Monday, July 4, 2011

Mega-what?

Washington Department of Fish and Wildlife has teamed up with the Port Townsend Marine Science Center to monitor crab megalops during the summer again this year. Most of Puget Sound has a healthy population of Dungeness crab, but some places like Hood Canal and the Tacoma Narrows have shown a decline in their population. So what are crab megalops and how do we find them?

Megalops are one of the stages of growth in a crab. They go through a few different stages of growth before turning into a mature crab. We are able to find these tiny megalops (about the size of rice grains) by deploying mesh bags with an anchor that hang from local docks. The megalops that are floating around in the water column will get stuck in the sampler that we collect and count each week.
This research will hopefully provide more information about crab populations in the Puget Sound.


Growth stages of a crab


2010 Abundance of crab megalops at various sample sites 


Crab Zoea, the growth stage before megalops


A week ago at the Port Townsend Marine Science Center there were thousands of crab zoea in the water, check out the video below to see how they move! You can find crab zoea on Fort Worden beaches right now, they are the tiny poky guys that you might be feeling when walking on the beach. Take a closer look next time you are visiting.


Crab zoea in a plankton sample

Valerie Lindborg
PTMSC Lab Coordinator




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