Population Characteristics, Habitats, and Movements of Lake Sturgeon (Acipenser fulvescens) in the Lower Niagara River

Abstract

Before my study, anecdotal information, such as incidental catches and reported sightings, provided the only means of assessing lake sturgeon, a species listed as threatened in New York State, in the lower Niagara River. The objectives of my study were to ( 1) assess the population of lake sturgeon by collecting and analyzing age, growth, and CPUE data, (2) compare the habitats and movements of adults and juveniles, and (3) identify potential spawning, feeding, and nursery habitats and compare use of these habitats between adults and juveniles. From late July 1998 through August 2000, 67 lake sturgeon were captured using gill nets, baited setlines, and SCUBA divers. Overall, divers (2.5 fish/night) performed better than gill nets (0.25 fish/night) and setlines (0.23 fish/night). Age of lake sturgeon captured ranged from 1 to 23 years, with most fish (n = 47) less than 10 years old. Six percent (4 out of 63) of the lake sturgeon captured had deformities, such as spinal curvature. Ultrasonic transmitters were attached to 24 fish (12 adults and 12 juveniles) to determine their habitat use and movements. Depth, current velocity, and substrate uses were similar between juvenile and adult fish. Monitoring the movements of adult fish during likely spawning temperatures (11 to 18°C) revealed that fish congregated both 8 to 10 km up river and within 5 km of the river's confluence with Lake Ontario. Based on the results of my study, I recommend that the lake sturgeon in the lower Niagara River remain listed as "threatened" by the NYSDEC and that the commercial and recreational fisheries remain closed. In addition, I recommend further studies investigating year class abundance, the cause of growth deformities, and the abundance and availability of food resources.