摘要
The Japanese common squid Todarodes pacificus is an economically important species with one year lifespan,which is significantly influenced by climatic and environmental variability. According to the fishery data of the winter cohort of T. pacificus from 2003 to 2012, as well as environmental data and the Oceanic Ni？o index（ONI,which was defined by the sea surface temperature（SST） anomaly in the Ni？o 3.4 region）, variations in the SST,chlorophyll a（Chl a） concentration, suitable spawning area（SSA） and sea surface height anomaly（SSHA） on the spawning ground of T. pacificus were examined under the El Ni？o and La Nina conditions. Their influences on squid abundance（defined by catch per unit effort, CPUE） were further assessed. The results showed that seasonal changes were found in SST, Chl a and SSA on the spawning ground of T. pacificus. Correlation analysis suggested that annual CPUE was significantly positively correlated with Chl a and SSA（p〈0.05）, but had insignificant relationship with SST（p〉0.05）. Moreover, the El Ni？o and La Ni？a events tended to dominate the changes of SSA and Chl a concentration in the key area between 25°–29°N and 122.5°–130.5°E, driving the variability of squid abundance. However, this influence varied with the intensity of each anomalous climatic event： the weak El Ni？o event occurred, the spawning ground was occupied by waters with enlarged SSA but with extremely low Chl a concentration, leading to low squid recruitment, the CPUE then decreased; the moderate intensity of El Ni？o event resulted in shrunk SSA but with high Chl a concentration on the spawning ground, the squid recruitment and CPUE increased; the moderate intensity of La Ni？a events yielded elevated SSA and high Chl a concentration on the spawning ground, the squid recruitment and CPUE dramatically increased. Our findings suggested that the ENSO events played crucial effects on the incubating and feeding conditions of the winter cohort of T. pacificus during the spawning season and ultimately affected its abundance.
The Japanese common squid Todarodes pacificus is an economically important species with one year lifespan,which is significantly influenced by climatic and environmental variability. According to the fishery data of the winter cohort of T. pacificus from 2003 to 2012, as well as environmental data and the Oceanic Ni？o index（ONI,which was defined by the sea surface temperature（SST） anomaly in the Ni？o 3.4 region）, variations in the SST,chlorophyll a（Chl a） concentration, suitable spawning area（SSA） and sea surface height anomaly（SSHA） on the spawning ground of T. pacificus were examined under the El Ni？o and La Nina conditions. Their influences on squid abundance（defined by catch per unit effort, CPUE） were further assessed. The results showed that seasonal changes were found in SST, Chl a and SSA on the spawning ground of T. pacificus. Correlation analysis suggested that annual CPUE was significantly positively correlated with Chl a and SSA（p〈0.05）, but had insignificant relationship with SST（p〉0.05）. Moreover, the El Ni？o and La Ni？a events tended to dominate the changes of SSA and Chl a concentration in the key area between 25°–29°N and 122.5°–130.5°E, driving the variability of squid abundance. However, this influence varied with the intensity of each anomalous climatic event： the weak El Ni？o event occurred, the spawning ground was occupied by waters with enlarged SSA but with extremely low Chl a concentration, leading to low squid recruitment, the CPUE then decreased; the moderate intensity of El Ni？o event resulted in shrunk SSA but with high Chl a concentration on the spawning ground, the squid recruitment and CPUE increased; the moderate intensity of La Ni？a events yielded elevated SSA and high Chl a concentration on the spawning ground, the squid recruitment and CPUE dramatically increased. Our findings suggested that the ENSO events played crucial effects on the incubating and feeding conditions of the winter cohort of T. pacificus during the spawning season and ultimately affected its abundance.
基金
China Postdoctoral Science Foundation under contract No.2017M611612
the National Key Technologies R&D Program of China under contract No.2013BAD13B01
the Doctoral Startup Scientific Research Foundation of Shanghai Ocean University under contract No.A2-0203-17-100313
the Open Fund for Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources under contract No.A1-0203-00-2009-5
the Shanghai Universities First-Class Disciplines Project(Fisheries A)
