With many fish species having been overfished for decades now, aquaculture, or the cultivation of aquatic life on land or in the sea, is an industry that has been growing year after year and providing more and more of the seafood we eat. The only problem with this trend lies in the fact that there are numerous adverse environmental effects and health risks associated with both land and ocean-based aquaculture. The University of Maryland Biotechnology Institute’s (UMBI) Center of Marine Biotechnology (COMB) has recently unveiled some extremely encouraging results from its contained recirculating aquaculture experiment that may lead to a new generation of bio-secure, contaminant-free, and sustainable cultivation of seafood, but it may be too little too late.
The Current State Of Ocean Affairs
According to Food and Agricultural Organization (FAO) statistics, 74% of the world’s commercially fished species are either depleted, overfished, fully-fished, or extinct. Scientists, as well as many in the fishing industry, agree that if current demand and fishing practices remain unchanged, most of the remaining fished species in the ocean will collapse within a few decades. This not only means you won’t have any fish to eat, but due to the breakdown in the food chain, chances are the oceans themselves will be void of the majority of life that currently inhabits it.
The ‘Less Bad’ Alternative…So Far
Overfishing, unfortunately, is nothing new. There have been a vast array of aquatic species raised under controlled conditions for decades now, and have likely been ending up on your plate more times than you probably realize. Yet like everything else that we as humans cultivate and industrialize on an enormous scale, aquaculture has suffered from almost the same transgressions. While it has somewhat eased the pressure on the Earth’s oceans to produce the seafood which we consume, it has created a slew of other problems that may end up being more destructive than overfishing.
Like large scale land-based animal farming, fish farms produce a huge amount of polluted effluent (waste water) consisting of fish waste, excess feed containing antibiotics/hormones, pesticides, and other various toxic chemicals used to either rear the fish or clean the cages and tanks in which they live. This effluent is usually discharged into local waterways or as is the case with shoreline and ocean-based aquaculture, released directly into the ocean. Depending on the species or type of aquatic life being raised, this effluent can range from the somewhat polluted to the down right toxic (salmon farms are notorious for producing the vilest toxic soups).
Not only is this polluted waste water negatively impacting and altering the sensitive ecosystems in which it is being released, but the entire life-cycle of the fish being raised, that you will someday consume, is spent in this toxic, and often times carcinogenic, soup. Given that almost all living things are a product of their environment, how healthy do you think a fish could be living their entire lives in such filth? The answer is obviously not very healthy at all.
In addition to the pollution reeking havoc on the immediate area in which it settles, ocean-based aquaculture poses yet another environmental threat; captive fish escapes. Over a million fish being raised in ocean captivity escape every year as nets and cages form holes that are not repaired in a timely manner. Now you’re probably thinking, “Yeah! They made it back home!”. While this may appear to be true, these ‘escapee fish’ don’t belong in the wild ocean and may actually become the cancer that wipes out their species.
Fish raised in captivity are not only subjected to a barrage of chemicals, hormones, and antibiotics, they often also carry parasites and viruses that have become extremely strong and nasty due to the resistance they’ve developed against the chemicals used to combat them. So when these fish escape and join native wild fish populations, these parasites and viruses can wipe out entire schools as they have no natural immunity to these superbugs. Another unfortunate side effect of captive fish escape occurs when they breed with native fish populations. The genetic makeup of captive fish is different from that of their ocean dwelling cousins. So when they intermix with the native populations, the gene pool becomes diluted and changes the genetic makeup of future generations of wild fish possibly making them more defenseless against the many threats they face in the wild.
The Safest, Cleanest, And Most Sustainable Fish Farm Yet
Responding to the above situations, scientists at UMBI’s Center of Marine Biotechnology (COMB) developed a new generation of marine aquaculture technologies that address and solve all the above concerns and can produce very clean fish without adverse effects on the environment. The system as described by COMB:
The core of the system includes biological filtration units that incorporate naturally occurring microbial processes (nitrification heterotrophic/autotrophic denitrification, sulfate reduction and anammox) to control and degrade waste compounds produced by fish that otherwise accumulate in system water and can harm the fish. The ultimate elimination of these compounds by select groups of microorganisms allows for the recycling of tank seawater eliminates the requirement of replacing or adding seawater. Moreover, the system collects and digests solid waste products that are derived directly from the fish or by the accumulation of uneaten feed to fuel additional microbial processes whose activities result in the production of methane gas, which can be captured and used as a source of energy.
The most significant benefit of recirculating mariculture is that it alleviates the potentially deleterious effect of fish farming on the environment. COMB’s recirculating system can grow high densities of commercially important marine fish with 99% containment of effluents, or better. The nominal amount of wastewater is disinfected and can easily be handled by a city or municipal sewer system—-there is no direct waste release to the environment. Moreover, the high percentage of recirculation efficiency, together with the disinfection of effluents, provides an increased level of bio-security.’ The risk of escape of farmed organisms to the environment and, in turn, biological pollution, is significantly reduced.
In addition to the many environmental benefits, there are also a number of practical advantages to recirculating marine aquaculture systems , making them the optimal approach for efficiently growing seafood in urban environments. They include:
- Recirculating systems, unlike net pens or ponds, usually use municipal water for artificial seawater preparation and are thus disease free. Moreover, water is continuously disinfected and potential pathogens are eliminated. Fish are grown in depurated water with no contaminants, toxins or off-flavor sources. Consequently, the produced fish are very clean’ and can be marketed as such.
- Environmental conditions (water temperature, salinity, etc.) can be fully tailored to optimally fit the requirements of the fish of interest, thus ensuring optimal performance and the fastest growth rates to market size. As such, recirculating systems are generic and can be modified to accommodate the species for which the market feasibility is highest.
- Because of the excellent water quality, fish can be grown in recirculating systems at very high densities. For our marine species, those densities are much higher than the densities practiced in the net-pen industry.
- Recirculating aquaculture facilities are fully contained and thus can be located almost anywhere; they can be developed in rural or urban areas, in inner cities and in most warehouses. Site selection is not dictated by proximity to a natural source of water (e.g. lake, ocean), but rather by the business opportunity.
A clean healthy fish.
The Good: An aquaculture system that seems to address, and in large part solve, the majority of the problems facing large-scale aquaculture. The self-contained nature of the system allows it to be placed virtually anywhere including densely populated cities (COMB’s facility is located in the basement of a campus building).
The Bad: The system is somewhat more complex than the typical fish pen most aquaculture farmers are used to. Likely more expensive upfront cost. It is unclear the effect treated effluent discharged into municipal systems will have. Using ‘tap water’ to create artificial seawater doesn’t seem as clean an idea as purported given the levels of chlorine in most municipal water. Compared to passive aquaculture, recirculating systems are more energy intensive.
The Bottom-Line: A hopeful glimpse of a possible solution to many inherit problems current aquaculture practices faces. With native fish species on the decline, and a still increasing demand for seafood, recirculating aquaculture may be the only viable method for providing clean sustainable seafood to the world.
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