Extending the Survival of Stocked Rainbow Trout

Recreational Fishing Grants Program Research Report

JULY 2011

Executive Summary

An experimental trial of the performance of two different hatchery strains of rainbow trout was undertaken to assess Fisheries Victoria's stocking practises. The trial tested the performance of:

• A Victorian strain produced from the Department of Primary Industries Fish Production Facility located at Snobs Creek (hereafter the Snobs Creek strain)
• A Tasmanian strain sourced from Tasmania's Great Lake population at Liawenee (the Tasmanian strain).

The two genetic strains were stocked simultaneously, at similar densities, sizes and ages. The trial was designed so that the anglers did not know the origin of the fish they were catching.

The trial was undertaken in a privately-managed small lake fishery where only catch-and-release fishing is permitted. This facility provided ideal circumstances for monitoring longevity, growth and catchability for both trout strains, because it eliminated recreational harvest as a potential confounding source of mortality.

Both the Tasmanian and Victorian strain of rainbow trout demonstrated:

• similar longevity
• similar growth rate
• similar catchablility.

Both the Tasmanian and Snobs Creek strain of rainbow trout survived in catchable numbers until they were 3–4 years old, when the trial ceased.

This study showed no evidence that the Snobs Creek strain of rainbow trout were genetically compromised. The apparent lack of rainbow trout older than 2 years in many open waters in Victoria is not due the strain of fish stocked into those waters.

Contact

If you would like to receive a full copy of this report please email Chris Padovani (chris.padovani@vfa.vic.gov.au).