it is not often sought.
ROUGH PIDDOCK
Zirfaea pilsbryi Lowe 1931
Description: Shells whitish, elongate, gaping widely at both ends. The smooth siphonate end separated from the roughened anterior end by a diagonal groove. Anterior end with numerous sharp projecting spines or teeth where concentric growth lines join radiating ridges. Siphons united and quite long, covered with a thin epidermis near the junction with the shell. Small, rounded flecks of horny material spotted irregularly over surface of siphons which cannot be withdrawn completely into the shell. Shell attains a length of five inches. Differs from the mud piddock by having a groove separating anterior and posterior ends; from the wart-necked piddock by having rounded spots on siphons and from other piddocks by not being able to withdraw its siphons into its shell.
Range: Nunivak Island, Alaska, to San Juanico Bay, Baja California.
Habits: Lives at a depth of 10 to 14 inches or more in heavy mud, clay or soft rocks in bays, lagoons and estuaries. Sometimes in soft rock along exposed areas of the open coast. Siphons are extended to the surface through a smooth, tapering hole and are slowly withdrawn when the animal is disturbed. Siphon holes are round and about a half inch in diameter, difficult to tell from some shrimp and crab holes. These piddocks are extremely slow burrowers and cannot escape in this manner. Best localities in California: Elkhorn Slough, San Francisco Bay, Bodega Bay, Tomales Bay, Humboldt Bay.
Use: Primarily used for food but because of the habitat in which it lives it is seldom sought by clam diggers. Should be thoroughly cleaned before eating to avoid a muddy taste.
FLAP-TIPPED PIDDOCK
Penitella penita (Conrad 1837)
Description: Shell thin, whitish, globular at the roughened anterior end and tapering rapidly to the posterior end. Dorsal hinge covered with a triangular-shaped accessory plate. Anterior end open and foot protruding during active burrowing stage and shelled over during later stages when full growth has been attained. At the time the anterior end shells over an elongate chitinous flap is formed at the tip of each shell. Attains a length of four inches. Differs from the mud, rough and wart-necked piddocks by being able to withdraw siphons into shell and from the plate-sided piddock by having chitinous flaps at posterior end in adult stages.
Range: Chirikof Island, Alaska, to Turtle Bay, Baja California.
Habits: Bores into clay, shale, sandstone or other soft rock on the open coast. Seldom deeper than five inches, siphons extended to the surface of the rock through a narrow passage. In soft rock areas where small round holes suggest the presence of these clams a sharp blow on the rock with a hammer will cause the flap-tipped piddock to squirt water from the siphon hole. Frequently found in the same rock formation as the wart-necked and plate-sided piddocks, the checked and pea-pod borers and the rock boring mussel. Best localities are Point Fermin, White Point, Carpinteria, Santa Cruz and Buhne Point in Humboldt Bay.
Use: Because of the habitat in which the flat-tipped piddock lives it is seldom sought. A rather mildly flavored clam and quite good in chowder. Sometimes used for fish bait.
Humboldt Bay—The markets are supplied with the Washington clam (Saxidomus) and the soft-shell (Mya). The rock cockle (Paphia) and the gaper (Schizothaerus) are also abundant enough to be of economic importance but only the former is at present used. The razor clam is found to a limited extent on the outer beaches and used locally. Certain regions of the bay receive sewage and precautions should be observed in the use of mollusks from these parts.
GAPER
Schizothaerus nuttalli (Conrad 1837)
Description: Among the largest California bivalves. Valves thin, whitish, covered with a thick, brown periostracum which is often badly eroded on large specimens and may be stained black if clams are living in mud. Siphons united and extremely long, incapable of being retracted into the valves. Siphons covered with a heavy, dark epidermis and tips with a pair of thick cutaneous flaps. often with small clumps of seaweed growing on siphon tips. Attains a length of eight inches and a weight of nearly four pounds. Differs from the dish clams and the California mactra by having cutaneous flaps on siphon tips and widely gaping shells at posterior end. Its differences from Schizothaerus capax are not known at this time. S. capax and S. nuttalli both occur in Humboldt Bay.
Range: Puget Sound to Scammons Lagoon, Baja California.
Habits: Lives at depths as great as three feet or more in fine sand or firm, sandy mud in bays, sloughs and estuaries as well as more quiet sheltered areas along the outer coast. Siphons form a tube which extends to the surface of the mud. Sometimes on foggy or cool cloudy days gaper clams will have several inches of their siphons exposed on the surface of the mud. On firm, sandy mud, a round opening an inch or so in diameter indicates the presence of this clam. If disturbed by vibrations of footsteps, etc. the siphons are withdrawn rapidly enough to squirt water several feet into the air. May frequently be located on the mud flats by the squirts of water particularly as the tide comes in. Probably one of the most common clams along the entire coast of California as it ranges from near the high tide line into water over 100 feet deep. Best localities: Alamitos Bay, Morro Bay, Elkhorn Slough, San Francisco Bay, Tomales Bay, Bodega Bay and Humboldt Bay.
Use: Highly esteemed for food and the object of a heavy sportfishery, particularly in Central and Northern California.
Other names: Summer clam, horse clam, otter shell, horse neck clam, big neck clam.
Humboldt Bay—The markets are supplied with the Washington clam (Saxidomus) and the soft-shell (Mya). The rock cockle (Paphia) and the gaper (Schizothaerus) are also abundant enough to be of economic importance but only the former is at present used. The razor clam is found to a limited extent on the outer beaches and used locally. Certain regions of the bay receive sewage and precautions should be observed in the use of mollusks from these parts.
