Overfishing of Inland Waters

Allan, J. David; Abell, Robin; Hogan, Zeb; Revenga, Carmen; Taylor, Barrie F.; Welcomme, R. L.; Winemiller, Kirk O.

doi:10.1641/0006-3568(2005)055[1041:ooiw]2.0.co;2

Cited by 586 publications

(477 citation statements)

References 29 publications

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“…For ecosystem processes that are positively related to the biomass of organisms, such as nutrient recycling, it is not surprising that loss of rare species would have only minor effects. The similarity between the results of random extinctions and loss of species in order of either body size or trophic position is intriguing, as large species and top predators are frequently considered to be most affected by human activities (3)(4)(5). However, our fishery surveys at each site indicate that fishermen target species whose combination of population density and body size give them relatively high biomass (SI Table 2).…”

Section: Discussionmentioning

confidence: 90%

“…Alternative scenarios set the probability of extinction for each species as directly or inversely proportional to specific traits, and we focused on four real-world patterns: a negative relationship between population density and extinction risk (28), a positive relationship between trophic position in the food web and risk (3)(4)28), a positive relationship between body size and risk (5,29), and a positive relationship between observed fishing pressure and risk. Trophic position was based on mean stable isotope ratios of nitrogen in dorsal muscle of each species (n ϭ 6 per species in most cases) (38).…”

Section: Methodsmentioning

confidence: 99%

“…Fish are the most species-rich group of vertebrates, and their diversity is threatened worldwide by overfishing, species introductions, and other factors (3)(4)(5)(6). Although the collective influence of fish on food web structure (7,8), nutrient cycling (9,10), and primary productivity (11) is well documented, the ecosystem-level effects of eroding fish species richness are unclear.…”

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confidence: 99%

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Fish extinctions alter nutrient recycling in tropical freshwaters

McIntyre

Jones

Flecker

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

309

234

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There is increasing evidence that species extinctions jeopardize the functioning of ecosystems. Overfishing and other human influences are reducing the diversity and abundance of fish worldwide, but the ecosystem-level consequences of these changes have not been assessed quantitatively. Recycling of nutrients is one important ecosystem process that is directly influenced by fish. Fish species vary widely in the rates at which they excrete nitrogen and phosphorus; thus, altering fish communities could affect nutrient recycling. Here, we use extensive field data on nutrient recycling rates and population sizes of fish species in a Neotropical river and Lake Tanganyika, Africa, to evaluate the effects of simulated extinctions on nutrient recycling. In both of these species-rich ecosystems, recycling was dominated by relatively few species, but contributions of individual species differed between nitrogen and phosphorus. Alternative extinction scenarios produced widely divergent patterns. Loss of the species targeted by fishermen led to faster declines in nutrient recycling than extinctions in order of rarity, body size, or trophic position. However, when surviving species were allowed to increase after extinctions, these compensatory responses had strong moderating effects even after losing many species. Our results underscore the complexity of predicting the consequences of extinctions from species-rich animal communities. Nevertheless, the importance of exploited species in nutrient recycling suggests that overfishing could have particularly detrimental effects on ecosystem functioning. biodiversity ͉ cichlid ͉ nutrient cycling ͉ stoichiometry ͉ species identity U nderstanding the consequences of species extinctions for ecosystem functioning is a critical challenge. There is substantial evidence that declining species richness alters ecosystem processes in experimental systems with simple spatial and trophic structure (1), but this relationship remains poorly understood in species-rich, natural ecosystems (2). The large size, high mobility, and complex trophic relationships of vertebrate species make assessing the potential consequences of their extinctions particularly challenging.Fish are the most species-rich group of vertebrates, and their diversity is threatened worldwide by overfishing, species introductions, and other factors (3-6). Although the collective influence of fish on food web structure (7,8), nutrient cycling (9, 10), and primary productivity (11) is well documented, the ecosystem-level effects of eroding fish species richness are unclear. Tropical freshwater fish are of special concern because they represent Ͼ10% of all vertebrate species (12, 13) and support Ϸ72% of global fish harvests from inland waters (14). These fisheries provide vital animal protein for hundreds of millions of people in developing countries and benefit terrestrial conservation efforts by alleviating demand for bush meat (15).Nutrient recycling offers an ideal quantitative basis for directly linking fish species and ecosys...

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Section: Discussionmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Fish extinctions alter nutrient recycling in tropical freshwaters

McIntyre

Jones

Flecker

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

309

234

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“…Major threats can be classified into overexploitation, water pollution, flow modification, destruction or degradation of habitat, and invasion by exotic species (Dudgeon et al, 2006). Different areas can suffer different dominant threats, such as the considerable water pollution in specific river sections of the upper Mekong (Kang et al, 2009) and overfishing in the floodplains of the lower Mekong (Allan et al, 2005). Among the three tributaries of the Irrawaddy in China, all threats mentioned above occur in the Daying and Ruili rivers.…”

Section: Existing and Potential Threatsmentioning

confidence: 99%

Fish assemblages and diversity in three tributaries of the Irrawaddy River in China: changes, threats and conservation perspectives

Yang

Jiang

Wang

et al. 2016

Knowl. Manag. Aquat. Ecosyst.

