Mr. Heithaus, Predator-prey and competitive interactions between sharks (order Selachii)and dolphins (suborder Odontoceti): a review, J ZOOL, 253, 2001, pp. 53-68
The importance of interactions between sharks and cetaceans has been a subj
ect of much conjecture, but few studies have addressed these interactions.
Sharks (order Selachii) have been hypothesized to be important predators on
dolphins and porpoises (suborder Odontoceti). Unfortunately, there are oft
en few data to back up claims that certain shark species are major threats
to cetaceans. To help identify potential shark predators in specific locati
ons, available data on interactions with odontocetes for all shark species
that may include cetaceans in their diet are reviewed. Shark species are ca
tegorized into groups based on predatory interactions with dolphins and por
poises (regular predators, occasional predators, potential predators, ectop
arasites and insufficient data). Several shark species that have been overl
ooked in the cetacean literature are identified as potentially important pr
edators while others that have been suspected to be important predators are
probably at most occasional predators. How shark predation can influence d
olphin populations, habitat use, group size and behaviour is discussed. How
risk of shark predation can vary with habitat attributes in both nearshore
and pelagic waters is also discussed. Predator-prey interactions have been
the focus of most studies of shark-dolphin interaction, but competitive in
teractions may also occur. The first analysis of shark-dolphin dietary over
lap is presented, which shows it to be significant between common dolphins
and several species of sharks, including species that prey upon these dolph
ins.