May 2018 Newsletter
BSFRF Hosts Scientific Workshop on
Tanner Crab Management Strategies
In December 2017 BSFRF hosted a collaborative workshop in Juneau. About 30 researchers and resource managers came together to share information and discuss the status of and options for improving the State of Alaska’s harvest strategy for bairdi Tanner crab. The event attendees included several crab biologists and researchers from the Alaska Department of Fish and Game (ADFG) and the National Marine Fisheries Service (NMFS) and several other stakeholders.

A primary workshop topic was the use of mature female biomass levels to control the fishery. Another fundamental component of the workshop addressed how the NMFS stock assessment model outcomes can be further integrated into management.
Under current regulations, when NMFS survey results show that a minimum level of mature female biomass is not met, the fishery is closed. Over the last 25 seasons, 13 seasons have been closed due to not meeting the minimum female biomass level. Over the last 3 seasons, the total allowable catch (TAC) has ranged from 0 to almost 20 million pounds.  

Workshop outcomes included discussions about improving the harvest strategy by considering more factors and other stock status indicators than female biomass alone. It was noted during discussions that the bairdi fishery is a male retention only fishery and has a low impact on females. A number of researchers from ADFG, NMFS and Canada presented updated information that suggested how new indicators of stock status could be defined and considered. 

The workshop recommendations included taking a longer-term view to further revise the bairdi harvest strategy within the current process for State of Alaska regulations. There are a lot of analyses and research efforts underway over the next several months which include close collaboration with a BSFRF-funded graduate student and crab managers at NMFS and ADFG that will help to inform the bairdi management process. 

A highlight of the workshop was the open discussions between co-managers of the bairdi crab resource, with industry stakeholders also present to participate and provide feedback. This was especially important given the recent volatility in the bairdi fishery.  Hosting this workshop was another example of how BSFRF works collaboratively to ensure the best science and data are used in Bering Sea crab management. 

Improved Snow Crab Model Depends on BSFRF Data 
Harvest management of Bering Sea crab relies heavily on surveys and models that can accurately determine the current abundance of crab. The models rely on a variety of parameters, such as crab growth rate, that are input into the models so the models’ outcomes accurately reflect stock status. Model outcomes are used to inform management for both the Federal guidelines and the State of Alaska harvest limits. These models have been in use for many years and continue to be improved by the scientists who use them.

The model used to determine the status of snow crab has faced some recent challenges in being able to accurately estimate growth for snow crab. Like all crabs, snow crab grow by molting, meaning they have a stairstep growth ‘curve’ because their growth happens in molt increments, rather than continuously. Snow crab, however don’t appear to grow like other Tanner crabs (bairdi), which show a straight-line relationship to their growth steps across all sizes. Snow crabs’ growth ‘curve’ is a bit skewed, with growth increasing sharply at smaller juvenile sizes and then lessening as snow crabs mature.

The Bering Sea snow crab model has historically had very few growth samples available to estimate growth. To try to get better growth data, the BSFRF has been conducting cooperative snow crab growth sampling and molt increment studies for the last five years. We have worked closely with Alaska Department of Fish and Game (ADFG) and National Marine Fisheries Service (NMFS) to capture snow crab of several different juvenile, pre-adult, and adult sizes on the Bering Sea shelf during the late winter, early-spring periods. These crabs have been held over extended periods to monitor and measure their growth when they molt. Each year our data has been added into the snow crab model, but the model continued to be challenged by some growth data gaps and how to interpret those gaps. Last year, because of the uncertainty about the growth data gaps, there was some concern for overall model performance and outcomes, which were somewhat unstable.

Fortunately, after the BSFRF 2017 growth data was input into the model, the model had enough growth data to more accurately determine the size of crabs where the change in growth rate was changing. This understanding of when the crabs’ growth rate lessons tied directly with the overall stability of the snow crab model ( see figure below showing model outcomes after BSFRF data was input ). The improved model performance was presented and reviewed at the January 2018 Crab Plan Team meeting and it was noted by the model assessment author that the new BSFRF data played a critical role in the model improvements. With the improved model stability, snow crab harvest management can proceed with more confidence. And that’s good for everyone involved, including our many industry supporters. 