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-Incompletely known fish assemblages and species diversity are substantial obstacles in fish conservation, particularly when their aquatic habitats are under threat due to rapid human-induced changes. Fish assemblages and diversity in three tributaries of the upper Irrawaddy River in China (the Dulong, Daying and Ruili rivers) were examined based on field collections and literature resources. The newly compiled fish assemblage recorded 85 species (in 8 orders, 20 families and 51 genera) distributed in the upper Irrawaddy. The fish compositions in the Daying (67 species, 44 genera, 19 families, 7 orders) and Ruili rivers (65 species, 44 genera, 19 families, 8 orders) were more similar to each other and more speciose than that in the Dulong River (14 species, 10 genera, 4 families, 3 orders). Two indices of taxonomic diversity (the average taxonomic distinctness (Δ + ), and the variation in taxonomic distinctness (Λ + )) were used to discriminate four collections spanning a ten-year period. A decrease in taxonomic diversity and an increase in unevenness of the fish assemblages were found in both the Daying River and Ruili rivers, which indicated that the impacts were accumulated gradually during this decade, when dams and the spread of non-native species were major threats. Comparatively speaking, the Dulong River is still in a near-natural state, and thus the fish community has experienced less disturbance. In situ conservation (nature reserves and tributary protection) and ex situ conservation (artificial propagation and release) should be combined and managed to promote fish conservation in the future. Key-words:Freshwater fish / taxonomic diversity / threats / dams / Irrawaddy Résumé -La diversité et les communautés de poissons dans trois affluents de la rivière Irrawaddy en Chine : changements, menaces et perspectives de conservation. Les assemblages de poissons et leur diversité spécifique incomplètement connus sont d'importants obstacles à la conservation des poissons, en particulier lorsque leurs habitats aquatiques sont menacés en raison des rapides changements induits par l'homme. Les assemblages de poissons et leur diversité dans trois affluents de la rivière Irrawaddy supérieure en Chine (les rivières Dulong, Daying et Ruili) ont été étudiés sur la base de collectes sur le terrain et des ressources de la littérature. L'assemblage de poissons nouvellement compilé comporte 85 espèces (8 ordres, 20 familles et 51 genres) répartis dans l'Irrawaddy supérieure. Les compositions de poissons dans les rivières Daying (67 espèces, 44 genres, 19 familles, 7 ordres) et Ruili (65 espèces, 44 genres, 19 familles, 8 ordres) sont plus semblables les uns aux autres et plus riches en espèces que dans la rivière Dulong (14 espèces, 10 genres, 4 familles, 3 ordres). Deux indices de diversité taxonomique (la taxonomique moyenne (Δ + ), et la variation de la distance taxonomique (Λ + )) ont été utilisés pour discriminer quatre échantillonnages couvrant une période de dix ans. Une diminution de la diversité taxonomi...

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“…Environmental change and intensive exploitation are putting pressure on natural resources worldwide (Allan et al 2005). These pressures are exacerbating tensions among user groups, and presenting governments with difficult challenges regarding how to sustainably manage natural resources while maintaining community resilience (Jentoft and Chuenpagdee 2009).…”

Section: Introductionmentioning

confidence: 99%

Getting past the blame game: Convergence and divergence in perceived threats to salmon resources among anglers and indigenous fishers in Canada’s lower Fraser River

Nguyen

Young

Hinch

et al. 2016

Ambio

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This article examines threat perception as a potential dimension of inter-group conflict over salmon fisheries in Canada's Fraser River watershed. Environmental changes and the entry of new user groups are putting pressure on both the resource and regulators, as well as threatening to exacerbate conflicts, notably between First Nation (indigenous) fishers and non-indigenous recreational anglers. While resource conflicts are often superficially conceptualized as cases of competing interests, we build on recent studies suggesting that conflicts are associated with deeper cognitive and perceptual differences among user groups. We report findings from 422 riverbank interviews with First Nation fishers and recreational anglers focusing on perceptions of threat to the fisheries. Responses reveal both substantial agreement and disagreement in threat perceptions between the two groups. These patterns provide a potential roadmap for consensus building, and suggest possible avenues for policy-makers to defuse the ''blame game'' that often dominates this type of conflict.

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Overfishing of Inland Waters

Cited by 586 publications

References 29 publications

Fish extinctions alter nutrient recycling in tropical freshwaters

Fish extinctions alter nutrient recycling in tropical freshwaters

Fish assemblages and diversity in three tributaries of the Irrawaddy River in China: changes, threats and conservation perspectives

Getting past the blame game: Convergence and divergence in perceived threats to salmon resources among anglers and indigenous fishers in Canada’s lower Fraser River

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