Offshore Fish Farming – Solution or Sci-Fi?

23rd February 2018

In January 2018 around 20,000 yellowtail kingfish escaped from the damaged sea pens of an offshore aquaculture research lease in Providence Bay, off Port Stephens, New South Wales.  The sea pen was part of a Marine Finfish Aquaculture Research Lease; a collaboration between Huon Aquaculture and the NSW Department of Primary Industries (DPI).  The projects aimed to evaluate the commercial viability of growing kingfish in sea cages, test the latest sea cage technologies and monitor the environment.  There are five sea pens in the lease, with each one able to hold 15,000-20,000 kingfish.  Severe weather and rough seas over a four day period was blamed for causing the damage that led to the fish escaping into the wild.  The so called ‘fortress pens’ were reportedly inundated by waves that were more than 11m high.

One man’s loss is another man’s gain and this incident was a 17,000-kingy windfall for the recreational fishers that happened to be at the right place at the right time, with Huon only able to recover 3,000 of the fish.  This disaster has set Huon Aquaculture back almost one million dollars.

However, this incident could just be one of many more to come as offshore or open ocean aquaculture starts to take off in Australia and globally.  Given estimates that by 2030 the world needs to produce 70% more food than it currently does to feed an ever increasing global population, the search for cutting edge innovation in food production has a lot of governments and companies looking at the oceans for a solution.

Norway has embarked on an ambitious project to set up the world’s first offshore fish farm – Ocean Farm 1.  They have built a fish farm in the middle of the ocean based on the same construction concept as submersible offshore installations such as oil and gas structures.  The fish farm is 68m high, 110m wide and 250,000m3 in volume. This is equivalent to 100 Olympic size swimming pools.  It is secured to the seabed by anchors and tethered at depths of between 100 and 300 metres.  It is large enough to fit an entire offshore platform inside that can stand up to 8-10 meters waves, with the capacity to raise 1.5 million fish annually.

The image below is Ocean Farm 1.  Its builders say it is a new and innovative design, developed to overcome the challenges of traditional inshore fish farming facilities by being located in deeper waters, further from the coast.

As well as feeding the world, proponents say that offshore fish farms have many benefits compared to inshore farms.  From a biological and an environmental standpoint, these structures will allow water to pass through the cages and wash away lice and other pollutants, giving the fish a habitat as close to natural as possible.  The risk of disease and infection is exacerbated by the stress of cramped conditions in fish farms will be a thing of the past as larger fish will be released into the larger.  The fish will also be fed 10 metres below sea level, forcing them to submerge to further reduce the risk of catching lice.

Oceanic fish farms could be established around retired offshore oil platforms.  This is particularly interesting given the aging of the 40 year old oil and gas infrastructure in eastern Bass Strait.

The jury is out as to whether offshore fish farming is going to solve world hunger with as little impact on the environment as possible. Inshore fish farms constantly struggle with disease, chemical runoff, damage to cages and fish escapes.  Is offshore or ocean fish farming the solution or will it just extend this issue out into the oceans – out of sight.