Spawning success and early life history of longnose suckers in Great Lakes tributaries

Abstract

Fish eggs and larvae are often subject to very high mortality, and variation in early life survival can be important for population dynamics. Although longnose suckers (Catostomus catostomus) are widespread in northern North America, little is known about their early life history. We examined fecundity and early larval survivorship during sucker spawning events in three small Lake Michigan tributaries. Although egg deposition varied 25% among spawning events, estimated larval export to the lake varied over 25,000-fold from around 1000 to 26 million. Based on variation in environmental conditions across years, it appears that spring flow and temperature may be important determinants of egg survival to larval outmigration. Larval age data suggest that most individuals that survived to outmigration hatched during a 2-day period despite adult spawning across at least 10 days. Most larvae spent <2 weeks in the stream and emigrated around the time of transition from endogenous to exogenous feeding before substantial growth occurred. In two of three cases, larvae drifted exclusively at night; however, high drift rates occurred during both day and night in the case where larvae were very abundant, suggesting densitydependent drift behaviour. Our results indicate that survival in tributary streams from egg deposition to larval export is highly variable in longnose suckers. These large differences in early life survival may translate into variability in recruitment, thereby influencing population structure and dynamics.

A portrait of a sucker using landscape genetics: how colonization and life history undermine the idealized dendritic metapopulation

“…In order to relate age with fecundity, FL was equated to total length in the following equation relating fecundity ( f is the number of eggs produced) with total length in centimetres (TL) (Childress et al . ) for longnose suckers in the Great Lakes. …”

Headwater Streams and Wetlands are Critical for Sustaining Fish, Fisheries, and Ecosystem Services

“…During spring, Longnose Suckers Catostomus catostomus undergo massive spawning runs from Lake Michigan into tributary streams (Figure 3). Egg and larval survival to outmigration appears to be strongly influenced by spring flow and temperature, and this variability can influence stock dynamics (Childress et al 2016). Egg mortality and excretion by migrating adult suckers contributes significant amounts of nitrogen and phosphorus to stream ecosystems.…”

Spawning Locations within and among Tributaries Influence Flannelmouth Sucker Offspring Experience

“…Even though this suggests that distances between some of our reaches (i.e., the mouth and headwater reaches) would satisfy the assumption of no movement among reaches, especially at earlier sampling periods, postemergent drift should be considered as a relevant yet variable process in larval sucker life histories (i.e., Childress et al. ). As such, one alternative explanation for our findings is that patterns in Flannelmouth Sucker arose from larger, more developed individuals being able to maintain a more upstream position in the network over time.…”