Recent Publications

For marine fishes that form spawning aggregations, vulnerability to aggregation fishing is influenced by interactions between the spatio-temporal patterns of spawning and aspects of the fishery that determine fishing effort, catch, and catch rate in relation to spawning. We investigated the spatio-temporal dynamics of spawning and fishing for the barred sand bass, Paralabrax nebulifer, in Punta Abreojos, Mexico from 2010 to 2012 as a means to assess its vulnerability to aggregation fishing by the local commercial fishery. Monthly, spatial patterns in gonadal development in collected females indicated that adults formed spawning aggregations at two sites in Punta Abreojos during July and August. Monthly patterns in the spatial distribution of fishing matched the spawning behavior of P. nebulifer, with effort and catch concentrated at spawning aggregation sites during those months. However, fishing effort, catch, and catch-per-unit effort did not increase during the spawning season, and fishing activities associated with the spawning season comprised only a small percentage of the total annual effort (22%) and catch (17%).Therefore, while the population of P. nebulifer at Punta Abreojos should be vulnerable to aggregation fishing due to the spatio-temporal dynamics of its spawning aggregations, vulnerability is greatly reduced, because fishing activities are not disproportionately focused on spawning aggregations and fishing methods are not optimized to maximize harvest from the aggregations. Differences between our results and previous studies on aggregation fisheries for P. nebulifer in California, USA, reinforce the importance of assessing factors influencing vulnerability to aggregation fishing at regional scales for prioritizing management efforts.

To gauge the collateral impacts of fishing we must know where fishing boats operate and how much they fish. Although small-scale fisheries land approximately the same amount of fish for human consumption as industrial fleets globally, methods of estimating their fishing effort are comparatively poor. We present an accessible, spatial method of calculating the effort of small-scale fisheries based on two simple measures that are available, or at least easily estimated, in even the most data-poor fisheries: the number of boats and the local coastal human population. We illustrate the method using a small-scale fisheries case study from the Gulf of California, Mexico, and show that our measure of Predicted Fishing Effort (PFE), measured as the number of boats operating in a given area per day adjusted by the number of people in local coastal populations, can accurately predict fisheries landings in the Gulf. Comparing our values of PFE to commercial fishery landings throughout the Gulf also indicates that the current number of small-scale fishing boats in the Gulf is approximately double what is required to land theoretical maximum fish biomass. Our method is fishery-type independent and can be used to quantitatively evaluate the efficacy of growth in small-scale fisheries. This new method provides an important first step towards estimating the fishing effort of small-scale fleets globally.

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. (C) 2017 Elsevier Ltd. All rights reserved.