What makes a modern Murray cod farm?

The defining features of a modern food producer are drawn from both within the industry and also out of our collective social responsibility. A modern Murray cod farm is environmentally-conscious, resource-efficient, highly-automated, scalable, profitable and, most importantly, is able to guarantee a consistent and premium-quality fish, all throughout the year.

However, when it comes to the individual details, every farm has their own way of doing things that depend on the resources they have at hand, the knowledge and experience that they have accumulated, and most importantly of all, their philosophy and vision for the future of their product, farm and industry.

Below, we present and explain our way of doing things. This is our interpretation of a modern Murray cod farm.

The importance of careful breeding

The most critical necessity of any food producer is having good quality production inputs. In a freshwater fish farm, the two key inputs are water and juvenile fish.

Regarding the first key input, water, we are fortunate to be situated along the Murrumbidgee and Murray river catchments, within the Murray cod’s natural habitat. As far as river water goes, our source is both natural and ideal. We also have access to pristine bore water, free from algae, bacteria and other organic matter, which we feed into our recirculating aquaculture systems in our nursery and grow-out systems.

While we are blessed with pristine and natural water as a result of our location, we have needed decades of dedicated breeding to produce multigenerational lineages of Murray cod broodstock that consistently spawn healthy, strong, fast-growing, disease-resistant fish that are highly-suitable for aquaculture and that also have the distinct depth of flavour found in wild Murray cod.

Thus, for any modern Murray cod farm, the most important input is also the most basic – carefully-bred, multigenerational broodstock that produce genetically-stronger larvae that become exceptionally healthy fingerlings that are both hardy enough for restocking wild populations and adaptable enough to be raised in aquaculture.

However, while this core input may seem like a simple matter, raising a sufficient number of high-quality, selectively-bred broodstock can require over 20 years of dedicated breeding. Only then, will a farm have a regular and dependable supply of healthy juvenile fish that are both suited for aquaculture and that will also have the required quality of taste and texture that is desired by end-market consumers.

At Uarah Fisheries, we first began our breeding program in 1977. Since then, for over 40 years, we have carefully bred and selected Murray cod for their natural strength and vitality, initially using a base of wild stock, but progressively incorporating more selectively-bred broodstock with each new season.

Today, we have a sizeable base of multigenerational lineages of Murray cod broodstock producing juvenile fish that excel in an aquaculture environment. Based on our experience and the extensive records we have kept since 1977, we have noticed a substantial and steady improvement in growth rates and disease resistance over the seasons as we have incorporated selective-breeding.

An additional feature of the breeding program at Uarah Fisheries is that we utilise natural spawning of Murray cod, rather than the artificial hormone-induced spawning process that is widely-used in the industry. In our experience, we have found that natural spawning in an outdoor pond environment, though more time-consuming and labour-intensive, produces far superior juvenile fish that exhibit favourable characteristics in terms of growth, hardiness and health.

Lastly, though it is often overlooked, another benefit of raising and managing our own broodstock and breeding season is that we can also maintain a longer season to introduce juvenile fish into the farm, and consequently ensure a steady supply of market size fish to the end consumer, all-year round. Likewise, it would be relatively simple to steadily scale up our production by retaining mature fish to add to our broodstock base, and thus, responsively expand our production volumes to meet increases in demand.

Therefore, by controlling the quality and supply of our two key production inputs – namely water and juvenile fish – we are able to ensure the best basis from which to produce a consistent and high-quality fish, that tastes great, and is available all through the year. Considering these above factors, an effective breeding program and selection of good quality broodstock is the fundamental building block of any modern Murray cod farm.

Our hatchery and nursery

The spawning and nursing process of newborn Murray cod is conducted differently at Uarah Fisheries to many other Murray cod hatcheries and farms. Not only do we adopt a natural spawning process, we also allow natural feeding for our Murray cod larvae to develop their immunal health, thus eliminating many potential problems later in the production cycle.

