In the waters around Japan where catches in certain fisheries are declining, Japan’s research catch of whales reveals that minke whales are eating at least 10 of the target species of these fisheries including Japanese anchovy, Pacific saury, walleye Pollock and others (Government of Japan, 2000).

Off the Pacific coast of Japan, Bryde’s whales feed on krill, Japanese anchovy and chub mackerel (Scomber japonicus). In the waters around Bonin Islands, they fed on krill and lantern fish. In the East China Sea, they fed mainly on Japanese pilchard (Sardinops melanostictus), Japanese anchovy and horse mackerel (Trachurus japonicus) (Government of Japan, 2000).

Sperm whales feed not only on squids but their diet also includes commercially important fishes such as rockfishes, cods, Pacific saury, and Japanese pilchard.

Trites et al., (1997) estimated that 84 species of marine mammals in the Pacific Ocean, totaling over 20 million individuals, consume about 150 million tons of food per year. This amount is approximately 3 times the annual commercial harvest of fisheries in the Pacific. They suggest that commercial fisheries target only 35% of the prey items sought by marine mammals and suggest that the most significant consumer of fish is probably other predatory fish, and not marine mammals. However, this does not negate the conclusion that marine mammals could have a very significant impact on returns to commercial fisheries even if these fisheries target only 35% of the prey items sought by marine mammals. Trites et al., also acknowledge that indirect competition might occur for the primary production which sustains both marine mammals and those species of fish caught in commercial fisheries.

According to the Norwegian feeding ecology research conducted between 1992 and 1994, the prey species consumed by minke whales change conspicuously according to area, season and year, and minke whales have flexible feeding patterns to match the local abundance of prey species (Haug et al., 1995). Further, it was suggested from the concurrent prey species surveys that minke whales showed a preference for herring (Clupea harengus) and capelin (Mallotus villosus). Data from Iceland indicates that of sixty-eight minke whale stomachs examined, 51% contained fish only, 22.1% krill only and 25.0% fish and krill together (Sigurjonsson et al., 2000).

By inputting these kinds of data into models, future forecasting is possible (Bogstad et al., 1997). For example, it was shown that, when minke whales increase, important fish resources such as cod decrease by predation, resulting in serious consequences for fisheries targeting these species (Schweder et al., 2000). Estimates from these models include the probability that close to 100,000 tons of cod are being consumed by cetaceans (Bogstad et al., 2000). The U.S. pamphlet ignores these scientific findings by simply saying "scientists do not yet understand ecosystem dynamics well enough…".