Hydroacoustics as a tool to examine the effects of Marine Protected Areas and habitat type on marine fish communities

Abstract Hydroacoustic technologies are widely used in fisheries research but few studies have used them to examine the effects of Marine Protected Areas (MPAs). We evaluate the efficacy of hydroacoustics to examine the effects of closure to fishing and habitat type on fish populations in the Cabo Pulmo National Park (CPNP), Mexico, and compare these methods to Underwater Visual Censuses (UVC). Fish density, biomass and size were all significantly higher inside the CPNP (299%, 144% and 52% respectively) than outside in non-MPA control areas. These values were much higher when only accounting for the reefs within the CPNP (4715%, 6970% and 97% respectively) highlighting the importance of both habitat complexity and protection from fishing for fish populations. Acoustic estimates of fish biomass over reef-specific sites did not differ significantly from those estimated using UVC data, although acoustic densities were less due to higher numbers of small fish recorded by UVC. There is thus considerable merit in nesting UVC surveys, also providing species information, within hydroacoustic surveys. This study is a valuable starting point in demonstrating the utility of hydroacoustics to assess the effects of coastal MPAs on fish populations, something that has been underutilised in MPA design, formation and management

Global human footprint on the linkage between biodiversity and ecosystem functioning in reef fishes

Copyright: © 2011 Mora et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Difficulties in scaling up theoretical and experimental results have raised controversy over the consequences of biodiversity loss for the functioning of natural ecosystems. Using a global survey of reef fish assemblages, we show that in contrast to previous theoretical and experimental studies, ecosystem functioning (as measured by standing biomass) scales in a non-saturating manner with biodiversity (as measured by species and functional richness) in this ecosystem. Our field study also shows a significant and negative interaction between human population density and biodiversity on ecosystem functioning (i.e., for the same human density there were larger reductions in standing biomass at more diverse reefs). Human effects were found to be related to fishing, coastal development, and land use stressors, and currently affect over 75% of the world's coral reefs. Our results indicate that the consequences of biodiversity loss in coral reefs have been considerably underestimated based on existing knowledge and that reef fish assemblages, particularly the most diverse, are greatly vulnerable to the expansion and intensity of anthropogenic stressors in coastal areas

Climatic influence on reef fish recruitment and fisheries

Este artículo contiene 5 páginas, 2 figuras.Interannual and interdecadal variability of the recruitment and spawning stock biomass of fish has been observed for many pelagic commercial species. For reef fish, climate variability has been considered only as a pre-recruitment factor that has stochastic impacts on the survival of eggs and larvae during their pelagic stage. Here we show that fisheries landings of reef fish are related to climatic conditions that occurred at the time of settlement. Using detailed studies on the life history of 2 important commercial species (yellow snapper and leopard grouper) and a compilation of landing statistics over 11 yr in the Gulf of California, we established that increasing recruitment translated into greater fisheries landings and increased revenue once individuals recruited into fishery stocks. Recruitment appeared to be modulated by El Niño/La Niña events. Monitoring of reef fish recruitment could be used to adapt artisanal fisheries management ahead of time, allowing regulation of effort or setting of quotas based on the variability of climate indices.This work was supported by the David and Lucille Packard Foundation, the Moore Family Foundation, and the Walton Family Foundation.Peer reviewe

Global human footprint on the linkage between biodiversity and ecosystem functioning in reef fishes

10.1371/journal.pbio.1000606PLoS Biology94e100060