Evaluating the efficacy of salmon bycatch measures using fishery-dependent data

ICES Journal of Marine Science ICES Journal of Marine Science (2015), 72(4), 1173– 1180. doi:10.1093/icesjms/fsu168 Contribution to the Symposium: ‘Fishery-Dependent Information’ Original Article Evaluating the efficacy of salmon bycatch measures using fishery-dependent data 1 North Pacific Fishery Management Council, 605 W 4th Avenue, Anchorage, AK 99510, USA Alaska Fisheries Science Center, 7600 Sand Point Way NE, Seattle, WA 98115, USA 2 *Corresponding author: tel: +1 907 271 2809; fax: +1 907 271 2817; e-mail: Stram, D. L., and Ianelli, J. N. Evaluating the efficacy of salmon bycatch measures using fishery-dependent data. – ICES Journal of Marine Science, 72: 1173 – 1180. Received 2 May 2014; revised 2 September 2014; accepted 4 September 2014; advance access publication 7 October 2014. The walleye pollock (Gadus chalcogrammus) fishery in the Bering Sea is one of the largest fisheries in the world. The North Pacific Fishery Management Council (NPFMC) provides management advice for this fishery, including the development of measures to minimize salmon bycatch to the extent practicable, one of the stated objectives of the US Magnuson– Stevens Fishery Conservation and Management Act National Standard Guidelines. Salmon have a unique cultural and nutritional importance in the State of Alaska and are the subject of fully allocated mixed commercial, recreational, and subsistence fisheries. Chinook salmon (Oncorhynchus tshawytscha) stocks in Alaska have been declining for the last decade, and all sources of mortality are being considered to help in rebuilding stocks. Given the extensive scientific National Marine Fisheries Service observer data collection programme, the NPFMC has developed bycatch management measures that place limits by fishery sector on the allowable catch of Chinook salmon. Part of this programme includes industry-proposed incentive programmes designed to encourage lower bycatch. Evaluating the efficacy of the new measures poses a number of challenges, particularly in light of changing ocean conditions (perhaps affecting the degree of overlap between pollock and salmon). In this study, data on pre- and post-programme implementation were evaluated to determine if the programme is meeting stated goals and objectives or if modifications are needed. These evaluations included consideration of fleet-level bycatch numbers and rates, seasonality of bycatch by sector, and individual vessel bycatch rates. Results suggest that revised management regulations appear to have resulted in reduced bycatch of salmon overall. Also, lower bycatch rates seem to reflect changing behaviour in response to new management measures. However, the extent to which the programme is effective at the vessel level remains difficult to ascertain without explicit vessel-specific benchmarks developed for evaluating programme efficacy. Keywords: Alaska pollock, bycatch, Chinook salmon, fishery management, incentives. Introduction The Bering Sea walleye pollock (Gadus chalcogrammus; known as Alaska pollock) fishery is one of the largest in the world, with the species contributing .40% to global whitefish production (Fissel et al., 2013). The fishery is divided between a seasonal winter fishery (“A” season) that focuses on prespawning aggregations of pollock producing highly valuable roe (Ianelli et al., 2013a) and a summer fishery (“B” season) extending from June to the end of October. The fishery is primarily pelagic, and catch of non-target species is very low, ,1% of the total pollock catch (Ianelli et al., 2013a). However, Chinook salmon (Oncorhynchus tshawytscha) are caught in significant numbers in some years (Figure 1). Chinook salmon have a designated status as a protected species under the groundfish fishery management plans in the North Pacific, with regulations implemented to ensure that all salmon caught incidentally as bycatch (Bycatch is defined under the Magnuson –Stevens Fishery Conservation and Management Act (2007) as “fish which are harvested in a fishery, but which are not sold or kept for personal use, and includes economic discards and regulatory discards”. [16 U.S.C. 1802 Section 3 (2)] [MSA Published by Oxford University Press on behalf of International Council for the Exploration of the Sea 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US. Diana L. Stram 1* and James N. Ianelli2 1174 D. L. Stram and J. N. Ianelli the performance standard. The plans, as reviewed by the Council, are designed to increase incentives for vessels to lower bycatch rates even in years when salmon encounters were low. The Council and stakeholders requested an evaluation of the efficacy of the new measures at reducing bycatch and maintaining appropriate vessel-level incentives. This study examines the first 3 years of the management programme compared with patterns before programme implementation. Individual vessel-level patterns of bycatch over time as well as sector-level performance are evaluated to assess the performance of the programme as a whole, whether individual vessel behaviour with respect to bycatch avoidance has changed, and what additional measures might be considered for further improvements. Methods Figure 1. Time-series of Chinook salmon bycatch and pollock catch, 1991 –2013. (2007)].) cannot be retained or sold. Catch of salmon species is designated as prohibited species catch (PSC) and is specified under the fishery management plans as a special category of bycatch. Some fraction of the salmon bycatch is donated to food banks using a third-party hunger-relief organization SeaShare. As of 2012, all salmon donated to the programme from fisheries in the Gulf of Alaska and Bering Sea are distributed within the State of Alaska (J. Harmon letter to E. Olson (NPFMC chair) April 2014 and Seashare.org). Genetic information indicates that the majority (65%) of the Chinook salmon caught in the Bering Sea pollock fishery originate from a single geographic region encompassing several western Alaskan rivers, including a genetically distinct group from the Canadian portion of the Yukon River (Myers and Rogers, 1983, 1988; Guthrie and Wilmot, 2004; Myers et al., 2004; Guyon and Guthrie, 2010; Guthrie et al., 2012, 2013, 2014; Ianelli and Stram, 2015). Since Chinook salmon are a highly valuable, culturally important species in Alaska, and the resource is fully allocated to commercial and subsistence users, minimizing the bycatch of this species in other fisheries is a subject for management consideration (Witherell et al., 2002; Stram and Ianelli, 2009). Western Alaskan Chinook populations have been depressed for several years causing extensive catch restrictions for communities dependent on the in-river availability of these resources, including a federal fisheries disaster declaration, virtual elimination of commercial harvest, and severe curtailment of subsistence harvests (Gisclair, 2009; Hilsinger et al., 2009; Howe and Martin, 2009; (...truncated)