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Trout Production Dynamics and Water Quality in Minnesota Streams
Author(s) -
Kwak Thomas J.,
Waters Thomas F.
Publication year - 1997
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1997)126<0035:tpdawq>2.3.co;2
Subject(s) - salmo , trout , salvelinus , rainbow trout , biomass (ecology) , brown trout , zoology , environmental science , population , fishery , streams , biology , water quality , salmonidae , ecology , fish <actinopterygii> , computer network , demography , sociology , computer science
We sampled fish assemblages and quantified production dynamics of brook trout Salvelinus fontinalis , brown trout Salmo trutta , and rainbow trout Oncorhynchus mykiss in 13 southeastern Minnesota streams during 1988–1990 to examine the influence of water quality on fish populations in fertile trout streams. Fish assemblages in 15 stream reaches were abundant, but low in diversity; 13 species were collected. Parameter means (ranges) over the reaches were species richness, 4.1 (1–8); density, 29,490 (1,247–110,602) fish/ha; and biomass, 253.5 (49.6–568.6) kg/ha. Means (ranges) for salmonids were annual mean density, 2,279 (343–8,096) fish/ha; annual mean biomass, 162.0 (32.5–355.5) kg/ha; and annual production, 155.6 (36.7–279.6) kg/ha. Salmonid production and mean biomass were greater during the spring‐fall interval than during fall‐spring; young cohorts (ages 0–1) contributed the greatest proportion to population biomass and production. Salmonid annual production‐to‐mean‐biomass ratio (P/B) averaged 1.06 (0.64–1.42), and means were significantly different among species (1.03 for brown trout, 1.54 for brook trout, and 1.92 for rainbow trout). A significant linear model was developed that describes P/B as an inverse function of population age structure and may be used to improve accuracy in approximations of annual production from mean biomass. Fish density, biomass, or production were not correlated with eight water quality variables describing ionic and nutrient content in these streams, but when data from other United States streams with a wide range in alkalinity were incorporated, salmonid production was strongly, positively correlated with alkalinity. The wide range in fish population and production statistics and their lack of correlation with water quality suggest that no uniform fish carrying capacity exists among these streams and that factors other than water fertility limit fish density, biomass, and productivity at this spatial scale, but the overall maximum production rate in the region may be governed by water quality.