Invasive green crabs threaten Dungeness in Coos Bay estuary

Invasive green crabs threaten Dungeness in Coos Bay estuary Jan 2, 2021 2:45:31 GMT

Quote

Post by Admin on Jan 2, 2021 2:45:31 GMT

WILLIAM LACKNER
Fri 1/1/2021 6:28 PM

Updated Dec 29, 2020; Posted Dec 29, 2020

Invasive green crabs threaten Dungeness in Coos Bay estuary.
It’s almost like something out of a horror movie. Waves of invasive European green crabs are threatening the Coos Bay estuary, and its existing population of Dungeness crabs, as well as clams ...

Green Crab - Eat the Invaders
Carcinus maenas Native range: Atlantic Europe, North Africa Invasive range: Northeast coast of North America, Pacific Northwest, Japan, Australia, South Africa, and South America Habitat: Thrives on a variety of substrates, from soft mud and sand to rocks and aquatic vegetation. Reproduces well in a wide range of temperatures and salinities. Description: Five spines on each side of carapace ...
eattheinvaders.org

Mediterranean Green crab Carcinus aestuarii - Wikipedia

Carcinus aestuarii is a littoral crab, native to the Mediterranean Sea.. Carcinus aestuarii bears some similarities to Carcinus maenas and was sometimes considered to be a subspecies thereof, rather than a species in its own right, but a molecular biological study using the COI gene found the difference between the two taxa to be substantial, supporting their status as separate species.
en.wikipedia.org

To the Honorable State Representative David Gomberg, State Senator Dick Anderson and Governor Brown.

It is our humble opinion that the actual impact of the Mediterranean Green crab is beyond the State of Oregon's ability to control them!!! However, The State does have the ability to limit the out of control number of Green crabs in Oregon's Estuaries.

The CDAO recommends allowing recreational crabbers unlimited harvest of Green crab for consumption. We suggest that the Crab Commission be assigned the responsibility of developing the most efficient methods for cleaning and cooking Green crab.

In addition, the State should implement a program based on the number of Green crabs caught for a cash reward.

The threat of the Green crab presents the opportunity to review and upgrade the current regulations of managing the crab species of interest to both recreational and commercial crabbers. .

Respectfully, William Lackner for the members of the Clam Digger Association of Oregon.

Invasive green crabs threaten Dungeness in Coos Bay estuary Jan 2, 2021 17:14:24 GMT

Quote

Post by Admin on Jan 2, 2021 17:14:24 GMT

Status of Green Crabs in Coos Bay: Monitoring Report 2020

By: Shon Schooler1, Sylvia, and Kathy Andreasen 1South Slough National Estuarine Research Reserve Oregon State University

Introduction:
The European green crab (Carcinus maenas) has been transported around the world during the last century and has colonized many temperate coastlines (Behrens Yamada 2001). Numerous research studies have examined the biology and ecology of green crabs and have generally found the green crab to be an aggressive invader that has the potential to negatively impact native species, important estuarine and marine habitats, and fisheries (Behrens Yamada 2001; Howard
et al., 2019; Malyshev & Quijo´n, 2011; Garbary et al., 2014; Neckles, 2015; Matheson et al., 2016). The green crab is currently invading the west coast of North America. Greens crabs became established in the San Francisco estuary prior to 1989 (Behrens Yamada, 2001). Since then coastal currents have been seeding green crab larvae into estuaries of the Pacific Northwest, including Coos Bay (Behrens Yamada et al., 2015). In the past, this migration appears to be linked to strong northwards currents during El Niño years (Behrens Yamada et al., 2015), as indicated by a mixture of high abundance years, low abundance years, and extinction events. However, since 2016 the abundance of green crabs has continuously increasing in Coos Bay and is now at levels where negative impacts are expected.

The purpose of this project is to monitor changes in green crab abundance and evaluate the young-of-the-year (YOTY)
age class in the Coos Bay Estuary. The project goals are to: 1) examine change in green crab abundance (CPUE) among
sites and over time, 2) examine the YOTY age class to assess size structure and determine whether recruitment is
occurring from within Coos Bay.

2

SOUTH SLOUGH NATIONAL ESTUARINE RESEARCH RESERVE
61907 SEVEN DEVILS ROAD, CHARLESTON, OR 97420 | 541-888-5558
Methods

At each of the 14 sites we set either six Fukui fish traps or six modified minnow traps during morning low tide and
retrieved traps at low tide the following morning (24 hours). Fukui and minnow traps were baited with raw tuna
enclosed in a plastic bait container and staked in place with a 20 inch steel rod. When traps were retrieved, the number of individuals of each crab species in each trap was recorded. Dungeness crabs (Metacarcinus magister), red rock crabs

(Cancer productus), and shore crabs (Hemigrapsus oregonensis and H. nudis) were counted but not measured. When
possible, we recorded water quality data (salinity, pH, temperature) at the trap site using a YSI hand-held meter.
European green crabs (Carcinus maenas) were counted in the field and then brought back to the laboratory and
measured for size (carapace width, mm), weight (g), and sex (m/f). Abdomen color and missing limbs were also
recorded.

Results

We set 184 crab traps (156 Fukui, 24 minnow) at 14 sites in Coos Bay from February through October of 2020. We captured 858 green, 10 Oregon shore, 141 Dungeness, and 99 red rock crabs. Overall catch-per-unit-effort (CPUE) was 4.66 for green, 0.05 for Oregon shore, 0.76 for Dungeness, and 0.54 for red rock crabs. This includes data for all traps at all sites for all sampling dates from February thru October 2020. Abundance among Coos Bay sites: To better compare sites, we selected only sites sampled using Fukui traps during the summer months (May-August)
(Table 1). The average CPUE was highly dependent on site. Green crabs were found at all sites, but were most common in the mid to upper estuary sites where adult Dungeness and red rock crabs were absent (Coos History Museum, Isthmus Slough). Red rock crabs were present only at sites lower in the estuary (Charleston Boat Basin, Empire Docks) and adult Dungeness crabs were most abundant at low and mid-estuary sites (Empire Docks, Indian Point N, Valino Island).

Forum

Invasive green crabs threaten Dungeness in Coos Bay estuary

Post by Admin on Jan 2, 2021 2:45:31 GMT

Post by Admin on Jan 2, 2021 17:14:24 GMT

Quick Reply