Abstract
The age and growth of the spot-tail shark, Carcharhinus sorrah, were estimated based on 327 specimens (171 females and 156 males) captured by the coastal/offshore longline or drift net fishery in the waters of the Taiwan Strait from October 2010 to December 2011 and July 2019 to August 2021. Sex-specific whole weight (W)—curved total length (TL) relationships were estimated as follows: W = 7.0 × 10−6 TL2.9313 (n = 171, and p < 0.05) for females, and W = 4.0 × 10−6 TL3.0516 (n = 156, and p < 0.05) for males. The periodicity of growth band pair (including translucent and opaque bands) deposition in precaudal vertebrae was assumed to be 1 year based on centrum edge analysis and verified by a statistical analysis. The band pairs after the birth mark were counted as 0–5 and 0–8 for females and males, respectively. The Gompertz and von Bertalanffy growth function best described the observed length-at-age data for females and males, respectively. The parameters for sex-specific growth equations were estimated as: L∞ = 158.6 ± 9.09 cm TL, kG = 0.2347 ± 0.0245 year−1, and c = −0.3233 ± 0.2043 (n = 171, and p < 0.01) for females, and L∞ = 170.2 ± 9.51 cm TL, k = 0.1461 ± 0.0182 year−1, and t0 = −3.1586 ± 0.2065 (n = 156, and p < 0.01) for males.
Highlights
Accepted: 10 March 2022Due to the decline of large shark catch, fishers shifted to targeting median and small sharks in recent years [1,2]
The analysis of covariance (ANCOVA) results indicated that there is no significant difference between males and females in the relationship between total length (TL) and pre-caudal length (PCL) (p > 0.05)
This study provides important information on the age and growth of the spot-tail shark in the waters of the Taiwan Strait, which can fill the research gap and could be used k/kR /kG
Summary
Accepted: 10 March 2022Due to the decline of large shark catch, fishers shifted to targeting median and small sharks in recent years [1,2]. Total annual landings of small sharks (including small/juvenile pelagic and demersal sharks) in Taiwan declined dramatically from 5905 tons in 1993 to 447 tons in 2013 [4], which implies that these stocks have been overexploited in the past two decades as fishing effort did not vary on a large scale. The spot-tail shark, Carcharhinus sorrah (Müller & Henle 1839), is widely distributed in the Indian Ocean and the West Pacific Ocean, from the Red Sea and East Africa to the Philippines and from China and Taiwan to Australian waters [5]. This small requiem species is found in the waters of the continental shelf and coral reefs around Taiwan [6]. It is a common species for local fishery and is caught by the coastal small-scale longline or Published: 12 March 2022
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