Humboldt Bay is the most economically productive port in the north coast study region, and is the largest port between San Francisco Bay and Coos Bay in Oregon. In 2000, Humboldt Bay was listed as one of 150 U.S. ports that handled more than one million tons of cargo (USCOP 2004). The growing and harvesting of oysters, which takes place in Arcata Bay, represents a significant commercial farming activity (Barnhart et al. 1992). More than 60% of the oysters sold in California are grown in Humboldt Bay (Schlosser et al. 2009). At least 110 species of fish have been reported from Humboldt Bay, including many commercially important species that spawn within the bay and several species of salmonids that spawn in the tributaries (Gotshall 1980; Barnhart et al. 1992). At least six fish species listed as threatened or endangered inhabit Humboldt Bay and its tributaries, including coho salmon, Chinook salmon, steelhead, longfin smelt, and the tidewater goby (Emmett et al. 1991; Moyle et al. 1995; DFG 2009b). Humboldt Bay also serves as an important nursery area for a variety of fish and invertebrate species, including English sole, Pacific herring, lingcod, Dungeness crab, leopard shark, rock crabs, some surfperches, and some rockfishes (Barnhart et al. 1992, Ebert and Ebert 2005). Other large fish species, such as bat rays and green sturgeon, can reach high abundances within Humboldt Bay, particularly during the summer months (Moyle et al. 1995; Gray et al. 1997). The bay also supports recreationally important bivalve species, particularly in South Bay, including gaper clams, Washington clams, and littleneck clams. DFG annual creel census surveys conducted from 1975 to 1989 reported annual effort and catch estimates as high as 6,639 diggers extracting 188,000 clams in 1982 (Collier 1992). A resumption of that study in 2008 showed sport clamming effort has decreased to an estimated 1,300 diggers extracting a total of 31,189 clams (Brooke McVeigh, DFG, personal communication).
Yellow Crab
Cancer anthonyi
Distinguishing Characters: Black-tipped pincers on the claws. The hands of the claws are large and quite smooth, resembling the rock crab in this respect. In fact, all of the legs of the yellow crab are quite smooth. The last five joints of the walking legs lack hair except for very short bristles on the end joints. These bristles may become indistinguishable to the unaided eye, on the last pair of legs. The tip of the last segment of the tail flap is pointed in both male and female, as for all other crabs described except the Dungeness crab.
Color: Yellow-brown, with a purple wash anteriorly and on the legs in some specimens. Underparts plain yellow or yellowish white.
Size: Attains a width of 7 inches across the back.
Distribution: Humboldt Bay to Magdalena Bay, Baja California, but generally uncommon north of Point Conception.
Rock crabs are shed along the entire California coast. The catch is made up of three species — the yellow rock crab (Cancer anthonyi), the brown rock crab (C. antennarius), and the red rock crab (C. productus). The commercial fishery is most active in southern California (from Morro Bay south), where 85 to 90 percent of the landings occur, and of lesser importance in northern areas (Monterey, Halfmoon Bay, and Eureka yield 10-15 percent), where a fishery for the more desirable Dungeness crab takes place. A major recreational fishery has not developed, but recreational crabbing is popular in many areas and is often conducted in conjunction with other fishing activity.
Sportfishing
Traditionally, sports anglers in Humboldt Bay have pursued several species of fish including perch, leopard sharks, jacksmelt, California halibut, bat rays and salmon. Improved boat launching facilities are located throughout Humboldt Bay and include facilities in Fields Landing, Samoa Peninsula (near the Coast Guard Station), at the Eureka Public Marina, under the southern end of the Samoa Bridge, at Hookton Slough on the Humboldt Bay National Wildlife Refuge, and at the Arcata Marsh and Wildlife Sanctuary. It is important to note that the Hookton Slough launching area is for non-motorized watercraft only and the Arcata ramp is shallow and usable only at high tides.
If you don't have access to a boat, Humboldt Bay offers several opportunities for fishing from shore. Some of the more popular shore fishing spots include the Del Norte Street Pier in Eureka, Elk River spit, Elk River (below the railroad bridge), Buhne Point in King Salmon, the mouth of Mad River slough, and the north and south jetties. Note that access to the south jetty is controlled by the County of Humboldt. Also note that both jetties are subject to large, unpredictable, and dangerous waves. Please check the local weather forecast and use extreme caution when fishing on the jetties or in the vicinity of Humboldt Bay's entrance.
Humboldt Bay is very productive clam habitat. Clamers seek clams such as littleneck, gaper, Martha Washington, and others. Popular claming areas include the foot of Del Norte Street in Eureka, the foot of Truesdale Street in Eureka, "Clam Island" across the channel from the Fields Landing Boat Ramp, and various locations in Arcata (North) Bay. Seasonally, recreational fishermen can catch Dungeness and red rock crabs in Humboldt Bay. Recreational fishing in Humboldt Bay is regulated by the California Department of Fish and Game. Before going fishing, claming or crabbing, be sure you have consulted current Fish and Game regulations for seasons, size limits, bag limits and legal fishing gear.
Humboldt Bay is the most economically productive port in the north coast study region, and is the largest port between San Francisco Bay and Coos Bay in Oregon. In 2000, Humboldt Bay was listed as one of 150 U.S. ports that handled more than one million tons of cargo (USCOP 2004). The growing and harvesting of oysters, which takes place in Arcata Bay, represents a significant commercial farming activity (Barnhart et al. 1992). More than 60% of the oysters sold in California are grown in Humboldt Bay (Schlosser et al. 2009). At least 110 species of fish have been reported from Humboldt Bay, including many commercially important species that spawn within the bay and several species of salmonids that spawn in the tributaries (Gotshall 1980; Barnhart et al. 1992). At least six fish species listed as threatened or endangered inhabit Humboldt Bay and its tributaries, including coho salmon, Chinook salmon, steelhead, longfin smelt, and the tidewater goby (Emmett et al. 1991; Moyle et al. 1995; DFG 2009b). Humboldt Bay also serves as an important nursery area for a variety of fish and invertebrate species, including English sole, Pacific herring, lingcod, Dungeness crab, leopard shark, rock crabs, some surfperches, and some rockfishes (Barnhart et al. 1992, Ebert and Ebert 2005). Other large fish species, such as bat rays and green sturgeon, can reach high abundances within Humboldt Bay, particularly during the summer months (Moyle et al. 1995; Gray et al. 1997). The bay also supports recreationally important bivalve species, particularly in South Bay, including gaper clams, Washington clams, and littleneck clams. DFG annual creel census surveys conducted from 1975 to 1989 reported annual effort and catch estimates as high as 6,639 diggers extracting 188,000 clams in 1982 (Collier 1992). A resumption of that study in 2008 showed sport clamming effort has decreased to an estimated 1,300 diggers extracting a total of 31,189 clams (Brooke McVeigh, DFG, personal communication).
