Population structure and food habits of white crappie Pomoxis annularis Rafinesque in a turbid Oklahoma reservoir

Abstract

We assessed population structure and food habits of white crappie Pomoxis annuluris Rafinesque in Lake Carl Blackwell, a turbid reservoir in north‐central Oklahoma, U.S.A. White crappie [n= 8549; total length (t.l.) mean = 147 mm, s.d.= 28 mm, range = 73–445 mm] were collected with gillnets, frame nets, and hoop nets. Proportional stock density was 2, as 97% of the fish were under 200 mm t.l. Relative stock density was 96, 2, 1, and 1 for ‘stock‐quality’, ‘quality‐preferred’, ‘preferred‐memorable’, and ‘memorable‐trophy’ lengths. Total annual mortality rate was 54% for fish older than 2 years. Growth was poor and lower than the Oklahoma‐Arkansas regional averages (P<0.01). Relative weights were 79, 86, 106, 109, and 123 for fish in the stock‐quality, quality‐preferred, preferred‐memorable, memorable‐trophy, and trophy size categories. Ephemeroptera nymphs were an important dietary component for fish 150 mm t.l. or smaller. Gizzard shad Dorosoma cepedianum (Lesueur) was a major forage item, especially for fish greater than 150 mm t.l. (P<0.01). Empirical information on prey availability indicates that the white crappie population is forage limited and that gizzard shad are not available in appropriate sizes or sufficient numbers to sustain the predator population. Poor fish condition, slow growth, and high mortality are probably the result of inadequate forage.