Derville et al. 2023: rasters of whale exposure to crab gear

Dataset produced by Derville et al. 2023 Biological Conservation, "Exposure of whales to entanglement risk in Dungeness crab fish-ing gear in Oregon, USA, reveals distinctive spatio-temporal and climatic patterns"<br><br>Abstract:Entanglement in fishing gear presents a major threat to marine mammals worldwide and a pressing concern for distinct populations of whales off the US West Coast. The lack of understanding of their fine-scale distribution in relation to fishing activity limits management efforts, specifically in Oregon. Based on year-round predictions of rorqual whale densities and fishing effort compiled from logbooks, we assess co-occurrence between commercial Dungeness crab fishing gear and whales over a decade (2011-2020) as an indicator of exposure to entanglement risk. Generalized Additive Models including temporal, climatic, and ocean upwelling predictors were used to investigate variations in exposure. Exposure peaked in April, at the onset of the upwelling season when whales were predicted to occur in greater numbers and closer to shore. Exposure remained constant until the end of the crab season in nearshore waters &lt;40 fathoms (73 m) and decreased past these depths. Across years, exposure was lower during the marine heatwave (2014-2016) when fishing was more active nearshore and whales were predicted to be less abundant. Exposure was higher before (2011-2013) and after (2017-2020) the heatwave, which correspond to negative phases of the Pacific Decadal Oscillation associated with stronger upwelling, indicating more productive conditions favorable to whales. A recent increase in exposure was also due to a slight shift in fishing effort towards deeper waters. These findings illustrate the use of fine-scale species distribution models to assess space-use conflicts in dynamic marine ecosystems and can be used to guide fisheries management to reduce entanglement risk in Oregon.<br>本数据集由Derville等人于2023年发表于学术期刊《生物保护（Biological Conservation）》的研究成果生成，研究论文标题为《美国俄勒冈州海域鲸鱼在珍宝蟹（Dungeness crab）捕捞渔具中的缠绕风险暴露特征：独特的时空与气候模式》。 摘要：渔具缠绕是全球海洋哺乳动物面临的首要威胁之一，同时也是美国西海岸周边特有鲸鱼种群亟需应对的紧迫议题。目前针对俄勒冈州海域，学界对鲸鱼与捕捞活动相关的精细尺度分布特征认知不足，这制约了当地渔业管理工作的推进。本研究基于全年须鲸（rorqual）种群密度预测结果，以及由捕捞日志汇编得到的捕捞努力量数据，以商业性珍宝蟹捕捞渔具与鲸鱼的十年（2011-2020年）空间共现情况为指标，评估鲸鱼面临的缠绕风险暴露水平。研究采用纳入时间、气候及海洋上升流等预测因子的广义可加模型（Generalized Additive Models），分析了风险暴露水平的变化规律。 风险暴露峰值出现在4月，即海洋上升流季节初期，此时预测的鲸鱼种群数量更多且分布更贴近近岸海域。在水深小于40英寻（73米）的近岸海域，风险暴露水平持续至珍宝蟹捕捞季结束均保持稳定，而在更深水域则逐渐下降。 跨年度来看，2014-2016年海洋热浪（marine heatwave）期间，尽管近岸捕捞活动更为频繁，但预测的鲸鱼种群丰度更低，因此风险暴露水平相对更低。在海洋热浪发生前（2011-2013年）及之后（2017-2020年），风险暴露水平更高，这两个时段对应太平洋年代际振荡（Pacific Decadal Oscillation）的负相位，此时上升流更强，海洋生产力更高，更适宜鲸鱼生存。近期风险暴露水平的上升还与捕捞努力量向更深水域小幅转移有关。 本研究结果证实了精细尺度物种分布模型可用于评估动态海洋生态系统中的空间利用冲突，相关结论可用于指导俄勒冈州的渔业管理工作，以降低鲸鱼缠绕风险。