Collecting crabs for Project Lab

Thought I would post a quick, brief update on my first time collecting green crabs in California! Armed with my Scientific Collecting Permit, I collected green crabs at two sites in Marin County. I deployed two collapsible traps baited with tinned fish at each site.

One of my sites is Miller Boat Launch. I deployed the traps here on Feb. 4, checked them on Feb. 5, and again on Feb. 7. On Feb. 5, I saw two larger male green crabs in the traps, along with tons of Dungeness crabs. I released the bycatch and kept the green crabs in the trap. When I checked the trap again on Feb. 7, one of the green crabs was gone! I wonder if I accidentally dumped it out with the Dungeness bycatch from that day, if it escaped, or if it was eaten by the other buddies in the trap. In any case, I didn’t want to leave with just one crab. I set myself a 45 minute timer and turned over cobbles at the small beach next to the dock. The tide was coming in throughout my beach-combing time. I noticed that the green crabs hung out just above or below the tide line. I found five additional crabs by turning over rocks! I spotted quite a few very small juvenile crabs as well, as well as an ovigerous female. Looking at the sizes of crabs present under the cobbles (both green crab and other species), I started thinking about ways to purposefully use size to isolate different recruit years and test differences in heat tolerance across recruitment years. I’ll need to do a couple more field collection days to really flush out this idea!

I was able to deploy traps at my second site on Feb. 5, then checked them again on Feb. 7. This is a known high yield site, and it definitely provided! I collected 47 total crabs from my two pots. Knowing how hard it can be to trap crabs in the winter, it’s good to know that this site is consistent across seasons. Quite a few of these crabs had more orange integument colors. The students will need to sort through the crabs to try and have an even distribution of sex and integument color. The crabs were all roughly the same size. My guess is that they settled last year.

I’ll likely need to collect once more at the end of this week, and my goal is to re-visit the high-yield site. We’ll see how well it holds up!

Going forward

1. Repeat green crab collection