A questionnaire survey was conducted on inhabitants of Kochi and its suburbs to clarify which types and how fish and shellfish are cooked. There was wide variation in the kinds of fish and shellfish that are cooked. Both bonito and dolphin, the species of fish with the largest catch in Kochi, are not most frequently cooked elsewhere. Cooks over 30 years of age in Kochi, however, tend to cook both bonito and dolphin more frequently than in other age areas, although the general method and spices used tended not to vary with age. Bonito is generally served uncooked with soy sauce. while dolphin is sprinkled with salt and then fried.
The difference in species most commonly eaten and the cooking methods used are sufficiently unusual to warrant an investigation into the relationship with the standard mortality rate in Kochi.