Suitability of foraging habitat for Eubalaena glacialis under future climate scenarios in the Northwest Atlantic Elem Sci Anth

The critically endangered North Atlantic right whale (Eubalaena glacialis) faces significant anthropogenic mortality. Recent climatic shifts in traditional habitats have caused abrupt changes in right whale distributions, challenging traditional conservation strategies. Tools that can help anticipate new areas where E. glacialis might forage could inform proactive management. In this study, we trained boosted regression tree algorithms with fine-resolution modeled environmental covariates to build prey copepod (Calanus) species-specific models of historical and future distributions of E. glacialis foraging habitat on the Northwest Atlantic Shelf, from the Mid-Atlantic Bight to the Labrador Shelf. We determined foraging suitability using E. glacialis foraging thresholds for Calanus spp. adjusted by a bathymetry-dependent bioenergetic correction factor based on known foraging behavior constraints. Models were then projected to 2046–2065 and 2066–2085 modeled climatologies for representative concentration pathway scenarios RCP 4.5 and RCP 8.5 with the goal of identifying potential shifts in foraging habitat. The models had generally high performance (area under the receiver operating characteristic curve > 0.9) and indicated ocean bottom conditions and bathymetry as important covariates. Historical (1990–2015) projections aligned with known areas of high foraging habitat suitability as well as potential suitable areas on the Labrador Shelf. Future projections suggested that the suitability of potential foraging habitat would decrease in parts of the Gulf of Maine and southwestern Gulf of Saint Lawrence, while potential habitat would be maintained or improved on the western Scotian Shelf, in the Bay of Fundy, on the Newfoundland and Labrador shelves, and at some locations along the continental shelf breaks. Overall, suitable habitat is projected to decline. Directing some survey efforts toward emerging potential foraging habitats can enable conservation management to anticipate the type of distribution shifts that have led to high mortality in the past.

极度濒危的北大西洋露脊鲸（Eubalaena glacialis）正面临严峻的人为致死威胁。近年来其传统栖息海域的气候变迁导致露脊鲸分布格局发生突变，对传统保护策略形成严峻挑战。若能开发可预测北大西洋露脊鲸潜在觅食新区域的工具，将可为主动式海洋保护管理提供关键依据。

本研究采用高分辨率模拟环境协变量训练提升回归树（boosted regression tree）算法，针对西北大西洋陆架（从中大西洋湾至拉布拉多陆架）范围，构建了基于哲水蚤（Calanus）物种特异性的北大西洋露脊鲸历史与未来觅食栖息地分布模型。研究基于已知的露脊鲸觅食行为约束条件，结合依赖水深的生物能学校正因子，调整哲水蚤属的露脊鲸觅食阈值，以此判定觅食栖息地的适宜性等级。

随后，将训练完成的模型投影至典型浓度路径（representative concentration pathway, RCP）4.5与RCP8.5情景下的2046–2065年及2066–2085年模拟气候态，以识别觅食栖息地的潜在空间变化。模型整体表现优异（受试者工作特征曲线下面积>0.9），分析结果显示海底环境与水深为影响觅食栖息地分布的关键协变量。

历史时段（1990–2015年）的投影结果与已探明的高适宜性觅食区域，以及拉布拉多陆架上的潜在适宜区域高度吻合。未来气候情景下的投影结果显示，缅因湾与圣劳伦斯湾西南部部分区域的潜在觅食栖息地适宜性将出现下降，而斯科舍陆架西部、芬迪湾、纽芬兰与拉布拉多陆架，以及大陆陆坡沿线部分区域的潜在栖息地适宜性将得以维持甚至提升。总体而言，北大西洋露脊鲸的适宜觅食栖息地预计将呈现缩减趋势。

将部分调查工作转向新兴的潜在觅食栖息地，可助力保护管理部门提前预判曾导致过往高致死率的分布变化类型。