A Humpback whale (Megaptera novaeangliae) feeding near Stellwagon Bank off the coast of Massachusetts.
Photo: Chris Johnson
June 7, 2004
"Do Whales Compete With Humans for Fish?"
In her latest log Genevieve Johnson writes about whales being made scapegoats for what is really human overfishing - a mistruth that is being promoted by the Japanese whalers who are trying to overturn the moratorium on commercial whaling by saying that whales are eating all our fish from the seas.
Dr. Seiji Ohsumi, Director of the Cetacean Research Institute (ICR), Japan's major institute for whale studies, co-authored a paper entitled Estimation of total food consumption by cetaceans in the world's oceans. This often quoted "scientific" source received no peer review. (How do I know this? Because if it had, it would have been torn to pieces by other scientists.) Nonetheless, it's used as the "scientific" [in quotes] rationale for a new diplomatic offensive Japan is mounting which attempts to make the world regard whales as greedy competitors to humans for fish from the sea. On November 17, 2000, Dr Ohsumi said that the need for Japan to carry out "scientific" whaling was because:
"Until recently, the question of 'what and how much whales are eating' has not been taken up as a subject for discussion, but we find it now necessary to deal with the issue."
This is spectacular nonsense (I think that's the appropriate technical term). Some of the first serious studies ever made about whales were about what whales eat (they were carried out in the roaring twenties of the last century before either Ohsumi or I were even born). since fishermen everywhere are always curious about what their prey eats it is not surprising that the analyses of stomach contents was one of the first things to which the whaling industry contributed data.
And because whalers were killing thousands of whales a year at that time, they had access to all the whale stomach contents they could handle. In fact, scientists on the Scientific Committee of the International Whaling Commission (the IWC which regulates whaling) have pointed out repeatedly to Japanese scientists on that committee that there is such a massive amount of data on diet from the hundreds of thousands of whales killed in earlier years that it is absurd to believe examination of the contents of a few hundred more stomachs will alter in any significant way what we already know about baleen whale diets.
Japanese whaling scientists such as Ohsumi know this too, but they go on with their "research" anyway because doing so fits their agenda and they have discovered such a rich vein of public sympathy to mine among those who assume that whales compete with humans, and they can see that repeating this nonsense is being effective in changing the minds of most listeners because they know little or nothing about ocean ecosystems. But their evidence isn't based on science it's pure spin-doctoring-in fact, the claim that it is science-based is the part of the charade I find hardest to take.
In the same document from which I have just quoted, Ohsumi also said:
"According to our calculations about how much food whales eat, it was found that the annual intake of food by whales in waters around the world is an estimated 280 million to 500 million tons. The world catch of fish is approximately 85 million tons (in 1994); so this means whales consume three to six times as much marine resources as humans do."
But let's look at the facts: the main food of sperm whales is large, benthic (deep-water) squid such as the famous giant squid-species for which whales do not compete with humans. We might like to eat such squid, but we can't even sample them, let alone supply an industry with them-no one has ever devised a means of catching a large benthic squid.
Because of this, it would be hard to imagine a major predator that competes less with humans than does the sperm whale. Ohsumi knows that, but when talking about how much food whales eat (by which most people assume he means the same things they think of as seafood), he includes the food tonnage eaten by sperm whales anyway (tonnage that accounts for about a third of his number). It would be no more accurate to say that sea fans compete with humans for seafood.
By far the greatest portion of the remaining two thirds of Ohsumi's number is krill - an incredibly abundant tiny shrimp that occurs worldwide, but that enjoys its greatest concentration in the Antarctic Ocean. Krill has the same distribution found in baleen whales. The reason, of course, is that krill is the chief prey of most baleen whales-not just in number but in biomass-baleen whales go where the krill are.
Ohsumi knows that too, but he lumps in the krill with the giant squid and calls it all seafood - which, of course, it is - only not the seafood we eat. Until relatively recently, humans ate no krill at all. Though we have begun to exploit it, it will be a long time, if ever, before the vastly diminished whale stocks in the Antarctic Ocean where krill is at its most abundant become any sort of significant competition for humanity's krill-fishing efforts. Besides, in order to reach that point, we would need first to build a vast, new infrastructure for catching, storing, processing and transporting krill-to say nothing of creating a stable market for it. And all of that is a larger investment than has ever been made at one time for any fish species. Ohsumi knows that too but by comparing the number of tons of the sorts of food that baleen and sperm whales eat with the number of tons of fish that humans eat, he is able to create the impression that whales are eating what we would otherwise get.
It is true that baleen whales made enough of an impact on krill stocks that when the whales were all but extirpated in the Antarctic by the whaling industry the krill-eating species of Antarctic seals, penguins and other seabirds increased. But even that does not constitute evidence that humans and other krill-eaters compete: humans don't eat Antarctic seals, penguins and seabirds.
There are also known instances in which, by eating smaller predators of commercially valuable fish, major predators such as whales have kept those smaller predators in check, and that without such controls, the lower levels of the food pyramids would get wiped out, thereby reducing the abundance of the predatory fish species for which there is a large human market (e.g. billfish, sharks, mahi mahi, tuna, Striped bass, bluefish, etc.).
Although aware of all of these points, Ohsumi persists in trying to persuade the World to believe that people need to cull whales. He made this perfectly clear on the same occasion from which I have been quoting him when he said:
"Because whales pose a threat to fisheries resources, there is the need to resume whaling also for the protection of the fishing industry."
But the only evidence we have, points to precisely the opposite conclusion: that whaling can put fishers out of business. It comes from a case in which whaling that occurred forty years ago in the northeast Pacific has started to put fishermen from that same area out of business. It is also an excellent example of how unexpected the results of hunting top predators such as whales can be.
What happened was this: after Japan's whalers had killed off most of the baleen whales around the Aleutian Islands the local killer whales, having lost a major food source, switched their focus to eating another marine mammal species-Stellar's Sea Lions. This was the largest, relatively slow swimming marine mammal in the area and having knocked its population way back the orcas switched their efforts to a smaller marine mammal species-the Northern Sea Lion. And having decimated that species they focused their attention on the smallest marine mammal in the area, the sea otter.
But the principle prey of sea otters is sea urchins, and with sea otters all but gone, the sea urchin populations exploded, overran the offshore kelp beds, and ate the kelp down to its holdfasts.
But kelp forests are the chief hiding places - the principle nurseries - of commercially important larval fish. It is here that they grow up until they are big enough to face the pressures of life in the open ocean. But without a place to hide, even from their weakest predators, larval fish couldn't grow big enough to swim back to sea and become a part of the ocean fishery. So ocean fish stocks near the Aleutians began to collapse, which caused a wave of bankruptcies among Alaskan fishermen. Thus, what the whalers were actually accomplishing way back in the middle of the last century when they were killing off the baleen whales around the Aleutian Islands, was to destroy the chances for future fishers, just being born at that time, who would someday want to go fishing in the waters from which the whalers were removing the whales.
The lesson from this unanticipated chain of consequence is clear: whaling hasn't made more fish available to humans, it has made less fish available.
The wider (and perhaps wiser) lesson it teaches is that in the web of life all things are connected, that the connections are sometimes extremely obscure, and that when we humans simply barge into that web we are likely to become entangled by the consequences of our own ignorance. Until, like the fly, we perish in the web because it was invisible to us.
© 2004 Written by Roger Payne