Life Histories of two Species of Catostomid Fishes in Sixteenmile Lake, British Columbia, with Particular Reference to Inlet Stream Spawning

Abstract

Inlet spawning migrations of longnose suckers (Catostomus catostomus) and white suckers (Catostomus commersonnii) in Sixteemile Lake commenced in the spring when daily maximum temperatures in the inlet reached S and 10 C, respectively. Migrating fish were trapped in the stream near the lake, marked by subcuticular injection of liquid latex, and recovered during their lakeward migration following spawning. Upstream migrants from later parts of the run spent less time in the stream than fish from early parts of the run. Longnose suckers returned to the lake before white suckers. The females of each species returned before the males. Spawning mortality was 10–40%. Suckers marked as mature spawners in 1956 made up an appreciable proportion of the spawning run for several years thereafter. Some fish spawned in several successive years. Scales did not provide a reliable measure of age of spawners, but recoveries of marked fish suggested maximum ages of 12–16 years. Growth of adult fish was 10–20 mm/year. Estimates of the adult population size were 2000 longnose and 800 white suckers of which 25–50% spawned each year. Low annual recruitment was indicated in these slow-growing populations. The downstream movement of sucker fry was nocturnal and largest when stream levels were high and the water turbid or the nights particularly dark. Peak fry migration was approximately 1 month after spawning. Several investigations have indicated the general similarity of inlet spawning migrations of rainbow trout, redside shiner, squawfish, and the two species of suckers.