Proceedings 2015/061
Proceedings of the Regional Peer Review of the Northwest Atlantic Spiny Dogfish (Squalus acanthias) Framework and Assessment; January 20-21, 2014, and May 29, 2014
Chairpersons: Christie Whelan and Tana Worcester
Editor: Lottie Bennett
Summary
A Maritimes Regional Science Advisory Process to review the Northwest Atlantic Spiny Dogfish Framework and Assessment was held from January 20-21, 2014, at the Bedford Institute of Oceanography, in Dartmouth, Nova Scotia, and was reconvened on May 29, 2014 (a 2011 meeting was terminated after the first day due to recognition that US landings data that had been provided were incomplete for analysis purposes). The meeting was attended by Fisheries and Oceans Canada (DFO) staff from Science, Resource Management, Policy and Economics, as well as non-government organizations, Aboriginal organizations and the fishing industry.
The model developed and accepted for assessment of Northwest Atlantic Spiny Dogfish in Canada is a forward-projecting stage-based (juveniles and adults, males and females), spatially explicit (two regions: Canada and United States (US)) population dynamics model with two time steps (November-April and May-October) in each year. For the 2014 assessment, this model was updated with data to 2013. There were no substantive changes to parameter estimates or temporal patterns in abundance estimates when the 2010 framework model was updated to 2013, and the fit remained reasonable. Population estimates from the model indicate a dramatic increase in abundance during the 1980s, peaking about 1992, and then declining. The updated model demonstrates increased abundance since 2009, especially of juveniles, with a total population abundance of 789.2 million Spiny Dogfish for 2013. Adult females have remained at relatively high abundance since 2006.
Projections to evaluate the consequences of various catch levels indicate that a total catch (US and Canada, landings and dead discards) of Spiny Dogfish in the vicinity of 47,350 metric tonnes (varies with assumed proportions of catch by region) would result in a 50% risk of decline in adult female biomass after 40 years. Abundance of adult females (SSN) at Maximum Sustainable Yield (SNNMSY) and Fishing Mortality on adult females (FSSN_MSY) were proposed for use to evaluate stock status. Given the low productivity and associated recovery time of Spiny Dogfish, 65% of SNNMSY (21.3 million) is proposed as a Lower Reference Point (LRP) for Spiny Dogfish and SNNMSY (32.8 million) is proposed as the Upper Stock Reference (USR). FSSN_MSY is 0.0723. Spiny Dogfish is currently above the USR; that is, in the healthy zone.
This proceedings report summarizes the relevant discussions and presents the key conclusions reached at the meetings. A Science Advisory Report (SAR) and a Research Document resulting from the meeting will be published on the DFO Canadian Science Advisory Secretariat website as they become available.
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