The Pismo clam, Tivela stultorum, gets its name from the Chumash Indian word “pismu,” meaning “tar,” because of the natural deposits of tar found in the Pismo Beach area. The Pismo clam is an important invertebrate species that once supported a significant commercial fishery, along with an extremely popular recreational fishery that still exists today. The commercial harvest of Pismo clams began in the early 1900s when horse-drawn plows were used to rake the Recreational Pismo Clam Fishery
Pismo clams remain an important sport fishery in California. They have a distinctive and excellent flavor; they are prepared as chowder, seafood cocktail, fried or eaten raw. Pismo clams have been linked to several human fatalities involving Paralytic Shellfish Poisoning (PSP). It is therefore advised that only the white meat be consumed and all dark meat and digestive organs be discarded.
The most common method of harvesting Pismo clams is with a six-tined potato fork. The digger works backward in a line parallel to the edge of the water probing with the fork, increasing the success rate with the broad side of the clam presented to the fork. Working parallel to the water is also a good safety practice
Annual Status of the Fisheries Report 6-2 since it allows the digger to watch for approaching breakers. Once a clam is struck it is lifted out and measured and placed in a sack, if legal. Regulations require that all undersize clams be reburied in the area from which they were dug. Another method is to shuffle one’s bare feet along the bottom until a siphon or shell is felt. Pismo clams can be visually spotted during low tide by looking for the tufts of commensal hydroids exposed above the surface of the sand.
Diving for Pismo clams has become an increasingly popular sport among the recreational community. Divers search just beyond the breakers by probing the sand with a knife or looking for siphons, exposed shells, or tufts of hydroids.
Diving for Pismo clams is particularly effective on beaches with a steeper sloping gradient. These types of beaches receive less exposure during low tide, and most of the clams are found in water too deep to target with a potato fork.
The historic epicenter of recreational clamming activity was once Pismo Beach itself. In 1949, an estimated 5,000 diggers per day harvested more than 2 million clams over a period of 2.5 months on a stretch of beach that had just been reopened to digging after being closed for 20 years. During that time, an additional estimated 1 million undersized clams were left stranded on the surface
and wasted on that same stretch of beach. Pismo Clam, Tivela stultorum Credit: Kai Lampson Annual Status of the Fisheries Report 6-3
The recreational digger has probably been the largest contributing factor to losses incurred in the Pismo clam population. Current regulations are in place to prevent such a massive depletion. Recreational clamming is regulated by a 10 per day bag limit and a minimum size of 5-inches (127-millimeters) north of the San Luis Obispo/Monterey county line and 4.5-inches (114-millimeters) south of this county line. Sub-legal clams must be immediately reburied. In addition, clamming is closed during parts of the year and in specific geographic locations (Table 6.1). Healthy populations of Pismo clams can be found from Santa Barbara County to the U.S. Mexico Boarder. Digging for Pismo clams is not nearly as popular as it once was. There are no current estimates for the number
of people who participate in the fishery, but Pismo clammers probably number in the several thousands.
Sea otters have been blamed for the loss of the recreational clam fishery at Pismo beach since the estimated sport catch declined form 343,000 clams in 1978 to zero by 1983. In actuality, the loss of the fishery at Pismo Beach cannot be entirely attributed to sea otter predation. The Pismo clam population was being fully utilized by the recreational fishery prior to the sea otter’s arrival; the otters simply tipped the balance and caused the population to collapse. There is some evidence to suggest that a Pismo clam fishery might be able to coexist in an area utilized by otters. Relatively low adult Pismo clam densities have produced successful sets in the past and could do so if sea otter foraging pressure was low. Sea otter pressure does decline in an area when the large peripheral male group moves on to new areas. Such an occurrence most likely explains the resurgence of a recreational fishery at Pismo Beach between 1990 and 1993. During this period sea otters were foraging offshore and in other areas. In 1992, sea otters were observed again foraging in the Pismo Beach area, and in 1993 the last take of a legal clam was reported.
Status of Biological Knowledge: The Pismo clam has two symmetrical shells that are hinged together with interlocking teeth at one end by a dark raised ligament. The shell is thick, and the outside is smooth with fine concentric growth lines. It is covered with what
appears to be a thin coat of varnish, the periostracum, which cracks and peels off when the shell is exposed to direct sunlight. The shells of individual clams are highly variable in both color and pattern. The characteristic color and pattern is solid pale buckskin, though they range from this to dark chocolate. Some individuals are marked with chocolate brown lines radiating from the margin.
Surveys have shown that these “striped” Pismo clams comprise about 5 percent of the total population. A third color pattern consists of three light streaks radiating from the margin, though these streaks generally disappear completely with age. The tendency for stripes or streaks is a natural variation and the sex of the clam cannot be determined by pattern.
Annual Status of the Fisheries Report 6-4
In the majority of Pismo clams, the sexes are separate with an equal proportion of males and females represented in populations. Pismo clams mature after their first winter in southern California and after their second winter in central and northern California. Sexually mature clams have been noted as small as 0.5-inches (12.7-millimeters) in shell length. Spawning usually begins in
late July or early August and continues through November. Fertilization occurs externally when the male releases sperm and the female releases eggs into the surrounding water. The number of eggs per female is proportional to a clam’s size. In laboratory-held clams, a 1.2-inch (30.5-millimeter) female contained 0.4 million eggs, and a 2.9-inch (73.7-millimeter) female had 4.7 million eggs. In comparison, a 5-inch (127-millimeter) female averages 15 million eggs. In nature, less than 1 percent of these eggs would become mature clams. Historic surveys have documented poor survival rates. For example, in one year only 33,000 clams resulted from an estimated 120 trillion eggs spawned. The mechanisms that cause these extremely high mortality rates and poor recruitment are not completely understood. Large surf, strong currents, shifting sand, red tide events, and sudden changes in temperature or salinity may all be contributing factors. Once a clam has settled out of the water column and onto the substrate, it is less susceptible to these forces, though mortality rates remain very high. Oil and other pollutants also play an important role in the mortality rate
of the Pismo clam.
