Improving estimates of recruitment and catchability of Jumbo squid Dosidicus gigas in the Gulf of California
We analyzed the effect of outliers of the catch-per-unit effort on the catchability coefficient estimated by using a depletion model. When we used catch-per-unit effort in the Delury model, we observed a curve in the regression of depletion against time. When we then solved the model with a normal p...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2008 |
| País: | México |
| Institución: | Instituto Politécnico Nacional |
| Repositorio: | Repositorio Digital del IPN |
| OAI Identifier: | oai:www.repositoriodigital.ipn.mx:123456789/13309 |
| Acceso en línea: | http://www.repositoriodigital.ipn.mx/handle/123456789/13309 |
| Access Level: | acceso abierto |
| Palabra clave: | Management catchability depletion model Recruitment Dosidicus gigas outliers squid |
| Sumario: | We analyzed the effect of outliers of the catch-per-unit effort on the catchability coefficient estimated by using a depletion model. When we used catch-per-unit effort in the Delury model, we observed a curve in the regression of depletion against time. When we then solved the model with a normal probability distribution, the catchability coefficient was poorly estimated. We improved the estimation of catchability using an algorithm that used a two-component-mixture probability distribution. The estimations for catchability (q) and recruitment (N0) were q = 0.41 X 10–3, N0 = 9.13 X 106, and the estimated likelihood was 2.65 X 104 using an algorithm of the normal probability distribution, whereas the estimations made using the algorithm of a two-component-mixture probability distribution were q = 0.23 X 10–3, N0 = 18.07 X 106, and the estimated likelihood was 4.89 X 106. The maximum likelihood estimated with the mixture-distribution algorithm was greater than the maximum likelihood estimated with the normal-distribution algorithm. We believe the two-component-mixture probability distribution fit the data better than the normal probability distribution. From this we determined the consequences on management when overestimations or underestimations of catchability are estimated. |
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