Growing salmon in Tasmania has some really big advantages and some very big challenges. Going through the advantages we have:
- The best strain of salmon in the world from a quality and yield perspective. Our fish are less fatty than farmed salmon from other countries which leads to firmer flesh and better tasting flesh. Our fish with their smaller heads and deep bodies give a better yield than fish from other countries.
- We have the best climate in the world for growing salmon and our fish grow at a faster rate than anywhere else in the world. We have more of the year where our temperatures are in the ideal range for maximum growth. Many countries have long periods of time with very cold temperatures and short days when the salmon don’t grow. We can have periods that are too hot but when you average it over the year we are well ahead in terms of growth rates.
- We are free of all the serious diseases that plague the salmon world.
- We have a clean environment in which to grow our fish
- We have a domestic market that takes most of the volume we produce. Not many other salmon producing countries have this advantage, most of their products must be exported.
- We have a large population close by in Asia that our industry can service with a premium product.
Innovations are often the result of turning our mind to the challenges we face. Some of these challenges are:
- Amoebic Gill Disease [AGD] that increases our growing costs, slows the growth of the fish, increases mortality.
- Our fish stocks as a result of their fast growth all mature after one sea winter. This has made the ability of supplying fish on a year round basis a very challenging problem
- Periods of warm water that in some years can be very stressful on the fish lowering o2 levels in the water, stressing the fish and in some instances led to disease out breaks.
- Direct loss of fish to predators such as seals
So how have we overcome some of these challenges. Because many of them are unique to Tasmania we have had to innovate to deal with them. Innovative solutions allow us to consistently produce the finest salmon in the world. Some of the key innovations we have implemented include:
Amoebic Gill Disease and Vaccine Development
Whilst not a true disease, AGD is caused when single celled animals called amoeba (protozoa) that live in the water column settle on the gills of our fish. They multiply and live on the natural mucous that the fish produces on its gills. This reduces the efficiency of the fishes gills and effectively “smothers” the fish if left untreated. We routinely check each pen of fish for settlement and when the time is right we will transfer the fish into a freshwater bath for some hours. The salmon are happy in either freshwater or seawater but the amoeba cannot tolerate freshwater and they burst. This leaves the salmon free from amoeba and the settlement cycle starts again. We haven’t yet found a way to prevent the amoeba from settling on the gill. The industry has co-operated on research projects to look at the feasibility of a commercial vaccine.
Selective Breeding Program
We see selective breeding coupled with vaccine development as our best long-term strategy to lower the incidence of AGD. We do know that some fish have an inbuilt resistance that slows settlement down and the Huon selective breeding program uses amoeba resistance as one of the criteria to identify brood stock that will be the parents of future generations of our salmon. With our own selectively bred fish we have managed to reduce the number of baths per cycle in the first generation. We have also increased growth by 20%. With our own new hatchery development and the SALTAS program, we can now put the majority of fish into seawater as selected stock.
Until other solutions are found we are left with the constant need to bathe our fish in freshwater. This did involve a process where fish are crowded in the cages and need to be pumped or lifted out of the water, de-watered so no salt water goes into the freshwater liner and then transferred into the freshwater. The initial solution was to use overseas technology – for example vacuum pumps. As we couldn’t afford one and thought that the use of it would overly stress the fish, we decided to invent something that would do the job. As Peter Bender was a cattle farmer prior to growing fish, he couldn’t see why we couldn’t transfer the technology used in that industry to the salmon farm.
So we set about building our first fish transfer race. This consisted of a small raceway that could be joined to a cage of fish to enable them to be swum into it, a paddle for moving the fish up the race and an elevator at the end with a slatted base that drained the saltwater off. Having worked with sheep and cattle over many years Peter was firmly of the belief that you should design your animal handling equipment to suit the animal that you are working with.
If you use this thought with fish we soon learnt that they like to go into a deeper area and if they are crowded and they see an empty area they will swim into it. We also found that they like to swim into the current. Using this knowledge we have built four designs of our fish race and we are now starting on the fifth. To our delight we discovered that although it was a bit slower than a fish pump and more labour intensive, we had virtually no mortality and the fish came back onto feed very quickly. This cannot be said of fish pumps. Over the years we have further refined our raceway system so it is now even better on the fish and far quicker than our fish pump. The model we use can transfer around 80 tonnes/hour with very low stress on the fish, lifting around 2 tonnes of fish each cycle. The fish do not need to be crowded as much as they would to get them to go through a conventional fish pump.
Our Tasmanian stock must supply year round harvest demand. To do this we had to extend its “normal” transfer window to allow fish to go to sea 8 months of the year. Our hatchery is built around recirculation technology with full control of temperature, water quality and photoperiod – acknowledged as world’s best coupled with innovative plantation irrigation to “treat” the small volume of water discharged each day. Because we reuse the water, our hatchery is virtually drought proof and ensures that we use very little of the available water flowing in the local rivers
Feeding appropriately is the most important aspect of growing any animal. Salmon are certainly no different. The difference with fish is that you can’t see what is happening. If you feed cattle a bale of hay you can tell when they have eaten it. With fish unless you utilise technology, you won’t really have a clue.