Little is known about the larval stages of the Pismo clam in nature. In laboratory culturing experiments, fertilized eggs hatched into larvae within approximately 48 hours. Laboratory larvae 60 to 70 hours old displayed the behavior of settling to the bottom and remaining benthic or near benthic throughout larval development. If larval Pismo clams in nature also exhibit a benthic phase, larval transport by near-shore currents may be limited, and recruitment would have to occur locally. At 22 to 55 days old clams have completely metamorphosed, developed a foot, and anchored themselves to sand grains with their thread-like byssus. The byssus helps the clam maintain itself in an environment of constantly moving sand and wave turbulence. As the clam increases with size the byssus disappears, and the clam’s weight and burrowing power helps to maintain its relative position on the beach. Pismo clams
characteristically orientate themselves vertically with the hinge and ex-current siphon towards the ocean, the mantle edge and in-current siphon towards the beach, and with the ligament at the center of the hinge oriented up. Pismo clams usually live in the intertidal zone on flat beaches of the open coast, but they have been found out to depths of 80 feet (24.4 meters), and are sometimes
encountered in the entrance channels to sloughs, bays and estuaries. Their normal depth in the sand is 2 to 6 inches (51 to153 millimeters). Burrowing is accomplished by moving the foot rapidly to loosen the surrounding sand. Jets of ejected water then help to further loosen the sand along the sides of the shell.
Annual Status of the Fisheries Report 6-5
The weight of the clam and the pull of the foot together drag the clam down through the sand.
The largest Pismo clam recorded in California came from Pismo Beach and was 7.37-inches (18.7-centimeters) across and estimated to be 26 years old. However, the size of a clam does not directly correlate with its age. A number of clams form Southern California have been aged as being over 35 years, though the majority of these clams were less than 6.5-inches (16.5-centimeters) across.
The oldest Pismo clam on record was collected from Zuma Beach, California and was estimated to be 53 years old, measuring only 5.25-inches (13.3-centimeters) across. The age of Pismo clams can be determined by the concentric growth rings on the shell. The rings alternate from darker to lighter color, and are usually formed during the fall and winter months when the clam is exposed to
prolong periods of disturbances, or during the spawning period.
The Pismo clam grows continuously throughout its life. As it grows the shell not only becomes thicker but increases in diameter. Growth varies considerably from month to month, with the greatest increase taking place in the spring, summer, and early fall months. The Pismo clam is about 0.009-inches (0.23-millimeters) at metamorphosis, and grows at an average rate of 0.084-
inches (2.1-millimeters) for the first three years. Growth slows considerably as the clam ages, with the increase in shell length not more than 0.2-inches (5-millimeters) per year at age 10. Growth rates are dependent on water temperature and vary among beaches. A 4.5-inch (11.4-centimeter) clam could be from 5 to 9 years old. Along the central coast of California, clams are estimated to reach 4.5-inches (11.4-centimeters) between ages 7 and 8.
Fossil remains of Pismo clams have been found in Pleistocene deposits at least 25,000 years old in Santa Barbara and San Diego Counties. Thus the species has been present along our coast since the time of the last ice age. The Pismo clam belongs to the Veneridae family, which is characteristic of tropical seas. Though the Pismo clam is not tropical in distribution, it prefers warmer
waters, being historically recorded from Half Moon Bay, California, to Socorro Island, Baja California Sur, Mexico. However, it has not been found at Half Moon Bay for decades, and its present range extends northward only to Monterey Bay.
Pismo clams have been historically found at three of the Channel Islands: Santa Cruz, Santa Rosa, and San Miguel islands. Healthy populations are known to currently exist at Santa Cruz and Santa Rosa islands, while San Miguel Island has not been surveyed for Pismo clams.
Unsuccessful attempts have been made to introduce Pismo clams as far north as Washington State. Pismo clams do not fare well in extremely cold water, and are very susceptible to freezing temperatures during low tide due to their shallow orientation in the sand. Surveys have shown that Pismo clams that have been translocated north of their historic range usually die within the first year of being planted.
Annual Status of the Fisheries Report 6-6
The Pismo clam is a detritus filter feeder, although living single-cell organisms comprise a considerable portion of the diet. Water is taken in through the in-current siphon that has a very fine net of delicately branched papillae across the opening. The net forms a screen that excludes the entrance of large particles, but permits the intake of water and food, which then pass over the gills where food particles are trapped in strings of mucus. The mucus is brought directly into the stomach where food is carried towards the liver, and larger particles are expelled through the intestine. Despite this elaborate system, more than half of the contents of the stomach and intestine are sand.
The types of food utilized by Pismo clams include detritus from disintegrating plant and animal cells, phytoplankton, zooplankton, eggs and sperm, and bacteria. A 3-inch (7.6-centimeter) Pismo clam filters an average of 15.9 gallons (60 liters) of water during its feeding per day or 482 gallons (1,824 liters) a month. This amounts to approximately 5,790 gallons (21,915 liters) of water per year being strained by one 3-inch (7.6-centimeter) clam.
