Shellfish biologists with the Nisqually Tribe are hoping a long-term study will give them a better understanding of shrimp in South Sound.
The issue is determining just how big, or small, the shrimp populations are, said Margaret Homerding, a shellfish biologist for the tribe.
“The state conducted surveys a decade ago, but did not catch any spot prawns,” she said in a tribal news release.
The tribe has been dropping three shrimp pots every few months in various locations from the Nisqually Reach to lower Carr Inlet. Each pot location is tracked by GPS data, and any catch is recorded.
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“We started surveying when we saw our crabbers pulling up spot prawns from their deeper pots,” Homerding said. “We are looking for all species of shrimp, but we’re focusing our efforts on spot prawns, which are the commercially valuable species.”
So far, spot prawns and dock shrimp have been the most abundant species in the tribal surveys.
The research will help guide the tribe and state co-managers create an accurate harvest regime for shrimp.
Homerding said one result could be a decision on whether there is a commercially viable tribal shrimp fishery. The tribe does not do any commercial shrimp fishing currently.
Currently, the tribe and state split a 3,000-pound quota for all shrimp species, including 1,000 pounds of spot prawns.
Other aspects of the surveys include tracking the sizes at which shrimp change from male to female. Because shrimp change sex during their life cycle, the relative sizes of male and female shrimp can tell biologists a lot about the health of the local population.
“If a population of shrimp is shrinking, we will see individuals changing sex earlier,” Homerding said in the release.
Shellfish managers will consider the data the tribe is collecting as a baseline for a healthy stock with little harvest pressure.
The tribe also is tracking when shrimp are spawning. Usually, shrimp fisheries close when female shrimp are carrying eggs, protecting them from harvest.
“There’s no reason to fish for shrimp when the next generation is at its most vulnerable,” she said.