by Walker D. Wright-Moore, Nursery Manager, Great Falls Aquaculture

 

Located in the heart of New England, Turners Falls, MA, is home to one of the longest operating and largest indoor RAS aquaculture farms in the United States. The farm has seen several species over the years, but for the better part of the last two decades it has become well known globally as one of the largest land-based producers of Barramundi, Lates calcarifer.

In the fall of 2018, Blue Stream Aquaculture acquired the farm from Australis Aquaculture and added Barramundi to their current operations producing rainbow and brook trout.

With a new name, Great Falls Aquaculture (GFA), carried on with business as usual, producing one of the highest quality farmed fish on the market. Annual production reaches 600 tonnes of fresh Barramundi, which a majority is sold wholesale to live retail markets in the Northeast US and Canada.

Barramundi- the biology

Barramundi, Lates calcarifer, also known as the Asian Sea bass, Australian Sea bass or Giant Perch is native to coastal tropical waters in the Indo-Pacific West region ranging from Northern Australian to Southeast Asia. They are recognised throughout their native region as an important recreational and commercial fishery, as well as an aquaculture species.

Barramundi are a euryhaline species, meaning they are able to tolerate a wide range of salinities.

They are also classified as catadromous, meaning spawning takes place in marine environments while a majority of their juvenile and adult life takes place in freshwater rivers or estuarine systems. This allows the aquaculture of barramundi in either freshwater or marine environments, which is a significant advantage to growers not located near the coast.

Barramundi are protandrous hermaphrodites, meaning they hatch as males and then switch sex to female later in life.

They do not become sexually mature as males for about 3-5 years and then will switch sex to female about 5-7 years old. This is beneficial from an aquaculture standpoint because reproductive development is energetically very costly and will reduce growth rates. Females are highly fecund and can produce up to 10 million eggs per spawn and their life span has been documented to at least 20 years of age.

Barramundi – the culture

The hatchery stages for barramundi take place in a marine environment (35ppt).

Broodstock are conditioned to spawn in captivity using photothermal regimes mimicking natural seasonal changes to stimulate sexual maturation and gonadal development. Females are induced to spawn when ovaries are fully developed and are then 'stripped' or allowed to tank spawn when eggs reach final oocyte maturation.

Fertilised eggs begin to hatch just 12-16 hours post-fertilisation with a yolk sac that lasts to first-feeding at just 48 hourspost hatch. Larvae are provided a diet of live zooplankton (enriched rotifers and artemia) for the first 10-15 days before beginning the weaning to commercial diets.

After approximately five days post hatch the fry can begin to tolerate the slow acclimation to freshwater over the next 20 days. GFA does not currently spawn broodstock, so fry must be sourced from other hatcheries.

Batches are generally stocked every 45-50 days in the nursery at 0.2g mean weight. The barramundi at GFA are cultured in freshwater, with temperatures that range from 27-30 deg C. It is not easy to match the species' native tropical water temperature during a New England winter, but using high-efficiency natural gas boilers, GFA can circulate hot water through heat exchangers in the systems to produce temperatures that are compliant to their desired environment.

These higher culture temperatures help create an elevated metabolism, an aggressive feed response and fast growth rates. Cannibalism can cause significant mortality throughout all stages of barramundi culture due to their aggressive nature and is most pronounced in the early stages.

Grading, or sorting the fish by size, every five-to-seven days and paying close attention to feeding regimes help to significantly reduce cannibalism during the early stages. As juveniles, grading happens less often, but is still a critical process for the success at GFA.

Victor Turcan, the production grow-out manager, stresses the importance of stocking uniform size groups into the final grow-out tanks.

'Grading takes a lot of work when the fish are larger, but it is worth it. We see better growth, higher survival, healthier fish and a better product reaching market size.'

All fish are vaccinated at two grams and again at 30-50g to boost the immune system and prevent pathogen outbreaks.

'Beyond good husbandry practices, good water quality and good biosecurity, vaccination is the best tool we have for pathogen control,' says General Manager Spencer Gowan. GFA operates with approximately two million gallons of culture water (7.57 million litres) filling 38 tanks in 12 separate RAS systems with tank sizes ranging from 10m3 to 600m3.

Culture densities range from 25-75kg/m3 and it takes 10-12 months to reach a 1.5lb/680g average harvest weight.

The farm-wide feed conversion (FCR) is 1.1-1.3:1 (every 1.1-1.3kg of feed is converted into 1kg of fish biomass). With around one million fish in the building, daily consumption of feed is approximately 2000kg/day.

The barramundi begin their time at GFA on very technical stock diets that rely on high levels of marine sourced proteins. As they grow, they transition to custom diets that include much less marine sourced protein, while increasing the inclusion of alternative protein sources but continuing to meet nutritional requirements for optimal growth and feed efficiency.

