Fisheries Research Group, United States of America.
Ecological Modelling Services and Marine Spatial Ecology Lab, University of Queensland, Brisbane, Australia.
PLoS One. 2024 Mar 28;19(3):e0301072. doi: 10.1371/journal.pone.0301072. eCollection 2024.
Several odontocete species depredate catch and bait from fishing gear, resulting in their bycatch and causing substantial economic costs. There are no known mitigation methods for odontocete depredation in pelagic longline fisheries that are effective, do not harm odontocetes and are commercially viable. Understanding odontocetes' depredation strategies can contribute to mitigating this human-wildlife conflict. Using observer data from the Hawaii-based tuna longline fishery, this study summarized teleost and elasmobranch species-specific mean posterior odontocete depredation rates using a simple Bayesian binomial likelihood estimator with a Bayes-Laplace prior. Depredation rates of species with sufficient sample sizes ranged from a high of 1.2% (1.1 to 1.3 95% highest posterior density interval or HDI) for shortbill spearfish to a low of 0.002% (0.001 to 0.003 95% HDI) for blue shark. Depredation of catch is a rare event in this fishery, occurring in about 6% of sets. When depredation did occur, most frequently odontocetes depredated a small proportion of the catch, however, there was large variability in depredation rates between teleost species. For example, bigeye tuna was two times more likely to be depredated than yellowfin tuna (odds ratio = 2.03, 95% CI: 1.8-2.3, P<0.0001). For sets with depredation, 10% and 2% of sets had depredation of over half of the captured bigeye tuna and combined teleosts, respectively. All elasmobranch species had relatively low depredation rates, where only 7 of almost 0.5M captured elasmobranchs were depredated. Odontocetes selectively depredate a subset of the teleost species captured within sets, possibly based on net energy value, chemical, visual, acoustic and textural characteristics and body size, but not median length, which was found to be unrelated to depredation rate (Pearson's r = 0.14, 95% CI: -0.26 to 0.50, p = 0.49). Study findings provide evidence to support the identification and innovation of effective and commercially viable methods to mitigate odontocete depredation and bycatch.
几种齿鲸物种会捕食渔具中的渔获物和诱饵，导致副渔获和巨大的经济损失。目前，在远洋延绳钓渔业中，没有已知的有效、对齿鲸无害且商业上可行的减少齿鲸捕食的方法。了解齿鲸的捕食策略有助于缓解这种人与野生动物的冲突。本研究利用来自夏威夷金枪鱼延绳钓渔业的观察员数据，使用简单贝叶斯二项式似然估计器和贝叶斯-拉普拉斯先验，总结了特定硬骨鱼和软骨鱼物种的平均后齿鲸捕食率。在有足够样本量的物种中，捕食率从短吻箭鱼的 1.2%（95%最高后验密度区间或 HDI 为 1.1-1.3）到蓝鲨的 0.002%（95%HDI 为 0.001-0.003）不等。在该渔业中，渔获物的被捕食是一种罕见的事件，约占渔获物的 6%。当捕食确实发生时，大多数情况下齿鲸只捕食了一小部分渔获物，但硬骨鱼之间的捕食率差异很大。例如，大眼金枪鱼被捕食的可能性是黄鳍金枪鱼的两倍（优势比=2.03，95%置信区间：1.8-2.3，P<0.0001）。在有捕食的渔获中，分别有 10%和 2%的渔获中捕获的大眼金枪鱼和所有硬骨鱼被吃掉了一半以上。所有的软骨鱼物种的捕食率都相对较低，在将近 500 万条捕获的软骨鱼中，只有 7 条被捕食。齿鲸选择性地捕食渔获物中一部分硬骨鱼，可能是基于净能量值、化学、视觉、听觉和质地特征以及体型，但与捕食率无关（Pearson's r=0.14，95%置信区间：-0.26 至 0.50，p=0.49）。研究结果为确定和创新有效和商业上可行的方法以减少齿鲸捕食和副渔获提供了证据。
