Relative importance of habitat and fishing in influencing reef fish communities across seventeen Pacific Island Countries and Territories

Abstract

Reef fish assessments were undertaken in 17 Pacific islands to describe the status of finfish resources in 63 villages where fishing is mainly artisanal. Surveys were performed by recording the number and size of edible fish species and benthic composition. Fishing impact was described through six proxies representing level of catch, alternative incomes, degree of commercial catch and country economic development derived from a simultaneous socioeconomic assessment. The relative importance of broadly defined habitat (geographical location, island and reef type, substrate composition) and fishing impact in controlling the distribution of fish trophic groups, families and species was measured through multivariate analysis. The extreme faunistic diversity was shown by the large variation in fish density (difference of up to an order of magnitude) and fish biomass (displaying a 20‐fold difference across the region). Herbivores were dominant in the eastern part of the region, at what we classified as complex islands and at islands with small lagoon and at coastal reefs, while carnivores were dominant at oceanic islands and atolls and at outer reefs. Specific habitat associations were shown for Scaridae, Acanthuridae, Siganidae, Balistidae, Lethrinidae, Lutjanidae and Serranidae. Relative importance and size decrease of several fish families (Mullidae, Scaridae, Lutjanidae and Serranidae) were related to high fishing impact. Acanthuridae and Lethrinidae appeared to have a role as opportunistic groups in impacted sites. The relative impact from fishing and habitat on fishes accounted for, respectively, 20 and 30% of variance, demonstrating the effect of human impacts even at such large scale and taking into account only limited fishing impact variables.

Farming behaviour of reef fishes increases the prevalence of coral disease associated microbes and black band disease

“…Hawaiian Islands [79]; Line Islands [80]). Although large-scale patterns in fish community structure are influenced by numerous factors, including historical biogeography, reef geomorphology and human activities unrelated to fishing [81,82], a global metaanalysis of local-scale studies has found a positive relationship between fishing pressure and damselfish abundance that is consistent with the earlier studies [83]. Regardless of the specific mechanism that underlies this relationship, our study indicates that an increase in intensive territorial grazers will be likely to have substantial implications for the structure of the benthic microbial community on coral reefs, potentially increasing reservoirs of opportunistic pathogens linked to coral disease as well as the occurrence of coral disease.…”

Drivers of protogynous sex change differ across spatial scales

“…The island types considered here can be qualitatively defined by their diversity and relative proportions of various habitats present. The presence, scale and proximity of particular habitats have a strong influence on the diversity and carrying capacity of reef fish assemblages [39,40], and analysis of fish communities on oceanic islands throughout the Pacific reveals predictable structuring of trophic groups based on the island types described here [20]. In particular, Pinca et al [20] found that, after partialling out the effects of fishing, parrotfish density and biomass was positively related to barrier reef systems with lagoons and negatively related to atolls and low complexity fringing reef systems, whereas fringing reefs supported greater mean body sizes.…”

“…The presence, scale and proximity of particular habitats have a strong influence on the diversity and carrying capacity of reef fish assemblages [39,40], and analysis of fish communities on oceanic islands throughout the Pacific reveals predictable structuring of trophic groups based on the island types described here [20]. In particular, Pinca et al [20] found that, after partialling out the effects of fishing, parrotfish density and biomass was positively related to barrier reef systems with lagoons and negatively related to atolls and low complexity fringing reef systems, whereas fringing reefs supported greater mean body sizes. Specific habitats prevalent in wave-protected environments like lagoons provide major nursery habitat for many parrotfishes, including C. spilurus [41,42], and therefore may boost abundance potential for adults.…”

“…latitudinal), quantity and distribution of habitats or resources and density-dependent processes. However, much of this work has focused on smaller spatial scales (among habitats), whereas potential regional or larger patterns in widely distributed species are necessary information for fisheries management [20].…”

Towards an ecosystem approach to small island fisheries: A preliminary study of a balanced fishery in Kotania Bay (Seram Island, Indonesia)

“…Increasing selective fishing pressure contributes to the truncation of age structure (Hsieh et al, 2006) and changes the composition of reef fish communities (Pinca, 2011). The impacts of fisheries can be detected in changing catch rates and catch composition (Welcomme, 1999).…”