scholarly journals Combining Weight-Length Relationships and condition factors to estimate the population structure for Skipjack tuna in the Western and Central Pacific Ocean

2014 ◽  
Author(s):  
Shaofei Jin ◽  
Xiaodong Yan ◽  
Heng Zhang ◽  
Wei Fan
Keyword(s):  
Population Structure ◽  
Pacific Ocean ◽  
Fork Length ◽  
Skipjack Tuna ◽  
Growth Phases ◽  
Central Pacific ◽  
Katsuwonus Pelamis ◽  
Central Pacific Ocean ◽  
Length Relationship ◽  
June July

The arguments between Weight-Length Relationship (WLR) and Condition Factor (K) have been lasted since the day they occurred. This paper described WLRs and Ks of Skipjack tuna (Katsuwonus pelamis) samples in Purse Seine fisheries from three cruises (August-September cruise (A-S) in 2009, November-December cruise (N-D) in 2012, and June-July cruise (J-J) in 2013) in the Central and Western Pacific Ocean (CWPO). The results showed that fork length of more than 70% of specimen was below 60 cm (76% in A-S, 87% in N-D, and 73% in J-J). b values of WLRs in class of fork length > 60cm were below 3 significantly (P = 0.062), while b values when fork length < 60 cm were > 3 significantly (P = 0.028). Moreover, K values in different fork length classes for each cruises had one turning point: 60-65cm for J-J, 60-65cm for N-D, and 55-60cm for A-S, and K values were still significantly larger than those of fork length < 40cm (P = 0.06). However, b values at larger fishes were significantly smaller than those of fork length <40cm. We suggest to combine WLRs and K values at different growth phases for evaluating population structure for skipjack tuna.

scholarly journals Combining Weight-Length Relationships and condition factors to estimate the population structure for Skipjack tuna in the Western and Central Pacific Ocean

2014 ◽  
Author(s):  
Shaofei Jin ◽  
Xiaodong Yan ◽  
Heng Zhang ◽  
Wei Fan
Keyword(s):  
Population Structure ◽  
Pacific Ocean ◽  
Fork Length ◽  
Skipjack Tuna ◽  
Growth Phases ◽  
Central Pacific ◽  
Katsuwonus Pelamis ◽  
Central Pacific Ocean ◽  
Length Relationship ◽  
June July

The arguments between Weight-Length Relationship (WLR) and Condition Factor (K) have been lasted since the day they occurred. This paper described WLRs and Ks of Skipjack tuna (Katsuwonus pelamis) samples in Purse Seine fisheries from three cruises (August-September cruise (A-S) in 2009, November-December cruise (N-D) in 2012, and June-July cruise (J-J) in 2013) in the Central and Western Pacific Ocean (CWPO). The results showed that fork length of more than 70% of specimen was below 60 cm (76% in A-S, 87% in N-D, and 73% in J-J). b values of WLRs in class of fork length > 60cm were below 3 significantly (P = 0.062), while b values when fork length < 60 cm were > 3 significantly (P = 0.028). Moreover, K values in different fork length classes for each cruises had one turning point: 60-65cm for J-J, 60-65cm for N-D, and 55-60cm for A-S, and K values were still significantly larger than those of fork length < 40cm (P = 0.06). However, b values at larger fishes were significantly smaller than those of fork length <40cm. We suggest to combine WLRs and K values at different growth phases for evaluating population structure for skipjack tuna.

Reproductive biology of male skipjack tuna Katsuwonus pelamis (Linnaeus) in the tropical western and central Pacific Ocean

2010 ◽  
Vol 76 (5) ◽  
pp. 785-793 ◽  
Author(s):  
Hiroshi Ashida ◽  
Toshiyuki Tanabe ◽  
Keisuke Satoh ◽  
Atsushi Fukui ◽  
Sho Tanaka ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Reproductive Biology ◽  
Skipjack Tuna ◽  
Central Pacific ◽  
Katsuwonus Pelamis ◽  
Central Pacific Ocean

scholarly journals Spawning frequency and batch fecundity of skipjack tuna Katsuwonus pelamis in the tropical west-central Pacific Ocean

2008 ◽  
Vol 74 (5) ◽  
pp. 802-808 ◽  
Author(s):  
HIROSHI ASHIDA ◽  
TOSHIYUKI TANABE ◽  
NOBUHIRO SUZUKI ◽  
ATSUSHI FUKUI ◽  
SHO TANAKA
Keyword(s):  
Pacific Ocean ◽  
Skipjack Tuna ◽  
Batch Fecundity ◽  
Central Pacific ◽  
Katsuwonus Pelamis ◽  
Central Pacific Ocean ◽  
Spawning Frequency ◽  
West Central

scholarly journals A Bayesian Multilevel Ordinal Regression Model for Fish Maturity Data: Difference in Maturity Ogives of Skipjack Tuna (Katsuwonus pelamis) Between Schools in the Western and Central Pacific Ocean

2021 ◽  
Vol 8 ◽  
Author(s):  
Jie Cao ◽  
Xuefang Wang ◽  
Matthew D. Damiano ◽  
Cheng Zhou ◽  
Jiangfeng Zhu
Keyword(s):  
Pacific Ocean ◽  
Ordinal Data ◽  
Gonadosomatic Index ◽  
Fork Length ◽  
Ordinal Regression ◽  
Maturity Stage ◽  
Skipjack Tuna ◽  
Central Pacific ◽  
Free Swimming ◽  
Central Pacific Ocean

The maturity ogive is vital to defining the fraction of a population capable of reproduction. In this study, we proposed a novel approach, a Bayesian multilevel ordinal regression (i.e., Bayesian continuation ratio model), to model the maturity ogive. The model assumes that the observed maturity stage originates from the categorization of latent continuous variables. We demonstrated this approach by testing whether there are differences in the maturity ogive of skipjack tuna (Katsuonus pelamis) in the western and central Pacific Ocean between two school types, i.e., free-swimming and floating-object-associated schools. The model results show that K. pelamis, given the same fork length, are more likely to have a higher maturity stage in a free-swimming school than those associated with floating objects. The gonadosomatic index revealed the same conclusion. Our results indicate that fish aggregation devices (FADs) could negatively affect the maturity of K. pelamis and consequently reduce the population reproductive potential. This study provides (1) an alternative approach to analyze fisheries ordinal data; (2) important quantitative evidence to evaluate the existing ecological hypotheses; and (3) implications for tuna fisheries management.

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