Chapter

Evidence for Bottom-Up Control of Upper-Trophic-Level Marine Populations

GEORGE L. HUNT JR.

in Whales, Whaling, and Ocean Ecosystems

Published by University of California Press

Published in print January 2007 | ISBN: 9780520248847
Published online March 2012 | e-ISBN: 9780520933200 | DOI: http://dx.doi.org/10.1525/california/9780520248847.003.0006
Evidence for Bottom-Up Control of Upper-Trophic-Level Marine Populations

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This chapter examines the evidence for a bottom-up limitation of upper-trophic-level fish, marine birds, and marine mammals. It presents evidence of the role of food limitation on population size and on individual body condition and growth, both of which can affect fecundity in fish. In marine birds and mammals, body condition similarly affects fecundity and the potential for survival to age of first breeding, as well as adult survival. The discussion then examines briefly aspects of the life history characteristics that would argue for a weak role of predation in the regulation of populations of upper-trophic-level species in the marine environment, the spatial scales at which one might expect top-down or bottom-up control to play a more decisive role, and how the relative mobility of predator and prey affect the likelihood of top-down control.

Keywords: upper-trophic-level fish; marine mammals; food limitation; fecundity; life history characteristics; predation

Chapter.  14185 words. 

Subjects: Aquatic Biology

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