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Title: Mucus: a new tissue fraction for rapid determination of fish diet switching using stable isotope analysis.

Author
item CHURCH, M. - Us Environmental Protection Agency (EPA)
item EBERSOLE, JOSEPH - Us Environmental Protection Agency (EPA)
item RENSMEYER, KIRK - Us Environmental Protection Agency (EPA)
item COUTURE, RYAN - Oregon Department Of Fish & Wildlife
item Barrows, Frederic
item NOAKES, DAVID - Oregon State University

Submitted to: Canadian Journal of Fisheries and Aquatic Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2008
Publication Date: 1/21/2009
Citation: Church, M.R., Ebersole, J.L., Rensmeyer, K.M., Couture, R.B., Barrows, F., Noakes, D.L. 2009. Mucus: a new tissue fraction for rapid determination of fish diet switching using stable isotope analysis. Canadian Journal of Fisheries and Aquatic Sciences 66:1-5. 2009.

Interpretive Summary: The ability to determine when fish change food sources in either wild or hatchery pond conditions can be important in understanding production efficiency. A method using stable isotopes was developed using fish mucus so that the sampling of fish was non-lethal. This procedure appears to be much more effective, and time sensitive, than using different tissue.

Technical Abstract: Stable isotope analysis of diet switching by fishes is often hampered by slow turnover rates of the tissues analyzed (usually muscle or fins). We examined epidermal mucus as a potentially faster turnover “tissue” that might provide a more rapid assessment of diet switching. In a controlled hatchery experiment, we switched the diet of juvenile steelhead (sea-run rainbow trout) from a plant-based feed with a low 13C and 15N to a fish-meal based diet with higher delta values. We found mucus to provide a significantly more rapid response to diet switching than muscle tissue, even for growing juvenile fish. Mucus may provide a rapid turnover tissue for analysis of diet (or habitat) switching by fish. It has the additional advantage that it may be sampled non-lethally in some fishes, thereby avoiding problems in studying threatened and endangered species. This is the first report of the use of mucus in stable isotope analyses of fish tissues.