Dungeness Crab in Puget Sound

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Dungeness Crab in an Aquarium Dungeness crab (Metacarcinus magister) 2.jpg
Dungeness Crab in an Aquarium

The Dungeness crab in the Puget Sound, Washington state is a non-genetically distinct population of Dungeness [1] that has been experiencing severely declining populations in the south sound region since 2013. [2] The cause of the decline is unknown, although it has been determined not to be due to overfishing. [2] [3] As crabbing seasons remain closed or severely limited throughout the south sound region, [4] research is focused primarily on larvae in order to predict future population size and study genetics. [5]

Contents

The Puget Sound context

Puget Sound Marine Areas Screen Shot 2024-03-05 at 3.41.48 PM.png
Puget Sound Marine Areas

In Washington state, the Puget Sound makes up marine areas 4-13 and is managed separately from the coast. Each marine area within the sound is additionally managed semi-separately and in cooperation with local indigenous tribes. [6] The Puget Sound is generally divided into five areas: the strait of Juan de Fuca, the San Juan islands, the northern sound, the southern sound, and Hood Canal. Marine areas 4, 5, and parts 6 are located in the strait. The rest of area 6 and all of 7 are located in the San Juan islands. The northern sound is made up of areas 8 and 9. The southern sound is made up of areas 10,11, and 13. Hood Canal is marine area 12. [6]

Dungeness are considered the most important fishery in Washington state with a 90-120 million dollar value annually. [7] In Puget Sound there is a yearly summer crabbing season open five days a week from the beginning of July to Labor Day. If populations are determined to be sufficiently abundant, an additional winter season will open in October, for seven days a week (closing on December 31). [6] Out of all the regions, the south sound region has historically had the lowest Dungeness numbers, [2] [3] [6] typically making up only 1-4.3% of the total catch. [3]

Genetics

In 2014, hind legs from 679 Dungeness from five locations in the Puget Sound (Skagit, Hood Canal, Port Townsend, Nisqually, and central sound) were collected. In 2015 hind legs from 1011 Dungeness from nine locations on the coast (three in Kalaloch, Westport, and Long Beach each) were collected. From each sample, 10 neutral microsatellite regions were examined. [1]

Out of all the sites, only Port Townsend and Long Beach were found to have FIS values indicating significant divergence from Hardy-Weinberg proportions. FST values indicated that Hood Canal was unique among all sites. Hood Canal is connected to the rest of the sound through only one opening in the north which is made shallower by a deep sill. This is most likely the reason for the FST calculation in this study. The FST of all other Puget Sound sites indicated differentiation from the coast but not from each other. Using tree topology, all Puget Sound sites, except for Hood Canal, were found to cluster strongly together. The coast sites clustered together weakly and separately from the sound. [1]

The authors of this study conclude that there is stronger connectivity within the Puget Sound and within the coast Dungeness populations than between them, although gene flow does still occur. The authors do point out, however, that it is possible for one population to seem genetically similar to another using neutral markers, even when no recent gene flow has occurred. [1]

Population decrease and response

In 2013, Dungeness crab harvest in the southern most marine area, area 13, began to decline at an unusually high rate. [2] By 2015, this decline had begun to be noticed throughout the southern Puget Sound region and into Hood Canal. [6] [8] By 2018, harvesting in marine area 13 had declined 97% since 2012 [2] [3] [8] and in marine area 11 had declined 87% since 2015. [8] At this point marine areas 11, 12, and 13 were closed for recreational crabbing with tribes in the areas additionally restricting harvesting to subsistence and ceremonial purposes only. [8] Although red rock crabs do not seem to be affected by whatever is causing the Dungeness decrease, the red rock crabbing season was additionally closed to reduce handling of Dungeness. [8]

