Japan's voracious appetite for seafood, which, probably more than any other single factor, is blamed for the serious depletion of marine wildlife worldwide, is actually not as voracious as it used to be. In 2008, the average Japanese household consumed 36 kg of fish, down 30 percent compared to 1986. The leveling of Japan's population has something to do with this drop, but it mainly has to do with a shift in preference toward more Western fare at the dinner table. Also, Japanese taste for fish has become more selective. Tuna sashimi remains a favorite, and salmon has even increased in popularity, something Norway and problem-plagued Chile, which export most of theirs to Japan, are grateful for. It is so-called "blue" fish, like the various species of mackerel (aji, saba, sanma, etc.) that have dipped in popularity.

Consequently, Japan's fishing industry, not to mention its mom-and-pop fish retailers, are looking at a cloudy future, and some regional fishing cooperatives are trying to cultivate interest in zako, literally "miscellaneous fish" or "small fry" that people in the distant past may have eaten out of necessity but today's consumers have never even heard of much less ever tasted. Fishermen in Toyama Prefecture, for instance, are catching more shiira, which in the West is known by the Hawaiian name mahi-mahi, a species that is notoriously difficult to prepare. The fishermen are not so much trying to convince housewives to buy shiira and cook it at home. Their main focus is on food companies that make kamaboko (fish cakes) and other processed seafood products. Currently, the most popular fish used for processed foods is cod, which has to be imported from Spain or Canada since Japan fished out most of its cod a long time ago. But the price of cod went way up two years ago, so companies are definitely interested in a substitute. Shiira is also increasingly being used as the fried bit of fish in convenience store bento.

Another appealing aspect of locally caught fish to food companies is that it's cheaper to ship and store than imported fish, which has to be refrigerated for its entire journey overseas. This doesn't necessarily help fishmongers, though, who sell directly to consumers. The trend nowadays is to buy fish that is easier to prepare — in other words, no de-boning and cleaning — and which doesn't smell so much when you cook it. That's why salmon is so popular and horse mackerel and squid are not. Another problem is that more and more people shop at supermarkets, which deal in volume and so prefer buying only popular fish. So far, supermarkets have shown no interest in trying to get customers interested in zako. The whole distribution structure discourages the marketing of new fish.