This study analyzed the interannual changes in the fraction of female brown shrimp Farfantepenaeus californiensis that were mature by assessing the performance of a 3-parameter versus a 2-parameter logistic model of maturity at length and the effect on the magnitude of length at first maturity (L50). Shrimp biological data were registered monthly from 1995 through 2015, off the southwestern coast of the Baja California Peninsula, Mexico. The model was fitted to the data by assuming two conditions for the asymptote, which represents the proportion of mature females: (1) asymptote equal to 1 (2-parameter), and (2) asymptote less than 1 (3-parameter). On the basis of Akaike's information criterion, the logistic model with asymptote less than 1 was selected as the best model. Therefore, the asymptote varied from 0.34 to 0.92, and the L50 ranged between 138 and 172 mm in total length. The estimates of the L50 for the 3-parameter model were lower than those for the 2-parameter model, avoiding misinterpretation of this quantity used in management. The results show a decline in the proportion of mature females, indicating that not all the female shrimp in the population spawn every year. The use of the 3-parameter model provided a better representation of the observed data and reliable parameter estimation.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 37 • No. 5