Exploitation and Mortality of Paddlefish in the Lower Tennessee and Cumberland Rivers

Abstract

We estimated commercial and sport fishing exploitation of the paddlefish Polyodon spathula population in the lower Cumberland and Tennessee rivers from 1991 to 1994 using tag and reward methods. Exploitation for fish tagged over 3 years was 20.0% in Lake Barkley, 25.4% in the Kentucky Dam tailwater, and 14.4% in Kentucky Lake, most of which was commercial in Kentucky Lake (88%) and sport in Lake Barkley (65%). Although commercial harvest is prohibited in the Kentucky Dam tailwaters, some paddlefish moved to areas where commercial fishing is allowed. Most paddlefish were harvested in the lake where they were tagged, but nine individuals moved among the major tributaries of the Mississippi River. We compared the Kentucky Lake commercial paddlefish harvest during the winter spawning run of 1991–1992 with that of 1985–1986. The 1985–1986 harvest followed high roe prices and earlier intense fishing pressure, resulting in high annual mortality (69%) and a relatively lower mean length (691 mm) and weight (5.7 kg). Annual mortality was lower (22%) in 1991–1992 with reduced fishing pressure. We estimated instantaneous mortality for 9–15-year-old fish (Z = 0.25) by analysis of a catch curve and separated fishing (F = 0.157) and natural mortality (M = 0.093). Even with total exploitation of 14.4%, the status of the paddlefish population in Kentucky Lake improved by 1992. There were more older paddlefish than observed 6 years before, the mean length (857 mm) and weight (11.5 kg) increased, and there were more gravid females. Commercial catch per unit effort increased from 3.7 kg/net-night in 1985–1986 to 38.3 kg/net-night in 1991–1992.