Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Habitat Profitability and Choice in a Sit-And-Wait Predator: Juvenile Salmon Prefer Slower Currents on Darker Nights

Neil B. Metcalfe, Sveinn K. Valdimarsson and Neil H. C. Fraser
Journal of Animal Ecology
Vol. 66, No. 6 (Nov., 1997), pp. 866-875
DOI: 10.2307/6002
Stable URL: http://www.jstor.org/stable/6002
Page Count: 10
  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Habitat Profitability and Choice in a Sit-And-Wait Predator: Juvenile Salmon Prefer Slower Currents on Darker Nights
Preview not available

Abstract

1. The profitability of a foraging site for a sit-and-wait predator depends on the range at which food items can be detected, as well as their arrival rate. A simple model for drift-feeding fish shows that potential profitability is dependent on the interaction between current velocity and light level, so that the water velocity at which intake is maximized is predicted to decrease with decreasing light intensity due to changes in detection range. 2. Experimental tests with juvenile Atlantic salmon showed that there was no difference in foraging efficiency between fish held in high and low velocity water until light intensities dropped below 0.1 lx (similar to full moon with a clear sky); however, below this point fish were more efficient at intercepting food in slower flowing water. 3. When given a choice of foraging location, juvenile salmon exhibited the predicted shift towards slower velocity microhabitats as light level was reduced; the most profitable feeding habitat for the fish was therefore dependent on the night-time conditions (overcast vs. full moon). The results may explain why foraging juvenile salmonids have been observed to undertake diel habitat shifts, and indicate that habitat suitability assessments made only under daylight conditions may be inappropriate.

Page Thumbnails

  • Thumbnail: Page 
866
    866
  • Thumbnail: Page 
867
    867
  • Thumbnail: Page 
868
    868
  • Thumbnail: Page 
869
    869
  • Thumbnail: Page 
870
    870
  • Thumbnail: Page 
871
    871
  • Thumbnail: Page 
872
    872
  • Thumbnail: Page 
873
    873
  • Thumbnail: Page 
874
    874
  • Thumbnail: Page 
875
    875