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New Projects Aim to Improve Stock Assessments

Jun 19, 2017
2017 Issue 2

In 2015, GMRI convened a series of meetings of commercial and recreational fishermen, scientists, and policy representatives from across the region to spark productive conversations and brainstorm ideas to improve stock assessment data and processes. This Fish Tank series culminated in a workshop held in November 2015, entitled Taking Stock: A Workshop to Collaboratively Improve Stock Assessments, where participants developed a set of prioritized research goals focused on improving stock assessments. After the workshop, the New England Fishery Management Council, the Northeast Fisheries Science Center and GMRI pooled resources to fund two projects that address these research goals. 

The two projects that were awarded funding are “Developing Applications of Fishery Catch Rates for New England Groundfish Stock Assessments” submitted by Steve Cadrin and Brooke Wright from UMass Dartmouth’s School for Marine Science & Technology (SMAST) and “Estimating catchability for an industry-based groundfish survey net in the Gulf of Maine” submitted by Bill Hoffman from the Massachusetts Division of Marine Fisheries (DMF).  Below are the preliminary results from the SMAST project; preliminary DMF results will be available soon.

The SMAST work aims to improve the data and models used to manage New England groundfish by developing a standardized fishery catch-per-unit-effort (CPUE) series for current and future New England groundfish stock assessments. The project is taking place in multiple stages. The first stage expands a review of existing CPUE models; the second stage brings together fishermen and scientists to identify information to be included in the new model; the third stage analyzes the new model, vessel trip report, observer, and study fleet data; and stage four distributes the results.

SMAST first began developing standardized CPUE data for the 2016 witch flounder stock assessment. They worked closely with fishermen to gather input on factors beyond abundance that may be influencing catch rates, as well as how to identify trips that were targeting witch flounder (commonly called grey sole). This was then applied to larger dealer and observer datasets to develop a standardized series of CPUE data. The results that stemmed from this project were used in the stock assessment models; however, the models were ultimately rejected as a basis for witch flounder fishery management due to strong retrospective patterns. Although the models were rejected, it was a great success that the CPUE data was incorporated by the working group. SMAST is further developing and refining their methods based on feedback and is currently working to apply their standardization methods to halibut and white hake assessments. 

GMRI is excited to continuing working with partners to improve stock assessments and will continue to provide updates on these projects and other Fish Tank series activities.