Saturday, November 27, 2010

Aquafarming: salmon and shrimp highlight risks and potential

Aquafarming, also known as aquaculture. To some it holds the key to truly sustainable seafood; to others it represents an ecological threat. On the one hand, aquafarming shifts the burden off wild fish populations but it also introduces potential ecological imbalances with excess antibiotic use, concentrated fish waste, and an unattractive ratio of the amount of feed required for a pound of fish.

Long time readers of this blog know what my position is. I favor aquafarming as I believe it holds the best potential, the best alternative to today's industrial fishing. As I see it, the concept of sustainable seafood indeed does relieve some of the pressure off declining fish populations, but it is only postponing the inevitable. So long as mankind interjects itself as a predator in a naturally balanced marine ecosystem, that system will ultimately suffer. Any seafood taken from the wild is "bushmeat" as Dr. Sylvia Earle describes it and, on land, we stopped taking bushmeat to feed the bulk of the population centuries ago.

While I am a supporter, I will also be the first to say that current aquafarming is beset with major problems that need to be addressed to protect surrounding waters and/or improve the quality of the end product. Take, for example, farmed salmon.

Genetically-Altered Salmon
While most of the salmon that is sold in markets is farmed, it is not done in the most efficient manner. It takes approximately 3 pounds of feed (usually fish meal products, which cuts into the populations of those fish used as feed) to produce 1 pound of salmon. Being sensitive to these types of imbalances (like the large amounts of CO2 produced to generate a gallon of CO2-reducing ethanol), researchers have been using gene-splicing to produce variants that grow faster - as much as twice as fast - thereby requiring less feed to reach a commercially marketable size. TIME magazine listed the new salmon as one of the top 50 best inventions of the year.

But would you consume genetically-altered salmon (or "Frankenfish" as its critics have dubbed it)? Well, we have been consuming genetically altered plants, like rice and corn for some time. And it would appear that the fast-growing salmon will likely gain approval for sale from the U.S. Food and Drug Administration (FDA); open hearings have now concluded but there are still some FDA committees that are looking into health issues such as allergies to the new salmon.

Some environmentalists opposed to genetically-engineered seafood are focusing arguments on the impact to wild populations if the new salmon were to be accidentally introduced into open water. Farmed salmon is usually raised on land but the potential is there for it to be inadvertantly introduced and the fear is that the new salmon would quickly come to dominate and eradicate the wild species. There has been talk of a "Trojan Gene" effect, used to describe the genetic advantage of the new salmon to take over.

This is being hotly contested, coming from an unusual source: the scientist first responsible for proposing the Trojan Gene hypothesis. The Los Angeles Times reported that Professor William Muir of Purdue claims his work on the Trojan Gene is being misrepresented. His original hypothesis was based on a genetically-altered salmon that grew faster and bigger, with size giving it a potentially distinct advantage. But the salmon that has been developed does not grower larger, simply faster.

According to the Times,
"Muir told the FDA Veterinary Medicine Advisory Committee evaluating the GE salmon that 'the data conclusively shows that there is no Trojan Gene effect as expected. The data in fact suggest that the transgene will be purged by natural selection. In other words the risk of harm here is low.'”

Exaggeration or misrepresentation, like negative politics, always succeeds in clouding the issue, so I suspect it will take some time before it is sorted out by the FDA and a decision is rendered as to whether genetically-altered fish will be available to the consumer. And then it will need to prove itself in the open marketplace.

Shrimp: Wild Caught or Farmed
The market demand for shrimp is another example of how aquafarming holds great potential but must address some serious issues. Shrimp is some of the most popular and affordable seafood in the world; but the two primary methods for harvesting shrimp leave much to be desired. For one, shrimp is caught in the wild using bottom trawling nets which rake across the ocean floor catching the bottom-dwelling shrimp but also a wide range of bycatch - from fish to sharks and rays to sea turtles. In the process, this fishing technique leaves behind a shattered and leveled seafloor, making it one of the must destructive fishing techniques currently used.

The other technique, typically found in Asian countries, is aquafarming shrimp in large but densely packed ponds. The possibility of disease in this situation is extremely high and so a variety of antibiotics get introduced - many of which can pose a threat to humans. The use of antibiotics has been a major issue throughout all of aquafarming because of the potential for diseases to develop drug-resistant strains.

The website takes the position that consumers should choose not to purchase or consume shrimp at all because of the dangerous or destructive outcomes of either shrimp fishing with bottom trawling nets or aquafarming. That would seem to be a logical position at first blush. However, with demand high and cost cheap, it is likely that the market for shrimp will remain for some time. Therefore, I would propose that efforts be concentrated on improving shrimp aquafarming as there does not seem to be another viable and effective method for catching wild shrimp that excludes bycatch or damage to the seafloor. Larger ponds, better water filtration, different or lower dosage antibiotics - there are many steps that could be researched.

Aquafarming: fraught with serious issues that need to be addressed if it is to be a viable alternative to destructive commercial over-fishing or to seafood bans, whether voluntary or imposed by species extinction. Economics and the need to feed a growing populace compels us to get aquafarming on a productive and environmentally-safe track.

Read about inventions in TIME.
Read about genetically-altered salmon in the
Los Angeles Times.
Read about shrimp at

No comments: