THE CENTRAL-PLACE TERRITORIAL MODEL DOES NOT APPLY TO SPACE-USE BY JUVENILE BROOK CHARR SALVELINUS-FONTINALIS IN LAKES

1. Territoriality is widely accepted as the mechanism responsible for density-dependent mortality, emigration, and 'self-thinning' of popula tions of juvenile salmonine fishes in streams. Numerous studies have f ocused on territoriality exclusively in stream (lotic) environments an d thus have fostered a stereotyped view of juvenile salmonines as sede ntary and territorial. We term this behavioural paradigm the central-p lace territorial model (CPTM). 2. We tested predictions characterizing the CPTM for young-of-the-year (YOY) brook charr (Salvelinus fontinal is) in two Canadian lakes to determine if territoriality may also pote ntially limit space and population size of brook charr in lakes. 3. Ou r findings were not consistent with the CPTM. Fish in both lakes were not central-place foragers. Maximum displacement distance did not incr ease with body length as predicted by the general salmonine model of G rant & Kramer (1990). Net displacement distance increased with the pro portion of time spent moving. Aggressive frequency was greatest for fi sh which spent large proportions of time moving and did not defend fro m a central-place. 4. Fish in both lakes were rarely aggressive, highl y active, and often moved back over the same areas. However, lake fish which migrated to a tributary stream had no net displacement (central -place foraging) illustrating the immediate effects of current on fora ging tactics and space-use. 5. The effect of hydrodynamic environment (flowing vs. still water) on fish behaviour needs to be explicitly con sidered in future models of salmonine behaviour.