Since 2015, the Washington Department of Fish and Wildlife (WDFW) has conducted yearly test fishing throughout the sound. [2] [3] This test fishing occurs in February and is conducted with pots that do not have escape rings, in order to catch females and smaller males. [2] In 2018, an average of 0.3 legal crabs per trap were found in the south sound. Although it is not stated what healthy numbers would be, considering this region has historically lower catch than other parts of the sound, the healthy population in marine area 8 had 17-34 legal crabs per trap in 2018. [2] One important note from the 2018 test fishing is that no crabs in the size range of 3.5 to 5.7 inches were found in the south sound. This indicates several years of crabs were missing from the area. [8] In 2022, there was a slight increase in crab populations with 0.97 legal crabs being found per pot. [3] In 2023, the average was 1.98 male crabs (legal and illegal size) per pot. [3]

The most recent update on marine area closures is the following: [4]

Research

In 2019, the Pacific Northwest Crab Research Group (PCRG) was founded. [5] [6] This group began with the goal of predicting adult crab abundance in the Puget Sound. This is done through counting of larval Dungeness and application of those numbers to an equation from a study conducted by the University of Oregon that predicts adult crab abundance four years into the future. [5] In the summer of 2022, the research was expanded to the coast of Washington and the section of the Salish Sea located in Canada. [9] That summer genetic research on the larvae also began. This research is funded through the summer of 2024. [10]

The PCRG collects larvae through a light trap made out of a water jug and LED lights. The lights turn on and off at dawn and dusk and attract the diel vertical migrator larvae. [5] Based on knowledge of typical larval delivery, traps are set at the beginning of April. Traps are checked throughout the summer and are removed from the water after two full weeks of no Dungeness larvae catch, which usually occurs in September. [11] The PCRG originally had ten locations (five in the San Juan region, one in the north sound, two in the south sound, and two in Hood Canal). In the 2023 summer season 20 locations were tested in Washington (three on the coast, six in the San Juan region, three in the north sound, six in the south sound, and two in Hood Canal) with an additional 25 in Canada. Running the sites were 13 tribes, 12 non-profits, 4 aquariums, 3 universities, 3 community centers, 2 museums, 2 boating clubs, 1 high school, the Washington Department of Fish and Wildlife, the Washington Department of Natural Resources, and Fisheries and Oceans Canada. [5] [9]

Results of the population research are verbally reported every winter at the annual meeting of the PCRG [12] and are briefly summarized in the Puget Sound Marine Waters' yearly publications. [13] Additionally, the Swinomish tribe reports annually on the five sites they manage in the San Juan islands. [11] Every year since 2019, larval size has decreased at all sites as the season progresses. It is theorized that the size differences indicate different origin populations for the larvae. The large larvae (seen in April, May, and June) are thought to be from the coast and the smaller larvae (seen in June, July, and August) are thought to be from local populations. [11] [12] [13] The first larvae of the season have been found in the San Juan islands every year. As the season continues, larvae are progressively found to the north and south. [13] Southern Hood Canal is thought to have a unique population of Dungeness as the first larvae at the site are consistently found around the same time as the San Juans despite being in a very isolated inlet. [13] From 2019 to 2021, the highest yearly count of Dungeness occurred in June. In 2022 and 2023, the highest yearly count occurred in July; these two years also saw a later start to the delivery season than in the past. It is thought that cooler temperatures impacted this change in larval delivery patterns. [12] [13] The central Salish Sea (from Whidbey Island to Horseshoe Bay) has consistently had the highest total catch of larvae with catch decreasing to the north and south. [12] [13] Catch is consistently the lowest at the site located in Washington marine area 13. [13]

The genetic portion of the PCRG research is ongoing and no progress reports have been published. [10]

Potential reasons for decline

Overharvesting has been determined not to be the reason for the decline in Dungeness crab. [2] [3] Harvesting in marine areas 12 and 13 have now been closed for six years; if overharvesting was the issue, populations would have recovered by now given that females are not harvested and males have at least a year of sexual maturity before they are of legal harvesting size. [2]

One hypothesis for the decline is warmer bottom conditions in the south sound due to shallower waters. [8] It is hypothesized that this may harm juvenile crabs more than adults. [3] Warmer surface temperatures may have a greater effect than warmer bottom waters, however. This is because the free-swimming larvae have a narrower temperature range than adults. [2] [3] Another hypothesis for decline is an increase in hypoxic conditions. [2] This hypothesis is particularly viable for the population in Hood Canal where hypoxic conditions have occurred in the past. [8] Ocean acidification is a third hypothesis for decline. [2] [7] Ocean acidification has been shown in laboratory conditions to delay development, increase mortality, and decrease exoskeleton size of larval Dungeness. [7] Testing in the wild has not yet occurred. The results of current and future research will deliver valuable information regarding these hypotheses.