Pismo clams have many natural predators: humans, sharks, rays, gulls; moon snails, Polinices spp.; crabs; sea otters, Enhydra lutris; and some species of surf fishes (such as the California corbina, Menticirrhus undulatus). Humans have utilized Pismo clams for food for over 2,000 years, as evident from shells and fragments found in the kitchen middens of Native Americans. Bat rays, Myliobatis californica, have developed an efficient technique to pull clams from their beds by using their “wings” to establish a suction force similar in manner to the way a plumber’s helper clears the drain of a kitchen sink. After the clams have been sucked from the sand, the ray can simply pick up, crush and swallow them. Gulls have learned to open live clams up to 3-inches (7.6-centimeters) in
diameter by carrying them up to 50 feet (15 meters) into the air with their beaks and dropping them onto hard-packed sand. It only takes several attempts before the Pismo’s shell shatters, or the abductor muscle tears, and the soft flesh is exposed. The moon snail drills a tiny hole in the clam’s thick shell with a rasping tongue or radula. Once the hole is completed the snail inserts its radula to
remove the soft flesh. Several crabs of the genus Cancer also feed upon Pismo clams. These crabs are able to crack clams up to 1-inch (25.4-millimeters) in diameter with their pincers.
Sea otters, efficient in harvesting Pismo clams, can quickly denude a local clam bed of everything except for small individuals. An adult sea otter needs to consume roughly 25 percent of its body weight each day in order to survive. An average male sea otter weighs 65-pounds (29.5-kilograms) and the females average 45-pounds (20.4-kilograms). This amounts to roughly 80 clams per otter
per day if Pismo clams are their primary food source. A single otter has been observed to eat 24 clams in 2.5 hours. The extension of the sea otter’s range to Monterey Bay in 1972, Morro Bay in 1973 and Pismo Beach in 1979 has precluded the recreational fishery for Pismo clams in those areas. In 1980, it Annual Status of the Fisheries Report 6-7 was estimated that otters consumed over 700,000 Pismo clams in the Pismo Beach area.
Parasites of Pismo clams include a polychaete worm that bores into the shell, and the more common larval cestodes, which occur as small yellowishwhite cysts. About one-third of all large Pismo clams are infected with cestodes. These cestodes have been identified as the larval stage of a tapeworm that infects stingrays and skates. Cestodes can impair the clam’s sexual development but are in no way harmful to humans. Trematodes have also been reported in some clam populations. A commensal hydroid colony, Clytia bakeri,
is often found attached to the edge of the shell nearest the surface, resembling a hairy tuft. Much less common are small, white, commensal pea crabs, Fabia spp., (which are occasionally found in the mantle cavity of clams and feed on
food particles collected in the gills).
Status of the Population
Over the past century, Pismo clam abundance has seriously declined in many parts of its historic range due to a number of fishery-dependent and fishery-independent factors. Historical observations have shown that Pismo clam populations are resilient and have the ability to rebound after just a few years of successful recruitment. The Department of Fish and Game first examined
recruitment in 1919, and annual surveys have been conducted from 1923 to 2000 to obtain information on age, recruitment, year strength, and exploitation trends. Originally only Pismo Beach was surveyed, but after 1948, beaches in Morro Bay, Cayucos, Monterey County, and from Santa Barbara County to San Diego County were included. From 2000 to 2005 only Coronado Beach in San Diego County has undergone an annual survey by the Department of Fish and Game. Surveys conducted form 2000 to 2005 at Coronado Beach indicated that the Pismo clam population was relatively stable and that some recruitment was taking place. Recent reports from clam diggers, as well as divers indicate that significant numbers of Pismo clams continue to be harvested from some of the beaches in southern California. In addition, Pismo clam populations at the Channel Islands appear to be stable, as shown by surveys conducted by the National Park Service.
Management Considerations
Past experience has shown that planting Pismo clams will most likely not expand the present range of the species, nor would it be expected to re-establish a population where the native stock is depleted. The spawn from planted clams would not help to repopulate a beach where the environmental conditions (shifting sand, erosion, pollution, etc.) are keeping the existing native population Annual Status of the Fisheries Report 6-8 at a low level. Pismo clams were sporadically planted on beaches from Washington to the Mexican border from 1900 to 1989 with extremely low survivorship. None of the clams planted north of Monterey Bay survived more than three years after being relocated, with an average survivorship of less than one year. Even under optimal conditions, considering natural mortality, not more than 200 out of 1,000 one- or two-year old clams would be expected to reach legal size.
In southern California, the planting of large clams has paradoxically had a negative effect on local populations. News of a planting project eventually spreads, and the public turns out in mass to search for these clams. Not only are the planted clams immediately removed, but most of the native stock is also taken and the beach is left more barren than before the project. Past projects
have shown that even if the clams are planted in Marine Protected Areas they are nevertheless not safe from poaching activities.
Christine A. Pattison
Associate Marine Biologist, San Luis Obispo, (Cpattison@dfg.ca.gov)
Revised June 2007
Kai M. Lampson
Marine Biologist, Santa Barbara, (Klampson@dfg.ca.gov)
Further Reading
Bureau of Marine Fisheries. 1949. The commercial fish catch of California for the
year 1947 with an historical review 1916-1947. Calif. Fish Bull. 74:267 pp.
California Fish and Game. 1922 Cold weather kills Pismo clams. Calif. Fish and
Game, vol. 8, pp. 124-125.
Fitch, J. E. 1950. The Pismo clam. Calif. Fish Game, 36(3):285-312.
Searcy-Bernal, R. 1989. Periodicity of internal growth rind deposition in the
Pismo clam (Tivela stultorum) from Playa San Ramon, B.C., Mexico. Ciencias
Marinas, 15(3):45-56.
Stephenson, M.D. 1977. Sea otter predation on Pismo clams in Monterey Bay.
Calif. Fish Game, 63(2):117-120.
Wendell, F., R. Hardy, J. Ames, and R. Burge. 1986. Temporal and special
patterns in sea otter expansion and in the loss of Pismo clam fisheries. Calif.
Fish and Game, 72(4):197-212.
