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Killer Fish Farms

Virginia Gascón González is Policy Advisor, Antarctic Krill Conservation Project. Rodolfo Werner Kinkelin, is Science Advisor, Antarctic Krill Conservation Project.

by Virginia Gascón González and Rodolfo Werner Kinkelin

A recent report by the United Nations Food and Agriculture Organization found that almost half of all the fish eaten worldwide are raised on fish farms rather than caught in the wild. It is likely that consumption of no other fish has soared more than that of farmed salmon, with production surging by almost 300% in 20 years.

Salmon are carnivorous, however, and to feed the voracious appetite of these legions of farm-raised fish, the aquaculture industry increasingly has turned its attention to a small crustacean commonly known as Antarctic krill. But that’s bad news for leopard seals and Adelie penguins, humpback and blue whales, and many other species, because most organisms in the Antarctic marine ecosystem eat either krill or something that eats krill.

Found in the cold waters of the Southern Ocean, krill constitute a key ingredient in fish oil and feed. Unfortunately, recent research indicates that expanded krill fishing might put the Antarctic ecosystem at risk. Representatives from the world’s major fishing nations, meeting this fall in Australia, have an opportunity to limit krill catches, thereby helping creatures that need krill to survive.

Although each krill may only grow to weigh about two grams, together they constitute one of the most abundant animal species on Earth. Indeed, krill form the largest known aggregation of marine life, with a biomass perhaps greater than any other multi-cellular animal organism on the planet.

This "pink gold" forms the heart of the Antarctic marine food web, and land-based krill predators, such as penguins and seals, are most vulnerable to krill scarcity. Scientists have found that demand for krill has begun to exceed supply in some areas of the Southwest Atlantic. As a result, penguins and albatrosses already experience difficulty rearing their offspring in areas such as South Georgia. And yet krill fishing is projected to grow.

The Southern Ocean contains the largest population of krill in the world. As krill tend to aggregate in concentrated swarms, they are easy to catch and have become particularly attractive to large-scale commercial interests. Moreover, krill fishing has recently been fueled by new technological advances such as vacuum pumps, which allow a single fishing vessel to catch and process huge amounts – up to 120,000 metric tons per season.

Furthermore, demand for krill products – from fish oil and feed to skin creams and other cosmetics – has increased over the past 20 years. As wild fish populations continue to decrease, in tandem with an ever-growing global appetite for seafood, the pressure on the aquaculture industry for fish feed will skyrocket. The increased demand for krill, together with the new catching and processing capabilities, has combined in a way that the Antarctic ecosystem might not be able to withstand.

But there is hope. The Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) was established in 1982, as part of the Antarctic Treaty System, in response to concerns that continued unregulated fishing might undermine the basis of the Antarctic food chain. The CCAMLR is governed by a commission of 24 member states – including Argentina, Australia, Chile, Japan, Norway, Russia, South Africa, South Korea, Ukraine, the United States and the European Union – that meets annually in Hobart, Australia, to discuss new fishing regulations concerning marine species in the Southern Ocean.

The CCAMLR has pioneered ecosystem and precautionary approaches to fisheries management, which are now central to maintaining Antarctic krill. Although the needs of krill-dependent species were previously considered for large areas of the Southern Ocean, the CCAMLR must still scientifically subdivide the overall catch limit into smaller units. This would help avoid local competition between krill vessels and the creatures that need krill to live, since krill fishing closely overlaps with the critical foraging areas for penguins and seals.

The CCAMLR’s members must honor the organization’s mandate for conservation and ensure that there is enough "pink gold" to feed the penguins and other wildlife that depend on it. The CCAMLR should also apply to krill fishing the same monitoring, control, and surveillance measures that it requires for all other fisheries.

Antarctic krill must not be fished to feed the fish farms of the world while starving the penguins, seals, whales, and other species whose survival depends on these tiny, but vitally important, creatures.

Copyright: Project Syndicate, 2006.


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It depends what fish you farm

Over the last year or so I have been avoiding buying trawled fish and instead buying farmed atlantic salmon on principle. So reading this piece came as something of a shock. Many fish stocks are in decline, and the oceans are being fished close to or beyond their limit. CO2 is raising sea acidity, and melting ice is altering salinity and temperature at various critical locations. Many variables operate and crystal balls have limited application.

