Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8711
Title: Experimental evidence for olfactory imprinting by sockeye salmon, Oncorhynchus nerka, at embryonic and smolt stages
Author: Michelle A. Havey, Andrew H. Dittman, T. P. Quinn, S. C. Lema, D. May
Publication Year: 2017
Journal: Transactions of the American Fisheries Society
Volume: 146
Issue: 1
Pages: 74-83
Keywords: imprinting,sockeye salmon,homing

Anadromous salmonids have an extraordinary ability to migrate back to their natal streams as adults for spawning but the mechanisms underlying this ability are incompletely known. Many experiments indicate that salmon imprint on natal odors at the smolt stage prior to seaward migration, but the life history and population genetics of some species, notably sockeye salmon Oncorhynchus nerka, suggest that imprinting likely also occurs during the period between hatching and emergence from the gravel as fry. To test the hypothesis that sockeye salmon imprint during this period, and to estimate the duration of odor exposure needed for imprinting at the smolt stage, we exposed juveniles to a mixture of odorants during either the alevin or smolt stage. The smolt exposure group was further divided into different exposure durations (six weeks, one week, and one day) to evaluate the duration of odor exposure needed for imprinting during the smolt stage. Imprinting was then assessed by testing fish as mature adults in two-choice mazes. Fish exposed either as alevins or for six weeks as smolts both spent significantly (P < 0.05) more time in the odor-scented arm compared with control fish (unexposed to the odors as juveniles), as did those exposed for six weeks at the smolt stage. Fish exposed to odors for one week or one day as smolts showed similar but weaker responses. Concurrent measures of gill Na+/K+-ATPase activity and thyroxine (T4) confirmed that the fish exposed as smolts were undergoing the parr-smolt transformation during exposure. We conclude that sockeye salmon are able to imprint as both alevins and smolts, and that longer periods of odor exposure yielded greater behavioral responses to odors as adults, though specific times within the parr-smolt transformation period may be more sensitive to imprinting than others.

Theme: Recovery and rebuilding of marine and coastal species
Foci: Characterize the population biology of species, and develop and improve methods for predicting the status of populations.
Evaluate the effects of artificial propagation on recovery, rebuilding and sustainability of marine and anadromous species.