Display Settings:

Format

Send to:

Choose Destination
Proc Biol Sci. 2006 Jan 22;273(1583):193-8.

Functional and aggregative responses of harbour seals to changes in salmonid abundance.

Author information

  • 1Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, Cromarty, Ross-shire IV11 8YJ, UK. s.middlemas@marlab.ac.uk

Abstract

There is intense debate over the potential impact of seal predation on declining salmon stocks in both the Pacific and Atlantic oceans. However, efforts to model such interactions have been constrained by a lack of data on the functional and numerical responses of these predators. Based upon theory, and data from small-scale terrestrial and freshwater systems, a type 3 functional response is expected to best describe predation by generalist pinnipeds. Similarly, theory also predicts that seal numbers should increase with salmon density in rivers following an aggregative response of predator to prey. We tested these predictions by studying the diet and local density of harbour seals in relation to seasonal variations in the abundance of salmonid in a Scottish river system. As predicted, the abundance of seals in the river was directly related to the abundance of returning salmon, and dietary data supported the type 3 functional response to changes in salmonid abundance. These studies provide empirical support for the use of type 3 response in modelling studies.

PMID:
16555787
[PubMed - indexed for MEDLINE]
PMCID:
PMC1560021
Free PMC Article

Images from this publication.See all images (2)Free text

Figure 1
Figure 2
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk