Population Dynamics of a June Sucker Refuge Population

Abstract

AbstractThe June sucker Chasmistes liorus is an endangered sucker endemic to Utah Lake in the Bonneville basin of the western United States. Little is known about the critical life history parameters for this species. We evaluated the life history characteristics of a June sucker refuge population using mark‐recapture techniques. The Red Butte June sucker population was structured as five stage‐classes: age 0, age 1, age 2, age 3, and adult. The first four annuli on opercles were estimated to form at approximately 57, 121, 184, and 259 mm total length (TL). The adult class comprised all June suckers 4 years and older; the oldest possible age for an adult was 16 years, these June suckers representing the original suckers used to establish this refuge population. Mean lengths of reproductive adults indicated sex‐specific differences in size at maturity; females were significantly greater in TL than males (402 and 378 mm, respectively). The estimated population size excluding age‐0 fish was 13,556 (95% confidence interval, 11,499–16,510) after adjusting for tag loss. Survival rates were estimated for all but the age‐0 class as follows: age 1, 0.4225; age 2, 0.4625; age 3, 0.8020; and adults, 0.9576. This study provides the first estimates of abundance and survival of juvenile June suckers as well as comprehensive life history data for a June sucker population.