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Marine Ecology Progress Series

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MEPS 444:223-238 (2012)  -  DOI:

Molecular detection of plaice remains in the ­stomachs of potential predators on a flatfish ­nursery ground

Aitor Albaina1,3,*, Martin I. Taylor1, Clive J. Fox2

1Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences, ECW Building, Bangor University, Bangor LL57 2UW, UK
2Scottish Association for Marine Science, Scottish Marine Institute, Oban, Argyll PA37 1QA, UK
3Present address: Laboratory of Genetics, Department of Genetics, Physical Anthropology & Animal Physiology, University of the Basque Country, Leioa 48940, Spain

ABSTRACT: Stomach contents of potential predators from a flatfish nursery ground on the Scottish west coast were examined visually and probed using a TaqMan real-time PCR based assay designed to detect plaice Pleuronectes platessa DNA. Stomachs from 1137 brown shrimp Crangon crangon, along with a lesser number of shore crab Carcinus maenas, grey gurnard Eutrigla gurnardus and Gobiidae were analysed. Overall 45% of shrimp tested positive for plaice DNA, a proportion considerably higher than in stomachs containing visually identifiable flatfish remains. When scaled to the population level, predation by shrimp generated an estimated mortality of ~9% d–1, which compares with a decline in plaice abundance from mid-May to mid-June of ~4.4% d−1. The discrepancy between mortality estimates based on molecular and catch-curve analysis might be due to sampling being conducted at low water between dusk and dawn, which would concentrate predators and prey at times coincident with peaks of shrimp feeding. In addition, the sensitivity of the TaqMan assay could have led to some over-estimation because non-fatal interactions may also have been detected, e.g. shrimp are known to nibble the fins of flatfish, that might result in a positive TaqMan result but not necessarily in mortality for the fish. The percentage of shrimp testing positive for presence of plaice DNA in their stomachs was also related to plaice density in a positive, linear manner. For less abundant predators, stomachs of 6% of shore crabs, 40% of gurnards and 11% of large gobies also tested positive.

KEY WORDS: Stomach contents · TaqMan real-time PCR assay · Pleuronectes platessa · Crangon crangon · Carcinus maenas · Predator−prey interactions · Nursery ground · Tralee Beach

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Cite this article as: Albaina A, Taylor MI, Fox CJ (2012) Molecular detection of plaice remains in the ­stomachs of potential predators on a flatfish ­nursery ground. Mar Ecol Prog Ser 444:223-238.

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