commfish / seak_sablefish

NSEI sablefish stock assessment
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Changes to sampling protocol on the NSEI longline survey #36

Open jysullivan opened 5 years ago

jysullivan commented 5 years ago

Proposal to release small fish on the survey that are outside of our systematic sampling framework (e.g. we always sample every 20th sablefish for l,w,s,mat, otos and every 21st fish for length only and they are retained on board regardless of size.)

Past concerns were that small fish released during the survey may not be equally available to the fishery due to hook shyness and this could alter the population estimate. I don’t know what your cutoff for length for tagging is these days and how that factors in to the question.; obviously you are not tagging fish below a certain size because they may/may not be retained in the fishery. In non-tagging years, we release small fish eye-balled at 18 inches and under.

If we were to shake the smalls, they would not be brought aboard. I would have the roller stopped prior to them twisting out the hook. We would have a look at the fish but often they are wiggling and kicking so may not be a good look. If we have to handle them to check for a clip prior to release, this would be time consuming, slow down the haul and tough on the fish so I would instead recommend that we just retain them.

All this said, we do not observe (at sea) fish taken on the survey for presence/absence of fin clip. If a 2019 tagged fish lost its tag prior to capture on the survey, the clip would 99.9% of the time go un-noticed as we do not observe survey fish for fin clips at the processor either. The only clipped fish we document from the survey are those in which a tag is recovered.

Contact: Mike Vaughn