Multicompartment Gravel Bed Flume to Evaluate Swim-Up Success of Salmonid Larvae

Abstract

Swim-up success, the proportion of fry emerging from a gravel redd, is difficult to quantify in the field, and currently available laboratory systems are limited. We used custom-built gravel bed flumes to assess the swim-up success of Rainbow Trout Oncorhynchus mykiss, Brook Trout Salvelinus fontinalis, and Cutthroat Trout Oncorhynchus clarkii. Flumes were built with compartments to separate individual egg batches, eggs were buried under gravel, and oxygenated water was supplied to simulate upwelling through the gravel. Temperature, dissolved oxygen, pH, and flow were constant between compartments and flumes operating in parallel. Swim-up success was scored both by the emergence of fry relative to the number of eggs placed in the flume (59–85% depending on species) and the hatching success (proportion of eggs that hatch and resorb their yolk sac) of a sample from the same clutch reared in a vertical incubator (62–84% depending on species). The gravel bed flumes could be used to estimate the swim-up success of salmonid egg clutches from hatchery stocks or fish from the wild or under experimental regimes of relevance to fishery or environmental assessment, including changes in pH, siltation, temperature, toxicants, or events simulating floods or droughts.

Received July 12, 2012; accepted October 11, 2012

ACKNOWLEDGMENTS

We thank H. Bird, J. Fearns, and K. Neilson for their tireless collection of swim-up, the Allison Creek Brood Trout Station staff for their expertise on spawning fish and egg incubation, and Sarah Bogart for the technical drawing of the flume. This project was funded by the Alberta Conservation Association and Metals in the Human Environment (MITHE)-NSERC Strategic Network.