Experimental Predictions of The Functional Response of A Freshwater Fish
Article first published online: 10 JUL 2013
© 2013 The Authors. Ethology published by Blackwell Verlag GmbH.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Volume 119, Issue 9, pages 751–761, September 2013
How to Cite
Murray, G. P. D., Stillman, R. A., Gozlan, R. E., Britton, J. R. (2013), Experimental Predictions of The Functional Response of A Freshwater Fish. Ethology, 119: 751–761. doi: 10.1111/eth.12117
- Issue published online: 20 AUG 2013
- Article first published online: 10 JUL 2013
- Manuscript Accepted: 13 JUN 2013
- Manuscript Revised: 24 APR 2013
- Manuscript Received: 6 MAR 2013
- Environment Agency and Bournemouth University
The functional response is the relationship between the feeding rate of an animal and its food density. It is reliant on two basic parameters; the volume searched for prey per unit time (searching rate) and the time taken to consume each prey item (handling time). As fish functional responses can be difficult to determine directly, it may be more feasible to measure their underlying behavioural parameters in controlled conditions and use these to predict the functional response. Here, we tested how accurately a Type II functional response model predicted the observed functional response of roach Rutilus rutilus, a visually foraging fish, and compared it with Type I functional response. Foraging experiments were performed by exposing fish in tank aquaria to a range of food densities, with their response captured using a two-camera videography system. This system was validated and was able to accurately measure fish behaviour in the aquaria, and enabled estimates of fish reaction distance, swimming speed (from which searching rate was calculated) and handling time to be measured. The parameterised Type II functional response model accurately predicted the observed functional response and was superior to the Type I model. These outputs suggest it will be possible to accurately measure behavioural parameters in other animal species and use these to predict the functional response in situations where it cannot be observed directly.