The term, 'fishery' is not meant to refer to fishes
exclusively. It comprtses forms such as the
enormous whales which are really mammals, on the one
hand, to fishes proper and to such forms as prawns, .
crabs, lobsters, shrimps, turtles, oysters, clams, and so
on. Species which swim about freely and migrate from
place to place, such as the tunas, sardines, mackerels,
etc. constitute pelagic fisheries; those which are confin
ed t,o the sea bottom mostly, flat fishes, perches, rays,
prawns, lobsters, etc. constitute tbe, demersal fisheries
