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Effectiveness of an Imposed Slot Length Limit of 12.0‐14.9 Inches on Largemouth Bass
Author(s) -
Eder Stephen
Publication year - 1984
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 - 10.1577/1548-8659(1984)4<469:eoaisl>2.0.co;2
Subject(s) - micropterus , bass (fish) , acre , fishery , electrofishing , fishing , zoology , lepomis macrochirus , biology , fish <actinopterygii> , agronomy
Watkins Mill Lake was opened to public fishing in 1974 with a minimum length limit of 15.0 in on largemouth bass (Micropterus salmoides). In 1976, the growth and size structure of large‐mouth bass were poor. The average length of Age‐V largemouth bass was 12.0 in and the Proportional Stock Density (PSD) was 1%. A regulation was established in 1977 to protect largemouth bass 12.0‐14.9 in long; with this slot regulation, fish less than 12.0 in and those 15.0 in and longer could be harvested while fish from 12.0 to 14.9 in long had to be released. Anglers removed an estimated 47 largemouth bass per acre during the first year of the experimental regulation. Thereafter, significant improvements in growth and size structure occurred. In 1982, the average length of Age‐V largemouth bass was 15.4 in; PSD and RSD 15 values were 50 and 24% respectively. Largemouth bass densities (≳ 7.0 in) were reduced from about 78 per acre in 1977 to about 23 per acre in 1981. Despite the reduction in numbers, their total weight harvested was comparable in 1977 and 1980. These harvests averaged 21 lbs per acre with the slot limit. The bluegill (Lepomis macrochirus) population exhibited a corresponding decline in growth, body condition, and size structure after the slot limit was initiated. Bluegills less than 3.0 in long were caught at a significantly higher rate by electrofishing after 1977. The largest harvest of bluegills (21 lbs per acre) occurred during the fourth year of the slot length limit. An excellent white crappie (Pomoxis annularis) population developed during the tenure of the slot length limit. Ten‐ to 12‐inch fish made up 31 and 17% of the white crappie harvest in 1979 and 1980, respectively, and the harvest averaged 25 lbs per acre during those years. Even with the improvement in the largemouth bass fishery, channel catfish (Ictalurus punctatus) continued to be the most preferred species. Forty‐two percent of total angling time was spent in pursuit of channel catfish, and annual harvests averaged 24 lbs per acre. Overall, the 12.0‐ to 14.9‐in slot length limit proved to be an effective management strategy for improving a slow‐growing, high‐density bass population in a lake with an annual fishing pressure that averaged 322 hours per acre. Most of the anglers approved of the regulation and cooperated with the program.