Brook Trout Production Dynamics in the Streams of a Low Fertility Newfoundland Watershed

Abstract

Production of brook trout Salvelinus fontinalis ranged from 99 to 651 g · 100 m−2 · year−1 among headwater streams of the Copper Lake watershed in insular Newfoundland. Ratios of annual production to mean annual biomass (P/B) ranged from 0.9 to 1.5 among the same streams. Empirical models developed from stream salmonid populations in the United States successfully predicted modal production based on water alkalinity and P/B ratios based on age-class structure of the populations. Differences in production among streams were consistent with previous work in low-fertility headwater systems, which suggests habitat attributes of the stream define salmonid production within the range dictated by the water fertility. The most important of these attributes in this study was food abundance. Substrate composition and habitat complexity may have played secondary roles in determining production in the most productive stream.