The Fourth International Stock Enhancement & Searanching

Poster Abstract

18. COMPARISON OF THE CAPTURE COMPOSITION IN NORTHWEST PACIFIC OCEAN IN DIFFERENT YEARS


LI Jian-Hua1, CHEN Xin-Jun1, 2, 3, LIU Bi-Lin1, 2, 3
1 College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China
2 The Key Laboratory of Oceanic fisheries resources exploitation of Shanghai education commission, Shanghai Ocean University, Shanghai 201306, China
3 The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Shanghai Ocean University, Ministry of Education, Shanghai 201306, China

Based on the samples from Chinese squid jigging vessels in the area of Northwest Pacific in 2007 and 2009, the annual biological characteristics of squid Omneaslrephes bartrami were studied and compared. The results showed that average mental length of male was smaller than female’s, the dominant group were 230-320mm and 200-320mm in male and female respectively, and the proportion of large individuals in 2009 was smaller than 2007.The sex ratio of female to male was nearly to 1:1.There were significant difference of relationship between mantle length and body weight in different sexes and years(P < 0.001). The squid maturity stage had no distinct difference between the two years, and dominant stage was and . Sex maturation of females was later than males and the proportion of matured individuals in 2007 was higher than 2009 both in male and female. The length and weight of indumenta gland of the squid were increased with development of the gland. The mantle length of first maturity were 337.02mm and 303.01mm for female and male respectively in 2007, while in 2009, the mantle length of first maturity for female was350-380mm which is similar to that of 2007, and that for male was less than 200mm, which is smaller than that of 2007. In conclusion, there were two cohorts in 2007 and 2009 in Northwest Pacific Ocean, Small population(S) and large population (L); there was an unusual cold water to south in the deep water of Northwest Pacific Ocean lead to the difference with 2007 in cohort.

Keywords: Omneaslrephes bartrami; Northwest Pacific Ocean; biological characteristics; inter-annual variations