Council Applauds Collaborative Effort to Determine Butterfish Stock Status
A new scientific assessment of the butterfish population indicates that the stock is not overfished and that overfishing is not occurring. These findings were detailed in the 58th Stock Assessment Workshop (SAW) Summary Report, which was released by the NMFS Northeast Fisheries Science Center last month after being approved by a panel of external peer reviewers during the Stock Assessment Review Committee (SARC) process.
“From a practical standpoint, the outcome we have now is that there are enough fish for a directed fishery while still accounting for the forage needs of other species and accommodating the longfin squid fishery. The fact that we’ve got people in other countries eating butterfish caught by U.S. fishermen cannot be overlooked.”
The results of this assessment are particularly significant because the status of butterfish had been classified as "unknown" since the previous assessment was completed in 2010 (SAW/SARC 49). Although the SARC review panel had agreed that overfishing was not likely occurring, it did not accept the adequacy of the biological reference points (BRPs) used for stock status determination.
The high degree of uncertainty in the previous assessment was due in part to the biology of the stock. Butterfish are relatively short lived and experience high rates of natural mortality. These factors make the stock size strongly dependent on recruitment, resulting in high variability in stock size estimates from year to year.
For the most recent assessment, scientists sought to reduce some of these sources of uncertainty by utilizing a new modeling approach that incorporated current research on estimation of catchability. This revised approach provided an improved basis for understanding the stock history and allowed for the successful estimation of BRPs. The reviewer summary found that the incorporation of new information from research studies "led to improved understandings of the population dynamics.”
In addition to determining that the stock was not overfished (at or above BMSY), the assessment concluded that the stock had been above the biomass target for the entirety of the time series used (1989-2012).
"This assessment represents tremendous progress that's being made through ongoing collaborative efforts to understand the dynamics and status of this fishery," said Council Chairman Rick Robins. "Having a conclusive, peer-reviewed stock assessment is a major leap forward in this fishery.”
Support for the stock assessment was expressed by a number of Council members and other attendees at the Council's most recent meeting in Montauk, New York. "A lot of people from many different disciplines played an integral part in the success of this, and I think the results speak for themselves," said Greg DiDomenico, Executive Director of the Garden State Seafood Association. "This type of collaboration needs to be applied to other species."
Meeting attendees also noted the contributions of Geir Monsen, an advisor to the Council who passed away last year. “Geir Monsen’s persistent encouragement to improve our understanding of this fishery has come to fruition,” stated Chairman Robins. “His efforts will benefit the resource, the fishery, and the Council.”
Although it has not yet been determined how the new assessment will affect butterfish quotas for 2015 and beyond, many fishermen are hopeful that higher quotas will allow for expansion of a directed butterfish fishery.
"From a practical standpoint, the outcome we have now is that there are enough fish for a directed fishery while still accounting for the forage needs of other species and accommodating the longfin squid fishery," said DiDomenico. "The fact that we've got people in other countries eating butterfish caught by U.S. fishermen cannot be overlooked."
A complete summary of the stock assessment results, including assessments for tilefish and northern shrimp, is available here.