Individual specialization and trophic adaptability of northern pike (Esox lucius): an isotope and dietary analysis

Citation
Cp. Beaudoin et al., Individual specialization and trophic adaptability of northern pike (Esox lucius): an isotope and dietary analysis, OECOLOGIA, 120(3), 1999, pp. 386-396
Citations number
51
Categorie Soggetti
Environment/Ecology
Journal title
OECOLOGIA
ISSN journal
00298549 → ACNP
Volume
120
Issue
3
Year of publication
1999
Pages
386 - 396
Database
ISI
SICI code
0029-8549(199908)120:3<386:ISATAO>2.0.ZU;2-P
Abstract
Northern pike (Esox lucius) are often considered to be specialist piscivore s, but under some circumstances will continue to eat invertebrates as adult s. To examine effects of fish assemblage composition on the trophic ecology of pike, we combined stable isotope analysis (SIA) of carbon and nitrogen and stomach content analysis (SCA) on pike from five lakes in northern Albe rta, three of which contain only pike ("pike-only") and two that also conta in yellow perch (Perca flavescens) or white sucker (Catostomus commersoni) ("pike-other"). Fish were more important as prey and empty stomachs, which often characterize piscivores, were significantly more frequent in pike-oth er than in pike-only lakes. However, even though invertebrates were more im portant for pike in pike-only lakes, SIA and SCA indicated that invertebrat es were also an important component of pike diets in pike-other lakes. SIA and SCA also revealed considerable intrapopulation variation in trophic eco logy, with individuals in some populations differing by as much as two trop hic levels. Comparisons of stomach contents and isotope signatures of the s ame fish suggested that within these variable populations, specialization o n invertebrates or fish was a long-term trait of some individuals. SIA indi cated that trophic position increased and diets shifted to a greater import ance of littoral prey as pike grew in pike-only lakes, but not in lakes wit h other fish present. Trophic adaptability in northern pike is expressed at both the population level, where the trophic ecology is sensitive to diffe rences in prey regimes, and at the organismal level, in the form of intrapo pulation variation and individual specialization.