Artisanal fish fences pose broad and unexpected threats to the tropical coastal seascape

Exton, Dan A.; Ahmadia, Gabby N.; Cullen-Unsworth, Leanne C.; Jompa, Jamaluddin; May, Duncan; Rice, Joel; Simonin, Paul W.; Unsworth, Richard K. F.; Smith, David J.

doi:10.1038/s41467-019-10051-0

Cited by 27 publications

(18 citation statements)

References 66 publications

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“…The levels of juvenile catch recorded for MNF are high and are comparable to other fishing gears that are being used in an unsustainable manner. A recent examination of static fish fence gears found a 40% juvenile fish count (Exton et al 2019), whilst beach seine net gears have been recorded in Kenya to have juvenile proportions at up to 68% (Mangi and Roberts 2006).…”

Section: Discussionmentioning

confidence: 99%

The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa

Jones

Unsworth

2019

Ambio

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Malaria is a serious global health issue, with around 200 million cases per year. As such, great effort has been put into the mass distribution of bed nets as a means of prophylaxis within Africa. Distributed mosquito nets are intended to be used for malaria protection, yet increasing evidence suggests that fishing is a primary use for these nets, providing fresh concerns for already stressed coastal ecosystems. While research documents the scale of mosquito net fisheries globally, no quantitative analysis of their landings exists. The effects of these fisheries on the wider ecosystem assemblages have not previously been examined. In this study, we present the first detailed analysis of the sustainability of these fisheries by examining the diversity, age class, trophic structure and magnitude of biomass removal. Dragnet landings, one of two gear types in which mosquito nets can be utilised, were recorded across ten sites in northern Mozambique where the use of Mosquito nets for fishing is common. Our results indicate a substantial removal of juveniles from coastal seagrass meadows, many of which are commercially important in the region or play important ecological roles. We conclude that the use of mosquito nets for fishing may contribute to food insecurity, greater poverty and the loss of ecosystem functioning.

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Section: Discussionmentioning

confidence: 99%

The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa

Jones

Unsworth

2019

Ambio

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“…Fishing nets, lines, and fences were reported to adversely impact marine fish and coral populations. Exton et al (2019) reported that artisanal fish fences, which funnel fish into a holding structure, cause habitat fragmentation, create physical barriers that interrupt natural movement of mobile species and benthic community structure, and remove large numbers of juvenile fish, which produces a corresponding decline in fish abundance on adjacent coral reefs. Gorgonian coral species in canyon systems of the western Ligurian Sea (northwestern Mediterranean Sea) were found to be negatively impacted by one or more types of derelict fishing gear, with fishing nets causing the greatest impact at most study sites (Giusti et al, 2019).…”

Section: Effects Of Fishing and Aquaculturementioning

confidence: 99%

Effects of pollution on marine organisms

Mearns

Morrison

Arthur³

et al. 2020

Water Environment Research

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This review covers selected 2019 articles on the biological effects of pollutants, including human physical disturbances, on marine and estuarine plants, animals, ecosystems, and habitats. The review, based largely on journal articles, covers field, and laboratory measurement activities (bioaccumulation of contaminants, field assessment surveys, toxicity testing, and biomarkers) as well as pollution issues of current interest including endocrine disrupters, emerging contaminants, wastewater discharges, marine debris, dredging, and disposal. Special emphasis is placed on effects of oil spills and marine debris due largely to the 2010 Deepwater Horizon oil blowout in the Gulf of Mexico and proliferation of data on the assimilation and effects of marine debris microparticulates. Several topical areas reviewed in the past (e.g., mass mortalities ocean acidification) were dropped this year. The focus of this review is on effects, not on pollutant sources, chemistry, fate, or transport. There is considerable overlap across subject areas (e.g., some bioaccumulation data may be appeared in other topical categories such as effects of wastewater discharges, or biomarker studies appearing in oil toxicity literature). Therefore, we strongly urge readers to use keyword searching of the text and references to locate related but distributed information. Although nearly 400 papers are cited, these now represent a fraction of the literature on these subjects. Use this review mainly as a starting point. And please consult the original papers before citing them.

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“…Coral reefs are among the most valuable and vulnerable ecosystems on the planet 1 , 2 . Loss of herbivory, largely driven by disease and the widespread unsustainable harvesting of fish and echinoids in small-scale fisheries 3 , 4 , has many negative impacts on coral reefs, but it is the associated macroalgae overgrowth that poses the greatest threat 5 . In the absence of herbivores, structurally complex, three-dimensional hard corals are replaced by structurally simple two-dimensional macroalgae 6 , 7 , which reduces habitat availability and drives decreases in species richness and abundance 8 .…”

Section: Introductionmentioning

confidence: 99%

The ecological importance of habitat complexity to the Caribbean coral reef herbivore Diadema antillarum: three lines of evidence

Bodmer

Wheeler

Anand

et al. 2021

Sci Rep

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When Caribbean long-spined sea urchins, Diadema antillarum, are stable at high population densities, their grazing facilitates scleractinian coral dominance. Today, populations remain suppressed after a mass mortality in 1983–1984 caused a loss of their ecosystem functions, and led to widespread declines in ecosystem health. This study provides three lines of evidence to support the assertion that a lack of habitat complexity on Caribbean coral reefs contributes to their recovery failure. Firstly, we extracted fractal dimension (D) measurements, used as a proxy for habitat complexity, from 3D models to demonstrate that urchins preferentially inhabit areas of above average complexity at ecologically relevant spatial scales. Secondly, controlled behaviour experiments showed that an energetically expensive predator avoidance behaviour is reduced by 52% in complex habitats, potentially enabling increased resource allocation to reproduction. Thirdly, we deployed a network of simple and cost-effective artificial structures on a heavily degraded reef system in Honduras. Over a 24-month period the adult D. antillarum population around the artificial reefs increased by 320% from 0.05 ± 0.01 to 0.21 ± 0.04 m−2 and the juvenile D. antillarum population increased by 750% from 0.08 ± 0.02 to 0.68 ± 0.07 m−2. This study emphasises the important role of habitat structure in the ecology of D. antillarum and as a barrier to its widespread recovery.

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Artisanal fish fences pose broad and unexpected threats to the tropical coastal seascape

Cited by 27 publications

References 66 publications

The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa

The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa

Effects of pollution on marine organisms

The ecological importance of habitat complexity to the Caribbean coral reef herbivore Diadema antillarum: three lines of evidence

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