title: Weight-length relationships and Fulton's condition factors of skipjack tuna (Katsuwonus pelamis) in the western and central Pacific Ocean.
abstract: This paper describes the weight-length relationships (WLRs) and Fulton's condition factors (K) of skipjack tuna (Katsuwonus pelamis) in purse seine fisheries from three cruises in the western and central Pacific Ocean (WCPO): August-September 2009 (AS09), November-December 2012 (ND12), and June-July 2013 (JJ13). The fork length and weight of a total of 1678 specimens were measured. The results showed that the fork length of more than 70% of specimens was below 60 cm (76% in AS09, 87% in ND12, and 73% in JJ13). The coefficient b in the combined sex group was 3.367, 3.300 and 3.234 in JJ13, AS09 and ND12, respectively. The b values of WLRs when fork length was >60 cm were significantly less than 3 (P = 0.062), but when fork length was <60 cm they were significantly greater than 3 (P = 0.028). The K value ranges of JJ13, AS09 and ND12 in different fork length groups were 1.3-1.84 (1.62 ± 0.18), 1.57-2.02 (1.86 ± 0.15), and 1.44-1.78 (0.65 ± 0.13), respectively. Moreover, K values in different fork length classes for each cruise had one turning point: 60-65 cm for JJ13; 60-65 cm for ND12; and 55-60 cm for AS09. The results of this study provide basic information on the WLRs and K values of skipjack tuna in different seasons and growth phases in the WCPO, which are useful for fishery biologists and fishery managers.
authors.affiliation: Key Laboratory of Regional Climate-Environment for Temperate East Asia (RCE-TEA), Chinese Academy of Sciences , Beijing , China ; University of Chinese Academy of Sciences , Beijing , China ; Key Laboratory of East China Sea & Oceanic Fishery Resources Exploitation and Utilization, Ministry of Agriculture, P. R. China (East China Sea fisheries Research Institute, Chinese Academy of Fishery Sciences) , Shanghai , China.
authors.forename: Shaofei
authors.initials: S
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University , Beijing , China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Yan
authors.affiliation: Key Laboratory of East China Sea & Oceanic Fishery Resources Exploitation and Utilization, Ministry of Agriculture, P. R. China (East China Sea fisheries Research Institute, Chinese Academy of Fishery Sciences) , Shanghai , China.
authors.forename: Heng
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Key Laboratory of East China Sea & Oceanic Fishery Resources Exploitation and Utilization, Ministry of Agriculture, P. R. China (East China Sea fisheries Research Institute, Chinese Academy of Fishery Sciences) , Shanghai , China.
authors.forename: Wei
authors.initials: W
authors.lastname: Fan
keywords: Condition factor; Purse seine fishery; Skipjack tuna; Weight–length relationship; Western and central Pacific Ocean