Lekanda Aitor, Boyra Guillermo, Handegard Nils Olav, Chust Guillem, Cotano Unai, Aldanondo Naroa, Astarloa Amaia, Iglesias Beñat, Rubio Anna, Louzao Maite
AZTI, Marine Research Division, Basque Research and Technology Alliance (BRTA), Txatxarramendi Ugartea z/g, 48395, Sukarrieta, Spain.
AZTI, Marine Research Division, Basque Research and Technology Alliance (BRTA), Herrera kaia, Portualdea z/g, 20110, Pasaia, Spain.
Mar Environ Res. 2025 Sep;210:107243. doi: 10.1016/j.marenvres.2025.107243. Epub 2025 May 23.
Small pelagic fish play a vital role in pelagic ecosystems and global fisheries, but their aggregative behavior poses challenges for accurate assessments. While the basic functions of schooling-defense, foraging, migrating and mating-are well-documented, the dynamics and variability of these aggregations are less well understood. This study analyzes data from the JUVENA survey (2013-2020) in the Bay of Biscay, examining 54,240 schools from 158 daytime fishing hauls. We analyzed the effect of local biomass fluctuations, dolphin density, planktivorous competition, euphotic zone depth, phytoplankton concentration, and geostrophic velocity on school size, packing density, and number for European anchovy (juvenile and adult), European sardine, and Muller's pearlside. Results indicated that changes in packing density and the number of schools are positively correlated with local biomass fluctuations, while school size is more significantly influenced by interspecies interactions and environmental conditions. The schooling behavior of juvenile anchovy is mainly density-dependent. In contrast, adult anchovy, sardine, and Muller's pearlside form smaller and more numerous schools under competitive or low food availability conditions offshore, and larger, denser, but fewer schools in low visibility coastal areas with high predator density as a defensive strategy. This study advances our understanding of the primary drivers of small pelagic fish schooling behavior in the Bay of Biscay, providing insights for effective management.
小型中上层鱼类在中上层生态系统和全球渔业中发挥着至关重要的作用，但其聚集行为给准确评估带来了挑战。虽然集群的基本功能——防御、觅食、洄游和交配——已有充分记录，但这些聚集的动态变化和变异性却鲜为人知。本研究分析了比斯开湾JUVENA调查（2013 - 2020年）的数据，研究了158次白天捕鱼作业中的54,240个鱼群。我们分析了当地生物量波动、海豚密度、浮游生物竞争、真光层深度、浮游植物浓度和地转速度对欧洲鳀（幼鱼和成鱼）、欧洲沙丁鱼和穆勒氏珍珠鱼的鱼群大小、聚集密度和数量的影响。结果表明，聚集密度和鱼群数量的变化与当地生物量波动呈正相关，而鱼群大小受种间相互作用和环境条件的影响更为显著。幼鳀的集群行为主要取决于密度。相比之下，成年鳀、沙丁鱼和穆勒氏珍珠鱼在近海竞争或食物供应不足的条件下会形成更小、更多的鱼群，而在捕食者密度高、能见度低的沿海地区，为了防御会形成更大、更密集但数量更少的鱼群。本研究增进了我们对比斯开湾小型中上层鱼类集群行为主要驱动因素的理解，为有效管理提供了见解。
