Distinguishing between juvenile anadromous and resident brook trout (Salvelinus fontinalis) using morphology |
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Authors: | Geneviève R Morinville Joseph B Rasmussen |
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Institution: | (1) Department of Biology, McGill University, 1205 Dr. Penfield Ave., Montreal, QC, Canada, H3A 1B1;(2) Rescan Environmental Services, Sixth Floor, 1111 West Hastings, Vancouver, BC, Canada, V6E 2J3;(3) Department of Biological Sciences, Water Institute for Semi-Arid Ecosystems (WISE), University of Lethbridge, 4401 University Dr. West, Lethbridge, AB, Canada, T1K 3M4 |
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Abstract: | Phenotypic variation linked to habitat use has been observed in fish, both between and within species. In many river systems,
migratory and resident forms of salmonids coexist, including anadromous (migrant) and resident brook trout, Salvelinus fontinalis. In such populations, juvenile anadromous (migrant) brook trout, prior to migration, inhabit regions of higher current velocity
than residents. Because it is more costly to occupy fast currents than slow currents, differences in morphology minimizing
the effects of drag were expected between the two forms. As predicted, migrant brook trout were found to be more streamlined
(narrower and shallower bodies) than resident brook trout, and these differences persisted into the marine life of the fish.
Migrants also exhibited shorter pectoral fins, which facilitate pelagic swimming, indicating that migrants, prior to their
migration to the sea, possess the appropriate morphology for swimming in open water habitats. The reported differences between
migrants and residents were powerful enough to derive discriminant functions, using only five of the seven measured traits,
allowing for accurate classification of brook trout as either migrants or residents with an overall correct classification
rate of 87%. Importantly, this study contributes to the notion that a link exists between morphology, habitat use, metabolic
costs and life-history strategies.
Contribution to the program of CIRSA (Centre Interuniversitaire de Recherche sur le Saumon Atlantique). |
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Keywords: | Fish shape Habitat use Coexistence Salmonid Metabolic costs Energetics Sea trout Migration Anadromy |
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