Cortes Island’s newest citizen science project, monitoring Dungeness crab larvae, was announced last Friday. Local diver Mike Moore, Helen Hall from the Friends of Cortes Island (FOCI) and Kelly Fretwell from the Hakai Institute joined Manda Aufochs Gillespie on CKTZ’s Folk U Friday.
Fretwell subsequently emailed Cortes Currents that this wasn’t really meant to be an announcement. Moore happened to walk by the radio station just as Hall was being interviewed, so Gillespie invited him to join them.
Moore explained that when he was diving around Hernando Island in the early 2000s, he saw hundreds of crabs mating in the sand flats at Stag Bay.
“I recently started diving down on Hernando Island again, just in the last five or six years and was really shocked. I could dive all season and not see a single Dungeness crab,” he said.
Moore cited two possible causes for their population decline:
- crab traps and the “tremendous amount of fishing gear” in the ocean.
- Juvenile Dungeness crabs are finding it difficult to form a shell because of the acidification of the ocean waters in the Salish sea
FOCI is one of the latest partners to join the Hakai Institute’s new Dungeness crab monitoring project. They will be putting a ‘light crab trap’ in Cortes Bay. Fretwell explained that traps are being deployed in an area stretching from Southwestern and Southeastern Vancouver Island up to Quadra and Cortes Islands. All of the lights will be turned on during the evening of April 15th.
“It’s just a very cool visual, having all these little lights popping up around the Salish sea at the same time,” she said.
Moore added, “These traps are about 35 centimetres in diameter. They float on the surface, go a metre deep, but they hang down into the water column. They have battery operated lights that illuminate the water column. Larva plankton creatures are attracted to the lights and they’ll swim towards it. It’s a live trap. The crabs just get held there under the lights. Then every two days normally, the trap keeper will come and pull it up onto the dock. In hot weather, we have to pull this trap every day.”
This is FOCI’s most recent citizen scientist project on Cortes Island. Previous ones include monitoring water quality in Hague and Gunflint Lakes, recording bird populations and observing sea star populations.
The latter was another joint project with Hakai.
Fretwell observed that there were 21 people sharing their observations of sea star observations in the Discovery Islands on iNaturalist when this project launched a year and a half ago. Now, 100 more people have become involved, and have added 490 more observations of sea stars.
Hall said, “Anyone can do this. You don’t have to be a scientist. Anyone can take part and learn a lot more about the species and the habitats around you. It’s a way of engaging people in the environment in a fun and interesting way.”
Moore said he would like to see kids involved in the Dungeness Crab Monitoring program.
Fretwell added, “If you want to learn more about the light trap project, you can go to https://sentinels.hakai.org/approaches/light-traps. You can also go to https://hakai.org/inaturalist/ to learn more about iNaturalist and there are links to our various iNaturalist projects that we have going on.”
This post was originally published March 2 and republished March 5 for the Saturday Round-up.
Top image credit: A light trap – Photo by Kelly Fretwell/Hakai Institute
Sign-up for Cortes Currents email-out:
To receive an emailed catalogue of articles on Cortes Currents, send a (blank) email to subscribe to your desired frequency:
- Daily, (articles posted during the last 24 hours) – [email protected]
- Weekly Digest cortescurrents – [email protected]