Artículos de revistas
Improving estimates of recruitment and catchability of Jumbo squid Dosidicus gigas in the Gulf of California
Fecha
2008Autor
Morales Bojorquez, Enrique
Hernández Herrera, Agustin
Cisneros Mata, M. A.
Nevarez Martinez, M. O.
Institución
Resumen
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.