The natural spawning season for Murray cod begins around late September every year. After spawning in ponds, we collect the Murray cod eggs to be rested in the hatchery for several days, after which they will hatch into larvae.

A portion of the larvae are then purchased by overseas and interstate producers. The remaining larvae are again deposited into specialised ponds, where they remain for approximately two months.

These ponds are carefully prepared and nurtured to ensure sufficient growth of zooplankton and other microbial life that will act as the food source for the Murray cod larvae.

Since the larvae are carefully exposed to a controlled outdoor environment, they are able to develop a level of immunal strength that is otherwise obtainable under an indoor environment.

Beginning around late November, once the Murray cod larvae have fattened up sufficiently and become fingerling-sized, they are again collected to be nursed and weaned in a designated recirculating aquaculture system in the nursery.

While this entire process is considerably labour-intensive and may seem redundant to many casual observers, and indeed many other Murray cod farmers, we have found that – in combination with the selected genetic attributes of our broodstock – this process of natural spawning and natural feeding for newborn Murray cod leads to significantly stronger, healthier and naturally more disease-resistant fingerlings. Thus, this process is necessary to guarantee a source of superior fingerlings for native restocking programs and for our own grow-out production systems.

Overview of recirculating aquaculture

At Uarah Fisheries, we favour the use of recirculating aquaculture for the grow-out of Murray cod juvenile fish to market size. The premise of recirculating aquaculture revolves around the key feature of recirculating the water in the aquaculture system. That is, water is continually recycled and reused in a recirculating aquaculture system. To maintain the quality of the water, recirculating aquaculture utilises a number of processes to filter, treat and oxygenise the water so that it can be reused.

Thus, in essence, a farmer using recirculating aquaculture is responsible not only for taking care of the fish, but quite literally the water as well. Where conventional aquaculture systems would simply discard wastewater and replace it with additional river water, recirculating aquaculture involves the control and maintenance of water quality and fish health down to the minutest details so as to minimise and treat waste, and retain as much water to be reused as possible.

Moreover, the benefits of recirculating aquaculture go far beyond the substantial water savings for the environment and the farmer. Recirculating aquaculture is synonymous with greater control over water environment parameters including temperature, oxygen levels and acidity, increased automation, scalability, minimisation and control of pests and the ability to promptly isolate and quarantine infections. These advantages, when combined with fish husbandry knowledge and experience, will almost always lead to superior water quality, healthier fish, faster growth rates, an all-year production cycle and, perhaps unexpectedly for those outside the industry, better-tasting fish, due to strict quality controls and the minimisation of stress placed on the fish.

However, even considering all of the above advantages, perhaps the most industry-defining feature of recirculating aquaculture is its adaptability to a multitude of environments – so as long as a modest but reliable supply of high quality water is present.

Although we, at Uarah Fisheries, are blessed with generous access to land and high-quality water deposits, it is possible for those without these ideal conditions to use recirculating aquaculture to raise Murray cod to a very good quality.

That is, even farmers in arid or urban environments, or even based abroad, can raise Murray cod in a recirculating aquaculture system. This is critical, as recirculating aquaculture thus presents a convincing solution to the major contemporary environmental issues of water depletion, water pollution and rampant commercial overfishing. Likewise, recirculating aquaculture presents a major opportunity for forward-thinking farmers to be first-movers to produce a new fish product in their market.

These numerous and critical advantages of recirculating aquaculture are all factors that drive our vision of spreading Murray cod aquaculture all around the world. Collectively, they open the possibility of Murray cod farming in almost any region, environment or country.

Indeed, we have been directly involved in spreading Murray cod aquaculture overseas with a number of joint venture projects being started since 2015. These projects are conducted with overseas investors and aim to directly supply to foreign markets.

We have also regularly supplied premium quality fingerlings to overseas farms since the 1980’s, These include farms from the Middle East, South East Asia and elsewhere in the Asia-Pacific.

