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Euridyce caudata  on a flat fish; likely  a Starry flounder
General News · 10th October 2022
Mike Moore
Dungeness crab are one of the most important commercial fisheries on the west coast of North America but their numbers have been in decline in recent years. The Sentinels Of Change light trap project sponsored by the Hakai Institute/Tula foundation and locally by the Friends of Cortes Island Society teamed up with the Pacific Northwest Crab Research Group from across the border in Puget Sound, to trap and count the larval stages of Dungeness crab (known as megalopae and instars) to examine how local numbers and distribution correlates to the number of adult crabs caught by the fishery four years later. This summer was the inaugural year for the Sentinels of Change project while the Pacific Northwest Crab Research Group had already been running the study in Puget Sound since 2019.

On April 15th, the light traps switched on throughout the Salish Sea and they continued to fish and collect data until August 31 when the study ended for the year. The Sentinels Of Change project ran 20 traps in Canadian waters while the Pacific Northwest Crab Research Group ran 17 traps in Washington’s Puget Sound. This resulted in a large amount of data that shows the distribution and movement of Dungeness crab larva throughout the entire Salish Sea. Check out the time lapse map at the bottom of the Sentinel’s webpage.

Locally, Kate Maddigan and Mike Moore coordinated the light trap in Cortes Bay. Mike is especially interested in this study having noted an apparent decline in the crab population from direct observation while diving the crabbing hotspots around Hernando, Savary and Marina Islands. Early season catches in the Cortes Bay light trap were promising. In fact we identified more species through the iNaturalist community
Kate and Monika check the light trap than any other station! (See list and photos below)

One of the most interesting creatures we caught was a quillfish. Trapped on May 3rd, this is apparently quite rare having only been caught a few times in light traps based in Friday Harbour. It seems to be quite good at avoiding plankton-tows and our record of it is the furthest north in the Salish Sea. This fish lives by hanging straight up and down in deep water looking towards the surface. When it sees a suitable prey item, it shoots upwards to grab it. The quillfish can reach lengths of about 30 cm and apparently lives in association with deep water, which may be why we find it here “At the deep end of the Salish Sea”.

On June 12 when we checked the trap, there were no crab larva inside of it. But Fergus Walker’s sharp eyes noticed movement on the outside of the trap; there were 41 Dungeness megalope averaging 4 mm wide clinging to it! Unfortunately, because they were found on the outside of the trap, they were not eligible to be counted in the data set. But it was very cool to see that number all at once because subsequent to that, our trap only caught small numbers (of up to four) and only on a few more occasions.

By the end of June, the warm brackish water layer that makes Desolation sound so comfortable for swimming had moved in to stay in Cortes Bay and our catches of everything dropped off to almost nothing. Perhaps the planktonic larvae were still there down deeper under the warm water layer?

On October 4 and 5th, Kate and Mike attended a season’s end gathering at the Hakai Institute on Quadra Island. It was fascinating to get a tour of the marine biology wet labs, the biodiversity labs and to learn about the genetic materials labs that can identify species or populations from tissue samples of contemporary organisms or from ancient DNA found in midden soil core samples dating back farther than 14,000 years.

We were shown some preliminary results of the data we had collected this year; and there is a lot more analysis of this data to be done over the winter. We also brainstormed on what went well this summer, what did not go so well and how to make the trap checking and data collection smoother and easier for next year. It felt really amazing to be amongst other passionate lovers of the Salish Sea and to be doing citizen science under the auspices of such a high calibre science facility as the Hakai Institute.

“Research Grade” Identified Species:

Dungeness crab- Metacarcinus magister
Grunt sculpin- Rhamphocttus richardsonii
Euridyce caudata
Stubby Bobtail Octopus- Rossia Pacifica
Quillfish- Ptilichthys goodei
Crescent gunnel- Pholis laeta
Blackclaw Crestleg Crab- Lophopanopeus bellus
Grooved Mussel Crab- Fabia subquadrata
Eurydice caudata
Threespine stickleback- Gasterosteus aculeatus
Cabezon- Scorpaenichgthys marmoratus

Other Identified Species:

Righteye Flounders- Suborder Pleuronectoidei
Euphotic Krill- Family Euphausiidae
Polychaete Worm- Alitta williami
Rockfish- Genus Sebastes
Caridean Shrimp- Infraorder Caridea
Hooded Shrimp- Order Cumacea
Spiny Lithode Crab- Acantholthodes hispidus
Northern Spearnose Poacher- Agonopsis Tulsa
Eelgrass isopod- Pentidotea resecata
Squid in a teaspoon; likely an opalescent
Turbellarian Flatworm- Genus Notocomplana
Pacific Sand Lance- Ammodytes personatus
Sailfin Sculpin- Nautichthys oculofasciatus
Opalescent Inshore Squid- Doryteuthis opalescent
Pipefish- Syngnathus Leptorhyncus

A Big Thank You! to our volunteers from this summer! Barry Saxifrage, Carrie Saxifrage, Monika Hoffman, Lorne Jacobson, Sadhu Johnston, Savana Young and Fergus Walker.

A Big Thank You as well to The Sentinels of Change and FOCI for providing this opportunity to dive deep into citizen science and into the realm of plankton creatures.

Would you be interested in joining us next year? Please contact Mike (250) 203-6756 or Kate (250) 935-0242 or FOCI
Dungeness crab megalope
Dungeness crab megalope