Nick Hawkins / Harbour porpoise, (Phocoena phocoena) Bay of Fundy, New Brunswick, Canada, September

Nick Hawkins / Harbour porpoise, (Phocoena phocoena) porpoising, Bay of Fundy, New Brunswick, Canada, August.

Roland Seitre / Finless Porpoises (Neophocaena phocaenoides) swimming in unison. Captive. Endemic to South East Asia and the Yangtse River.

Florian Graner / Harbour porpoise {Phocoena phocoena} Sognefjord, Norway. Composite

Todd Pusser / Dall's porpoise at surface {Phocoenoides dalli}, Central Bering Sea, Alaska

Florian Graner / Harbour porpoise {Phocoena phocoena} off Isle of Man, Irish Sea, UK. Digital composite

Mark Carwardine / Harbour porpoises (Phocoena phocoena) - rare picture of small group Bay of Fundy, New Brunswick, Canada

Mark Carwardine / Harbour porpoises (Phocoena phocoena) trapped inside herring weir off the coast of Nancy's Head, Campobello Island, Bay of Fundy, New Brunswick, Canada. September 2018

SCOTLAND: The Big Picture / Harbour porpoise (Phocoena phocoena), wild group. Shetland, Scotland, UK, October.

Nick Hawkins / Harbour porpoise, (Phocoena phocoena) Bay of Fundy, New Brunswick, Canada, August.

Rebecca Robinson / Illustration of Killer whale / Orca (Orcinus orca) breaching sequence in profile, showing how it catches seals and porpoises / dolphins.

Brent Stephenson / Dall's porpoise (Phocoenoides dalli) two breaking the surface with their characteristic rooster tail of spray, off Kayak Island, Alaska, United States, July.