Fishery and hunting have relatively small volume and are mostly concentrated in the river deltas. Data are available for the Khatanga Bay and deltas of the Lena and Yana rivers from 1981 to 1991 which translate into about 3,000 tonnes of fish annually. Extrapolated, they give the following annual estimates (in thousand tonnes) by species: sardine (1.2), Arctic cisco (2.0), Bering cisco (2.7), broad whitefish (2.6), Muksun (2.4) and others (3.6). Hunting sea mammals is only practiced by native people. In particular, walrus hunting is only allowed by scientific expeditions and local tribes for subsistence.