Estimation of mean annual natural mortality for adult male snow crab Chionoecetes opilio in the southern Gulf of St. Lawrence : Estimation du taux de mortalité naturelle chez les males adultes du crabe des neiges Chionoecetes opilio dans le sud du golfe Saint-Laurent

The central interest of the present paper is to obtain a reasonable estimate of the mean annual instantaneous natural mortality rate in the sGSL (referred to as natural mortality hereafter). [...] One is the mortality rate term M. and the other is the catchability coefficient of the catch gear relative to the trawl, denoted q. (2). [...] The means of the variables were those found by the methods described above and the variances were the kriging variances obtained from analysis of the survey data and the error estimates for the catch data. [...] The data model is incorporated into the analysis via the likelihood function, which is a probability distribution of the data given the parameters (Efron, 1986). [...] Simulation with NLLS Results from the regressions based on the simulation approach are summarized in Table 3. The 95% CI for the M estimates in the sGSL using model I ranged from 0.15 to 0.39 with a mid value of 0.27, while assuming a constant catchability of 1. Model II results showed that for the whole sGSL, the mean M was 0.48 with a 95% CI ranging from 0.15 to 0.82, while the mean value of q w