Biology and ecology of lake sturgeon Acipenser fulvescens in the Grasse River, New York

The objectives of this dissertation were to (1) evaluate the age, growth, mortality, and abundance of lake sturgeon Acipenser fulvescens in the Grasse River, New York; (2) characterize seasonal movement patterns and mesohabitat use for adult and juvenile lake sturgeon in the Grasse River, New York; and (3) quantify the immediate and delayed post-procedure mortality for shovelnose sturgeon after insertion of an endoscope through an incision. I determined age for 196 of 211 lake sturgeon by examination of sectioned pectoral fin rays. Ages ranged from 0--32 years and the annual mortality rate for fish between ages 7 and 14 was 16.8%. The weight (W, g) to total length (TL, mm) relationship was W = 1.281 x 10-6TL 3.202. The von Bertalanffy growth equation was TL = 1,913(1 -- e-0.0294(t+9.5691)). An open population estimator using the POPAN sub-module in the Program MARK produced an abundance estimate of 793 lake sturgeon (95% CI = 337--1,249). Minimum daily distances moved were greater for adult lake sturgeon during the spring season than those observed for juvenile lake sturgeon. I was unable to detect significant differences in displacement or absolute distance moved by adult and juvenile lake sturgeon within any of the four seasons. Differences in mean home range size between adult and juvenile lake sturgeon were detected during the spring season. Lake sturgeon in the Grasse River behaved as would be expected for the species. Adult and juvenile fish within the three river reaches made use of core areas on either a seasonal or annual basis. Lake sturgeon demonstrated a greater use of pool mesohabitat and lower use of run mesohabitat under both low and mid flow conditions. During the majority of the year, adult and juvenile lake sturgeon demonstrated a greater use of silt substrate. Sex of adult fish was determined using an abdominally invasive endoscopic technique. The immediate and post-procedure survival of sturgeon subjected to that surgical technique was assessed using shovelnose sturgeon. The initial and latent survival rates of test fish was 100%. Short procedure duration and high post-procedure survival make the technique ideal for collecting biological data from sturgeon during field studies such as the Grasse River.