Fishing for krill

Piano player at Raw Sugar

On several occasions, I have discussed the concept of ‘fishing down’ through marine food webs: starting with the top predator species, like tuna, and moving to smaller and smaller creatures as the big ones are depleted. In the waters around Antarctica, this process has come very close to reaching its logical extreme. Fishing for krill has become a big business.

Krill are shrimp-like marine invertebrates that make up a significant portion of the world’s zooplankton: the tiny creatures that eat phytoplankton algae. They, in turn, are eaten by all manner of other creatures, ranging up to large whales. Fishing them extensively risks knocking a whole tier out of the food web, with unknown but potentially severe consequences for all other forms of life in the ecosystem.

The krill that are caught are processed for fatty acids, used to make medicine, and fed to farmed fish. In particular, they are useful for giving farmed salmon more of a red colour, in contrast to the sickly looking pale pink much of farm salmon takes on. The current annual catch is estimated to be between 150 – 200,000 tonnes: much of that taken from the waters around Antarctica. Through the use of new technology, a planned new ship (the FV Saga Sea) will apparently be capable of collecting 120,000 tonnes annually. That is nearly one 1000th of the low estimate for the total global biomass of krill, and more such ships are planned.

While it may be that fishing for krill at this scale doesn’t pose a danger to marine ecosystems, it is worth noting that we have no scientific basis for being confident of that. An experiment is simply being performed in unregulated waters, which will have unknown future consequences. As with so many other instances of humanity’s engagement with the natural world, one cannot shake the sense that we are being awfully reckless.

Author: Milan

In the spring of 2005, I graduated from the University of British Columbia with a degree in International Relations and a general focus in the area of environmental politics. In the fall of 2005, I began reading for an M.Phil in IR at Wadham College, Oxford. Outside school, I am very interested in photography, writing, and the outdoors. I am writing this blog to keep in touch with friends and family around the world, provide a more personal view of graduate student life in Oxford, and pass on some lessons I've learned here.

14 thoughts on “Fishing for krill”

  1. “Tell you what – I’ll tie this noose around my neck. Then, you kick the stool out from under me, ok?”

  2. In a way, this is like knocking out the base of the food web.

    In another, though, it is a bit like the argument that eating plants is better than eating meat, because the conversion of plants into meat wastes energy. Maybe krill are the best thing we have to grind up and feed to farmed carnivorous fish.

  3. This post has produced some remarkably specific Google adverts including “krill oil” which is presumably the substance you’re referring to.

  4. Often, Google ads are trying to make money off of things I am condemning in my posts.

    There are certainly valid reasons for disliking them. If you want them gone, I encourage the use of the AdBlock plugin for Firefox.

  5. In another, though, it is a bit like the argument that eating plants is better than eating meat, because the conversion of plants into meat wastes energy.

    This is an interesting argument.

    All else being equal, it is probably better to feed krill to farmed fish than it is to feed them smaller fish. That being said, there is a decent case that we should only be farming vegetarian fish in the first place, and that there should be much stronger regulation of the whole practice.

    In any case, this krill fishing isn’t displacing some prior anchovy harvest – it is putting a new strain on the oceans.

  6. I still like the idea of only allowing fishing using vessels and equipment from the age of sail (aside from safety gear).

    Getting rid of spotter planes, bottom trawling, satellite location of hydroclines, fish aggregation buoys, and three-dimensional maps of sea mounts would do an awful lot to improve the sustainability of fishing worldwide.

    Unlike agriculture, where new technology can increase long-term yields, new technology in fishing can only ever serve to increase the catch rate and reduce the long-term sustainability of fisheries.

    Plus, it would be pretty cool to have fleets of wooden tall ships back on the oceans.

  7. “Through the use of new technology, a planned new ship (the FV Saga Sea) will apparently be capable of collecting 120,000 tonnes annually. That is nearly one 1000th of the low estimate for the total global biomass of krill, and more such ships are planned.”

    It is absurd that one ship could potentially destroy annually 0.1% of a species. In most sectors, when you get to the point when ten units of consumption per year equal one percent of the species, we call that species endangered.

  8. Tristan,

    It’s much bigger than that. Krill aren’t just one species – they are an important component of an entire tranche of the marine food web (zooplankton).

    I don’t really know about the accuracy or precision of the numbers in this post, but if the sources are right, this kind of fishing is really very worrisome.

  9. To think that a mere thousand ships could empty the see of this tranche of marine food is very scary. (Although, of course there would be diminishing marginal catch, but then again, probably beyond some destruction the tranche would not come back).

