MEPS 388:169-184 (2009)  -  DOI: https://doi.org/10.3354/meps08096

Trophic effects of fishing southern rock lobster Jasus edwardsii shown by combined fatty acid and stable isotope analyses

M. A. Guest1,*, S. D. Frusher1, P. D. Nichols2,3, C. R. Johnson4, K. E. Wheatley4

1Tasmanian Aquaculture and Fisheries Institute, Marine Research Laboratories, Nubeena Crescent, Taroona, Tasmania 7053, Australia
2CSIRO Marine and Atmospheric Research, Castray Esplanade, Hobart, Tasmania 7000, Australia
3Antarctic and Climate Ecosystems, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia
4School of Zoology, University of Tasmania, Private Bag 5, Hobart, Tasmania 7001, Australia

ABSTRACT: The southern rock lobster Jasus edwardsii is a commercial species that has benefited from the complete protection offered by no-take reserves, with higher abundances and larger animals recorded in reserves than in adjacent fished areas. What remains unclear is whether there is any change in the diet of lobsters in reserves, for example, as a result of increased intraspecific competition for food. We used combined chemical tracers to examine the diet of lobsters in fished and reserve areas in 2 bioregions in eastern Tasmania. δ15N values of lobsters were richer in fished than in reserve areas, indicating that lobsters eat a greater proportion of food items from higher trophic levels in fished areas. Mixing models suggest that ascidians, sea urchins and the turbinid gastropod were all important food sources for lobsters, but the importance of these food items differed between bioregions. This spatial variability may suggest that the small size of the reserve in one bioregion is inadequate at ensuring the diet of lobsters is protected from fishing pressure. Fatty acid profiles of lobsters supported the importance of these food sources to lobsters. Differences between bioregions, or inside and outside of reserves, were not apparent using fatty acids. The present study highlights that lobster fishing has the capacity to alter the trophic status of prey for generalist predators and suggests that fatty acid analyses may be limited in detecting changes in the dietary composition of such generalist feeders.


KEY WORDS: Effects of fishing · Food webs · Marine protected areas · Stable isotopes · Fatty acids


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Cite this article as: Guest MA, Frusher SD, Nichols PD, Johnson CR, Wheatley KE (2009) Trophic effects of fishing southern rock lobster Jasus edwardsii shown by combined fatty acid and stable isotope analyses. Mar Ecol Prog Ser 388:169-184. https://doi.org/10.3354/meps08096

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