SeaWeb - Ocean Briefing Book

Culling Whales To Boost Commercial Fisheries

The Problem

Commercial whaling interests are increasingly arguing that the world’s whale populations are growing rapidly and are consuming massive amounts of marine species, to the extent that they are threatening fish populations and directly competing with commercial fisheries. In publications and speeches, pro-whalers have been using this argument as justification for a resumption of full-scale commercial whaling.

The Debate

In a 1999 publication, the Institute of Cetacean Research (ICR)—the body which oversees Japan’s scientific whaling program—claimed that cetaceans consume between 280 million and 500 millions tons of aquatic life each year: “roughly three to six times the recent total estimated worldwide marine commercial fisheries catch.”
Two years later, Masayuki Komatsu, then Japan’s deputy commissioner to the International Whaling Commission (IWC), expanded on the assertion: “Whales are eating fish to depletion,” he wrote; “We need to cull whales in order to achieve sustainable utilization of the fish.”
However, although cetaceans undeniably consume large amounts of marine life, the exact amount they consume is unknown. Other researchers have challenged the ICR’s claims, arguing that, even assuming the accuracy of the ICR’s figures, it does not follow that cetaceans are impacting fish populations or commercial fisheries.
The ICR’s figures, for example, suggest that 22% of total food consumption by cetaceans is by baleen whales in the Southern Ocean, and 51% by sperm whales worldwide. But examination of stomachs from whales killed in the past by commercial whaling has repeatedly demonstated that Antarctic baleen whales eat almost exclusively krill, for which there is little commercial demand; and sperm whales’ diet has similarly been shown to be dominated by deep-sea squid, for which there is no commercial fishery. The remaining 27% includes consumption of planktonic organisms by Northern Hemisphere baleen whales, and the diet of smaller cetaceans such as dolphins, porpoises, and beaked whales. The amount of commercially-valuable fish species consumed by the great whales is therefore likely only a fraction of the total figure claimed by the ICR.
Furthermore, even if cetaceans did consume large amounts of commercially-valuable fish, it does not follow that those fish would then be available to commercial fisheries. Critics of the ICR’s position point out that a large proportion would succumb to natural mortality, while others would be eaten by predators such as other marine mammals, seabirds, or predatory fish. Indeed, such critics argue, it is predatory fish that consume by far the largest amount of fish in the ocean.

The Context

Blaming marine mammals for the decline in fish populations or commercial fisheries is not new. From 1976 to 1982, fishermen at Iki Island in Japan killed approximately 6,100 dolphins and small whales, which they alleged were responsible for declines in catches of yellowtail. Politicians and fisheries interests in Newfoundland repeatedly argue that harp seals should be culled to allow recovery of groundfish populations. The notion that marine mammals need to be controlled as part of a system of “multi-species management”was also behind the establishment in 1992 of the North Atlantic Marine Mammal Commission (NAMMCO), created by Iceland, Norway, and the Home Rule governments of Greenland and the Faeroe Islands as an intended regional alternative to the IWC.
Despite the claims by the ICR and allies that whale populations are rapidly increasing and have largely recovered from previous over-hunting by commercial whalers, few other researchers agree that this is the case. It is widely accepted that the Eastern North Pacific gray whale population had rebounded to its estimated pre-exploitation level, and possibly exceeded it; however, the only other populations of whales known to be increasing are southern right whales, bowhead whales in the Western Arctic, and some populations of humpback whales. For many other populations, little remains known of baseline levels, present sizes, or current trends; it is generally considered, however, that most populations of great whales have yet to show any significant sign of recovery, and that almost all remain massively depleted.
The notion that it is essential to examine whales’ stomachs to determine their diet and thus their potential impact on fish populations has become the primary rationale for the ICR’s ‘scientific whaling’ program. In 2002, the ICR used the argument to justify expanding its North Pacific whaling program to include sei whales, even though previous Japanese studies showed that sei whales feed almost exclusively on tiny planktonic organisms called copepods.
Representatives of the Japanese whaling industry have been making the argument that whales need to be culled to protect fish populations with particular urgency and frequency at regional fisheries fora involving eastern Caribbean, Pacific island, and west African states in an apparent attempt to secure support for Japan’s whaling policy. Environmentalists charge that Tokyo is using fisheries aid to many of these same countries to induce them to join the IWC and support Japan.