Fish board splits on Bering Sea Tanner season

There will be no bairdi Tanner crab season in the Bering Sea this year after the Alaska Board of Fisheries voted it down on a split vote, in spite of some reputable science showing a limited harvest could happen without harming stocks.

The fishery was closed after the summer trawl survey did not show a necessary abundance of female crab.

However, the Bering Sea Fisheries Research Foundation, which brings together stakeholders and crab scientists in the Bering Sea to further scientific understanding in the region, conducts annual side-by-side surveys with the National Marine Fisheries Service to inform trawl selectivity.

The foundation evaluated two independent summaries of the 2016 summer survey data in order to better understand the current stock status.

While the foundation does not engage in policy, its work further informs the best available science.

They submitted a letter to the Board of Fisheries detailing the BSFRF survey analysis with several points showing the viability of a small fishery.

Both surveys confirmed a declining trend in female crab abundance, but the relationship of the two surveys significantly changed in 2016.

The BSFRF suggested 23 percent more mature females than the NMFS survey.

The BSFRF also suggested that record warm bottom temperatures may have been the reason fewer mature female crabs were seen at the NMFS survey stations.

While survey methods have changed and resulted in lower selectivity for crab, the harvest strategy has not adjusted. The existing mature female bairdi biomass threshold is biased by higher survey selectivity prior to 1982.

One of the most important points raised at the meeting is that facts on the ground raise significant questions, suggesting that the actual mature female bairdi biomass, as observed during the survey, is significantly higher than the estimate of female maturity.

The Alaska Department of Fish and Game uses a cutoff of a 79mm carapace for the western area and 85mm for the eastern to define female maturity.

However, physical observation on board the survey vessel showed that a significant number of mature female crab, based on the condition of the abdominal flap, were sexually mature despite being well below 79mm in carapace size, which suggests that the process is significantly under-counting mature bairdi female crab.

Based on this science and what harvesters and processors say is a need to update the state’s harvest strategy, a very conservative 4 million pound quota was proposed.

The mature male biomass is at 100 million pounds, which puts abundance at 177 percent of maximum sustainable yield.

Cristy Fry can be reached at realist468@gmail.com.

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