Performance comparison between logistic and generalized surplus-production models applied to the Sillago sihama fishery in Pakistan

Autor: Shabir Ali Amir, Muhsan Ali Kalhoro, Qun Liu, Sher Khan Panhwar
Rok vydání: 2012
Předmět:
Zdroj: Journal of Ocean University of China. 11:401-407
ISSN: 1993-5021
1672-5182
Popis: The catch and effort data of Sillago sihama fishery in Pakistani waters were used to investigate the performance of two closely related stock assessment models: logistic and generalized surplus-production models. Compared with the generalized production model, the logistic model produced more reasonable estimates for parameters such as maximum sustainable yield. The Akaike’s Information Criterion values estimated at 4.265 and −51.152 respectively by the logistic and generalized models. Simulation analyses of the S. sihama fishery showed that the estimated and observed abundance indices for the logistic model were closer than those for the generalized production model. Standardized residuals were distributed closer for logistic model, but exhibited a slightly increasing trend for the generalized model. Statistical outliers were seen in 1989 and 1993 for the logistic model, and in 1981 and 1999 for the generalized model. Simulated results revealed that the logistic estimates were close to the true value for low CVs (coefficients of variation) but widely dispersed for high CVs. In contrast, the generalized model estimates were loose for all CV levels. The estimated production model curve parameter ϕ was not reasonable at all the tested levels of white noise. With the increase in white noise R2 for the catch per unit effort decreased. Therefore, we conclude that the logistic model performs more reasonably than the generalized production model.
Databáze: OpenAIRE
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