Wrasse (British Seas)

Whilst the British coastline has estuaries and extensive areas of sandy shore with embayments and estuaries where soft sediments accumulate, the remaining coastline is predominately rocky. Here, the firm surfaces, nutrient rich water and good illumination provide an ideal environment for a diversity of sessile organisms. They, in turn, are grazed and predated upon by fish and other animals. It is in these rich sublittoral habitats that some of the world's 600 species of wrasse (family: Labridae) are commonly found.

Along the north European coast, seven * species of wrasse are found, and of these four are common in British waters. They all have a similar silhouette. They are laterally compressed, covered in large scales and have one dorsal fin which runs almost the entire length of the elongated body. Two of them, the Goldsinny and the Corkwing. are small growing at most to 15 cm. In comparison, the Cuckoo and Ballan Wrasse may grow to 35 cm and 51 cm respectively.
 
 

The most memorable thing about wrasse is undoubtedly their brilliant coloration. They may never display the startling colours of their cousins the tropical Cleaner fish, but they are eye-catching.

Goldsinny, Centrolabrus rupestris, are brown to orange-red, with a dark spot on both the head end of the dorsal fin and in front of the upper margin of the tail fin. Corkwing, Symphodus melops (=Crenilabrus), are usually a mottled olive colour but may have blue and/or orange lines under their head and belly in addition to a large spot just before the tail fin. Ballan Wrasse, Labrus bergylta, are also predominately shades of olive green/brown and again this can be overlaid with a dappling of red and white spots.
 
 

Of the four, it is without question the Cuckoo Wrasse, Labrus bimaculatus (= L.mixtus), which is the most colourful. Both the young and the breeding females are orange to red in colour and each has three dark spots towards the end of the dorsal fin. In contrast, the male has a vivid blue head which is overlaid with a mosaic of dark purple lines. The rest of the body is bright yellow or orange and the tail is edged with a wide band of similar royal blue to that of the head.

All wrasse have thick protruding lips, and there are strong teeth, both in the jaws (for biting and rasping) and on the pharyngeal bones in the throat (for gripping and crushing). With these teeth they are able to enjoy a mixed menu of shelled animals including barnacles, other crustaceans, and molluscs.

Many species of marine fish can at times be plagued by sea lice. Farmed salmon are particularly susceptible to being parasitised by Lepeophtheirus salmonis in the crowded conditions of the cages. To kill the lice the salmon have been exposed to a chemical called 'Nuvan' which is added to the seawater in the cages. However, this chemical is unselective and can kill, or have an adverse impact on crustaceans and a number of other types of marine animals that can be found in the vicinity. Study has shown that Goldsinny are particularly fond of sea lice, and a number of salmon farms are experimenting with these wrasse to see whether this small fish can keep the lice under control. This has meant that these wrasse are caught in increasing numbers and can command a modest price, whereas previously they were thought valueless because they are inedible.

Wrasse are unusual in that they they are one of the few fish that are able to change sex during their life. In both the Ballan and the Cuckoo Wrasse, the complex behaviour starts when the fish are about six years old. In any one stretch of coastline their will be a single dominant male and if he dies the next most senior female undergoes a sex change and becomes the next 'top' male! In spring, when courtship starts, the already colourful male Cuckoo Wrasse becomes even brighter so as to attract as many females as possible.

Breeding behaviour is similar in most wrasse. An exception is the Goldsinny which spawns in moderately deep water, with pelagic larvae. These breeding habits mean that they have not, as yet, bred in captivity.

Other wrasse have a ritual courtship in which the male prepares a nest. This may be a collection of small stones, weed, or simply an area of rock. First, he cleans the stones with his teeth; then he binds them together with seaweeds and mucus. Once the nest is ready, he will entice a female to lay her eggs for him to fertilize. He will then guard and fan the eggs until they grow, hatch, and are dispersed within the upper reaches of the sea, where there is an ample supply of planktonic food.

Wrasse are slow growing and long lived (up to 20 years). Their longevity is also helped by being considered inedible by the British, although the French consider these fish to be an essential ingredient in bouillabaisse. They are caught by anglers, but are usually returned to the sea.

Indeed, as many an observant diver will testify, when left to their own devices they frequently settle down, leaning a little to one side, to sleep peacefully amongst the rocks.

* Five species have been confirmed as breeding in British seas. The other species is the Rock Cook, Centrolabrus exoletus, which is a suitable aquarium fish.

Stella Turk (Cornwall) has reported two instances of the Mediterranean Rainbow Wrasse, Coris julis, off the Cornish coast.

In the 19th century there is also one record of the northern Scale-rayed Wrasse, Acantholabrus palloni. An excellent photograph of this fish can be found on the Norwegian web site:
 

Norwegian Marine ***
These web pages are recommended.

Biomar Photographs:

Ballan Wrasse

Goldsinny

Rock Cook 

BMLSS: 

Corkwing Wrasse 

wrasse  | ras |  n. Pl. -s, same. L17. [Corn. wrah f. MCorn. gwrah = Welsh gwrach lit. 'old woman, hag'. Cf. OLD WIFE 2(a).] Any of numerous perciform marine fishes of the family Labridae, esp. the genus Labrus, which have a single long dorsal fin of which the anterior part is spiny, are frequently brightly coloured, and are common inshore fishes in all temperate and tropical seas. Usu. w. specifying wd.
Ballan wrasse, cuckoo wrasse, Maori wrasse, rainbow wrasse, red wrasse, etc

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Excerpted from The Oxford Interactive Encyclopedia
Developed by The Learning Company, Inc. Copyright (c) 1997 TLC Properties Inc. 

Jim Anderson's Scottish nudibranch pages

Wrasse notes