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Reduced body weight of Pacific saury (Cololabis saira) causes delayed initiation of spawning migration
Fisheries Oceanography ( IF 2.6 ) Pub Date : 2022-03-08 , DOI: 10.1111/fog.12579
Shigeho Kakehi 1 , Midori Hashimoto 2 , Miyako Naya 3 , Shin‐ichi Ito 4 , Hiroomi Miyamoto 3 , Satoshi Suyama 3
Affiliation  

The fishing grounds of the Pacific saury began shifting eastward after 2013 and deviated further east in 2019 and 2020. Consequently, the migration pattern from the pre-fishing distribution to fishing grounds may be changing. This study investigated inter-annual variations in westward spawning migration parameters using a migration model. Case studies were conducted to estimate optimal values for the initiation date of spawning migration and migration speed during spawning migration. The estimated optimal initiation date of spawning migration from 2003 to 2018 was July 13 to August 8, with an average of July 31. However, in 2019 and 2020, the initiation date of spawning migration was August 22 and September 5, respectively, significantly later than that in 2003–2018 (p < .01). The estimated optimal swimming speed during spawning migration in 2019 and 2020 was not significantly different from that in 2003–2018 (p > .7). These results indicate that delays in the initiation of spawning migration occurred in 2019 and 2020, leading to an eastward shift of fishing grounds. The mean body weight of the age-1 Pacific saury in the pre-fishing season had a significant negative correlation (p < .01) with the initiation date of spawning migration. This result suggests that Pacific saury with low body weight continues to feed for growth instead of initiating spawning migration. However, body weight at initiation of spawning migration had a significant decreasing trend (p < .01), indicating that the Pacific saury had to start spawning migration despite low body weight in recent years.

中文翻译:

秋刀鱼 (Cololabis saira) 体重减轻导致产卵洄游开始延迟

太平洋秋刀鱼的渔场从 2013 年以后开始东移,并在 2019 年和 2020 年进一步向东偏移。因此,从捕捞前分布到渔场的迁徙模式可能正在发生变化。本研究使用迁移模型调查了向西产卵迁移参数的年际变化。进行案例研究以估计产卵迁徙开始日期和产卵迁徙期间迁徙速度的最佳值。2003年至2018年产卵洄游的最佳起始日估计为7月13日至8月8日,平均为7月31日。然而,2019年和2020年,产卵洄游的起始日分别为8月22日和9月5日,明显较晚高于 2003-2018 年 ( p < .01)。2019年和2020年产卵洄游期间估计的最佳游泳速度与2003-2018年没有显着差异(p  >.7)。这些结果表明,2019年和2020年产卵洄游开始延迟,导致渔场东移。1龄秋刀鱼在捕捞前的平均体重与产卵洄游开始日期呈显着负相关( p  < .01)。这一结果表明,体重较轻的秋刀鱼继续以生长为食,而不是开始产卵迁徙。然而,产卵迁移开始时的体重有显着下降的趋势(p < .01),这表明尽管近年来秋刀鱼体重较低,但它不得不开始产卵迁徙。
更新日期:2022-03-08
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