Predator aggregations during eulachon Thaleichthys pacificus spawning runs

Predators congregated in large numbers during the 1996 and 1997 spring spawning runs of eulachon Thaleichthys pacificus Richardson (Osmeridae) in the lower reaches of the rivers entering Berners Bay, southeastern Alaska. Predator abundance rose rapidly at the beginning of the runs and was significan...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 2002-04, Vol.231, p.229-236
Main Authors: MARSTON, Brian H, WILLSON, Mary F, GENDE, Scott M
Format: Article
Language:English
Subjects:
Agnatha. Pisces
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Autoecology
Biological and medical sciences
Brackish
Eumetopias jubatus
Freshwater
Fundamental and applied biological sciences. Psychology
Haliaeetus leucocephalus
Laridae
Marine
Osmeridae
Phoca vitulina
Protozoa. Invertebrata
Thaleichthys pacificus
Vertebrata
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Summary:Predators congregated in large numbers during the 1996 and 1997 spring spawning runs of eulachon Thaleichthys pacificus Richardson (Osmeridae) in the lower reaches of the rivers entering Berners Bay, southeastern Alaska. Predator abundance rose rapidly at the beginning of the runs and was significantly correlated with an index of eulachon abundance within years. Gulls (Laridae) were the most abundant predators, with a daily average peak of 40000 during the 1996 run, at a density of 3000 km super(-2). A daily average peak of over 250 Steller sea lions Eumetopias jubatus and harbor seals Phoca vitulina fed on eulachon early in the run in both years. Daily average counts of bald eagles Haliaeetus leucocephalus approached 600 on the lower reaches of the rivers, and many others foraged upstream. Eulachon are unusually high in lipid content, and many of the prodigious spawning runs in Alaska and British Columbia occur in spring, when predator energy demands are high. We suggest that spring spawning runs of eulachon and other forage fishes are an ecological cornerstone for regional coastal ecosystems, supporting large numbers of wildlife species.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps231229