We worked with the team at AQ1 Systems to help them develop and commercialise a feeding system that utilises underwater infra-red sensing technology to identify if feed pellets have not been eaten by the time they reach a certain depth in the pen. The system controls the automated feeders, stopping the flow of pellets when the number of pellets passing the sensor reaches a certain level. This not only prevents wastage but maximises growth and gives every fish an opportunity to eat until they are satisfied. This reduces the variation in size within the population and produces better yields and better quality fish. I have no doubt that a lot of the success of our company has been due to this technology and our application of it. We were the first company in the world to embrace this technology.
In order for this feeding system to work efficiently we have developed our own feed bins, spinners for spreading the feed and our boats for filling the hoppers. We started with 70Kg capacity hoppers in 60 metre circumference pens and now have 6 tonne hoppers in 168 metre circumference pens. Other hoppers are mounted on the side of the pen and blow or flick the feed in from the edge. We decided that this wasn’t as good as central distribution where the spread of feed would be better. So we put ours in the middle of the pen on an endless rope that enables it to be dragged to the side for filling. This gives a good spread ensuring all the fish get access to food and prevents feed being blown or swept out of the pen by wind or current.
Because our feed bins are unique we needed to come up with a method of filling them. We had to design a boat that was capable of doing this reliably. Again we have been through several designs. The first one held 1 tonne of feed and filled 70Kg bins. The latest vessel shown here holds 100 tonnes of feed in 8 compartments and can fill a 6 tonne hopper in 7 minutes.
In order to supply fish in the early part of the season we need to put our smolt to sea early and grow them as quickly as possible to ensure an acceptable harvest weight 12 months later. Unfortunately this process will lead to a proportion of the stock deciding to mature after around 6 months in the sea. These are, of course, the bigger fish in the population.
We have managed to largely overcome this issue by using underwater lights in our pens. This persuades the fish that summer has come early and they decide that they aren’t big enough to mature so they delay this decision til the next summer. A bonus to this is that the fish believing it is summer grow very strongly following their natural instinct.
Tasmania is the warmest location in the world where Atlantic salmon can be grown. Average temperatures range between 11oC winter minimum (5m depth) 18oC summer maximum (5m depth). With high temperatures comes lower oxygen solubility. This combines to not only stress the fish, it decreases growth as they go ‘off’ their feed.
In order to combat this we have a programme of moving our fish from the more sheltered sites within the Huon Estuary to sites further south that are far more exposed. These sites are marginally cooler and generally have better oxygen levels that the estuarine sites during the summer months.
Pillings Bay empty by December / Deep Bay empty by November / Police Point empty by November
Small fish are held at Garden Island and Flathead through summer. Large fish are held in the southern sites through summer
Having clean nets is of paramount importance in order to maximise water flow through the pens. The incoming water supplies oxygen to the fish and the out-flowing water carries carbon dioxide and dissolved nitrogen compounds away, ensuring that the fish enjoy the best possible environmental conditions. We use very heavy, strong nets with a large mesh size on the outside of each pen and lighter “soft” nets inside the pen. This combination has historically provided a safe and secure home for our fish and also a barrier against seals which, if given the chance, will demonstrate that they like to eat Huon salmon too! In fact the large mesh outer net extends to around 2.5 metres above the water surface to prevent seals from climbing into the pens sample our products.
We use a combination of techniques and technologies to keep our nets clean. At different points in the production cycle we will physically remove the nets from the pen and take them to our net facility at Port Huon for cleaning, refurbishment and redeployment. This innovation has effectively reduced the direct loss of fish to seals over the years. Whilst the nets are in use, our Tasmanian designed and built net cleaning boats use an innovative cleaning head to remove seaweed and fouling organisms from the net without disturbing the fish.
Humane Harvesting Practices & Processing
There is no point in producing the best fish in the world if they aren’t harvested properly. Two-three years work could be down the drain in a few minutes if the fish undergo too much stress during the harvesting process. Stressed fish will have poorer flesh quality, soft flesh and gaping. In order to improve our harvest methods we worked with Bruce Goodrick from Seafood Innovations. In a world first we installed automatic stunning and bleeding machines at our farm at Hideaway Bay. This technology again utilises the salmons same natural instincts to swim into a water current. The fish swim down a slide, are automatically stunned, rolled over and bled. The fish by moving naturally into the stunner exhibit little stress. This is confirmed by the long pre-rigor time that allows us to gut and fillet the fish to achieve premium quality. This is a good example of working with local suppliers to solve problems and deliver world-class results.
Investment in primary processing capability including novel gutting, grading, yield management and inventory control systems has increased production capacity, improved product quality and reduced costs
At Huon we try to develop an open culture that focuses on:
- Innovation to overcome challenges
- Involving the entire workforce
- Encouraging debate and questions
- Celebrating the need for change
This formula has proven to be a successful one for our business as we continue to find solutions to the challenges we face, and strive to produce the most premium salmon in the world.