SEAFWA 2016

AUTHORS: Bobby Reed, Eric Shanks, Kristi Butler - Louisiana Department of Wildlife and Fisheries

ABSTRACT: While primarily an inhabitant of the Mississippi River basin, several disjunct populations of paddlefish (Polyodon spathula) occur in the smaller rivers along the western gulf coast of Louisiana. Paddlefish were studied in the Mermentau River in southwest Louisiana to better understand population characteristics in this small coastal river. The growth, mortality, fecundity, age frequency, sex ratio, and population estimates were determined from paddlefish (n = 1,414) collected from 1990 to 2006. The gender-combined sizes ranged from 496 to 1,017 mm eye-fork length, and ages ranged from 2 – 16 years (males) and 5 – 16 years (females). Instantaneous mortality rates were moderate (Z = 0.36, r2 = 0.91) when compared to other Louisiana populations from the Mississippi River basin. Observed annual growth rates of paddlefish from mark and recapture efforts ranged from 7 mm to 35 mm per year. The sex ratios of fish collected on the spawning grounds ranged from 1.0 : 1.1 to 6.6 : 1, males to females, while those sampled in summer habitat were nearly 1 : 1. Fecundity determined from 90 hatchery spawned females ranged from 38,400 to 226,800 ova with an average of 125,040 per spawn. The population of breeding adults was estimated to be 27,273,000 (95% CI = 19,013 – 40,769). While geographically separated from the Mississippi River population, Mermentau River paddlefish exhibit similar life history characteristics.