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Evaluation of Minimum‐Size Limits and Reduced Daily Limits on the Crappie Populations and Fisheries in Five Large Missouri Reservoirs
Author(s) -
Colvin Michael A.
Publication year - 1991
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(1991)011<0585:eomsla>2.3.co;2
Subject(s) - fish <actinopterygii> , fishery , limit (mathematics) , yield (engineering) , zoology , environmental science , geography , biology , hydrology (agriculture) , mathematics , geology , physics , mathematical analysis , geotechnical engineering , thermodynamics
Populations of white crappies Pomoxis annularis were studied at five Missouri reservoirs to evaluate the effects of minimum‐size regulations and reduced daily limits. Models of equilibrium yield per recruit indicated that regulations that reduced or eliminated the harvest of age‐1 and age‐2 fish resulted in harvest of fewer fish but increased yield to the fishery. Peak yield occurred when white crappies were first harvested at age 3. After restrictive regulations were imposed, a significantly greater proportion of the harvest shifted to age‐3 and older fish at Pomme de Terre (15‐daily limit), Wappapello (10‐daily limit), Stockton (10‐in size limit), and the James River Arm of Table Rock (10‐in size limit), but not at Lake of the Ozarks (15‐daily limit). Although mean lengths of harvested white crappies were highly variable, they increased more in reservoirs with minimum‐size limits. The greatest increase was in the James River Arm, where the mean length increased from about 7 to 11 in after imposition of the size limit. Even though the harvest shifted to older white crappies at Wappapello, mean lengths of harvested fish did not increase, because growth was slower during years of the 10‐daily limit. Most anglers complied with restrictive regulations; the estimated harvest of sublegal fish was always less than 10% of the legal harvest at reservoirs with minimum‐size limits, and less than 1% of the anglers kept more than the daily limits at all reservoirs. White crappie populations at Missouri's large reservoirs can benefit from restrictive regulations if the populations contain few age‐4 and older fish and have satisfactory growth.