MEPS 462:205-218 (2012)  -  DOI: https://doi.org/10.3354/meps09748

Identification of marine fish egg predators using molecular probes

Clive J. Fox1,*, Martin I. Taylor2, Jeroen van der Kooij3, Natasha Taylor3, Stephen P. Milligan3, Aitor Albaina4, Sonia Pascoal2, Delphine Lallias2, Marjorie Maillard2, Ewan Hunter3

1Scottish Marine Institute, Scottish Association for Marine Science, Oban PA37 1QA, UK
2Molecular Ecology and Fisheries Genetics Laboratory, ECW Building, School of Biological Sciences, Bangor University, Bangor LL57 2UW, UK
3Centre for Environment, Fisheries and Aquaculture Science, Pakefield Road, Lowestoft, Suffolk NR33 OHT, UK
4Laboratory of Genetics, Department of Genetics, Physical Anthropology & Animal Physiology, Basque Country University, Leioa 48940, Spain

ABSTRACT: Mortality during the egg and larval stages is thought to play a major role in determining year-class strength of many marine fish. Predation of eggs and larvae is normally considered to be a major factor but the full suite of predators responsible has rarely been identified. Potential predators on a patch of plaice Pleuronectes platessa eggs located in the eastern Irish Sea were mapped using acoustics and sampled by trawl and a plankton multi-net. Gut contents of 3373 fish, crustacea and cephalopods sampled in the area were screened using a plaice-specific TaqMan DNA probe. Herring Clupea harengus and sprat Sprattus sprattus dominated trawl catches and showed high positive TaqMan responses (77 and 75% of individuals tested respectively). Locations of clupeid schools also broadly corresponded with the distribution of fish eggs in the plankton. Whiting Merlangius merlangus were also reasonably abundant in trawl hauls and 86% of their stomachs tested positive for plaice DNA. Species showing lower levels of positive TaqMan response included mackerel Scomber scombrus, poor cod Trisopterus minutus, squid Loligo spp., dogfish Scyliorhinus canicula and weever Trachinus vipera. Non-reactivity of all negative controls precluded the occurrence of cross-contamination, and positive reactions from demersal species, such as dogfish and weever, may have resulted from secondary predation. No benthic macro-crustaceans tested positive. Samples of planktonic organisms yielded 13% positive TaqMan reactions, mainly from clupeoid or sandeel (Ammodytidae) larvae, but also included some Malacostraca and Amphipoda. Use of the molecular approach allowed rapid screening of a large number of potential predators of plaice eggs, and the results provide a more holistic description of the predator community than has previously been achieved.


KEY WORDS: Herring · Sprat · Predation · Fish eggs · Plaice · Recruitment


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Cite this article as: Fox CJ, Taylor MI, van der Kooij J, Taylor N and others (2012) Identification of marine fish egg predators using molecular probes. Mar Ecol Prog Ser 462:205-218. https://doi.org/10.3354/meps09748

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