Ideal free distribution theory as a tool to examine juvenile coho salmon (Oncorhynchus kisutch) habitat choice under different conditions of food abundance and cover
Gr. Giannico et Mc. Healey, Ideal free distribution theory as a tool to examine juvenile coho salmon (Oncorhynchus kisutch) habitat choice under different conditions of food abundance and cover, CAN J FISH, 56(12), 1999, pp. 2362-2373
Citations number
35
Categorie Soggetti
Aquatic Sciences
Journal title
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES
We investigated the mechanisms affecting habitat choice by juvenile coho sa
lmon (Oncorhynchus kisutch) in relation to the patchy distribution of food
and cover. We tested the following hypotheses: (i) the distribution of juve
nile coho, both between patches in a pool and between separate pools in a c
hannel, corresponds numerically to the food input rate of those habitat pat
ches as predicted by the "input-matching rule" of ideal free distribution (
IFD) and (ii) the addition of instream cover, by increasing visual isolatio
n among competitors, promotes input matching both within and between pools.
We conducted our experimental work in artificial channels and we used two
different types of cover, instream and overhead. In the absence of cover an
d with either no differences or relatively small differences in food abunda
nce between patches, the spatial distribution of juvenile coho responded nu
merically to the input rate of food as predicted by the IFD. However, when
differences in food abundance between patches were relatively large or cove
r was present, fish distributions consistently undermatched food input rate
in the rich patch. Coho foraged in open patches away from cover within sin
gle pools but preferred pools with cover when choosing between separate poo
ls. Several IFD models were used to examine the observed dispersion pattern
s.