Dynamics of prey moving through a predator field: a model of migrating juvenile salmon

Authored by Donald L DeAngelis, JH Petersen

Date Published: 2000

DOI: 10.1016/s0025-5564(00)00017-1

Sponsors: Bonneville Power Administration

Platforms: No platforms listed

Model Documentation: Other Narrative Mathematical description

Model Code URLs: Model code not found

Abstract

The migration of a patch of pl-ey through a field of relatively stationary predators is a situation that occurs frequently in nature. Making quantitative predictions concerning such phenomena may be difficult, however, because factors such as the number of the prey in the patch, the spatial length and velocity of the patch, and the feeding rate and satiation of the predators all interact in a complex way. However, such problems are of great practical importance in many management situations; e.g., calculating the mortality of juvenile salmon (smolts) swimming down a river or reservoir containing many predators. Salmon smolts often move downstream in patches short compared with the length of the reservoir. To take into account the spatial dependence of the interaction, we used a spatially-explicit, individual-based modeling approach. We found that the mortality of prey depends strongly on the number of prey in the patch, the downstream velocity of prey ill the patch, and the dispersion or spread of the patch in size through time. Some counterintuitive phenomena are predicted, such as predators downstream capturing more prey per predator than those upstream, even though the number of pl-ey may be greatly depleted by the time the prey patch reaches the downstream predators. Individual-based models may be necessary for complex spatial situations, such as salmonid migration, where processes such as schooling occur at fine scales and affect system predictions. We compare some results to predictions from other salmonid models. (C) 2000 Elsevier Science Inc. All rights reserved.

Tags

Individual-based model Fish Population-models Largemouth bass Chinook salmon Columbia river Smallmouth bass Squawfish ptychocheilus-oregonensis John-day-reservoir Northern squawfish