Age and growth study of striped bonito, Sarda orientalis, in the waters off northeastern Taiwan
Date Issued
2015
Date
2015
Author(s)
Ho, Yu-Hsuan
Abstract
Age and growth of striped bonito, Sarda orientalis, in the waters off northeastern Taiwan were examined based on counts of growth rings in the first dorsal spine, stained vertebra and sectioned sagittal otolith. A total of 195 fish was collected from the catches of set-net, danish seine and longline in Dong’ao, Nanfang’ao and Chenggong fishing ports respectively during December 2013 and November 2014. Body sizes of the collected fish ranged from 30.8 to 80.2 cm in fork length, and 0.42 to 7.69 kg in round weight. The relationship between round weight and fork length was RW = 0.0128 × FL3.0406 with r2 = 0.9729. In the preliminary tryout, the first dorsal spine was discarded due to serious vascularization, and the growth parameters estimated using stained vertebra had big bias owing to the lack of daily increments, thus, the sagittal otolith were used for age determination throughout this study. Daily increments on sectioned sagittal otolith were read for fish younger than 1 year while annuli were read for fish older than 1 year old. The numbers of daily increments ranged from 113 days to 451 days, with the average percent error (APE) of 0.81% and coefficient of variation (CV) of 1.05%. For the numbers of annuli ranged from 1 to 5 rings, the precision was 5.30% in APE and 7.13% in CV. The length of fish that reached 1 year old was around 54 cm in fork length. All data were separated at 245 days into two groups for fitting Gompertz growth function and von Bertalanffy growth function, respectively. The Gompertz growth function fitted the fish younger than 245 days was Lt = 61.189 × e(– e -2.909(t -0.181)); the von Bertalanffy growth function fitted the fish older than 245 days was Lt = 84.015 × (1 – e -0.322(t + 2.074)). Back-calculated hatching dates span from January through June closing to the spawning season estimated by reproductive biology study of striped bonito in the waters off northeastern Taiwan.
Subjects
striped bonito
age and growth
otolith
rings
growth functions
Type
thesis
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