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The effects of parasitism and body length on positioning within wild fish shoals
Author(s) -
Ward A. J. W.,
Hoare D. J.,
Couzin I. D.,
Broom M.,
Krause J.
Publication year - 2002
Publication title -
journal of animal ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.134
H-Index - 157
eISSN - 1365-2656
pISSN - 0021-8790
DOI - 10.1046/j.0021-8790.2001.00571.x
Subject(s) - shoal , shoaling and schooling , fundulus , biology , parasitism , context (archaeology) , ecology , population , fish <actinopterygii> , zoology , fishery , oceanography , demography , geology , paleontology , host (biology) , sociology
Summary1 The influence of body length and parasitism on the positioning behaviour of individuals in wild fish shoals was investigated by a novel means of capturing entire shoals of the banded killifish ( Fundulus diaphanus , Lesueur) using a grid‐net that maintained the two‐dimensional positions of individuals within shoals. 2 Fish in the front section of a shoal were larger than those in the rear. 3 Individuals parasitized by the digenean trematode ( Crassiphiala bulboglossa , Haitsma) showed a tendency to occupy the front of shoals. Parasitized fish were also found more in peripheral positions than central ones in a significant number of shoals. 4 Shoal geometry was affected by the overall parasite prevalence of shoal members; shoals with high parasite prevalence displayed increasingly phallanx‐like shoal formations, whereas shoals with low prevalence were more elliptical. 5 There was no relationship between body length and parasite abundance or prevalence in the fish population which suggests body length and parasite status are independent predictors of positioning behaviour. 6 Solitary individuals found outside shoals were both more likely to be parasitized and had higher parasite abundance than individuals engaged in shoaling. 7 Differences in the shoaling behaviour of parasitized and unparasitized fish are discussed in the context of the adaptive manipulation hypothesis.