Fish are something of an anomaly in the culinary world. Individuals either love fish, or hate it. There are few middle-of-the-road opinions on fish as food. I fall into the love category. I could (and have at times) eat fish every day. In the not-so-distant past, fish were considered a renewable resource that could never be over-exploited. However, it seems that we may have underestimated ourselves. World-wide studies seem to indicate that our voracious appetite for tuna and salmon may result in their complete extinction as soon as the year 2015. In an attempt to prevent such a catastrophic environmental calamity, we have used our innate ingenuity to find a solution that preserves the wild species, and at the same time feeds our insatiable appetite for tilapia, and smoked salmon. That solution is fish farming. But is it really the right course to take? There are as many detractors as supporters. What is the truth about fish farming?
Fish farming is exactly what it sounds like. Commercially breeding and raising fish in captivity for food, just as we do cattle, pork, and poultry. The main fish being raised are catfish, tilapia, carp, trout, and salmon. Tuna require a lot of water to swim in, and are large and powerful enough to be dangerous, so they are not particularly suited for fish farms. In the near future, however, there may be ocean ‘cowboys’ that herd the large schools of tuna around, and protect them from predators. Perhaps a GMO version of tuna, the pelangus, could be created that could be controlled much like cattle.
There are two basic types of farming, each with it’s own advantages for each species. The first is the Integrated Recycling System. There are three major concerns in fish farming; oxygenating the water and removal of waste, food, and disease/parasite control. The Integrated system manages these problems by putting the fish in a closed system made up of plastic tanks in a greenhouse. Hydroponic gardens are placed next to, between and around the tanks. This system is best suited for herbivorous fishes like tilapia and carp. The greenhouse keeps it warm enough for algae to grow, which is eaten by the tilapia and carp. The water is circulated out of the tanks and through the hydroponic gardens, usually planted with herbs such as basil and parsley. The fish waste, in the form of nitrates and phosphates, is used by the plants for food, thus making them grow, and cleaning the water. As the water circulates back around, filters remove any remaining waste such as ammonia. The water is bubbled back into the tanks, aerating it completely, and the cycle starts all over. The water is lightly salted to keep the fishes electrolytes in balance. The herbs are sold to restaurant wholesalers. Two variations of this system are the Pond System, where stock ponds are substituted for tanks, and the Composite System, where several fish species that compliment each other, rather than compete, are raised together, creating a mini eco-system. The waste waters from these ponds are used to water and fertilize nearby fields. This is the most popular system for raising catfish. These systems have the advantage of no danger of fish escaping to the wild, or spreading disease to wild populations. The only way they can escape may be in the event of severe flooding. Another advantage of these systems is that water quality can be completely controlled, sterilized, and monitored for parasites.
The other system is the Cage System, in which fish such as salmon, and trout, are raised in cages placed in rivers and in the ocean. These fish are carnivorous and are fed fish meal, made from wild fish. Opponents of fish farming say that this is as hard on the wild fish as netting them would be. However, the fish used for fishmeal are less exploited species such as menhaden, shad, and other rough fish. The Cage System requires that the fish be kept in dense populations, so the fish best suited for this are ones that school. Salmon, and trout are the most common species raised this way. The natural circulation of the water keeps it fresh and clean, but care must be exercised to guard against both escapes, which could contaminate wild species with the Genetically Engineered (GMO) fish, and parasites. Sea Lice, in particular, have been a major problem. Sport fishermen complain that the fish farms use up all the resources that the wild fish need, and spread Sea Lice, which can be deadly for the fish.
GMO fish are identical on a plate to their wild relatives. The only difference is that GMO salmon do not have the characteristic ‘pink’ color to their flesh, so a harmless additive is put into their food to turn the flesh pink. As with all other GMO foods, there have been ‘scare’ stories about them causing cancer, and other health problems, but they are all unfounded. GMO foods have been tested more completely than any other food offered to the public, and they have passed with flying colors. And, they may save the wild populations by reducing the commercial fishing pressure on them. The other advantages to farm-raised fish are that they reach the market much fresher than their wild relatives, have been more closely monitored for disease and parasites, have been exposed to far less pollutants, and much less stress.
The problems with fish farming are that the fish are treated with antibiotics, and a small amount of it does get into the water. This is not a problem for tank-raised fish, but for caged fish, the antibiotics could get into the water system, and create drug-resistant forms of disease. There is concern about GMO fish escaping and breeding with wild fish, thus destroying the wild species from the genes out. This has been studied in laboratories, and GMO fish can breed successfully with wild fish, but the offspring seldom survive, so that danger is very remote. The major concern with caged fish are Sea Lice. The dense population of fish in one spot also cause more Sea Lice, which do get loose and infest wild fish. In some areas, juvenile wild fish experienced as much as a 50% mortality rate from Sea Lice coming from fish farms. This has been greatly reduced since the advent of effective vaccines, and other control methods for the farmed fish. This has reduced the populations of Sea Lice greatly, and methods of control will continue to improve. And so that the fish farms do not completely use up resources from wild fish, the cages are relocated on a regular basis to give the area time to recover, much like rotating crops and cattle in different fields. Studies indicate that wild fish populations do decline in the presence of a lot of fish farms, but new techniques are reducing this greatly. On land, livestock production also reduces the populations of wild animals in the area, so this is not a new phenomena.
Fish farming is a new field, and will undoubtedly get much more efficient as time goes by. It’s problems are not much different than when we first started raising cattle, pork and poultry, nor will the effect on wild fish be much different. The truth about fish farming is that it works, and will work even better in the future.
There are continuous studies being done on GMOs, but for now, I wouldn’t worry about it much. Go ahead and eat what you like. Chances are, you’ll be fine…..