Estimate of reproductive value of the big eye Priacanthus macracanthus
in the north-eastern waters off Taiwan |
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| Authors: | Kwang-Ming LIU Kuo-Yau HUNG AND Shoou-Jeng JOUNG |
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| Institution: | Department of Fishery Science, National Taiwan Ocean University, Keelung 202, Taiwan |
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| Abstract: | ABSTRACT: The reproductive value and population status of the big eye in the north-eastern Taiwan waters was estimated by demographic analysis using available life-history parameters. Life-history tables were constructed using estimates of natural mortality ( M ) of 10.4920/year for age 0 and 0.3256/year for ages 1–9, with a maximum age of 9. Age-specific batch fecundity ( Fe ) was from Fe = 1391.34e0.1782 FL . The age-specific proportion of maturity was estimated from the relationship between the proportion of female maturity ( Pr ) and fork length ( FL ): Pr = 1/(1 + e15.081?0.796 FL ). Females mature at age 3 and mature females reproduce every year. The population increase rate (λ) was estimated to be 20.5% per year and the generation time ( G ) was 6.25 years without exploitation. The net reproductive value ( R0 ), generation time and intrinsic rate of natural increase ( r ) decreased with increased fishing mortality. For fixed fishing mortality, when F = 1.2/year and fishing started at age 3, R0 was estimated to be 1.0 and the population was considered to be in equilibrium. For age-specific fishing mortality, when fishing started at age 3, R0 was estimated to be 0.96/year, G being 6.18 years, and the population decreased 0.7% per year. The big eye population had a strong resilience as long as F < = 1.3/year started at an age that was older than the age at maturity (i.e. 3 years old) but would decline when intensive fishing ( F > = 1.2/year) started at age 2 or younger. Sensitivity analysis indicated that the mortality of age 0 is the most sensitive parameter in demographic analysis. |
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| Keywords: | demographic analysis fecundity north-eastern Taiwan Priacanthus macracanthus reproductive value |
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