Therefore, the recirculating aquaculture system is perhaps the aquaculture system that is most in line with our definition of the modern Murray cod farm as an efficient, environmentally-sustainable, scalable and highly-automated farm that can be controlled to ensure a premium-quality product. Even with its significant overhead costs, recirculating aquaculture is seen by many in the industry as the aquaculture system of the future, or perhaps, even the system of today – as we have long believed.

Our recirculating aquaculture grow-out system

We pioneered the use of recirculating aquaculture systems to produce Murray cod in the late 1980’s. Today, we have almost 30 years of experience in the recirculating aquaculture of Murray cod, and continue to produce premium quality Murray cod that consistently fetches market prices that are up to 40 per cent higher than the average wholesale price of farmed Murray cod from other producers.

Combined with our knowledge and experience in Murray cod biology and husbandry practices, recirculating aquaculture allows us to have almost complete control over the growth and quality of the fish we produce. Indeed, through our monitoring and recording of water quality and fish health data, recirculating aquaculture has indirectly enabled us to greatly expand our working knowledge of Murray cod biology and improve our husbandry practices.

Our current grow-out systems are larger recirculating aquaculture systems into which the juvenile fish from the nursery are introduced once they become too large for the smaller tanks in the nursery. This event occurs in the weeks prior to the introduction of new season fingerlings into the nursery, between November and January. Once introduced into the larger tanks in the grow-out systems, the juvenile fish have more room to swim and feed, and thus grow more quickly.

As with all indoor systems in our farm, our grow-out systems use pristine bore water to eliminate the possibility of any outside contaminants or diseases being introduced. Our grow-out systems incorporate all of the main subsystems common to modern recirculating aquaculture systems, including drum filters that provide mechanical filtration of suspended solids, biofilters consisting of friendly bacteria that remove waste ammonia, and oxygenators that add fresh oxygen into the systems. Various other subsystems are used for specific fish sizes, but the key principles remain – conservation of water, monitoring and control of water quality, careful management of fish health, and automation of repetitive tasks while allowing for human action where required.

For all of our production systems, we reuse even the small amount of water that is eventually discharged as wastewater. Our discharged wastewater flows into a specialised outdoor drainage pond where it becomes a nutritional source to raise zooplankton and other microbial life that will become the food source for new season fish larvae. Thus, no water is wasted in our recirculating aquaculture systems, no matter whether it is recirculated through the systems or ejected into the drainage pond. Correspondingly, none of the water in our recirculating aquaculture systems are discharged into local river systems, where it could otherwise be a pollutant.

We independently developed our first recirculating aquaculture systems in the 1980’s, when we were the first to demonstrate the feasibility of recirculating aquaculture of Murray cod.

At the time, we had pursued this venture despite the existence of long-standing doubts from the scientific and industrial communities as to its feasibility, mostly due to the aggressive and territorial nature of wild Murray cod.

Since then, we have rebuilt, adapted and refined our existing recirculating aquaculture systems, and built new systems, with the development of new technologies and with our increasing understanding of Murray cod biology and husbandry practices.

Today, our current systems are specially-designed for Murray cod aquaculture, while minimising maintenance requirements, providing superb water quality, and allowing for responsive control over water quality and fish health factors.

At the same time, we have found Murray cod to be a highly-adaptable species that will thrive in aquaculture, including in recirculating aquaculture systems and even in overseas environments, both rural and urban. With the correct parameters and effective maintenance, and water and fish health management, Murray cod can reach market size quickly with few complications.

However, perhaps the greatest advantage of using recirculating aquaculture to raise Murray cod, is that Murray cod grown in well-managed recirculating aquaculture systems will generally have a superior flavour even compared to wild Murray cod. As Murray cod is a fish that closely reflects its environment – especially water quality – wild Murray cod will tend to have what is often referred to as a “muddy” flavour that reflects their diet and behavioural tendencies as a bottom feeder. In contrast, Murray cod that are farmed in sufficiently clean water, such as those raised in well-managed recirculating aquaculture systems, will not exhibit these “muddy” qualities in flavour, while still retaining the umami-rich, hearty flavour that is unique to Murray cod.