  10. Ocean food webs

    “The second trophic level (primary consumers) is occupied by zooplankton which feed off the phytoplankton. Together with the phytoplankton, they form the base of the food pyramid that supports most of the world’s great fishing grounds. Zooplankton are tiny animals found with the phytoplankton in oceanic surface waters, and include tiny crustaceans, and fish larvae and fry (recently-hatched fish). Most zooplankton are filter feeders, and they use appendages to strain the phytoplankton in the water. Some larger zooplankton also feed on smaller zooplankton. Some zooplankton can jump about a bit to avoid predators, but they can’t really swim. Like phytoplankton, they float with the currents, tides and winds instead. Zooplanktons can reproduce rapidly, their populations can increase up to thirty percent a day under favourable conditions. Many live short and productive lives and reach maturity quickly.

    Particularly important groups of zooplankton are the copepods and krill.”

  11. Plankton, the base of the ocean’s food web, steadily declining

    Caroline Alphonso
    Globe and Mail Update Published on Wednesday, Jul. 28, 2010 1:04PM EDT Last updated on Wednesday, Jul. 28, 2010 2:05PM EDT

    The foundation of the marine food web is being threatened as a new Canadian study reveals that phytoplankton – tiny microscopic organisms – have been steadily declining over the past six decades.

    For the first time using both historical records and recent oceanographic data, a team from Dalhousie University found phytoplankton declines of about 1 per cent of the global average every year, and about 40 per cent since 1950. The study, published Wednesday in the journal Nature, involved a three-year analysis.

    “This is a definite wake-up call that our oceans are becoming increasingly stressed and this is another indicator of that,” said lead author Daniel Boyce, a marine ecologist and doctoral student at Dalhousie. “It’s quite shocking to think that there’s been a 40 per cent decline at the base of the food chain over the past 50 years. I think it’s absolutely cause for concern.”

    Phytoplankton form the basis of the marine food chain, feeding everything from tiny zooplankton to large mammals and fish. Their decline could affect everything, and eventually impact humans.

  12. FEW have heard of the mesopelagic. It is a layer of the ocean, a few hundred metres below the surface, where little light penetrates, so algae do not live. But it is home to animals in abundance. There are bristlemouths: finger-sized fish with gaping maws that sport arrays of needle-like teeth. They number in the quadrillions, and may be the most numerous vertebrates on Earth. There are appendicularians: free-swimming relatives of sea-squirts a few millimetres across. They build gelatinous houses several times their body-size, to filter food from the water. There are dragonfish (pictured). They have luminescent spotlamps which project beams of red light that they can see, but their prey cannot. There are even squid and swordfish—creatures at least familiar from the fishmonger’s slab.

    And soon there will be nets. Having pillaged shallower waters, the world’s fishing powers are looking to the mesopelagic as a new frontier. The UN’s Food and Agriculture Organisation reported in 2002 that the fish-meal and fish-oil industries would need to exploit this part of the ocean in order to feed fish farms. In the past nine months Norway has issued 46 new licences for vessels to fish there. In September the government of Sindh, a province that is home to most of Pakistan’s fishing fleet, issued a draft policy on licensing mesopelagic fishing in its waters. And at the North Atlantic Seafood Forum, held in March, in Bergen, Norway’s principal port, the session about fishing the mesopelagic was entitled “the Big Apple”.

    Until now, the only sensible way to probe mesopelagic activity has been by sonar. This is, indeed, how the zone was discovered, in 1942, by an American anti-submarine research project. From their earliest days such soundings suggested a lot of creatures live in the mesopelagic. They are sufficiently abundant that the equipment then available saw the zone as a “false bottom”, beneath which sonar could not penetrate and submarines might thus hide. But it was subsequent probing by a Spanish expedition, the Malaspina circumnavigation in 2010, which came up with the current 10bn-tonne estimate and showed just how big a part of Earth’s biosphere the mesopelagic actually is.

    Combining data from these three types of robots will paint a more accurate picture of life in the mesopelagic, and thus of its importance to matters climatic. In collaboration with NASA, WHOI also hopes to find variables that are observable by satellite and that correlate with the health of the mesopelagic and the size of its carbon flux. The principal satellite involved here, if it can survive the Trump administration’s budget proposal to cut its funding to zero, will be PACE (short for Plankton, Aerosol, Cloud, ocean Ecosystem). This is scheduled for launch in 2022. Though PACE will not be able to see directly into the mesopelagic, it will be able to measure, from the spectrum of light reflected from the ocean, things like rates of plankton consumption.

    The forthcoming decade should, then, serve to start answering the question of how much fishing of the mesopelagic can be undertaken without disrupting it—and with it, its role in climate regulation. Once the fleets start hauling in their catches, the temptation will be to collect more and more. History shows that such piscatorial free-for-alls usually end badly. In the case of the mesopelagic, though, regulators will start with a clean slate, and thus a rare opportunity to agree in advance a way of stopping that happening. Whether they will take it is another matter.

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