Conservation Aquaculture of Northern Leatherside Chub and Effects of Temperature on Egg Survival

Abstract

AbstractWe present 4 years of data that refine aquaculture protocols for the northern leatherside chub Lepidomeda copei, a species of conservation concern in the Intermountain West. Experiments examined life history traits (age at first spawning and thermal limits to egg hatching success) and aquaculture techniques (brood density, spawning substrate type and surface area, and feeding methods for fry). Tests showed that leatherside chub can reproduce as early as age 2. Multiple spawns per female during a year were also documented. Survival of eggs was compared at incubation temperatures of 18.4, 23.0, 24.6, and 26.8°C. Eggs at 18.4°C had the highest survival to hatching (54.0%); eggs at 26.8°C had significantly lower survival (1.5%). Egg survival at 23.0°C and 24.6°C (32–33%) was significantly lower than survival at 18.4°C. Aquaculture experiments showed that the mean total number of eggs produced did not significantly differ between brood densities of 8.4 (1,246 ± 1,236 eggs [mean ± SD]) or 16.8 (2,224 ± 1,600 eggs) fish/m3. Studies showed that leatherside chub preferred spawning over natural cobble substrate to spawning over marble substrate. More eggs were recovered from a three‐substrate tray treatment (1,350 cm2) than from a single tray treatment (450 cm2). Fry given brine shrimp Artemia spp. with probiotic bacteria or fed with an automated, more continuous drip feeder did not show any advantages in growth over time. Juveniles at rearing densities of 800, 1,700, and 3,400 fish/m3 did not differ significantly in growth rates, deformities, or mortalities. This research provides general guidelines for rearing northern leatherside chub and some additional information on the species’ life history.