Project number: 2016-229
Project Status:
Completed
Budget expenditure: $99,800.00
Principal Investigator: Tim Dempster
Organisation: University of Melbourne
Project start/end date: 17 Jan 2016 - 31 May 2016
Contact:
FRDC

Need

For several years, Huon has been monitoring temperature, salinity and DO conditions at its Maq harbour sites to understand the spatial and seasonal variability in the environment. This pre-existing, long-term data set has clearly identified the summer months as a critical production period given the combination of high temperatures and low dissolved oxygen at production depths within the cages. Monitoring of the environment in MH in late 2015 and early 2016 shows that dissolved oxygen levels at cage production depths are the poorest on record over the past 5 years. This pre-existing work has identified a clear need to understand the coping strategies of salmon under summer conditions.

High-resolution data on salmon swimming depths and schooling densities in relation to temperature and dissolved oxygen, in particular, will enable determination of how it can best manage current and future production in MH. This includes implementing cage management strategies to minimise negative impacts upon production, timing harvests to avoid compromising the production potential of its farms, and setting appropriate stocking densities for each cage.

In March 2016, the Tasmanian government will re-visit production limits for Macquarie Harbour. Detailed information from this project is needed for inclusion in Huon’s submission as part of this process.

Objectives

1. Document the swimming depths and densities of Atlantic salmon in production cages in Macquarie harbour during the critical summer production period
2. Measure the cage environment (temperature, salinity and dissolved oxygen) and how it varies with depth during the critical summer production period
3. Combine the environmental and group-based salmon data to determine if salmon have coping strategies to select depths which confer optimal temperatures and dissolved oxygen levels
4. Make recommendations for management strategies to optimise summer production, improve fish welfare and production performance

Final report

ISBN: 978 0 7340 5302 2
Author: Tim Dempster

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