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<span class="mw-page-title-main">Puget Sound</span> Deep water sound of the Salish Sea in northwestern Washington, United States

Puget Sound is a sound on the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins. A part of the Salish Sea, Puget Sound has one major and two minor connections to the Strait of Juan de Fuca, which in turn connects to the open Pacific Ocean. The major connection is Admiralty Inlet; the minor connections are Deception Pass and the Swinomish Channel.

<span class="mw-page-title-main">Klallam people</span> Coast Salish ethnic group

The Klallam are a Coast Salish people Indigenous to the northern Olympic Peninsula. The language of the Klallam is the Klallam language, a language closely related to the North Straits Salish languages. The Klallam are today citizens of four recognized bands: Three federally-recognized tribes in the United States and one band government in Canada. Two Klallam tribes, the Jamestown S'Klallam and Lower Elwha Klallam, live on the Olympic Peninsula, and one, the Port Gamble S'Klallam, on the Kitsap Peninsula in Washington state. In Canada, the Scia'new First Nation is based at Becher Bay on southern Vancouver Island in British Columbia.

<span class="mw-page-title-main">Swinomish people</span>

The Swinomishpeople are a Lushootseed-speaking people Indigenous to western Washington state.

<span class="mw-page-title-main">Eastern oyster</span> Species of bivalve

The eastern oyster —also called the Atlantic oyster, American oyster, or East Coast oyster—is a species of true oyster native to eastern North and South America. Other names in local or culinary use include the Wellfleet oyster, Virginia oyster, Malpeque oyster, Blue Pointoyster, Chesapeake Bay oyster, and Apalachicola oyster. C. virginica ranges from northern New Brunswick south through parts of the West Indies to Venezuela. It is farmed in all of the Maritime provinces of Canada and all Eastern Seaboard and Gulf states of the United States, as well as Puget Sound, Washington, where it is known as the Totten Inlet Virginica. It was introduced to the Hawaiian Islands in the 19th century and is common in Pearl Harbor.

<i>Callinectes sapidus</i> Species of crustacean

Callinectes sapidus, the blue crab, Atlantic blue crab, or, regionally, the Maryland blue crab, is a species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico, and introduced internationally.

<span class="mw-page-title-main">Hood Canal</span> Fjord in Washington state, United States

Hood Canal is a fjord forming the western lobe, and one of the four main basins of Puget Sound in the U.S. state of Washington. It is one of the minor bodies of water that constitute the Salish Sea. Hood Canal is not a canal in the sense of an artificial waterway—it is a natural feature.

<span class="mw-page-title-main">Dungeness crab</span> Species of crustacean

The Dungeness crab makes up one of the most important seafood industries along the west coast of North America. Its typical range extends from Alaska's Aleutian Islands to Point Conception, near Santa Barbara, California. Dungeness typically grow 6-7 inches at their widest point and inhabit eelgrass beds and sandy bottoms. Its common name comes from the Dungeness Spit in the Strait of Juan de Fuca, Washington state, United States, which shelters a shallow bay inhabited by the crabs.

<span class="mw-page-title-main">Environmental issues in Puget Sound</span>

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<span class="mw-page-title-main">Dungeness, Washington</span> Unincorporated community in Washington, United States

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<span class="mw-page-title-main">Puget Sound king crab</span> Species of crustacean

The Puget Sound king crab, is a species of king crab which inhabits the oceans of the Pacific coast of North America from Alaska to central California. Adults are orange, red and purple in color, while juveniles are either mostly orange or have small blotches of red and purple. They can be recognized by their blunt bumps on their carapace. Puget Sound king crabs are larger than the similar brown box crab, with an average size of 6–10 inches (15–25 cm).

