Projected Scenarios for Coastal First Nations’ Fisheries Catch Potential under Climate Change: Management Challenges and Opportunities

Studies have demonstrated ways in which climate-related shifts in the distributions and relative abundances of marine species are expected to alter the dynamics and catch potential of global fisheries. While these studies assess impacts on large-scale commercial fisheries, few efforts have been made to quantitatively project impacts on small-scale subsistence and commercial fisheries that are economically, socially and culturally important to many coastal communities. This study uses a dynamic bioclimate envelope model to project scenarios of climate-related changes in the relative abundance, distribution and richness of 98 exploited marine fishes and invertebrates of commercial and cultural importance to First Nations in coastal British Columbia, Canada. Declines in abundance are projected for most of the sampled species under both the lower (Representative Concentration Pathway [RCP] 2.6) and higher (RCP 8.5) emission scenarios (-15.0% to -20.8%, respectively), with poleward range shifts occurring at a median rate of 10.3 to 18.0 km decade-1 by 2050 relative to 2000. While a cumulative decline in catch potential is projected coastwide (-4.5 to -10.7%), estimates suggest a strong positive correlation between the change in relative catch potential and latitude, with First Nations’ territories along the northern and central coasts of British Columbia likely to experience less severe declines than those to the south. Furthermore, a strong negative correlation is projected between latitude and the number of species exhibiting declining abundance. These trends are shown to be robust to alternative species distribution models. This study concludes by discussing corresponding management challenges that are likely to be encountered under climate change, and by highlighting the value of joint-management frameworks and traditional fisheries management approaches that could aid in offsetting impacts and developing site-specific mitigation and adaptation strategies derived from local fishers’ knowledge.已有研究表明，气候变化引发的海洋物种分布与相对丰度变化，将重塑全球渔业的种群动态及捕捞潜力。尽管现有研究多聚焦大型商业渔业的气候变化影响评估，但针对小型自给型与商业渔业的量化影响预测研究仍较为匮乏——而这类渔业对诸多沿海社区而言，兼具经济、社会与文化价值。本研究采用动态生物气候包络模型（dynamic bioclimate envelope model），针对加拿大不列颠哥伦比亚省沿海地区第一民族（First Nations）兼具商业与文化价值的98种被开发利用的海洋鱼类及无脊椎动物，预测其相对丰度、分布与物种丰富度因气候变化产生的变化情景。在低排放情景（典型浓度路径[RCP] 2.6）与高排放情景（RCP 8.5）下，多数受访物种的丰度预计将出现下降（降幅分别为15.0%至20.8%）；相较于2000年基准，到2050年时物种的分布将以每十年10.3至18.0公里的中位速率向极地迁移。尽管整个沿海区域的捕捞潜力预计将出现累计下降（降幅4.5%至10.7%），但研究结果显示，相对捕捞潜力的变化与纬度之间存在显著正相关：不列颠哥伦比亚省北部与中部沿海的第一民族领地，其捕捞潜力降幅或将低于南部领地。此外，纬度与丰度下降的物种数量之间也存在显著负相关。上述趋势在替换物种分布模型后仍保持稳健。本研究最后讨论了气候变化背景下可能面临的相关渔业管理挑战，并强调了联合管理框架与传统渔业管理手段的价值——这类框架与手段有助于抵消气候变化带来的影响，并基于当地渔民的传统知识制定针对性的减缓与适应策略。