Bairdi Tanner crab is the larger cousin of snow crab.            Credit: AK Bering Sea Crabbers

 

The harvest strategy for Bering Sea Tanner crab is getting a closer look by fishery managers for the first time in nearly 20 years.

And we know a lot more about the crab and life cycle in 20 years. What most important is that when the harvest strategy was put into place the stock was considered overfished and was in a rebuilding status and now it is is one of the more healthy stocks in the Bering Sea. 

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Tyson Fick is spokesman for the trade group Alaska Bering Sea Crabbers.  Bairdi Tanners had become Alaska’s biggest crab fishery with harvests trending upwards to 20 million pounds two years ago. But last year, to the shock of everyone, the fishery was shut  down when surveys showed a drop in female crabs.

When we look at it we wonder what the utility is to have such a hard switch based solely on female abundance, and that is unique for Tanners in the harvest strategy. It’s all about a female threshold as the on/off switch whether or not to have a fishery. In most other crab stocks you look at the whole biomass, males and females combined. 

A meeting last month brought stakeholders and managers to the table to revise the Tanner harvest strategy.  Fick says an adjustment was made to the definition of female crab maturity.

They previously said if it’s 85 millimeters, it’s a mature crab. When we actually did the observations with observer data, we found that was in some years missing almost half of the mature females that were out there because they were maturing at a smaller size. 

The crabbers also want to include crab further west that were not included in survey estimates. That can add up to 10 percent extra crab in the biomass or even more.  It was agreed that reference years used in stock modeling would be adjusted and updated from 1977 to 2010 to 1982 to 2016.

The front end of that is what’s most important because that comes right at a major regime shift in the Bering Sea with ocean conditions changed and became more friendly to finfish than shellfish. So it kind of over-inflated the historical biomass estimate if you include the time series going back farther than 1982 and that lines up with what federal scientists have been saying. 

Other changes were discussed, but Fick says changing the regulation to use females-only as stock indicators is key.

Particularly having some flexibility to look at if the female abundance came in just below the threshold but then the male abundance was way up at the top end of the chart like last year. 

Fick has high praise for the crab collaboration, saying it diffuses tension heading into the fall fishing season.

If we had not taken care of that at this meeting it would have set things up for a collision course for a highly contentious meeting  in the middle of what should be crab fishing season. So we’re really happy that this work was done and we’re going into the season with an idea of how to deal with it should this situation arise again.

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