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Deep Sea Trawling, Fish Populations, Seamounts, and a Moratorium

Cottage Pie's picture

The ocean floor of the deep sea has its own mountains, called seamounts, which rise from 500 to 1,000 meters above the surrounding sea floor. (1, 2)  It is not known exactly how many seamounts lie beneath the big blue, but it has been estimated that the Atlantic Ocean possesses 800 or more and that the Pacific has 30,000 plus. On harder portions of the seamounts “ancient forests” made up of “cold water corals, soft seapens, sponges, and seawhips grow.” (1, 2) These organisms house other sea creatures such as crustaceans and sea spiders. On top of that, seamounts also provide protection to small sea fish such as the orange roughy and deepwater oreo who swim close to the seamounts in order to prevent being swept away by the current. On the softer sediment of seamounts grow worms and more slipper lobsters. The seamounts number one threat is bottom trawling.

Bottom trawling, also known as Benthic trawling, is a fishing practice in which one or two boats drag a cone shaped net along the bottom of the ocean floor in order to catch deep sea fishes. (4) While this technique is effective, in that bottom trawling will catch pretty much any object that gets in the net’s path and therefore could not possibly miss its target (the target being fish) and while there are few vessels (200 world wide) that actually use this fishing practice with their catch only constituting for .2% of the total world fish catch it also results in a mass destruction of the ocean floor and all that lives on it, including organisms not targeted by the fishing industry. 

In other words the destruction caused by these 200 ships far outweighs the damage they do to the population of future generations than the benefit does of gaining more fish for consumption in a shorter period of time. A good analogy regarding the logic of deep sea trawling is put forth by Dr. Alex Rogers a senior research fellow at the Zoological society of London, UK: "It's the equivalent of clearing out old-growth forest to collect squirrels. It's a practice on land that just wouldn't be acceptable." (7)

A recent study by an international team of researchers to be published in the journal Science found that since the seas are currently being over fished there will be no fish to fish for by about 2050 if the situation (in part caused by trawling) remains the same. To paraphrase researcher Boris Worm of the Dalhousie University in Canada, there are only so many fish in the sea; we have fished one third of the stocks, and we will get through the rest. (6) One of his research partners, Steve Palumbi of Stanford University, adds in, that, “(u)nless we fundamentally change the way we manage all the ocean species together, as working ecosystems, then this century is the last century of wild seafood.”

This recent study resulted in proof that the decline in the population of seafood species is on a global scale. In order to come to this conclusion and find proof the scientists analyzed results from 32 experiments involving the fate of marine species on small local scales and then tracked 1,000 years of change in species diversity across 12 coastal areas. In each of these coastal areas they took into account “trends affecting between 30 and 80 economically and ecologically important species,” and what information old archives, fishery records, sediment cores and archaeological data could provide to them.

These large marine ecosystems (LMEs), the 12 coastal areas that the scientists studied, were found to have produced 83% of global fisheries yields over the past 50 years. Lastly, the scientists researched the recovery of biodiversity in areas closed to fishing and marine reserves due to the fact that these places would be where fish populations could safely recover. The scientists’ exhaustive and methodical research resulted in their conclusion that by 2048 the seas would be fished to a point of no return for fish populations. 

However, the study does not directly point fingers as to who or what the cause of this population decline is, but rather pushes the fact that “cumulative harm has be done across the board.” (6) As Carl Gustaf Lundin, head of the global marine programme at IUCN, the world Conservation Union points out, “The benefits of marine protected areas are quite clear in a few cases; there’s no doubt that protecting areas leads to a lot more fish and larger fish, and less vulnerability . . . But you also have to have good management of marine parks and good management of fisheries. Clearly fishing should not wreck the ecosystem, bottom trawling being a good example of something which does so.” (6) At the top of the next page is the evidence the study provided.

The fishing industry in the UK has rejected the aforementioned study, the UK itself supports a moratorium on trawling, just not it’s fishing industry. “According to the UK seafood industry body, and the Scottish Fishermen’s Federation (SFF) the study does not deal with reality or note continuing attempts to protect fish stocks.” (8) The SFF chief executive, Bertie Armstrong makes the claim that the timescale in the study is too long and does not take into account Europe’s preventative efforts to stabilize and recover the fish population. He further points out that the study neglected to mention the 1992 Johannesburg convention, where “the world environment leaders agreed to try to restore fish tocks to sustainable levels by 2015.” (8) I feel it’s worth it to note, however that if that be the case why is it that the fish population has declined rather than risen? The UK seafood industry is now doing it’s own research, because it doubts the scientists findings, and acknowledges that there is more to be done, but also feels that it is “moving in a positive way and (that) this should be recognized.”(8)

As of last Wednesday, November 15, 2006, “(t)he line (that) the [deep sea fishing nations] have take up to now is, ‘yes we will do something about it (deep sea trawling) if you can prove to us that vulnerable ecosystems occur where we are fishing’,” said Alex Rogers of the Institute of Zoology in London. Alex Rogers is one of the authors of a study that will provide evidence for a moratorium to be placed on deep sea trawling.

