Reproductive Ecology and Spawning Substrate Preference of the Northern Leatherside Chub

Conservation of rare fishes is often hindered by a lack of understanding of their basic life history characteristics. We used captive‐breeding studies to determine the preferred spawning habitat and early life history characteristics of the northern leatherside chub Lepidomeda copei , a small cyprinid native to the upper Snake River basin and the Bear River drainage in the Bonneville Basin (Idaho, Utah, and Wyoming). In the first study, wild adult northern leatherside chub were given a choice of four habitats (two shallow riffle habitats and two deeper pool habitats), each with four spawning substrates (large cobble, small cobble, pebble, and a coarse artificial spawning mat) in a large rectangular tank. In the second study, adults were given a choice of three locations with different water velocities (9.5, 12.9, or 19.0 cm/s) but the same substrate size (small cobble). Successful spawning occurred in both studies. Northern leatherside chub spawned almost exclusively over the small cobble substrate (99.6% of total young). Habitat selection was significant, but the patterns were not consistent across tanks; uncovered pool habitat was selected in two tanks and the upper riffle habitat was primarily selected in the third tank. In addition, northern leatherside chub preferentially chose the site with the highest flow (19 cm/s) for spawning. Early life history characteristics (embryo size, time to hatch, larvae size, eggs per spawn, time to swim‐up, and fry growth) were estimated from the reproductive output of the spawning studies. Small cobble is needed for northern leatherside chub reproduction, and its availability may be among the limiting factors for northern leatherside chub populations.