ISSN:
1522-9602
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Mathematics
Notes:
Abstract Prominent and persistent cyclic fluctuations in the abundance of consecutive year-classes occur in some sockeye salmon populations throughout the species' range. We review and test a number of explanations for the existence of these cycles using qualitative biological arguments, including a consideration of the synchrony of cycles among populations. Most of the hypotheses involve mechanisms that would reinforce synchronous population fluctuations within watersheds. However, the 4-year cycles characteristic of many Fraser River sockeye populations are sometimes out of phase with each other, both among populations which migrate together as mixed stocks while vulnerable to commerical fisheries, and among populations whose juveniles share the same nursery lake habitat (Shuswap Lake). Such asynchrony suggests that the mechanism(s) causing population cycles can operate independently within reproductively isolated populations. Of the mechanisms reviewed here, only those involving genetic effects on age at maturation, or on resistance to disease or parasites, or those involving depensatory predation soon after fry emergence, appear to offer satisfactory explanations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02464832
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