Age and growth of the bigeye tuna, Thunnus obesus, in the western Pacific Ocean
Sun, C.-L.; Huang, C.-L.; Yeh, S.-Z. (2001). Age and growth of the bigeye tuna, Thunnus obesus, in the western Pacific Ocean. Fish. Bull. 99(3): 502-509
In: Fishery Bulletin. US Government Printing Office: Washington, D.C.. ISSN 0090-0656; e-ISSN 1937-4518, more
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| Keywords |
Swordfish
Swordfish
Marine/Coastal |
| Authors | | Top |
- Sun, C.-L.
- Huang, C.-L.
- Yeh, S.-Z.
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| Abstract |
Bigeye tuna (Thunnus obesus) age and growth studies were last conducted in the western Pacific in 1967 and no study has ever attempted to age bigeye tuna from this area by using dorsal spines. The objective of our study was to estimate bigeye tuna age and growth rate in the western Pacific based on counts of growth rings on sections of the first dorsal spine. Length and weight data, and the first dorsal spine from bigeye tuna in the Tungkang (southwest of Taiwan) fish market were collected monthly from February 1997 to January 1998. In total, 1149 specimens were collected. The fork lengths of individuals ranged from 45.6 to 189.2 cm. Cross sections from dorsal spines were taken and examined under a dissecting microscope equipped with an image analysis system. The monthly percentage of specimens having a terminal translucent zone indicated that growth rings formed once a year; therefore, the age of each fish was determined from the number of visible growth rings. Von Bertalanffy growth parameters were estimated for males, females, and both sexes combined. There was no significant difference between males and females. The parameter estimates for the combined sexes were asymptotic length (L-infinity) = 208.7 cm, growth coefficient (K) = 0.201/yr, and age at zero length (t(0)) = -0.9906 yr. |
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