Aquaculture: Threat or Savior for Open Ocean Fisheries

Aquaculture

What is aquaculture?

Aquaculture is the cultivation of the natural produce of water, i.e. fish, algae, shellfish. It is essentially the farming of aquatic organisms for food. Unlike fishing where we go out into the ocean and take wild fish, aquaculture raises fish from birth. The fish are placed in ponds, or cages, where they develop until they are mature enough to be taken from the pond and used for food and other products.

Fish Farms

This is a diagram of an open ocean aquaculture fish net (Davidson, 2006)

This is a graph of total fish production per year, both aquaculture and fisheries - The Global Education Project

There are inland Fish farms, which consist of ponds where the fish are placed in great numbers. There are also off-shore fish farms. These off shore rigs consist of a gigantic net placed in the ocean at a specified depth. The nets allow great concentrations of fish in a small area. The hopes are that they polluting the environment less with these open ocean systems as the fish waste will filter through the net into the ocean below. There is much more water in the ocean than in the inland ponds, and thus the waste is not as harmful, however still not necessarily good for the environment. Most of these off-shore rigs are placed within the specified country's Exclusive Econonmic Zone (EEZ). No where in the ocean do thousands of fish live in such close quarters, and in contained areas, otherwise fishing would be childs play. Aquaculture essentially makes it so. They lower baskets into the fish net or pond and raise out the catch. There is no by-catch associated with Aquaculture, and thus more money can be made with less adverse affects on the environment. There is a buoy on the top of it where the technicians can feed and monitor the fish. People are starting to come together now and utilize the potential of the decomissioned off-shore oil rigs in the Gulf of Mexico. They are beginning to transform the oil rigs into fish farms.(Naylor, 2005)

A Texas Oil Rig turned Fish Farm (Food and Water Watch)

Concerns With Open Ocean Fishing

The largest concern each year for fishermen is that simply the fish have run out. Over fishing has been a problem for man since we discovered how to fish. Terry McCarthy points out the most notable example of over fishing is the decimation of the cod populations in the North Atlantic in his article Playing God With Cod. Cod has been a staple of our diet since before America was even colonized. In 1970 fishermen took 3.1 million tons of cod from the ocean, this number has plummeted to 800,000 tons today. The fishing grounds off the east coast of Canada, around Newfoundland, collapsed and fishing there was banned in 1992. Since the collapse fishing has moved into the North Sea, however the same problem persists there as well as the annual cod take is down 75% from 15 years ago. (McCarthy, 2005)

Canada's Atlantic Cod Catch 1950 - 2000 The Global Education Project

According to Kher Unmesh’s article, Oceans of Nothing, open ocean fisheries will disappear by the middle of this century. Marine Biologist Boris Worm led a team of 13 researchers studying global catch data over the past 50 years, and they came to the conclusion that the fishermen of today will not have anything left in the oceans to catch. He claims “None of us regular working folk are going to be able to afford sea food…Its going to be too rare and expensive.”(Unmesh, 2006)

The human population has doubled since 1950, and so has our appetite for fish. Global Consumption of fish has doubled since the early 1970’s and will continue to grow with population, income, and urban growth in the developing world. More than 60% of marine fish stocks, the ones which information is readily available, are either fully exploited or over exploited, as well as 13 of the world’s 15 major ocean fishing grounds are now fishing at or beyond full capacity. (Naylor, 2005)

Concerns With Open Ocean Aquaculture

Leading Aquaculture Producing Countries The Global Education Project

The largest concern among scientists dealing with open ocean fish pens is the pollution. Nowhere in the ocean do 90,000 fish live in containment or in such close quarters. The shear amount of fish in such a contained space has scientists worried about the water around the pens and the sea floor below, as feces will now enter the water in much greater concentrations. Charles E. Helsley led a team of researchers from the University of Hawaii at Manoa and ran their own experiment testing this hypothesis that the fish pens will increase the toxicity of the surrounding environment. In the spring of 1999 they placed between 50,000 and 70,000 moi in their pen. The pen was an OceanSpar 3000 from a firm in Seattle. They harvested 50,000 fish in September of ’99 and continued into October. Throughout the 8 months that the fish were cultivating in the pen they made observations of the sea floor and surrounding water. They observed no noticeable changes, and decided that something must have gone wrong in their experiment due to the marine community claiming that the pens were detrimental to the environment, so they conducted the experiment again, this time with twice as many fish in the pen. Again they noticed no severe changes in the environment. The organisms dwelling on the ocean floor seemed to act in a positive manner due to the extra food sinking down from the pen above. The only noticeable changes were the increases ammonium concentrations outside the pens, but this number quickly diminished after the experiment was run and over.()

Is Aqauculture the Savior of Open Ocean Fisheries?

According to Rosamond Naylor and Marshall Burke aquaculture was first dreamed up in response to diminishing wild fish stocks around the world. Bluefin Tuna is emerging as another large aquaculture project due to declining populations in the open ocean. The juveniles are caught in the wild, then put into the pens until they are of marketable size. The cage can then be refilled again with their offspring. Many countries are now getting in on the game and starting up offshore aquaculture rigs all around their EEZ. Countries like Canada, which is farming Black Cod, and Norway, which is farming Halibut, are producing numbers that have not been seen for years and are shipping a good portion of their farmed fish to the high-end markets in Japan. The Atlantic cod, which has not seen a strong population since the collapse of the fishery off of eastern Canada, is not being farmed by Norway, the UK, Canada, and Iceland. They are having much success with this fish and Canada and Scotland are getting ready to follow suit and start their own Codfish pens. (Naylor, 2005)

There are positives and negatives associated with aquaculture. Inland Fish Farms historically have had very polluted ponds after they farm the fish. Open ocean pens are more optimistic, as the ocean current helps carry away waste and dilute it about the entire ocean not just one small pond. open ocean fisheries have been over exploited for years, and thus we have aquaculture. As open ocean fish stocks become more and more depleted we will rely more heavily upon aquaculture. The problem with depleting wild fish is that there will not be much genetic diversity in the pens after a few generations. This poses a threat if the penned fish escape into Open Ocean, but only if they escape on a mass scale.

Bluefin Tuna inside an Open Ocean Pen, with a researcher inside(Davidson, 2006)