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Haliotis kamtschatkana, common name the northern abalone, threaded abalone, or pinto abalone, is a species of large sea snail, a marine gastropod mollusc in the family Haliotidae, the abalones.

<i>Cancer productus</i> Species of crab

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<span class="mw-page-title-main">Skagit Bay</span> Bay and strait within Puget Sound, Washington, United States

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<span class="mw-page-title-main">Netarts Bay</span> Bay in Oregon

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<span class="mw-page-title-main">Swinomish Indian Tribal Community</span> Federally recognized tribe in Washington (state)

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<span class="mw-page-title-main">South Puget Sound</span> Region in Washington, United States

South Puget Sound is the southern reaches of Puget Sound in Southwest Washington, in the United States' Pacific Northwest. It is one of five major basins encompassing the entire Sound, and the shallowest basin, with a mean depth of 37 meters (121 ft). Exact definitions of the region vary: the state's Department of Fish and Wildlife counts all of Puget Sound south of the Tacoma Narrows for fishing regulatory purposes. The same agency counts Mason, Jefferson, Kitsap, Pierce and Thurston Counties for wildlife management. The state's Department of Ecology defines a similar area south of Colvos Passage.

References

  1. 1 2 3 4 Jackson, Tyler M.; O’Malley, Kathleen G. (June 2016). "Comparing genetic connectivity among Dungeness crab (Cancer magister) inhabiting Puget Sound and coastal Washington". Marine Biology. 164 (6). doi:10.1007/s00227-017-3152-7. ISSN   0025-3162.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 The Washington Department of Fish and Wildlife (2020-03-11). "WDFW works to manage and restore Dungeness Crab in Washington waters". Medium.
  3. 1 2 3 4 5 6 7 8 9 10 Friedrich, Ed (2023-06-22). "State keeps South Sound closed to crabbing for sixth summer". Gig Harbor Now.
  4. 1 2 "Recreational crabbing to open July 1 for many Puget Sound marine areas | Washington Department of Fish & Wildlife". wdfw.wa.gov. 2023-06-14.
  5. 1 2 3 4 5 "Larval Crab Monitoring". Pacific Northwest Crab Research Group. 2023.
  6. 1 2 3 4 5 6 Washington Department of Fish and Wildlife (April 26, 2021). "2019-21 WDFW Puget Sound Dungeness Crab Fishery Report" (PDF). Washington Department of Fish and Wildlife.
  7. 1 2 3 Bednaršek, Nina; Pelletier, Greg; Ahmed, Anise; Feely, Richard A. (2020). "Chemical Exposure Due to Anthropogenic Ocean Acidification Increases Risks for Estuarine Calcifiers in the Salish Sea: Biogeochemical Model Scenarios". Frontiers in Marine
  8. 1 2 3 4 5 6 7 8 Thompson, Sara (July 1, 2018). "Crabbing Season Closed in South Sound". Key Peninsula News.
  9. 1 2 "Partners | Sentinels of Change". sentinels.hakai.org. 2022.
  10. 1 2 Buckner, Emily (2022-09-14). "Summer/Fall 2022 ~ Newsletter". PNWCrab. Retrieved 2024-03-04.
  11. 1 2 3 Grossman, Sarah K; Cook, Claire E; Barber, Julie S (August 2023). "Swinomish Larval and Juvenile Dungeness Crab Monitoring Report for 2021" (PDF). Swinomish Indian Tribal Community.
  12. 1 2 3 4 Coordinator, PCRG (2024-02-22). "Winter 2024 ~ Newsletter". Pacific Northwest Crab Research Group.
  13. 1 2 3 4 5 6 7 "Puget Sound Marine Waters Overviews". Puget Sound Partnership on Box.
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