Sustainable aquaculture: Net Pens vs. RAS!

Sustainable aquaculture: Net Pens vs. RAS!

Fish consumption worldwide has doubled since 1960 to 20 kg per person per year in spite of the fact that capture fisheries continue their downward production spiral. That was the message Manuel Brange, director of the FAO Fisheries and Aquaculture Policy and Resource Division (FIA), delivered as he introduced the latest edition of FAO’s report: the State of the World Fisheries and Aquaculture – 2016 (SOFIA).

Mr. Brange pointed out that fully a third of capture fisheries worldwide are being fished unsustainably and in areas like the Mediterranean that figure is 60 percent.
Aquaculture, he explains, is the reason for the increase in consumption.

Mr. Brange warned against oversimplifying the link between fishery exploitation and catch decline. While unsustainable fishing pressure is indeed a global threat, some efforts to return wild fishery stocks to sustainable levels contribute to lower production. In the long run, predictions are that the rebuilt stocks will once again allow greater productivity assuming greed-driven, over-exploitative practices will not be revisited.

The economic incentive for both capture and cultured fish industries is immense, $148 billion in 2014 up from $8 billion in the 1970s. Those dollar figures are more than simple off-the-boat sales. They reflect jobs and commerce in seafood at every level. The economic importance of fishery trade is paramount to developing nations that account for $80 billion of the global total. That’s a figure greater than rice, coffee, meat and sugar combined.

This is particularly true in developing countries where this figure accounts for $80 billion worth of that sum. This is bigger that rice, coffee, meat, and sugar put together.

While the growth of aquaculture is key to meeting the need to increase the worldwide marine protein supply, Mr. Brange underscores the equally important goal of the world and FAO of safeguarding sustainability of the planet’s fishery resources.

One recent measure that has recently entered into force is the Port Measures Agreement to prevent, deter, and eliminate illegal, unreported, and unregulated (IUU) fishing.

IFCNR applauds the Port Measures agreement and similar initiatives as important steps for the future. Still, one glaring truth remains. Capture fisheries in any form will not meet the increase in future fish consumption. That is where, as Mr. Brange suggests, the global focus must shift to Aquaculture.

In theory, aquaculture can expand using three techniques: open-pond farming, marine net pen aquaculture, and/or land-based recirculating aquaculture systems (RAS).

Open-pond aquaculture is nearly as old as history. Today’s commercial application is a well-documented, non-sustainable solution. A vast geographical footprint often involving destruction of tens of thousands of acres of mangrove forests, untreated wastewater flowing into rivers and bays, lack of control of and pathways for the spread of disease, all combined into an environmental nightmare.

Marine net pens emergence promised to produce vast quantities of marine fish with little or no environmental damage associated with open ponds: tidal movement to disperse waste, confined netted areas keeping farmed fish separate from wild species. Reality more and more is proving a poor fit with net pen theory. The huge mass of confined fish attracts swarms of sea lice, tiny parasitic crustaceans damaging the health of farmed and wild fish alike. Significant numbers of fish escape from their pens and hybridize wild stocks. Uneaten feed, feces, pesticides and more blanket seabeds smothering benthic level sea life. Multiple pens anchored in narrow tributaries exhaust dissolved oxygen.

A joint Norwegian and U.S. study compared net pens to RAS techniques and found RAS the economic and environmental preference. (See: Land Based RAS and Open Pen Salmon Aquaculture: Comparitive Economic and Environmental Assessment by SINTEF Fisheries and Aquaculture of Norway and The Conservation Fund’s Freshwater Institute of the USA). That study underscored the misconception at the core of the prevailing belief that net pens outscore RAS in dollars returned at a lower cost. Farming premium priced fish, produces far better profits via RAS methods than net pens.

IFCNR feels however that this study does not go far enough in environmental assessment comparisons.

Net pens introduced into a pristine ocean waters teaming with rich biodiversity results in acute negative effects. A few years after net pens are in place local biodiversity can be altered dramatically. Concentrated waste with a mixture of fish feces, antibiotic laden uneaten fish feed, and decaying dead salmon carcasses all affects the bethnic area that lies below. The present response is to push these farms further and further out into the Ocean. Farms are also dosed with potent anti-parasitic drugs to control sea lice, also kills other crustacean such as various species of shrimp. New and old diseases are passed on to wild stocks that pass by. Ocean areas once thriving with biodiversity such as dolphins, wild salmon, sea lions, seals, whales, seabirds birds etc. dependent upon the ocean eco-system from tiny organisms in habiting the ocean floor to alpha-species and sea mammals, bears that dependend on that biodiversity are acutely affected. These areas can be compared to an industrial waste dump. Further, Norway warned against catching and consuming escaped fish for fear of antibiotic and pesticide overloads.

By comparison, RAS recirculates and re-uses its water. It does not discharge waste back into the environment. Covered, bio-secure RAS farms control the environmental parameters that dramatically reduce or eliminate the threat of disease. Growth and efficiency of the species are enhanced thanks to an ideal, predator and stress-free environment. Local eco-systems are untouched. In fact, IFCNR is working with some RAS systems to improve the environment by means of a conservancy using native fauna and flora (a topic for another time).

IFCNR believes land-based, bio-secure RAS is the future of sustainable aquaculture for all the reasons stated above as well as its ability to relieve a great deal of fishing pressure off captive fishery species. Increasing captive harvest yields to address the ever-increasing demand for marine protein will only cause the percentage of overfished stocks to increase. The ability of aquaculture to continuously and sustainably up harvest totals is the only logical solution. Shifting the industry to RAS methods is the ideal for the needs of both humans and the environment alike.


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