In order to go about proving this without collecting data on each individual seamount to prove their vulnerability the researchers tackled the problem from a different angle. The research team “linked measurements of physical characteristics of oceans, such as temperature and salinity, to the presence of stony corals, which are heavily relied upon by invertebrate species and so are a good indicator of a system’s diversity.”(7) They then hypothesized where such corals would exist based upon their research and compared their educated guess as to where the coral would be, to areas that were being bottom trawled. ‘There was a lot of overlap,’ meaning that the trawlers had already trawled the precious coral beds leaving behind a coral graveyard\. “I think what we have done with this report is reverse the burden of proof on to the fishing regulators and fishing industry,” said Dr Rogers. “If you want to fish them, really you are going to have to prove to us that it is not going to do significant damage to these habitats.” (7)

Due to the fact that stony coral, an important part of the seamount ecosystem can live up to 1800 years and are extremely slow growing, not only are the fish being trawled up, but also prevented from repopulating due to loss of habitat from the trawling. “All evidence points to” the fact that deep-sea organisms take a longer period of time to recover than non-deep sea organisms, for example the life span of an orange roughy is roughly 120 years, the first 30 of which are spent reaching sexual maturity. The current estimate of recovery goes from “decades to hundreds of years- if they recover at all.” (1)

Some people, however, such as the founder of a major Canadian seafood company, John Risley of Clearwater Seafoods do not buy into the fact that deep sea trawling is not the best practice. It would seem to them at least that them that the present gains from trawling far outweigh the significant losses that will be incurred when the fish run out. Anyways, John Risley claims that “(t)here is zero scientific evidence, not one shred of scientific evidence, that these fisheries do any damage to the bottom environment whatsoever. We could not have a shrimp fishery, we could not have a ground fishery, we could not have a scallop fishery, we could not have a clam fishery, if it wasn’t for bottom trawling.” Risley made this statement on November 15, 2006 at a speech to St. John’s Board of Trade hours after the UN’s draft report discovered that wherever trawlers nets go the oceanic deforestation of coral results. 

According to Risley he is not against the protection of “sensitive” areas of the ocean floor, but maintains that it would be ineffective because if they don’t trawl there some other countries trawling will.  Ransom Myers, a fisheries biologist from Dalhousie University Halifax agrees with Risley’s opinion that most trawling occurs in areas that have already been trawled and therefore no coral is being destroyed. However, there happens to be no coral there because it has previously been destroyed. Myers suggests that a moratorium should only be placed upon those areas that have not yet been trawled but that trawling should continue in those areas that have already been so trawled.

It should be noted, that it would seem to be that many people acknowledge the devastation caused by deep sea trawling, and really the only people coming out and saying that this is not the case would be people with biases, such as owners of Sea food companies and the Industry as a whole. However, trawling does provide countless numbers of people across the world with jobs (not necessarily working the trawlers but processing the fish, selling the fish etc.) and through this, a way to feed their family. So while there is an easy answer to this situation, stop deep sea trawling, there is also an economical factor that needs to be considered, however, I feel that it is worse for people employed by the fishing industry in the long run when there are no more fish to fish for, or package, or sell.

There are several good reasons to stop the trawling of our oceans, be it the destruction of ancient coral or the well being of the fishing industry with the future in mind. Lastly, if deep sea trawling is not stopped previously unknown species will go undiscovered, perhaps forever if they become extinct. According to Dr. Alex Rogers British Atlantic Survey (BAS), “ on one seamount in the Tasman Sea, we found 850 species of which a third haven’t been found anywhere else . . . And on the Norfolk Ridge near New Caledonia there are a dozen seamounts which have been explored. Here there were found around 1,200 species, a half of them new to science.” (3) “Think of it as driving a huge bulldozer through a lush and richly populated forest and being left with a flat, featureless desert. Think of it as beef farming by dragging a net across entire fields, cities and forests to catch a few cows. It’s like blowing up Mars before we get there.” (1)




1. Save deep sea life

2. Jewels of the Sea-Seamounts


3. Deep-sea trawling’s ‘great harm’


4. Bottom Trawling


5. Case for trawl ban ‘overwhelming’


6. ‘Only 50 years left’ for sea fish


7. Scientists call for deep-sea trawling ban


8. Vanishing seafood study dismissed

9. No Proof bottom trawling is damaging: Clearwater chief