But over the last weekend I had the opportunity to discuss the argument put forward here by González and Kinkelin with a marine biologist.  As a result I conclude that buying farmed atlantic salmon is probably no worse, and may be environmentally more sound, than buying trawled fish.

All fish have to eat something, and will thereby deprive some other creature of a meal. Oceanic food webs are complex, but in general carnivorous fish (and most of them are carnivorous) attack prey considerably smaller than themselves. This is understandable, as they can more readily both outswim it and swallow it. But at the same time catching it has to be worth the effort; so sharks don’t usually bother chasing sardines. At any particular stage of a fish’s growth, the capacity of its mouth gives a reasonable indication of the size of the servings of food it is eating.

A mature atlantic salmon may be several steps up a food chain. At each step along the chain there is a large mass and energy loss as prey tissue is converted to predator tissue. As a very rough rule of thumb, there is a 90% drop in both at each stage: 100 kg of autotroph (eg plant) tissue is needed to make 10 kg of herbivore tissue, which will in turn convert to 1 kg of carnivore tissue. So shortening its food chain is a good way for a species to increase its population and overall biomass. This fact is well illustrated in the case of the baleen whales: huge mammals that feed directly on krill, with each animal living as a mobile sieve.

That being said, only 5% of the anchovies caught off Peru are for human consumption. The rest go fo animal feed, which is arguably a criminal waste. Feeding krill to animals is arguably not much better, though perhaps not as bad as bulldozing Amazon rainforest in order to grow soybeans, which are then transported all the way to China and there fed to chickens.

The most effective use we could make of krill would be to eat it directly ourselves as a sort of ‘fish paste’ , though the memory of sandwiches made of one such concoction    which were inflicted on me as an innocent primary school pupil is, even now, almost more than I can bear. (I refer of course to 'Peck's Paste'.) The next best way to use it would be as feed pellets of appropriate size fed to farmed salmon. Arguably, the worst way is by catching a top predator such as a shark (sold as ‘flake’), 1000 kg of which may swim around at the top of a food pyramid whose base consists of maybe a thousand tonnes of krill. 

So I conclude that we have a brilliant future in front of us if we can make krill one of our staples. I have never tasted anything prepared from it, but given that it consists largely of small shrimp-like organisms, it should be possible. Mind you, I say that tentatively, as a few years ago the CSIRO put quite a bit of time and money into a project to find acceptable recipes for the cooking of European carp. They gave up in the end.

What I would really like to see, and subsidised by taxpayers’ money to get started, is aquaculture of the rock blackfish, otherwise known as black drummer (Girella elevata).  A better eating fish simply does not exist. And it is an omnivore whose diet consists largely of the seaweed known as ‘sea lettuce’(Ulva sp). Years ago, experienced Sydney rock fishermen used regularly to risk life and limb fishing for them in that body of water known locally as ‘The Murk’. The Murk owed its existence to Sydney’s sewage, a large part of which made its way into the blue Pacific at an outfall at Bondi. Seaweeds thrived in The Murk, and blackfish came for them by the thousand.

That would be the ideal sewage treatment, in my opinion. Turn it into seaweed, and then into blackfish.

We omnivorous humans have had a pretty hefty impact on the biosphere, but given that we number 6 billion or so, it is not as bad an impact as it could have been. Had we been exclusively carnivorous, like the large cats, we would have had the choice of much smaller numbers or much smaller clothes. Had we been exclusively herbivorous, we would be roaming around in enormous herds, but each of us would have the IQ of a sheep or a goat.

John the Baptist, at least in his wilderness period when his diet was locusts and wild honey, had arguably the second shortest food chain of any figure in recorded history. The shortest was undoubtedly that of St Cuthbert of Lindisfarne (d. 687 AD). Legend has it that he lived exclusively on a diet of raw onions. No doubt it shortened a few of the theological discussions he had with his fellow monks, but it still would have been better than Peck’s Paste.

(I was reliably informed by a fellow pupil that they made Peck’s Paste from fish guts boiled in bilge water. I believed it then, and still do now.)

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