Dm. Mason et Sb. Brandt, EFFECTS OF SPATIAL SCALE AND FORAGING EFFICIENCY ON THE PREDICTIONS MADE BY SPATIALLY-EXPLICIT MODELS OF FISH GROWTH-RATE POTENTIAL, Environmental biology of fishes, 45(3), 1996, pp. 283-298
Spatially-explicit modeling of fish growth rate potential is a relativ
ely new approach that uses physical and biological properties of aquat
ic habitats to map spatial patterns of fish growth rate potential. Rec
ent applications of spatially-explicit models have used an arbitrary s
patial scale and have assumed a fixed foraging efficiency. We evaluate
d the effects of spatial scale, predator foraging efficiency (combined
probabilities of prey recognition, attack, capture, and ingestion), a
nd predator spatial distribution on estimates of mean growth rate pote
ntial of chinook salmon, Oncorhynchus tshawytscha. We used actual data
on prey densities and water temperatures taken from Lake Ontario duri
ng the summer, as well as, simulated data assuming binomial distributi
on of prey. Results show that a predator can compensate for low foragi
ng efficiency by inhabiting the most profitable environments (regions
of high growth rate potential). Differences exist in predictions of gr
owth rate potential across spatial scales of observation and a single
scale may not be adequate for interpreting model results across season
s. Continued refinements of this modeling approach must focus on the a
ssumptions of stationary distributions of predator and prey population
s and predator foraging tactics.