Weymouth, F.W. 1923. The life history and growth of the Pismo clam (Tivela
stultorum Mawe). Calif. Fish and Game Commission, Fish
Annual Status of the Fisheries Report 6-9
Table 6.1. Regulations governing the take of Pismo clams, 1911 - present
Year Minimum Size Limit Bag Limit Remarks
1911 13 inches circumference
(about 4? inches diameter)
200 license required for sale of Pismo
clams
1915 12 inches circumference (about 4½
inches diameter
50
1917 4¾ inch diameter 50 Monterey Bay between Pigeon Point
and Yankee Point open only between
September 1 and April 30. All other
areas open year round.
1921 4¾ inch diameter 36
1927 5 inch diameter 15 Shipping of clams by common carrier
prohibited and no clam out of the shell
may be possessed unless being
prepared.
1931 5 inch diameter 15 Sport fishing license required to take
Pismo clams
1933 5 inch diameter 15 No digging for clams between ½ hour
after sundown and ½ hour before
sunrise. No clam digging implements
in possession on beach during these
hours.
1947 5 inch diameter 15 No Pismo clams taken in California
can be sold
1948 5 inch diameter 10
1949 5 inch diameter 10 All undersized clams must be returned
form the hole which dug or to deep
water.
1986 5 inch diameter north of the boundary
between San Luis Obispo and
Monterey counties
4 ½ inch diameter south of the
boundary between San Luis Obispo
and Monterey counties
10 May be taken in Santa Cruz and
Monterey counties September 1
through April 30. In all other counties,
except in state marine reserves or other
marine protected areas which prohibit
the take of clams, Pismo clams may be
taken all year.
Data source is the Bureau of Marine Fisheries, California Division of Fish and Game (1950) Fish Bulletin
(1911-1949) and California Code of Regulation, Title 14. Natural Resources (2005)
Annual Status of the Fisheries Report 6-10
Table 6.2. Commercial landings of Pismo clams (round weight in pounds) in California and imports
of shucked meat (pounds) from Mexico, 1916-1947
Year Landings From California
Imports From Mexico
Year Landings From California
Imports From Mexico
1916 220,600 ------ 1932 110,300 ------
1917 502,100 ------ 1933 106,200 ------
1918 665,700 ------ 1934 140,700 ------
1919 417,500 ------ 1935 181,900 *14,224
1920 299,000 ------ 1936 209,800 ------
1921 219,500 ------ 1937 224,000 ------
1922 193,500 ------ 1938 214,600 ------
1923 237,900 ------ 1939 192,700 ------
1924 293,100 ------ 1940 167,500 ------
1925 323,200 ------ 1941 168,800 10,837
1926 274,300 ------ 1942 93,600 90,979
1927 133,000 ------ 1943 45,900 565,764
1928 125,800 ------ 1944 34,500 1,464,974
1929 109,700 ------ 1945 26,100 6,676,775
1930 108,900 ------ 1946 69,200 1,426,062
1931 104,700 ------ 1947 60,600 159,968
------ No Pismo Clams were imported
* Live weight reported on fish receipts have been divided by 8 to supply the cleaned weight given here.
Data source is Bureau of Marine Fisheries (1949) Fish Bulletin with historical review (1916-1947).
Annual Status of the Fisheries Report 6-11
Dungeness crab: Dungeness crab, Cancer magister, range from the eastern Aleutian Islands, Alaska, to around Santa Barbara (Santa Barbara County); however, the species is considered rare south of Point Conception (Santa Barbara County). Dungeness crab prefer sandy and sand-mud bottoms but may be found on almost any bottom type. They may range from the intertidal zone to a depth of at least 750 ft, but are not abundant beyond 300 ft.
The Dungeness crab population off California, as demonstrated by tagging experiments, consists of five sub-populations, located in Avila-Morro Bay, Monterey, San Francisco, Fort Bragg, and Eureka- Crescent City. Only the latter three are commercially important. DFG surveys indicate that the San Francisco and Fort Bragg sub-populations combined are smaller than the sub-population extending from Eureka into Oregon. Little or no intermixing of the sub-populations occurs. Tagging studies have also demonstrated random movement by both sexes. At times, an inshore or offshore migration may be observed, but most movement is restricted to less than 10 miles. Movement of up to 100 miles has been noted for individual males, but female movement appears to be much more limited.
The commercial fishery for Dungeness crab occurs from Avila (San Luis Obispo County) to the California-Oregon border, with commercial and recreational seasons beginning in late fall and ending in early summer. Northern California fishing grounds extend from Fort Bragg to the California-Oregon border, with the prime area located between Eureka and Crescent City. Almost all of California’s commercial Dungeness crab catch is landed in the trap fishery.
There is limited sport take of Dungeness crab in central and northern California. The total annual recreational harvest is unknown, but it is believed to be less than 1% of the commercial take. The recreational fishery is managed through seasonal and area closures, gear restrictions, size limits, and a limit on the number of crabs that may be possessed. Either sex may be taken in the recreational fishery. In northern California the size limit is 5.75 in. across the widest part of the carapace and the bag/possession limit is 10 crabs (DFG 2004a).
Clams: There are primarily three types of clams (razor, gaper, and Washington) that are targeted by recreational clammers in the north coast study region. The Pacific razor clam (Siliqua patula) ranges from western Alaska to Pismo Beach, California, and is generally found on flat or gently sloping sandy beaches with a moderate to heavy surf. Razor clam shells are long and thin, with fragile, shiny valves. Razor clams attain their maximum rate of growth during their first year of life. The growth rate remains high through the second or third year, after which it slows markedly. The largest razor clam on record in California was a seven-inch specimen taken from Clam Beach in 1979.
