Climate ready Tasmanian smolt
Seawater temperatures continue to rise in Tasmania, resulting in the window of suitable temperatures for smolt transfer to sea shortening. Atlantic salmon production in Tasmania requires the production of harvestable product all year round, which is currently achieved through detailed production plans that rely on smolt transfer to sea from March until October each year.
As climate change is resulting in warmer temperatures during March, there is a need to understand the risks to production that this shift poses, as well as understanding the additional costs to production that warm water inputs create. This trial is needed to inform commercial decisions around smolt input timing in warm years, and to examine the influence of oxygenation on osmoregulatory performance during warm water transfer.
Development of a hydrodynamic model to investigate near field and regional connectivity around Okehampton Bay
TASSAL: Developing kelp culture in Tasmania
TSGA IPA: CSIRO: reducing the burden of gill disease
Tassal: Flesh quality issues in spring grown Atlantic Salmon
Following customer complaints of excessive gape in harvested product in September 2016, there was a requirement to understand factors that may be contributing to quality issues. Historical records revealed that this is a common complaint during this period of the harvest cycle and this research is the first step in developing a long term strategy for understanding the issue and improving the consistency of harvest product throughout the year.
The aim of this study is to
(i) develop techniques to document and compare fish quality within CSIRO and Tassal,
(ii) benchmark the texture and gaping status of harvest fish
(iii) explore biochemical and structural factors that correlate to gaping
(iv) develop a longer term approach to monitoring and managing seasonal flesh quality issues.
Tassal: improved Atlantic Salmon enclosure netting
Tassal farms Atlantic salmon in Tasmania, with the salmon typically contained using a single layer of netting constructed from polymeric (filament) fibres. These nets have approximately a 6 year lifespan during which time the breaking force for the strongest nets used decreases from 300 kg to around 160 kg. The nets are often damaged by predators (sharks and seals) attempting to take salmon from inside the nets.
There is evidence that sharks can bite and cut through the net but there is no direct evidence that seals damage the nets through biting (but this cannot be discounted). It would appear that seals tend to work on a hole or weakness through repeated nose/head punching at the aperture in an attempt to snare fish as they swim past. The seals also attempt to extract dead fish by the head or tail through the netting apertures.
Net damage and consequent stock loss is a major problem that Tassal wishes to address. Tassal has tried numerous netting systems to address the issues including wire netting, fine wires interlaced within the polymer netting structures, high strength fibre (e.g. Dyneema), plastic meshes etc all without commercial success (based on cost, practicality, poor service life due to corrosion etc.).
One approached currently being investigated by Tassal, which is showing promise, is the use of a stiffened polymer fibre netting material provided by a Japanese company. This product is expensive but not unacceptable if it provides a solution. However supply of this netting appears restricted and the company cannot currently supply to Tassal requirements. Based on the production process of the Japanese supplier, mesh sizes and netting width is limited.
Tassal: Long range seasonal forecasting of environmental conditions to improve husbandry in Tasmanian salmon farming
Tassal: Amoeba biology diagnostics and farm management strategies for Amoebic Gill Disease (AGD)
TSGA IPA: Tassal: Innovative Seal Exclusion Technology
Tassal is in a position where it is has become necessary to re-evaluate the measures taken for seal management and has made a commitment to zero destruction. Although relocation is used as an interim, it is recognised by all parties that this is a costly and temporary solution. Relocation carries the risk of alienating important stakeholders such as recreational and commercial fishers, who are negatively impacted by the process.
Despite the increased attention and budget dedicated to this issue, seal strikes, trappings and relocations continue to increase. Seal interactions have on numerous occasions resulted in documented and medically treated injuries and have presented, through aggressive and threatening behaviour, an unacceptable OH&S risk to marine farm employees. In order to resolve this challenging issue, a systematic co-ordinated approach is needed, with the trial and implementation of new exclusion and deterrent methods a priority.
Tassal has employed Wildlife Management Officers, whose sole responsibility is to audit and manage seal interactions, and continues to look for improved forms of exclusion technology and to gain an increased understanding of seal behaviour. As protocols dictate, Tassal works with the DPIPWE Wildlife Management Branch to evaluate new exclusion equipment.
The monofilament nets currently being used are easy for seals to breach and kikko nets have proven successful in exclusion on a small scale. It is essential that Tassal trials kikko nets in full scale commercial conditions, at high risk sites before committing to company wide implementation. Kikko nets are a significant departure from current technology and due to the expensive nature of the product, a considerable increase in overhead costs would result. Full scale trials must take place to ensure the nets are a viable investment, as there is the possibility that they will not be successful in exclusion when implemented across an entire lease.