Critical assessment and ramifications of a purported marine trophic cascade

When identifying potential trophic cascades, it is important to clearly establish the trophic linkages between predators and prey with respect to temporal abundance, demographics, distribution and diet. In the northwest Atlantic Ocean, the depletion of large coastal sharks was thought to trigger a t...

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Bibliographic Details
Published in:Scientific reports Vol. 6; no. 1; p. 20970
Main Authors: Grubbs, R. Dean, Carlson, John K., Romine, Jason G., Curtis, Tobey H., McElroy, W. David, McCandless, Camilla T., Cotton, Charles F., Musick, John A.
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 15.02.2016
Nature Publishing Group
Subjects:
704/158
704/158/853/2006
Abundance
Animals
Atlantic Ocean
Bivalvia - physiology
Demography
Ecosystem
Feeding Behavior
Fisheries
Food Chain
Humanities and Social Sciences
Life history
Mollusks
multidisciplinary
Population Dynamics
Predation
Predators
Predatory Behavior
Prey
Reproduction
Science
Sharks
Sharks - physiology
Shellfish
Skates (Fish) - physiology
Sustainable fisheries
ISSN:2045-2322, 2045-2322
Online Access:Get full text
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Summary:When identifying potential trophic cascades, it is important to clearly establish the trophic linkages between predators and prey with respect to temporal abundance, demographics, distribution and diet. In the northwest Atlantic Ocean, the depletion of large coastal sharks was thought to trigger a trophic cascade whereby predation release resulted in increased cownose ray abundance, which then caused increased predation on and subsequent collapse of commercial bivalve stocks. These claims were used to justify the development of a predator-control fishery for cownose rays, the “Save the Bay, Eat a Ray” fishery, to reduce predation on commercial bivalves. A reexamination of data suggests declines in large coastal sharks did not coincide with purported rapid increases in cownose ray abundance. Likewise, the increase in cownose ray abundance did not coincide with declines in commercial bivalves. The lack of temporal correlations coupled with published diet data suggest the purported trophic cascade is lacking the empirical linkages required of a trophic cascade. Furthermore, the life history parameters of cownose rays suggest they have low reproductive potential and their populations are incapable of rapid increases. Hypothesized trophic cascades should be closely scrutinized as spurious conclusions may negatively influence conservation and management decisions.
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ISSN:2045-2322
2045-2322
DOI:10.1038/srep20970