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Prey preferences of a riverine population of juvenile chinook salmon, Oncorhynchus tshawytscha
Author(s) -
Sagar P. M.,
Glova G. J.
Publication year - 1987
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1987.tb05269.x
Subject(s) - biology , predation , oncorhynchus , chinook wind , juvenile , fishery , population , ecology , spring (device) , zoology , fish <actinopterygii> , mechanical engineering , engineering , demography , sociology
The diet of juvenile chinook salmon and the foods available to them were studied during spring and summer in a large, braided, New Zealand river. During both sampling periods fish and potential prey were collected at dawn and dusk. Analysis showed that in spring the feeding rate increased at dawn, when aquatic taxa comprised the majority of their prey. Prey of terrestrial origin dominated the diet at dusk in summer but formed only about 1% of the diet during spring, when few such prey were available. During spring the fish selectively preyed upon larger nymphs of the mayflies Deleatidium spp. However, in summer chironomids, other dipterans, and trichopterans were consumed to the exclusion of Deleatidium . Most of the chironomids and trichopterans taken were pupae or emerging adults and it is suggested that this may reflect differences in vulnerability during the diurnal emergence period.