Feed costs are one of the highest fixed expenses of an RAS operation along with power, oxygen and labour. Developing strong working relationships with aquafeed producers to ensure supply of the highest quality feed is certainly one of the most critical components to overall production success.

Barramundi – the market

Barramundi is a highly versatile white fish that has a mild buttery flavour and flaky texture.

If you are looking for a brain boost, barramundi (skin on) have high levels of Omega-3 fatty acids, similar to those found in salmon. A large majority of the fish produced at GFA leave the door still swimming on the way to live-markets in the US and Canada.

Shipping live fish emphasises the importance of a high quality, vigorous final product that not only tastes good, but also has an excellent appearance.

In preparation for transport, market size fish are transferred from the grow-out systems into a holding system where temperatures are cooler, water is cleaner and they reside for five-toseven days to be 'polished.' The polishing process ensures a clean consistent flavour and texture of the final product and is also key for the success of potential long transport times.

Barramundi are harvested for live haul into 250gal (946L) insulated totes supplied with pure oxygen (densities ranging from 1-2lbs/gal (120-240kg/m3) depending on the duration of their journey to market) and sold wholesale to seafood distributors, who transport, hold and deliver directly to retail markets and consumers.

Asian markets in large metropolitan areas provide an outlet for producers that is consistent and consumes large quantities of seafood. The demand for a quality product is high and a premium price is met for the ultra-fresh barramundi.

Over the last year, GFA felt the market effects of the Covid-19 pandemic as much as every other aquaculture producer.

With the disruption and uncertainty of wholesale markets, Mr Gowan's team quickly set up an online store and began offering a number of product options via local sales, shipping and delivering directly to customers.

'Getting our product out into our local community was something we wanted to make happen for years, but Covid helped make that a priority.'

In addition to barramundi, GFA also processes and distributes Fresh Rainbow trout and Brook trout to local markets and restaurants. The trout are farm-raised by partner farms, Blue Stream Aquaculture, in Cape Cod and Charlestown, NH.

GFA also made production changes such as lowering temperatures in the culture tanks and reducing feeding rates.

'We were able to make moves to keep our inventory healthy and living. That is the advantage of being an indoor facility. We can control the temperature and therefore regulate the metabolism of the animals in a way that preserves our biomass to be sold when optimum conditions prevail.

'An outdoor farmer does not have that luxury. It is not the most efficient way to operate, and we could not sustain it long-term, but it is better than being forced to sell the team's hard-work at a loss or worse.'

RAS Technology

Great Falls Aquaculture could be considered a veteran in the RAS game.

The facility has a long history and has helped pioneer RAS technology on a commercial scale in the US. The current operation benefits daily from an experienced staff with a substantial amount of in-house knowledge.

This is highlighted by Roscoe 'Rocky' Perham, Facility Manager/Engineer who has been growing fish for 35 years including 30-years of design and development at the Turners Falls facility, Sasha Dyer, Fish Health Manager, who has been with the farm for nearly 26 years and the rest of the management team who have each worked in the building for nearly 10 years.

The RAS design integrates mechanical and electrical engineering with natural biological and chemical processes to create an environment that promotes as close to optimal and predictable growth as possible.

System components include drum filters, fluidised bed bio-filters, CO2 stripping, u-tube oxygenation and ozone disinfection, automated oxygen, pH and temperature control, and nearly 200 alarm points throughout the farm that alert staff to action 24/7, 365 days a year.

These systems generally exchange <10% of the system volume daily making these 'water re-use systems' a viable method to raise significant biomass with limited water usage. This is not to say that a sufficient and extremely reliable water source is not needed for land-based aquaculture.

On the contrary, selecting a farm site with access to an abundant water source is imperative and should be considered in the earliest stages of planning. The system water exchange is important to prevent the accumulation of nitrate, the end product of the bio-filter nitrification of ammonia, which will cause chronic stress at high concentrations.

Depending on the profile of the incoming water source, pre-treatment to remove metals or hardness may also need to be considered.

Passion, hard work, attention to detail

The farms longevity in Turners Falls does not mean that we are not constantly faced with new and unexpected challenges in many aspects of fish culture and business.

It would be fair to say the farm has survived its initial growing pains and will continue to be a leader in sustainable aquaculture for many years to come.

The employees that operate the RAS cannot be given sufficient credit. Management and husbandry is the backbone of day-to-day operations carried out by the staff and it takes passion, hard work, attention to detail, and consistency. It is 'lucky' to be building from more than a decade (16 years) of barramundi culture experience, R&D, and continual production process refinements, complimented with the benefits of an outstanding team.

Water quality, fish health, waste management, sustainability and producing a high-quality product is always the company's focus, but striving for constant improvement, adapting to challenges and making sure it creates a positive environment where employees feel valued is also at the top of the list. It's not just about the fish; it is also about the people who raise the fish.

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