Stock assessment by larval surveys of the winter population of Todarodes pacificus Steenstrup (Cephalopoda: Ommastrephidae), with a review of early works
Stock assessment by larval surveys of the winter population of Todarodes pacificus Steenstrup (Cephalopoda: Ommastrephidae), with a review of early works
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通过对 Todarodes pacificus Steenstrup（头足类：Ommastrephidae）冬季种群幼虫调查进行种群评估，并对早期作品进行回顾
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
Taisuke Watanabe
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作者：
T. Okutani;Taisuke Watanabe
本文根据日本“Soyo-Maru”号考察船1959-1976年1 - 3月在九州南部至本州中东部太平洋沿岸海域进行的浮游生物网采，对日本太平洋柔鱼（Todarodes pacificus Steenstrup）冬季种群的幼虫丰度和分布格局进行了研究。幼虫丰度指数（LI）进行了比较与CPUE（每船日渔获量），成年股票大小的招聘指数。
这一种群的主要产卵场位于九州西南部。幼虫（rhynchoteuthion）的生长，而他们的平流黑潮向东北方向。因此，早期幼虫在西部更丰富，而晚期幼虫在东部更丰富。死亡率似乎是最高的阶段高达几毫米DML比后期阶段。
太平洋冬季种群的存量规模波动很大。它从1960年的高峰期下降到非常低的水平。股票规模的减少分三个阶段进行。
1960-1963年：虽然1960年级的种群规模（CPUE）很大，但该年级产生的幼虫种群（LI）非常低，导致随后几年的补充量（CPUE）下降。
1964-1969年：1964年的幼虫丰度是第二高的（仅次于1960年），但招募量非常低，可能是因为在幼虫和高级阶段之间的生存条件不利。这一失败导致1965年和随后年份的幼虫丰度进一步下降。
1970-1976年：幼虫数量仍然很低，CPUE自1970年以来有所下降。
由于短寿命（一年）的这种鱿鱼，突然减少的幼虫丰度和/或招聘有一个严重的影响股票大小。种群的未来恢复将取决于有利于九州南部早期阶段生存的生物和物理条件。
成鱼单位努力量渔获量与次年幼虫丰度之间的显著正相关表明，幼虫丰度可用于评估中华绒螯蟹冬季种群的产卵群大小。太平洋。
This is a study of larval abundance and distributional pattern of the winter population of the Japanese common squid, Todarodes pacificus Steenstrup, based on plankton net collections made by the R/V Soyo-Maru during January to March (1959–1976) in the seas extending from the south of Kyushu to the Pacific coast of central and eastern Honshu. The larval abundance index (LI) was compared with CPUE (catch per boat day), an index of recruitment of adult stock size.
The main spawning ground of this population is located to the southwest of Kyushu. The larvae (rhynchoteuthion) grow while they are advected by the Kuroshio Current to the northeast. Hence early larvae are more abundant in the west, while advanced larvae are more abundant in the east. Mortality seems to be highest for stages up to several millimeters DML than for later stages.
The stock size of the Pacific winter population has fluctuated greatly. It declined since the peak 1960 year class to very low levels. The decrease of the stock size took place in three phases.
1960–1963: While the stock size (CPUE) of the 1960 year class was large, the larval population (LI) produced by this year class was very low, resulting in a decrease of recruitment (CPUE) in following years.
1964–1969: The larval abundance for the 1964 year class was second highest (next to 1960) but the recruitment was remarkably low, probably because of unfavorable conditions for survival during the period between larval and advanced stages. This failure caused a further decrease of larval abundance for the 1965 and subsequent year classes.
1970–1976: The larval abundance remains at a very low level and CPUE has declined since 1970.
Because of the short life-span (one year) of this squid, abrupt decreases of larval abundance and/or recruitment have a serious effect on stock size. The future recovery of the stock will depend on biotic and physical conditions that are favorable for the survival of early stages south of Kyushu.
A significant positive correlation between catch per effort of adults and the abundance of larvae (LI) in the following year indicates that larval abundance can be used to assess the size of the spawning stock of the winter population of T. pacificas.