A new love song CD with a difference could make a splash by featuring sea creatures including an amorous haddock.
The British Library collection includes marine mating calls.
Whale and dolphin sounds may be familiar but deeper in the North Sea the recorded sounds include a male haddock searching for a mate.
The haddock courting noises start as slow knocks and turn into a quicker hum that sounds similar to a small motorcycle revving its engine.
The CD contains the noises of North Sea haddock recorded in laboratory conditions in Aberdeen. The experts believe that replicates the "at sea" sound.
Sounds of the Deep also features a walrus diving for food and the clicks, whistles and buzzes of the Atlantic Spotted Dolphin.
The British Library sound archive's wildlife curator, Cheryl Tipp, said of the haddock: "It really is quite a novel sound, it's fascinating.
"The knocks turn into a hum. "We are thrilled to present these captivating new collections of marine life and coastal wildlife sounds and hope that wildlife enthusiasts will find them fascinating."