Stochastic estimation of the catchability and recruitment of the jumbo squid Dosidicus gigas (D'Orbigny, 1835) Of The Gulf Of California, Mexico

In this paper a depletion model with two different approaches (stochastic and deterministic) was analyzed, in order to compare the observation error hypothesis in the catch-per-unit effort (CPUE) data, and the process error in the model, as well as its effect on the recruitment and catchability estimates in the jumbo squid fishery from the Gulf of California, Mexico. Results showed an underestimation of the catchability (q) when the deterministic aproach was used. The observation error showed a bias in q (+31%) higher than in recruitment (+8%), while a Monte Carlo simulation estimated a negative bias for q, and a positive bias in recruitment. The computation of the expected value of catchability ( E(ˆqCPUE/Ci)) was 2.8 × 10–4, while the confidence intervals with the deterministic model were 3.3 × 10–4 < q < 4.1 × 10–4, showing that the estimate of E(ˆqCPUE/Ci) was not within these confidence intervals.  E(ˆqCPUE/Ci) fitted the model to the data, describing the trend of the CPUE index in time, and its implications in the management of the jumbo squid fishery

Overlap in the type and size of the prey that compose the diet of the pacific sardine Sardinops caeruleus (Girard, 1856), thread herring Opisthonema libertate (Gunther, 1867) and northern anchovy Engraulis mordax (Girard, 1856) in the Gulf of California

We present the results of the analysis of overlap in the diet of the Pacific sardine Sardinops caeruleus, the northern anchovy Engraulis mordax and the thread herring Opisthonema libertate. These are the most commercially important species of small pelagic fishes in the fishery that is developed in the Gulf of California. Although the diet of these species is very similar, the overlap is only significant between the northern anchovy and the thread herring. As these two species do not overlap spatially in the Gulf of California, the possibility of competition for food between them is considered unlikely