Beaches in Del Norte and Humboldt counties are some of the best places in California to take razor clams. Clam Beach and Crescent City both support similar fisheries where beds are divided into north and south beaches with alternate year closures in effect. In both areas, the northern beach was more heavily fished and more productive than the southern beach for many years. The El Niño events of the past two decades have had large storms associated with them and this may have had some impact on northern California razor clam populations. The razor clam population in the Crescent City area is recovering, but the Clam Beach population is still much diminished from former levels. The recreational daily bag limit is 10 per person. (DFG 2001a) Gaper clams are found from Alaska to Scammon’s Lagoon, Baja California. Both the Pacific (Tresus nuttalli) and fat gaper (Tresus capax) live in fine sand or firm sandy-mud bottoms in bays, estuaries, and more sheltered outer coast areas. They are found from the intertidal zone to depths of at least 150 feet. The Pacific gaper is the most commonly taken gaper clam in California. A closely related species, the fat gaper, is the predominant gaper clam taken in Humboldt Bay, where it is very common in the intertidal zone. Gaper clams live to a maximum age of 17 years and can attain a length of 10 inches with a weight of approximately five pounds. The fishery for the gaper clams, the
Pacific gaper (Tresus nuttalli) and the fat gaper (Tresus capax), is almost exclusively sport, however, Ecological Setting 35 the Fish and Game Code allows these clams to be harvested commercially in Humboldt Bay. The Pacific and fat gaper support a significant sport fishery that takes place in intertidal areas of bays with sand and mud bottoms. Humboldt Bay is the largest gaper clam fishery in the state where a take of 25 clams per day is allowed. (DFG 2001a) The range of the Washington clam is from Humboldt Bay, California, to San Quentin Bay, Baja California. This species lives at depths of 12 to 18 inches in mud, sandy mud or sand of bays, lagoons and estuaries. Two principal species of Washington clam are harvested in California. The Washington clam (Saxidomus nuttalli) is the principal species sought, and the best yielding localities include Humboldt Bay. The second popular Washington clam, the butter clam (Saxidomus giganteus), formerly known as the smooth Washington clam, is seldom taken south of Humboldt Bay. In only one California locality, near Fields Landing in Humboldt Bay, is this clam common enough to support a minor fishery. Sport clammers in Humboldt Bay are permitted to take 50 Washington clams in combination with no more than 25 gaper clams. (DFG 2001a) Description—This large, heavy-shelled form is familiar to most Californians as it is very common in the markets. The valves are large, massive, thick and so hard on the outer surface as to dull a file rapidly. In size it exceeds most clams here considered, the gaper and the geoduck being the only forms to equal it. Specimens were measured having a length of seven inches and several larger examples weighing over four pounds (and hence longer) are recorded, one with an authenticated weight of 4 pounds 3 ounces. The weight of those exceeding the legal size of 4¾ inches is considerably less than this, averaging about 1⅓ pounds. The color of the adult is a pale buckskin with some faint light purplish concentric markings, and this latter color is still more marked on the siphonate end. Occasional specimens, perhaps two or three in a hundred, show striking radiating stripes of light chocolate brown, running from the umbo to the margin and increasing in width with increase in size of the shell. They vary in width and arrangement in different parts of the shell and in the two valves. Among very small clams, this chocolate color is not rare, but no adults entirely brown were seen though some are reported. The pigment forming the rays is superficial, lying only in the outer part of the shell where it is deposited by the mantle, which apparently differs, in these cases, in pigment forming power in different parts. The shell is overlaid by a thick glossy periostracum, giving the valves an appearance of being varnished. In large specimens this wears off on the older portions about the umbo. The animal has a thin muscular foot of the plowshear shape and short siphons, separate at the tips.
Habitat and habits—The Pismo clam is sharply limited to exposed sandy beaches and if transplanted to the sheltered waters of bays, as is sometimes done by clam diggers to ensure a supply when tides are unfavorable, it does not thrive and soon dies. Here on the long beaches exposed to the constant pounding of the surf which its heavy shell fits it to withstand, it flourishes in what might be thought an unfavorable environment. Its abundance in the early days is a matter of common ― 30 ― knowledge and all have heard of its being plowed out by the farmers and picked up from the furrows unfortunately in part to be wastefully fed to hogs or chickens. Even in recent years, it has been abundant enough so that during the past four years (1916–1919) the beaches of Morro, Pismo and Oceano furnished yearly over 150,000 individuals weighing on the average over 200 tons. Its heavy shell might protect it against the force of the surf but another danger, perhaps even greater, threatens it. Only those who know the beaches intimately realize to what an extent the sand is a FIG. 19.
Digging Pismo clams, Oceano. Digger returning with his fork and a "limit" of clams in his "drag." changing thing. Pounded and scoured by the waves which act according to the tide now at this level and now at that, the surface of the beach trodden by the bather which seems so hard and to the casual eye so unchanging from day to day, is really in a state of constant flux, being now cut down and now built up sometimes to a depth of a few inches and sometimes to a foot or so. This and some of the work that deals with the wave action has been already referred to. often during a month or an entire season one kind of action will predominate and the diggers who daily frequent the beach and study it as a sailor does the sea, can point out a stranded buoy or stump or rock now bare, that last season was covered, or which now can barely be seen though before it was conspicuous. Such erosion or filling amounting to several feet is common. Below tides the sand is even more at the mercy of the water. On the broad, gently shelving beaches where the ― 31 ― Pismo clam is most at home, the sand is piled up in offshore bars lying below ordinary low tide, though perhaps bared at extreme low ebbs, and usually separated from the exposed beach by channels varying from two or three to a dozen feet deep. These bars are relatively transient, some lasting for several months, while others may last but a single tide, being formed and scattered with amazing rapidity, if the waves and tides occur in the correct sequence. How destructive such changes may be, is seen in some winters when the heavy cutting surf washes out and rolls up the beach such numbers of the clams that windrows are found at high tide line. This occurred, for instance, in December, 1915. That the constant shifting of the apparently monotonous sands is not always fatal to this clam in spite of its stout shell is due to its constant activity. When new bars form and rise, the animals are found at the surface. When the bar is swept out it is seldom that more than a stray individual washes up and this can only mean that the clam is constantly and actively burrowing up or down to escape being buried too deeply to reach its supply of water or to avoid being completely dislodged and thrown to the mercy of the surf.
