Fishery-Independent Data Reveal Negative Effect of Human Population Density on Caribbean Predatory Fish Communities

BACKGROUND: Understanding the current status of predatory fish communities, and the effects fishing has on them, is vitally important information for management. However, data are often insufficient at region-wide scales to assess the effects of extraction in coral reef ecosystems of developing nations. METHODOLOGY/PRINCIPAL FINDINGS: Here, I overcome this difficulty by using a publicly accessible, fisheries-independent database to provide a broad scale, comprehensive analysis of human impacts on predatory reef fish communities across the greater Caribbean region. Specifically, this study analyzed presence and diversity of predatory reef fishes over a gradient of human population density. Across the region, as human population density increases, presence of large-bodied fishes declines, and fish communities become dominated by a few smaller-bodied species. CONCLUSIONS/SIGNIFICANCE: Complete disappearance of several large-bodied fishes indicates ecological and local extinctions have occurred in some densely populated areas. These findings fill a fundamentally important gap in our knowledge of the ecosystem effects of artisanal fisheries in developing nations, and provide support for multiple approaches to data collection where they are commonly unavailable

Patterns of distribution and movement of fishes, Ophthalmolepis lineolatus and Hypoplectrodes maccullochi, on temperate rocky reefs of south eastern Australia

Current ecological models predict that reef fish assemblages will be strongly influenced by habitat type. Here we test hypotheses about habitat types and abundance patterns of temperate reef fishes from broad spatial scales (100 s of km) to small spatial scales of metres to tens of metres. Habitat preferences are also described over long periods of time (22 years) for two abundant taxa. Patterns of distribution and abundance varied over ∼ eight degrees of latitude (29.9–37.5°S) along the coast of New South Wales, Australia. Ophthalmolepis lineolatus (Labridae) preferred kelp and Barrens habitats and juveniles were most abundant in habitats rich in algae. This species also increased in abundance from North to South. In contrast, Hypoplectrodes maccullochi (Serranidae) were usually only found in the Barrens habitat and great variation was found among locations. Both taxa were most abundant on urchin grazed deep reefs (over 10 m deep). Habitat preferences of O. lineolatus and H. maccullochi appeared resistant to major environmental perturbations that included large El Niño events in 1991, 1998 and 2002. Home ranges of O. lineolatus varied from 52 m2 to 1,660 m2 and often overlapped; fish of all sizes were most abundant in algal dominated habitat. Limited movements and small home ranges (2.1–11.6 m2) combined with a strong affiliation for shelter indicated that most H. maccullochi are strongly site-attached. Habitat type is important to these taxonomically different fishes, but to varying degrees where H. maccullochi was more of a habitat specialist than O. lineolatus and would be more vulnerable to perturbations that alter Barrens. Changes in reef habitats will have a great influence on fish assemblages and this should also be considered in coastal planning (e.g. for Marine Protected Areas, MPAs) and the assessments of resistance and resilience of fishes to climate change