Influence of Angling on Age Structure and Growth of Bluegills in Northern Wisconsin Lakes
Date
2005Author
Vorass, Michael T.
TenEyck, Matt
Swenson, Bill
Ney, John
Metadata
Show full item recordAbstract
Abstract: Bluegill sunfish (Lepomis macrochirus) have long been heavily targeted by anglers in a
consumption oriented fishery. Anglers catch bluegill over a wide size range but only harvest those
large enough to have food value. Analysis by WDNR of the size structure and harvest from Wisconsin
lakes indicates that the abundance of desirable sized bluegill in both populations and creel have
dropped considerably. This research will analyze patterns of growth of bluegill from northern
Wisconsin lakes and develop growth comparisons between stunted and non-stunted bluegills.
Objectives are to: 1.
Describe and compare patterns of growth in bluegill populations that vary in harvest pressure and
quality status; 2. Determine the growth potential of a stunted bluegill population. Methods
consisted of age and growth analysis from heavily fished versus lightly fished lakes in the same
watershed. Scales from these populations came from samples taken and archived by the WDNR and
supplemented as necessary by field sampling bluegill populations. Growth of immature bluegills from
one stunted and one non-stunted population was compared in a controlled laboratory setting. The
fish were fed live mealworms at a ration of 4% for 26 days and 6% for another 30 days. Length and
weight measurements were determined at periodic intervals. Results indicate both Crystal and Deep
Lake grew at different rates when ration sizes were increased in a control environment suggesting
genetics maybe a factor in their life history. Back calculation comparison of Crystal and Deep Lake
showed similar growth rates for ages 1-4, but superior growth seen by Crystal Lake for age 4-8 with
a decrease in growth by Deep Lake.
Subject
angling
age structure
Bluegills
Northern Wisconsin Lakes