For this activity its large muscular foot with its thin knifelike edge is well fitted though its heavy shell is less readily drawn through the sand than is that of its neighbor on these beaches, the razor clam. Small individuals up to 30 or 40 mm. (1½ inches) bury themselves readily if thrown out on the firm wet sand just above the wash of the waves. Some watched on Oceano Beach were covered in 30 to 45 seconds. Adults find this more difficult but will bury themselves if they are covered with water and can get time between the waves which sweep them up and down the beach, to get a "foothold."
Another delicate adaptation is found in the siphons. These, as already stated, are short, a condition found in most actively burrowing forms. The exhalent tube is somewhat the shorter and its delicate, thin walled tip, rimmed with a few short tentacles, closes in a line parallel with the margins of the shell when no current is passing out. At other times, the current of water will prevent the entrance of sand. The inhalent siphon is somewhat enlarged at the tip and ends in a broad flat surface that to the first glance shows no opening. If one has the patience to examine this surface with a low power lens as the animal lies at rest in some little pool; it will be seen that the aperture is closed by a delicate system of branched tentacles so closely placed that while every sand grain dropped upon them is securely supported the water has free access to the mantle cavity through this living screen. As the water flowing over them nearly always contains some sand and at times is filled with whirling clouds of it, the value of this arrangement is obvious, since the supply of water bears both oxygen and food to the clam.
It was noted by Thompson* that the razor clam is found with the hinge toward the open ocean and he has suggested that this position bears some relation to the question of water supply to and from the siphons. The question of position was carefully studied in the Pismo clam and the same condition was found, the hinge being almost invariably ― 32 ― turned seaward. The testimony of the diggers, also, was to the effect that the clam was turned crosswise of the beach. Whether this position is related to the water supply or to wave action, there seems no data on hand to decide, but the fact is clear.
One should picture the Pismo clam, then, with its heavy strong shell shielding it from the blows of the surf, maintaining itself by ceaseless activity in sand that, wave driven, flows day and night and by means of its screened siphon tubes obtaining a stream of water from which it strains organisms too small to see, yet which, in the aggregate, form clam meat harvested yearly to the amount of hundreds of tons. Though once present between tides in such immense numbers a digger might obtain all he wanted dry shod at low tide, continued fishing has FIG. 20. Digging Pismo clams, Oceano, Diggers returning with clams. The automobile in the distance gives some idea of the width and levelness of the beach. reduced these more easily reached individuals, and now the clammer must get his supply almost wholly from the bars just mentioned. Perhaps it may not be amiss to picture to the person who relishes the Pismo clam in chowder or soup how it is obtained. At low tide the clam digger in old clothes, slicker coat and pants and "sou 'wester" and armed with a potato fork wades out to the bars. Here, he "feels" for the clams, thrusting the fork into the sand very much as in spading with a spading fork though without "turning up" the sand. The row of tines are usually turned across and not parallel with the water line to avoid "straddling" the clam and when a shell is struck it is lifted out. As the beaches are pure sand with very seldom a dead shell or stone, anything struck is pretty sure to be a clam. In order to leave the hands free, the clams are carried in a sack fastened to the ― 33 ― belt or over the shoulder or what is now more common, a long netted bag or "drag" with a light wooden hoop to hold the mouth open. This is usually fastened to the belt with a "snap" as there often arise occasions when the waves place a digger where fifty to eighty pounds of clams are a distinct embarrassment and must be quickly cast off.* The sack is long enough to rest on the ground so that the weight is not directly borne, but dragged along, hence the name (see figure 21).
As was before stated, the clams in the shallowest water are earliest cleaned out so that at this present time the lowest tide is the best, and FIG. 21. Gear used in digging Pismo clams, Oceano. "Rake" with extension handle and rope by which it is pulled through sand, fork and "drag" with snap and belt. other things being equal, the tallest man gets the most clams. As a result of this, the digger will be seen working far out from shore as shown in figure 1 and since on these exposed beaches the surf is never ceasing, it is not uncommon to see the combers break over the shoulder or even the head of the digger, though at other times he may be only waist deep. At times this may partake of the exhilaration of surf-riding with an anchor of clams to prevent being swept too far, but at sunrise of a foggy day with a cold wind whipping the spray from the breakers it is a life of exposure.
Another danger is also present. The channels separating the bars from the higher beach are often deeper than can be waded and with swift currents. Sometimes such a bar can be reached only at a single point where the channel is partially bridged by a spit and the location of this must be carefully kept in mind when returning from the bar. ― 34 ― When the tides come at two or three o'clock in the morning, lanterns are usually ranged on the beach to mark the route to the bar, a precaution very necessary since directions are surprisingly hard to tell in the fog and darkness.
Though under ordinary conditions the clam is found by "feeling" along, they may be located on undisturbed exposed bars or beaches by tiny holes overlying the siphons or sometimes a sunken area overlying the whole shell and apparently caused by its movements.
Use—The Pismo clam is a distinctively Californian bivalve and enjoys a high reputation as a food mollusk, being widely used in soups, chowders, fritters and baked in the half shell. The greater part of the shipments from the San Luis Obispo coast find their way to San Francisco and the bay cities or to Los Angeles. Here they are used by restaurants or cafes rather than retailed. In the South a very large proportion are used for bait in surf fishing.
Distribution—"Santa Cruz, California, and south to Socorro Island" (Lower California) Dall. It was found at Halfmoon Bay just south of San Francisco (Heath) and to some extent on nearly all favorable beaches south to the Mexican boundary. As previously explained, it may be expected on exposed sandy beaches particularly where the beach is wide and the slope gentle. At present a few are marketed from Monterey Bay but practically all come from Morro, Pismo and Oceano, where these conditions are best fulfilled. Formerly it was abundant on various more southern beaches near Carpinteria and at Long Beach, but these no longer yield it in commercial quantities. Recently (1919) some have been imported from Turtle Bay, Lower California.
Several attempts to transplant the Pismo clam to various points outside this range on the California and Oregon coast have been made, but as yet without success.
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inches diameter)