OSLO, July 21 (Reuters) - Small fish play a big role in the oceans and catches should be cut sharply to safeguard marine food chains from plankton to blue whales, an international team of experts said on Thursday.

Rising human exploitation of little fish -- including anchovy, sardine, herring, mackerel and capelin -- had had far less attention in marine research compared to big commercial species such as cod, tuna, swordfish or salmon, they said.