Rapid Global Expansion of Invertebrate Fisheries: Trends, Drivers, and Ecosystem Effects

Abstract

BackgroundWorldwide, finfish fisheries are receiving increasing assessment and regulation, slowly leading to more sustainable exploitation and rebuilding. In their wake, invertebrate fisheries are rapidly expanding with little scientific scrutiny despite increasing socio-economic importance.Methods and FindingsWe provide the first global evaluation of the trends, drivers, and population and ecosystem consequences of invertebrate fisheries based on a global catch database in combination with taxa-specific reviews. We also develop new methodologies to quantify temporal and spatial trends in resource status and fishery development. Since 1950, global invertebrate catches have increased 6-fold with 1.5 times more countries fishing and double the taxa reported. By 2004, 34% of invertebrate fisheries were over-exploited, collapsed, or closed. New fisheries have developed increasingly rapidly, with a decrease of 6 years (3 years) in time to peak from the 1950s to 1990s. Moreover, some fisheries have expanded further and further away from their driving market, encompassing a global fishery by the 1990s. 71% of taxa (53% of catches) are harvested with habitat-destructive gear, and many provide important ecosystem functions including habitat, filtration, and grazing.ConclusionsOur findings suggest that invertebrate species, which form an important component of the basis of marine food webs, are increasingly exploited with limited stock and ecosystem-impact assessments, and enhanced management attention is needed to avoid negative consequences for ocean ecosystems and human well-being.

Recovery of marine animal populations and ecosystems

“…The best strategies for recovery include: (i) raising public and political awareness; (ii) taking legal action and enforcing management plans; (iii) addressing cumulative human impacts; (iv) maintaining or restoring biodiversity and ecosystem complexity; and (v) planning for the long term, as recovery of long-lived species and complex ecosystems might need decades, if not centuries after major threats have been removed or reduced. These lessons learned from past recoveries of many marine mammals, birds, reptiles, some fishes and habitats could be applied to species that are currently undergoing strong population declines but have received little protection so far, such as many sharks [28,50,87], and to species that are increasingly exploited with little management in place, such as many invertebrates [88]. Whereas much trial and error was previously involved in finding the right management and conservation actions, current and future recovery plans could be better informed and take hold before populations or habitats reach critically low levels.…”

Marine defaunation: Animal loss in the global ocean

“…The status held by some of these defaunation winners in the oceans may, however, be ephemeral. Many of the marine species that have initially flourished as a result of defaunation have themselves become targets for harvest by prey-switching humans as is evidenced by the recent global expansion of marine invertebrate fisheries (39).…”

Extinctions in ancient and modern seas

“…By contrast, fossil extinction rates are well known for several invertebrate groups (e.g., echinoids, bryozoans, and bivalves) for which current risk assessments are either data deficient or lacking, but some records on historical extinctions exist. These discrepancies reflect the selective historical exploitation and current conservation of vertebrate megafauna [39,40] and the greater fossilization potential of invertebrates with biomineralized elements. As invertebrates comprise most of the marine metazoan diversity, are key components of marine food webs, and provide critical ecosystem services, improving the assessment of their current risk would greatly enhance understanding of the resilience of marine ecosystems and how current and potential future extinction risks compare with those in the geologic past.…”