Peterson Megan J, Mueter Franz, Criddle Keith, Haynie Alan C
School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Juneau, Alaska, United States of America.
Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, Seattle, Washington, United States of America.
PLoS One. 2014 Feb 18;9(2):e88906. doi: 10.1371/journal.pone.0088906. eCollection 2014.
Killer whale (Orcinus orca) depredation (whales stealing or damaging fish caught on fishing gear) adversely impacts demersal longline fisheries for sablefish (Anoplopoma fimbria), Pacific halibut (Hippoglossus stenolepis) and Greenland turbot (Reinhardtius hippoglossoides) in the Bering Sea, Aleutian Islands and Western Gulf of Alaska. These interactions increase direct costs and opportunity costs associated with catching fish and reduce the profitability of longline fishing in western Alaska. This study synthesizes National Marine Fisheries Service observer data, National Marine Fisheries Service sablefish longline survey and fishermen-collected depredation data to: 1) estimate the frequency of killer whale depredation on longline fisheries in Alaska; 2) estimate depredation-related catch per unit effort reductions; and 3) assess direct costs and opportunity costs incurred by longliners in western Alaska as a result of killer whale interactions. The percentage of commercial fishery sets affected by killer whales was highest in the Bering Sea fisheries for: sablefish (21.4%), Greenland turbot (9.9%), and Pacific halibut (6.9%). Average catch per unit effort reductions on depredated sets ranged from 35.1-69.3% for the observed longline fleet in all three management areas from 1998-2012 (p<0.001). To compensate for depredation, fishermen set additional gear to catch the same amount of fish, and this increased fuel costs by an additional 82% per depredated set (average $433 additional fuel per depredated set). In a separate analysis with six longline vessels in 2011 and 2012, killer whale depredation avoidance measures resulted in an average additional cost of $494 per depredated vessel-day for fuel and crew food. Opportunity costs of time lost by fishermen averaged $522 per additional vessel-day on the grounds. This assessment of killer whale depredation costs represents the most extensive economic evaluation of this issue in Alaska to date and will help longline fishermen and managers consider the costs and benefits of depredation avoidance and alternative policy solutions.
虎鲸（逆戟鲸）的掠夺行为（即鲸鱼偷取或破坏渔具上捕获的鱼）对白令海、阿留申群岛和阿拉斯加湾西部的裸盖鱼（黑鳕）、太平洋大比目鱼和格陵兰庸鲽底栖延绳钓渔业产生了不利影响。这些相互作用增加了与捕鱼相关的直接成本和机会成本，并降低了阿拉斯加西部延绳钓捕鱼的盈利能力。本研究综合了美国国家海洋渔业局观察员数据、国家海洋渔业局裸盖鱼延绳钓调查以及渔民收集的掠夺数据，以：1）估计阿拉斯加延绳钓渔业中虎鲸掠夺的频率；2）估计与掠夺相关的单位捕捞努力量渔获量减少情况；3）评估阿拉斯加西部延绳钓渔民因与虎鲸相互作用而产生的直接成本和机会成本。在白令海渔业中，受虎鲸影响的商业捕捞作业比例最高，其中裸盖鱼为21.4%，格陵兰庸鲽为9.9%，太平洋大比目鱼为6.9%。1998年至2012年期间，在所有三个管理区域中，观察到的延绳钓船队在遭受掠夺的捕捞作业中，单位捕捞努力量渔获量平均减少幅度为35.1%至69.3%（p<0.001）。为了弥补掠夺造成的损失，渔民设置了额外的渔具以捕获相同数量的鱼，这使得每次遭受掠夺的捕捞作业的燃料成本额外增加了82%（每次遭受掠夺的捕捞作业平均额外增加433美元燃料成本）。在2011年和2012年对六艘延绳钓船进行的另一项分析中，虎鲸掠夺避免措施导致每艘遭受掠夺的船日的燃料和船员食物平均额外成本为494美元。渔民因时间损失的机会成本平均为每增加一个船日522美元。对虎鲸掠夺成本的这一评估是阿拉斯加迄今为止对该问题最广泛的经济评估，将有助于延绳钓渔民和管理者考虑掠夺避免措施和替代政策解决方案的成本与收益。
