Temporal variations in hatch date and early survival of Japanese anchovy ( Engraulis japonicus ) in response to environmental factors in the central Seto Inland Sea, Japan
Temporal variations in hatch date and early survival of Japanese anchovy ( Engraulis japonicus ) in response to environmental factors in the central Seto Inland Sea, Japan
复制标题
日本濑户内海中部日本鳀鱼（Engraulis japonicus）孵化日期和早期存活率随环境因素的变化
DOI：
10.1111/fog.12535
复制
发表时间：
2021
影响因子：
2.6
通讯作者：
Yoneda Michio
中科院分区：
文献类型：
--
作者：
Fujita Tatsunori;Yamamoto Masayuki;Kono Naoaki;Tomiyama Takeshi;Sugimatsu Koichi;Yoneda Michio
繁殖成功可能受到产卵季节与幼虫生存的最佳环境条件之间的匹配或不匹配的影响。然而，了解时间因素如何影响种群动态具有挑战性。在日本西部濑户内海中部的 Hiuchi-nada，日本鳀鱼 (Engraulis japonicus) 的捕捞量在过去十年中显着减少。为了探究这种下降的原因，我们利用 1994 年至 2019 年（26 年）4 月至 8 月的鸡蛋调查和商业捕捞数据来检查鸡蛋产量、孵化日期和早期存活率与环境因素的关系。耳石微观结构分析表明，大多数上岸幼鱼和幼鱼（新鱼）在五月和六月孵化。在研究期间，卵和新招募的丰度呈负相关。直到 2000 年代中期，在特定季节 16-24°C 的水域中，从孵化到补充的存活指数较高。此后，它们在研究的温度范围内下降，并在过去五年中保持相对较低的水平。 2015-2019年桡足类无节幼体密度显着高于2002-2005年，可能是由于气温升高的影响，但2015-2019年5月和6月桡足类无节幼体密度与幼体密度的比值分别约为2002-2005年的34%和66%。这些发现和这些水域的水动力特征表明，最近新招募丰度的下降部分是由于幼虫存活率下降，这是由于生命早期阶段群体内对猎物的竞争加剧所致。
Reproductive success can be influenced by the match or mismatch between the spawning season and optimal environmental conditions for larval survival. However, it is challenging to understand how temporal factors affect population dynamics. In the central Seto Inland Sea, Hiuchi‐nada, western Japan, the recruitment of Japanese anchovy (Engraulis japonicus) has markedly decreased in the last decade. To explore the causes of this decline, egg survey and commercial catch data from 1994 to 2019 (26 years) between April and August were used to examine egg production, hatch date, and early survival in relation to environmental factors. Otolith microstructure analysis indicated that most landed larval and juvenile fish (recruits) hatched in May and June. Egg and recruit abundances were negatively correlated over the study period. The survival indices from hatching to recruitment were higher in waters at 16–24°C in a given season until the mid‐2000s. Thereafter, they decreased over the studied temperature range and remained relatively low over the last five years. The copepod nauplii densities from 2015 to 2019 were significantly higher than those from 2002 to 2005 due possibly to the effect of increasing temperature, but the ratio of copepod nauplii density to larval density in May and June from 2015 to 2019 was approximately 34% and 66% of those from 2002 to 2005, respectively. These findings and the hydrodynamic features of these waters suggest that the recent decline in recruit abundance is partly due to a decrease in larval survival in response to increasing intracohort competition for prey in early‐life stages.