BSFRF Supports Graduate Student’s
Historical Logbook Research 
BSFRF is dedicated to improving the science that informs Bering Sea crab fishery management. Besides conducting its own collaborative research, BSFRF also supports other scientists who are conducting research that improves our understanding of crab life history and effects of management actions on crab populations.

BSFRF recently supported the research of Leah Sloan Zacher, a doctoral student in the College of Fisheries and Ocean Sciences at the University of Alaska Fairbanks. During an internship with the Alaska Bering Sea Crabbers Leah learned that many years of logbooks from the crab fisheries existed with a plethora of data related to where and how much crab were harvested in Bristol Bay. The data in the logbooks were underused because the logbooks are in hard copy form ( see photo ). BSFRF gave $33,000 to the University of Alaska Fairbanks so Leah could transcribe the logbook data from 2005-2016 into computer spreadsheets for upload into a geographic information system (GIS) for analysis and mapping purposes.

Leah was particularly interested in the distribution of Bristol Bay red king crab during the crab harvest season. The BSFRF was also interested in the data to inform whether the current trawl closure areas in Bristol Bay (the Red King Crab Savings Area and the Nearshore Bristol Bay trawl closure area) are in the right places to protect red king crab.

The resulting maps show where fishermen were catching the most crab. Leah also used the data to calculate the catch per unit effort (CPUE) by location. The data were aggregated to protect the confidentiality of the logbook data. See map below.

Leah found that the areas of higher abundance of red king crab shifted seasonally and were different in the logbook data collected during fall harvest season than in the summer trawl data collected by NOAA annually. Currently, NOAA conducts summer trawl surveys to estimate abundance and distribution of red king crab and many other species. “NOAA does a summer survey,” explained Leah. “But the logbook data showed that crab distributions in the fall are very different than those reported from the summer survey.”

Leah also found that temperature was really important for fall crab distribution. When bottom temperature is really warm in the Bering Sea, the crab aggregate in the center of the Red Kind Crab Savings Area. In cold years, the crab congregate more in a line along the Alaskan Peninsula, south and east (in the Nearshore Bristol Bay trawl closure area). These results support the assumption that the trawl closure areas are protecting red king crab. Which closure area is more important depends on whether it’s a cold year or a warm year.

Leah presented this research to the Science and Statistical Committee of the North Pacific Fishery Management Council in December 2016 and at the Crab Science Symposium in September 2017 and has submitted it for publication in the journal PLOS ONE. She recently defended her dissertation, which included a chapter on the logbook data as well as chapters on her work studying parasites in red king crab. “The funding from BSFRF was critical to my logbook research,” said Leah. “If it hadn’t been for their support, we wouldn’t have this understanding of crab distribution fluctuations.”

Map: Yellow/gold areas are locations with a high autumn king crab abundances in at least one year (2005 - 2016). The darker the color the more years that area had a high crab abundance.
ASMI Responsible Fisheries Management Certification Program updates

The Alaska Seafood Marketing Institute’s (ASMI) Responsible Fisheries Management (RFM) Certification Program is an internationally recognized seafood certification program based on the United Nations Food and Agriculture Organization (FAO) Code of Conduct for Responsible Fisheries, and the FAO Guidelines for Ecolabelling of Fish and Fishery Products from Marine/Inland Fisheries. In December 2017, Bristol Bay red king crab, St. Matthew Island blue king crab, and Eastern Bering Sea snow crab fisheries received re-certification under the RFM program. Also in December 2017, Bering Sea Tanner crab and Aleutian Islands golden king crab fisheries were newly certified under the RFM program. 

Upcoming Events

Crab Plan Team mtg: May 8-10, Anchorage AK

NPFMC mtg: June 4-12, Kodiak AK

Crab Plan Team mtg: Sept. 9-13, Seattle WA

Crab Science Symposium, Sept. 14 ( tentative ) Seattle. WA

NPFMC mtg: October 1-9, Anchorage, AK

NPFMC mtg: December 3-11, Anchorage, AK
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If you want more information or have questions about our work, please contact:

Scott Goodman, Executive Director,
Doug Wells, Board President,
Gary Stauffer, Science Advisor,

Bering Sea Fisheries Research Foundation | May 201 8 |