Cetacean bycatch (or cetacean by-catch) is the accidental capture of non-target cetaceans such as dolphins, porpoises, and whales by commercial fisheries.[1] Bycatch can be caused by entanglement in fishing nets and lines, or direct capture by hooks or in trawl nets.
Cetacean bycatch is increasing in intensity and frequency.[2] This trend is likely to continue due to the pressures of human population growth on the environment, the growing popularity of seafood, and the commercialization of deep-sea fishing as operations expand into waters which were previously protected. These commercial fishing vessels come into both direct and indirect contact with cetaceans. An example of direct contact is the physical contact of cetaceans with fishing nets. Indirect contact occurs through marine food chains, which are destabilized by the commercial fishermen severely reducing local fish populations that cetaceans rely on for food. In commercial fishing practices, cetaceans are captured as bycatch but then retained because of their value as food or bait.[3]