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Temporal and Spatial Abundances of Larval Walleyes in Two Tributaries of Lake Champlain
Author(s) -
Mitro Matthew G.,
Parrish Donna L.
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<0273:tasaol>2.3.co;2
Subject(s) - tributary , stizostedion , larva , environmental science , hydrology (agriculture) , abundance (ecology) , ichthyoplankton , fishery , ecology , biology , geography , geology , fish <actinopterygii> , cartography , geotechnical engineering
We collected migrating larvae of walleye Stizostedion vitreum in the Poultney and Missisquoi rivers in 1994 to provide data for developing indices of juvenile walleye abundance. These Vermont rivers drain to southern (Poultney) and northern (Missisquoi) Lake Champlain. We determined the temporal and spatial distributions of larvae migrating from each river by collecting larvae in drift nets at stations below spawning areas. Comparisons of larval densities among dates and time of day within each river were made with standardized densities adjusted for daily changes in discharge in surface migration areas. The greatest standardized larval density at the station near the spawning area in the Poultney River was 2.0/m 3 at 2055 hours and the greatest density at the down‐stream station was 2.0/m 3 at 0030 hours; peak densities at the downstream station occurred about 3.5 h later than those at the upstream station. In the Missisquoi River, the greatest standardized larval density was 2.8/m 3 at 2130 hours. Standardized larval densities changed across dates in a quadratic pattern by time of day; quadratic linear regression models fit to observed densities yielded estimates of total walleye numbers during the 12‐d migration period in which densities peaked during a 2‐ to 3‐d period. We estimated that 528,000 (95% confidence interval: 307,000–778,000) walleye larvae migrated from the Poultney River and 1,306,000 (891,000–1,727,000) walleye migrated from the Missisquoi River.