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Large ocean fish could be gone by 2050, study says

The views expressed are those of the author and are not necessarily those of Scientific American.

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Tuna at the Tsukiji fish market in JapanOverfishing large predators such as shark, tuna and cod in the past 40 years has left the oceans out of balance, and could result in the disappearance of these fishes by 2050, according to Villy Christensen of the University of British Columbia’s Fisheries Center.

Christensen made this prediction at a panel, “2050: Will There Be Fish in the Ocean?” on February 19 at the annual meeting of the American Association for the Advancement of Science in Washington, D.C.

With the disappearance of these large fishes, populations of smaller, plankton-eating fishes such as sardines, anchovies and capelin have doubled, Christensen reported. His team studied data from more than 200 marine ecosystem models, which arrived at more than 68,000 estimates of fish biomass for years ranging from 1880 to 2007.

Whereas the absence of predators allows tiny fish to thrive (Christensen likens it to “when the cats are away, the mice will play”), it also leaves them vulnerable to disease and boom-and-bust cycles. The resulting mass die-offs could lead to algae blooms or large pockets of bacteria that would deoxygenate the surrounding water, leaving large portions of the ocean as dead zones, unable to sustain life.

Smaller fishes such as sardines are not heavily consumed by humans these days. Instead, they are mostly ground into meal or used for fish oil. Christensen advised his audience to try to turn that around and eat the smaller species instead of the bigger, more valuable tuna and cod. “We should be encouraging people to eat more sardines and herrings—and less predator fish,” he said.

Photo: . Via Wikipedia

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  1. 1. jtdwyer 1:51 am 02/25/2011

    "We should be encouraging people to eat more sardines and herrings–and less predator fish."

    Wouldn’t switching to sardines and herrings simply deplete their populations?

    Could the near tripling of the world’s human population since 1950 have contributed to the depletion of predatory sea fish during the past 40 years?

    So if the global population increases by nearly 30%, from nearly 7 to 9 billion, by 2050 as predicted by the U.S. Census Bureau, how many of those billions of people will suffer from malnutrition? Is it time to start moving even further down the ocean’s food chain?

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  2. 2. oldvic 8:49 am 02/25/2011

    In principle, harvesting from lower levels in the food chain means accessing a larger population (there is far more biomass in sardines than in all their predators). Wikipedia’s article is interesting:
    Ideally, it seems to me that we should base our food harvesting in a balanced extraction from every relevant trophic level: mostly vegetable matter, with a lower quantity from herbivores and a lower still quantity from predators.
    That way we would make an efficient use of the "food energy" we need without distorting the system as the article illustrates; and we would still be able to enjoy all the food types we’ve come to like.
    Obviously, if we then use such improvements as an excuse to go on increasing our already bloated numbers, we’ll simply be ensuring a bigger problem down the road.

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  3. 3. jtdwyer 11:58 am 02/25/2011

    Interesting, but I’m not sure how convincing it is:
    "Humans are generally primary and secondary consumers, and thus represent usually second and third trophic levels. Most humans are omnivores, which means they consume both plants and animals and therefore consume from different trophic levels. It has often been noted in the discussion of trophic levels that consuming a vegetarian diet would mean eating at a lower trophic level and would cause less energy to be lost."

    It seems to me that there is very little plant biomass that can be consumed by humans, as we do not have the specialized digestive systems of true herbivores. Our consumption of terrestrial plant material is pretty much limited to a narrow range of leafy plants, fruits and vegetables. The general concept does seem more sound than just picking off the top of the food chain unless we were to cultivate their production (i.e., fish farming).

    I suspect we’d only produce more humans, though, given increased nutritional resources. According to Census Bureau estimates, the human population reached 1 billion for the first time around 1800, 2.5 billion by 1950 and nearly 7 billion now.

    Some are encouraged by predictions that the population will soon stabilize, but IMO we’ve already destabilized the Earth’s resources.

    I think the population growth correlates very well with the increased availability of nutritional resources, including the institution of crop rotation, soil fertilization and agricultural mechanization. Agricultural production is, of course, subject disruption due to major climate instabilities.

    Meanwhile, mechanization of wild seafood harvestation, especially during the past 50 years or so as the human population increased so dramatically, has enormously increased the nutrients available for economic human consumption, but also resulted in the depletion of these naturally occurring resources.

