An interdisciplinary approach to evaluate the status of large-bodied Serranid fisheries: The case of Magdalena-Almejas Bay lagoon complex, Baja California Sur, Mexico

Groupers are an important part of the world-wide catch of finfish and are of great importance to artisanal and sport fisheries. Their biological characteristics, including very large size, slow growth, longevity, late age-at-maturity and the tendency to form spawning aggregations makes them particularly vulnerable to overfishing. In Baja California, Mexico, the lack of robust historical catch data and fishery independent estimates of abundance hinders the assessment of temporal trends in population size and the evaluation of grouper population dynamics, as well the development and implementation of adequate management plans. Using an interdisciplinary approach that included (1) the review of non-scientific historical documents, (2) analysis of official catch records, (3) interviews with three generations of fishermen and (4) visual censuses to estimate abundance and the current size distribution, we reconstructed the historical abundance and maximum sizes of six species of Serranids of the genera Epinephelus and Mycteroperca as well as Stereolepis gigas in the Magdalena-Almejas Bay lagoonal complex in northwestern Mexico. Although catch volumes increased by 225% during the last 13 years, fishermen perception indicated a 30% decrease in the estimated maximum size and 57% decrease in the maximum weight captured over the past four decades. Based on insight gained from the four approaches, the general trend suggested an overall decrease in the abundance of some species. However, these changes were not perceived equally by the three generations of interviewed fishers; only older fishermen (>55 years of age) perceived a drastic decrease in population size. It is therefore important to involve young fishers in educational programs to avoid incurring in a shifting baseline syndrome. The limited quantitative data available for the region coupled with a trend toward lower abundance and smaller maximum sizes makes the implementation of specific monitoring and management measures for these species imperative.