Premium
Effects of Mechanical Harvesting of Eurasian Watermilfoil on Angling for Bluegills in Fish Lake, Wisconsin
Author(s) -
Unmuth Jean M. L.,
Hansen Michael J.,
Rasmussen Paul W.,
Pellett Thomas D.
Publication year - 2001
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(2001)021<0448:eomhoe>2.0.co;2
Subject(s) - fishing , fishery , biology , lepomis macrochirus , myriophyllum , abiotic component , shore , biomass (ecology) , vegetation (pathology) , invasive species , ecology , fish <actinopterygii> , aquatic plant , medicine , macrophyte , pathology
We examined changes in angling effort, catch and catch rates, and fishing and natural mortality of bluegills Lepomis macrochirus associated with mechanical plant harvesting in a lake heavily infested with Eurasian watermilfoil Myriophyllum spicatum. In August 1994, 18% of the total plant biomass was removed in a radial pattern of 2‐m‐wide channels in Fish Lake, Dane County, Wisconsin. After the vegetation removal, winter angler hours increased significantly, whereas summer angler hours did not. The number of boat trips in summer increased significantly, but the number of shore trips did not. Catch rates and total catch of bluegills did not change significantly, but the size structure of harvested bluegills increased. Catches of bluegills by shore anglers decreased in summer, whereas catches of bluegills by boat anglers increased. Natural mortality declined for bluegills of ages 4–6, but fishing mortality more than doubled for bluegills of the same ages. We conclude that removal of Eurasian watermilfoil may increase winter angler effort, decrease natural mortality of bluegills, and increase fishing mortality of bluegills. We also conclude that removing vegetation may improve the quality of the bluegill fishery, as evidenced by the increase in the number of larger bluegills harvested. However, this study lacked the replication and controls needed to separate the effects of plant harvesting from those of other biotic and abiotic factors.