The Ainu were basically a hunting-gathering population but fish from the sea, rivers, and lakes was an important source of food for most Ainu. Ainu men fished and hunted sea and land mammals, while women were responsible for gathering plants and storing food for the cold season. Large animals such as bear, deer (in Hokkaidō), musk deer, and reindeer (in Sakhalin) were usually caught using individual techniques of hunting, although cooperation among individuals sometimes took place, especially among the Hokkaidō Ainu. They used the bow and arrow, the set-trap bow, the spear, and various kinds of traps for hunting land mammals, often combining different methods. The hunting techniques of the Hokkaidō Ainu were on the whole technologically more developed than those of other Ainu. They used trained dogs for hunting, and, in some areas, even for fishing. In addition, they used aconite and stingray poison for hunting, which ensured that wounded animals would fall to the ground within a short distance. Large fish such as trout and salmon were important foods, obtained by means of detachable spearheads. The Ainu also used nets, various traps, weirs, and the line and fishhook.
Animal domestication was most highly developed among the Sakhalin Ainu, who engaged in selective breeding to create strong and intelligent male sled dogs and in castration of the dogs to preserve their strength for pulling the sleds, which were an important means of transportation during the harsh winters. The Hokkaido Ainu alone engaged in small-scale plant domestication prior to the introduction of agriculture by the Japanese government.