First year growth and survival of common carp in two glacial lakes

Abstract

Abstract Cohorts of common carp, Cyprinus carpio Linnaeus, were monitored from hatch through the next spring in two South Dakota, USA lakes to identify factors affecting year‐class strength. Hatching occurred over 37‐ and 47‐day periods in the two lakes. Common carp that hatched earlier achieved greater total lengths at the end of the first growing season (Brant Lake: r = −0.84, d.f. = 77, P < 0.001; Campbell Lake: r = −0.87, d.f. = 78, P < 0.001). Mean daily growth rates were approximately 1.0 mm day−1 and similar between lakes. Total length was positively related to daily growth rate in the two lakes, indicating that members of the cohort that grew faster achieved greater total lengths by time of capture. Hatch date was inversely related to daily growth (fish hatched earlier grew faster) in one lake (r = −0.44, d.f. = 77, P < 0.001) but not the other (r = −0.04, d.f. = 78, P = 0.678), suggesting that length at the end of the growing season can be affected by length of growing season and growth rate. Overwinter survival of age‐0 fish appeared to be size dependent because age‐1 common carp length–frequency distributions from both lakes comprised only of the larger cohort members present the previous autumn.