Triggerfish

 

When I first started compiling the list of the rarer fish from off Sussex in 1959, the Trigger Fish was rare in the eastern English Channel. The first one was taken in 1967 from a lobster pot off Worthing. Since then, a large number have been taken each year. In 1995, one trawler had 9 in one haul. They were all returned to the sea alive. This fish is easy to keep in large Public Aquaria and one was usually on show at the old Brighton Aquarium, now the Brighton Sea Life Centre

A large school of these fish have been resident under the Mumbles Pier, near Swansea,  for many years now as can be attested by the local anglers who catch them every summer, with weights of 1 kg to 2 kg being the norm. I have never seen a young or baby Triggerfish nor heard of one being seen or caught so we have to assume that they are summer visitors.  

The species found in British seas during the summer months and autumn is Balistes capriscus (=B. carolinensis). This is a new specific name for this fish. Graham Pickett (MAFF) reports the incidental capture of a specimen in Southampton water in a routine beam trawl in late September 1992. It was about 40 cm long. A further two were captured in the trawl in the east Solent, south of Hayling Island. The latter are authenticated reports east of the Isle of Wight. In 1992, fishermen reported catches of this fish off Sussex in large numbers, instead of the odd one, for the first time.

Chris Clark has caught Triggerfish on many occasions on rod and line. All captured specimens are returned which is certainly becoming the practice amongst sport anglers. Chris reports that the fish fight hard and are very hardy and returns are likely to have a 90% survival rate.

There are several mysteries surrounding the behaviour and occurrence of this fish in British seas. Chris, who as an angling writer, has many contacts around these islands and lives in Hampshire, assures me that Triggerfish congregate before returning west to warmer waters in late September.

The second puzzle is their path of arrival. Peter Glanvill, in the article in the Winter 1995 issue of Glaucus, thought that the fish followed the northern English Channel coast eastwards and settled around wrecks and rocky outcrops. Records from Cornwall are always earlier in the year. There are very few records from the Brittany coast but there are not many areas where the fish can be caught by anglers from the shore in France.

As this spring has been cold it will interesting to hear of the first reports of Triggerfish caught this year.

Biology

The Trigger Fish, Balistes carolinensis, is the only member of the family Balistidae that has been recorded in British seas. The fish breeds in much warmer waters where it is a common fish. Only during the summer months do adult fishes venture into the English Channel and up the west coast of Britain. Off the Cornish coast they are now found nearly every year, but in the seas off Sussex they are recorded about once a decade.

There are no records of breeding in British seas, or larvae found in the plankton. It is reckoned that the fish drift in with the ocean currents. The young fish live amongst Sargassum weed in the Atlantic Ocean.

Dorsal Fin

All trigger fishes are characterised by an unusual dorsal fin arrangement. The first dorsal spine is very strong and is so arranged that it is connected in function with the second spine. The fish wedges itself into a crevice for safety and secures itself there by erecting the strong first spine and locking it into position with the second. When the second spine is depressed it acts as a trigger to unlock the first spine.

Teeth and Feeding

The jaw of the Trigger Fish contains eight strong incisor teeth which it uses to chisel holes in mussels and other hard shelled molluscs to get at the soft flesh inside (see 06.01.13). It can also attack and eat crabs.

The Triggerfish can attain a length of 40 cm. The reason for the hard bony plates on the side of the fish behind the gill cover is not known to the writer of this summary.

This fish is common in the Mediterranean Sea, Atlantic Ocean and the Caribbean Sea.

The fish fares well in Public Aquaria, where it can be seen in most British establishments.

 

Triggerfish Balistes carolinensis

Balistes carolinensis
The triggerfish Balistes carolinensis. Image width ca 33 cm.
Image: Paul Parsons / www.aquapix.com

Balistes carolinensis
Balistes carolinensis recorded and expected distribution in Britain and Ireland

Grey to greenish brown, commonly called the grey triggerfish.
Diamond shaped body flattened sideways.
Small mouth and fleshy lips.
Up to 41cm, usually 25cm.
Poor swimmers.

Eastern Atlantic from North Sea to Angola.
Shallow rocky areas or wrecks.
Found in waters of temperature greater than 12°C.

Trigger fish can lock their dorsal fin, it can only be unlocked by depressing the second spine, the 'trigger'.
Spawn in the Mediterranean in water warmer than 21°C.
Poor swimmers so may arrive via the Gulf Stream.
May increase in numbers because of warmer seas due to global warming.
Records needed.

 

 

Family:  

Balistidae (Triggerfishes)

 

Order:  

Tetraodontiformes  (puffers and filefishes)

Class:  

Actinopterygii (ray-finned fishes)

FishBase

Grey triggerfish

Max. size:  

60.0 cm TL : max. published weight: 6,150 g

Environment:  

reef-associated; marine ; depth range 0 - 100 m

Climate:

subtropical; 58°N - 37°S, 98°W - 36°E

Importance:  

fisheries: commercial; gamefish: yes; aquarium: public aquariums

Resilience:  

High, minimum population doubling time less than 15 months

Distribution:  
Gazetteer

Eastern Atlantic: Mediterranean to Moçamedes, Angola. Western Atlantic: Nova Scotia (Canada), Bermuda, and northern Gulf of Mexico to Argentina (Ref. 7251).

Morphology:  

Dorsal spines (total): 3; Dorsal soft rays (total): 26-29; Anal spines: 0; Anal soft rays: 23-26. Tall, with a small mouth and plate like scales (Ref. 35388). Three faint irregular broad dark bars on body; a narrow pale transverse band on chin; small light blue spots on upper half of body and median fins, and irregular short lines ventrally (Ref. 13442).

Biology:  

Inhabits bays, harbors, lagoons, and seaward reefs (Ref. 9710). May drift with young at surface among Sargassum (Ref. 9710). Usually solitary or in small groups (Ref. 9710). Feeds on benthic invertebrates like mollusks and crustaceans (Ref. 4727). Consumed mostly fresh, smoked, and dried salted. The flesh is of excellent quality. Because it is resistant to capture, it proliferates and competes for food with other species (Ref. 5377).

 

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