Franco Banfi / Short-finned pilot whale (Globicephala macrorhynchus) dorsal fin surfacing. South Tenerife, Canary Islands, Atlantic Ocean

David Fleetham / Great white shark (Carcharodon carcharias) dorsal fin visible on surface. Guadalupe Island, Mexico.

Tony Wu / Indo-Pacific sailfish (Istiophorus platypterus) in feeding frenzy, with the remains of a previously large school of sardines (Sardina sp) in background. Isla Mujeres, Cancun, Mexico.

Espen Bergersen / Killer whale / Orca (Orcinus orca) male surfacing at sunset, Kvaloya, Troms, Norway October

Tony Wu / Humpback whale (Megaptera novaeangliae) female with calf, pursued by males during heat run. Vava'u, Kingdom of Tonga. Pacific Ocean.

Jordi Chias / Split level view of Blue shark (Prionace glauca) at surface at sunset, Azores Islands, Portugal, Atlantic Ocean

Wild Wonders of Europe / Widstrand / Dorsal fin of Orca / Killer whale (Orcinus orca) surfacing, Senja, Troms County, Norway, Scandinavia, January. Cetaceans are attracted to this area to feed on the large numbers of spawning Herring fis...

Brent Stephenson / Type B Killer whale (Orca orcinus) surfacing, close-up, Antarctic Sound, Antarctic Peninsula, Antarctic, January.

Ben Hall / Orcas (Orcinus orca) pair in sea surrounded by mountains, Iceland, January.

Richard Robinson / Hector's dolphin (Cephalorhynchus hectori) Akaroa Harbour, South Island, New Zealand, November. Editorial use only.

Gabriel Rojo / Orca (Orcinus orca) baby age 10 days, swimming with his mother. Punta Norte Natural Reserve, Peninsula Valdes, Chubut Province, Patagonia Argentina

Chris & Monique Fallows / Indo Pacific Sailfish (Istiophorus platypterus) feeding on sardines, Isla Mujeres, Mexico.

Chris & Monique Fallows / Split level shot of Great white shark (Carcharodon carcharias) fin above the water and leisure boat in the background, with Seal Island, False Bay, South Africa.

Alex Mustard,Alex Mustard / A signal blenny (Emblemaria hypacanthus) displays its showy dorsal fin as it extends out of its tube home. La Paz, Mexico. Sea Of Cortez, East Pacific Ocean.

Steven Kazlowski / Killer whale (Orcinus orca) large pod with one male approaching, in Kenai Fjords National Park, Chiswell Islands National Marine Sanctuary, South Central Alaska, USA

Alex Mustard / Basking shark (Cetorhinus maximus) rear view of shark feeding at the surface on plankton, Cairns Of Coll, Isle of Coll, Inner Hebrides, Scotland, UK, North East Atlantic Ocean, June

Alex Mustard / 2020VISION / Dorsal fin of a Basking shark (Cetorhinus maximus) at the surface, Cairns of Coll, Inner Hebrides, Scotland. UK, June.

Cheryl-Samantha Owen / Blacktip reefs sharks (Carcharhinus melanopterus) dorsal fins visible at sea surface at dusk, Aldabra Atoll, Seychelles, Indian Ocean

Kathryn Jeffs / Southern Type B Killer whale (Orcinus orca) hunting Weddell seal (Leptonychotes weddelli), Antarctica. Taken on location for BBC Frozen Planet series, January

Martin Camm / Carwardine / Illustration of Striped dolphin (Stenella coeruleoalba), Delphinidae (Wildlife Art Company).

Sergey Gorshkov / Salmon (Salmonidae) migrating to spawn in Lake Kuril, Kamchatka, Far East Russia, August

Juan Carlos Munoz / Great white shark (Carcharodon carcharias) with dorsal fin showing above water. False Bay, South Africa, July 2010

Jeff Rotman / Great White shark (Carcharodon carcharias) surfacing with head and dorsal fin visible, Dyer Island, South Africa, Atlantic Ocean.

