Length-frequency yield and biomass per recruit analysis for yellowfin tuna Thunnus albacares (Bonnaterre 1788) in the Arabian Sea off Oman

Abdel-Barr M., . and El-Sayed A., . and Al-Oraimi A., . Length-frequency yield and biomass per recruit analysis for yellowfin tuna Thunnus albacares (Bonnaterre 1788) in the Arabian Sea off Oman. pp. 290-302. ISSN 0116-6514

The present study was carried out to evaluate the stock of Thunnus albacares (Bonnaterre 1788) in the Arabian Sea off Oman. A random sample of 3 690 fish representing a wide range of total lengths (44-156 cm) and weights (3-64 kg) were collected from Al-Sharqya area Oman from January to December 2007. Length-frequency analysis and yield and biomass per recruit models were used. Values of the von Bertalanffy growth parameters fit to size-at-age data were: asymptotic length (L)188.2 cm curvature parameter (K) 0. 33 year-1 and hypothetic age at zero length (t0) 0.66 year. Using the length-converted catch curve total mortality (Z) was estimated as 1.72 year-1. Natural mortality coefficient M was 0.53 year-1 and fishing mortality coefficient F was 1.19 year-1. The mean length at first capture (Lc) estimated from the analysis of probability of capture of each length class was 69.67 cm. The yield per recruit (Y/R) was 8 983 g per recruit(g/r) which is less than the maximum value (9 683 g/r) that could be obtained at a fishing mortality of 0.6 year-1. The biomass per recruit (B/R) represented about 10 of the virgin biomass indicating a state of overexploitation. To increase the Y/R and B/R of T. albacares the results suggest increasing the length at first capture through increasing the mesh size of artisanal gillnets.

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Abstract

The present study was carried out to evaluate the stock of Thunnus albacares (Bonnaterre 1788) in the Arabian Sea off Oman. A random sample of 3 690 fish representing a wide range of total lengths (44-156 cm) and weights (3-64 kg) were collected from Al-Sharqya area Oman from January to December 2007. Length-frequency analysis and yield and biomass per recruit models were used. Values of the von Bertalanffy growth parameters fit to size-at-age data were: asymptotic length (L)188.2 cm curvature parameter (K) 0. 33 year-1 and hypothetic age at zero length (t0) 0.66 year. Using the length-converted catch curve total mortality (Z) was estimated as 1.72 year-1. Natural mortality coefficient M was 0.53 year-1 and fishing mortality coefficient F was 1.19 year-1. The mean length at first capture (Lc) estimated from the analysis of probability of capture of each length class was 69.67 cm. The yield per recruit (Y/R) was 8 983 g per recruit(g/r) which is less than the maximum value (9 683 g/r) that could be obtained at a fishing mortality of 0.6 year-1. The biomass per recruit (B/R) represented about 10 of the virgin biomass indicating a state of overexploitation. To increase the Y/R and B/R of T. albacares the results suggest increasing the length at first capture through increasing the mesh size of artisanal gillnets.

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Item Type:	Article
AGROVOC Term:	Thunnus albacares
AGROVOC Term:	Tuna
AGROVOC Term:	Biomass
AGROVOC Term:	Yields
AGROVOC Term:	Mortality
AGROVOC Term:	Fishing
AGROVOC Term:	Overexploitation
AGROVOC Term:	Gillnets
AGROVOC Term:	Artisanal fisheries
AGROVOC Term:	Catches
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 06:28
URI:	http://webagris.upm.edu.my/id/eprint/23697

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