    I’m afraid the relatively sudden loss of this crucial source of nutrition will have devastating results for the now enormous mass of global humanity.

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  4. 4. scientific earthling 11:43 pm 02/25/2011

    All our problems stem from one fact: Our species has overpopulated the biosphere. Balance in the biosphere is lost, negative feedbacks that controlled our numbers have been circumvented and we continue to breed like rabbits.

    The scientific communities have been marginalised, and economists ruled (the dimwits believe resources are infinite). More people = bigger markets. Now its payback time. Get ready for earthworm burgers and grasshopper wraps.

    China is the sole country that acted to save the biosphere. Population control is the only single answer, all the rest is political correctness gone mad.

    Malthus’s day of glory is here. Too bad he is not anywhere to know his theory was basically correct.

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  5. 5. jtdwyer 1:35 am 02/26/2011

    I generally agree with your sentiments, but I’m compelled to point out that China’s population control was implemented solely for the economic benefit of the Chinese, not as an altruistic measure to improve global conditions.

    As a result, China has been able to improve the education of its work force, providing for enormously increased industrialization which has included the construction of a very large number of coal fired power generation facilities. As I understand, China is now the greatest contributor to atmospheric co2 levels. I think they are also the largest and certainly fastest growing economies in the world, although their per capita income levels are still very low.

    Not to criticize the Chinese. In the 1990s I met with some engineers in Tokyo who intimated that while, in the 1980s Americans had been encouraged to implement the brilliantly successful Japanese business strategies of ‘Just in Time’ inventory management, now (in the 1990s) Japanese businesses were being implored to implement the brilliantly creative strategies of successful American businesses. The Chinese had the wisdom to avoid both, but I strongly suspect their success has already peaked. Perhaps India will produce the next brilliant strategy…

    The global population reached 1 billion for the first time ever around 200 years ago and has since increased by 590%, to 6.9 billion. It’s projected to increase 30% by 2050.

    I agree that the only recourse for humanity is to somehow reduce the current population before it collapses on its own.

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  6. 6. 3:47 pm 03/3/2011

    Excellent article, we must change our ways, fish farming is that only way we can indulge our tastes without destroying the environment. It seems so arrogant that we can destroy the wild places, they do not even belong to us!

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  7. 7. bucketofsquid 12:45 pm 03/7/2011

    "It seems so arrogant that we can destroy the wild places, they do not even belong to us!" – aquaponics

    All places started as wild places and thus either all places belong to us or none of them do.

    The only real solution is to reduce population. I have done my part by having only 2 children and they are both boys. Women are the controling factor in population growth so by having only boys (obviously not intentionally) I have reduced the long range global population by that tiny fraction of a percent. If 6 billion more people do something similar such as stopping after their first girl is born or by random chance not having girls then we may actually survive without a catastrophic die off of humans. Personally I’m expecting the mass die off. I think it will hit first in India when there are sufficient crop failures world wide.

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  8. 8. 2:59 pm 03/7/2011

    I find it physically painful to see forests and erstwhile wild places burned to convert them to farmland, there must be a line drawn, we cannot occupy every square inch, just because we are so very good at it.
    Human population will inevitably increase, but it must only be at increased density on the land we have taken already, and therefore food must be farmed in an efficient non polluting way, this is in our interests.
    There are international laws giving all the surface of the planet to the countries nearest it, all of the sea will be owned, mined or farmed. This is a huge change in thought, it may protect wild animals in enlightened countries, but it might be the start of total, arrogant, human domination.

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  9. 9. JDahiya 8:51 am 03/8/2011

    jtdwyer, this: "It seems to me that there is very little plant biomass that can be consumed by humans, as we do not have the specialized digestive systems of true herbivores. Our consumption of terrestrial plant material is pretty much limited to a narrow range of leafy plants, fruits and vegetables." is not true. Most of our consumption of plants is in the form of cereal grain, and not vegetables, which is also reflected in the primary agricultural output globally. Cereals are grasses, which are the most dominant plains plants, too, which implies that we have significant plant biomass accessible to us, if we choose to eat at that trophic level.

    Given that we only consume the seeds, there is considerable wastage, but it is much less than feeding the grass to a sheep or cow at the next trophic level and eating that instead.

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