Mark Carwardine / Pacific white-sided dolphin / Lag (Lagenorhynchus obliquidens) swimming fast, showing dorsal fin, Johnstone Strait, Vancouver Island, British Columbia, western Canada

Doug Perrine / Dorsal fin of Great white shark at surface {Carcharodon carcharias} Gansbaai, South Africa

TOM WALMSLEY / Killer whale (Orcas) two adult males at surface {Orcinus orca} Tysfjord, Norway. winter

TOM WALMSLEY / Killer whale (Orca) surfacing showing dorsal fin, eyepatch and blowhole {Orcinus orca} Iceland

Jeff Rotman / Fisherman holding dorsal fin cut from Scalloped Hammerhead shark {Sphyrna lewini} caught on longline, Cocos Island, Costa Rica, Pacific Ocean

Brandon Cole / Killer whales {Orcinus orca} at surface, San Juan Islands, Washington, North America. NOT FOR SALE IN USA

Brandon Cole / Killer whales {Orcinus orca} surfacing at dusk San Juan Islands, Washington, USA. NOT FOR SALE IN USA

Brandon Cole / Killer whales near oil tanker {Orcinus orca} San Juan Islands, Washington, USA, NOT FOR SALE IN USA

Brandon Cole / Killer whales surfacing {Orcinus orca} San Juan Islands Washington. NOT FOR SALE IN USA

Brandon Cole / Male Killer whale blowing at surface {Orcinus orca} Vancouver Island, British Columbia, Canada. NOT FOR SALE IN THE USA

Brandon Cole / Male Killer whale surfacing {Orcinus orca} Frederick Sound, Southeast Alaska NOT FOR SALE IN THE USA.

Flip Nicklin / Orca (Orcinus orca) adult and breaching calf, southeast Alaska

Hiroya Minakuchi / Orca (Orcinus orca) pod surfacing, Prince William Sound, Alaska

Hiroya Minakuchi / Orca (Orcinus orca) pod surfacing, Hokkaido, Japan

Pete Oxford / Whale Shark (Rhincodon typus) swimming with other tropical fish, note satellite tag to right of dorsal fin, Wolf Island, Galapagos Islands, Ecuador

Konrad Wothe / Orca (Orcinus orca) female surfacing and spouting beside conifer-covered coastline, Inside Passage, Alaska

Flip Nicklin / Sperm Whale (Physeter macrocephalus) surfacing, New Zealand

Flip Nicklin / Orca (Orcinus orca) resident pod A-5 at rest, Johnstone Strait, British Columbia, Canada

SCOTLAND: The Big Picture / Dorsal fins of two Bottlenose dolphins (Tursiops truncatus) with oil rig in background, Chanonry Point, Moray Firth, Scotland, UK. June.

SCOTLAND: The Big Picture / Two Bottlenose dolphins (Tursiops truncatus) passing a kayaker near Chanonry Point, Moray Firth, Scotland, UK. July.

SCOTLAND: The Big Picture / Minke whale (Balaenoptera acutorostrata) at the surface with large commercial ship in background, Near Cromarty, Moray Firth, Scotland, UK. August.

David Fleetham / Pyramid butterflyfish (Hemitaurichthys polylepis), with dorsal fins flared, line up for the attention of an endemic Hawaiian cleaner wrasse (Labroides phthirophagus), Hawaii, Pacific Ocean.

Gabriel Rojo / Killer whale / Orca (Orcinus orca) hunting Sea lions (Otaria flavescens) close to the shore, Punta Norte Nature Reserve, Peninsula Valdes, Patagonia, Argentina, Atlantic Ocean.

Gabriel Rojo / Two Killer whales / Orca (Orcinus orca) hunting Sea lions (Otaria flavescens) close to the shore, Punta Norte Nature Reserve, Peninsula Valdes, Patagonia, Argentina, Atlantic Ocean.