To market

We sell our Murray cod at three separate life stages – as larvae, as fingerlings and as table fish.

Our Murray cod larvae are highly-sought after by other Murray cod producers, both local and overseas. Murray cod larvae naturally hatch with their yolk sacs still attached, and are thus able to sustain themselves for up to seven days without an external food source. Furthermore, due to their small size, they also consume far less oxygen and produce less waste than fingerling stage Murray cod. As a result of these factors, Murray cod larvae are highly-suited to transport over long distances and for durations of up to several days – even to overseas. Indeed, Murray cod larvae now account for most of our annual exports.

However, it is necessary that the purchaser has a managed recirculating aquaculture system or a suitable open pond system to receive the larvae after transport due to the relative fragility of the fish in their larval stage.

Murray cod fingerlings are a good alternative to Murray cod larvae for producers who want a more mature seed stock to accelerate their grow-out production. Our Murray cod fingerlings are bred to be exceptionally hardy and strong, and can be suitable for local and overseas producers who are beginning to trial production of Murray cod or who do not have the experience or controlled parameters to nurture newborn Murray cod larvae. Overall, Murray cod fingerlings account for up to a third of our annual export volume.

Our Murray cod fingerlings are also highly-sought after by government and local community restocking programs in Victoria and New South Wales. Under these programs, the fingerlings are purchased and released into local waterways of the Murray-Darling basin to replenish native populations. At this size, juvenile Murray cod will have already developed the necessary hardiness to thrive in the wild.

Our Murray cod table fish are mostly produced to two market sizes – a smaller live fish of between 0.6 to 1.0 kilograms and a larger chilled fish of between 1.0 to 1.5 kilograms. Both are sourced domestically to premium wholesalers in Sydney and Melbourne, who then supply the fish to selected retailers and restaurants. We are currently extending our market reach to include Canberra and, with recent and upcoming upgrades to grow-out production infrastructure, we hope to supply all Australian states with premium-quality Murray cod in the near future. Likewise, we are also able to export directly to international markets.

A modern farm’s pursuit of perfection

Throughout each step of our production cycle, we ask ourselves how to ensure that our fish can emerge in the best possible quality from each step. From breeding and nursery techniques, natural spawning and feeding, to water quality management and controls over fish health in the grow-out systems, we strive to improve our existing practices and find a way of doing things that is both good for the fish and sustainable for the environment..

This is why we have chosen to employ practices like natural spawning and natural feeding, and to use production systems like recirculating aquaculture – despite their greater costs – so that we can meet our target of quality and sustainability at each step.

In this continued pursuit of perfection, we have found that the critical enabler to our assurance of quality is our full control over the entire production process – from breeding to spawning to nursing to growing-out to sales and marketing, we have control over the quality of inputs and practices employed at each step.

We are one of the only Murray cod farms to have control over the entire production cycle, and we are the only one to our knowledge that employs such strict practices and quality controls at each stage.

Nor is our level of stringency arbitrarily determined – we have been refining our practices since we began our hatchery operations in 1977. Thus, we have come to determine these specific parameters for Murray cod production based on extensive experience. Even today, we are constantly trying new technologies or refining existing practices to improve or assist the process.

As such, we are convinced that this stringency in quality control is required to ensure that the fish are as healthy as possible and will be of the best quality when they reach the market.

This is our vision of Murray cod farming that we wish to spread throughout the world via joint ventures and partnerships with regional stakeholders. Likewise, this is the philosophy that guides our produce to market for Australian and global consumers.

Ultimately, this what we believe constitutes a modern Murray cod farm.