Although the cuckoo wrasse is widely distributed and fairly common, it is little known to anglers when compared with the more abundant ballan and corkwing wrasse. One reason for this is its solitary life-style – it doesn’t form schools but keeps to its own territory.
The cuckoo, at 35cm (14in), is one of the larger species of wrasse in British waters — only the ballan (40cm/16in) is bigger – and is easily identified by its body shape and colouring. The head and jaws are elongated and its large, thick-lipped mouth is packed with teeth. The dorsal fin is long with a spiny part of 16-18 spines and a soft rear section with 11-14 branched rays. However, there’s no need to count the rays when the fish’s colour is so striking.
Female cuckoo wrasse, and the young of both sexes, are pink/orange on the back with a paler underside. They also have three large black blotches on the back – the first and second on either side of the back half of the dorsal fin and the third on the tail. Mature males have a brilliant blue head, the blue continuing on to the body and back. The remainder of the male’s body and fins is yellow or orange.
Cuckoo wrasse migrate locally, coming into rocky inshore waters in the summer where they can be caught in as little as 10m (30ft) of water. In winter they move offshore to escape the colder shallow water. They are sensitive to cold temperatures and a severe winter can cause fatalities.
The geographical distribution of the species confirms this: the fish ranges throughout the Mediterranean and along the North African coast, but extends no farther north than the Shetland Isles.
Like all wrasse, the cuckoo has a formidable set of conical teeth used for prising molluscs off rocks. It sucks in prey through its fleshy lips and then crushes it with powerful pharyngeal teeth at the back of the throat. In addition to molluscs, it eats crustaceans, including squat lobsters and swimming crabs.
The cuckoo wrasse is active during the day but seeks refuge in rock crevices and dense weed at night.
Spawning takes place in early summer. The male attracts the female with an elaborate ‘dancing’ display, during which its whole head may blanch to a pure white then back to blue every few seconds. Having been won over, the female builds a nest by jamming pieces of seaweed and debris into a rock crevice. Males are highly territorial and fiercely drive away rivals that come too close while the female is laying her eggs.
Strangely, all cuckoo wrasse are female for the first few years of life – the reasons for this are not really known. They are slow-growing and take about six years to become sexually mature. Some remain female for the rest of their life but about half change sex at 7-10 years old.