The grey triggerfish which has long been considered a seasonal visitor to the British coast is thought to follow the gulf-stream into our waters, dying when sea temperatures fall. In the Eastern Atlantic this species is found from Angola to the Mediterranean but in the Western Atlantic from Bermuda to Nova Scotia. This has led researchers to start asking the question “is it possible triggerfish are seasonal migrants not just visitors?” There is precedent for this: Until recently it was thought that occasional leatherback turtles seen around the west coast of Britain were lost but recent research has shown they conduct visits to feast on the abundance of jellyfish around our west coast in summer.
A second question is “is it possible triggerfish have started breeding in our coastal waters?” Data from the southeast US and Gulf of Mexico place B. capriscus breeding season between April and September. However, details are sketchy; the temperature range for spawning is contentious, with one source stating spawning begins in waters as cold as 12C, another that the temperature must be above 21C. In addition grey triggerfish will aggressively defend their nests but grey triggerfish around the UK are considered docile with no reports of them attacking divers. This raises interesting questions and to answer these questions, researchers have started a volunteer triggerfish monitoring programme. Triggerfish are caught by local anglers and tagged with a T-bar tag on the main dorsal fin (not the fin with the trigger), just visible in the pictures below. If these fish are re-caught the tag number and location where they are caught can be reported by clicking on the Reporting Form link in the side bar or here
How can you help? Currently there is very little information regarding Triggerfish in British coastal waters any information about their movements is valuable so the researchers would like reports of any sightings of triggerfish to be reported via the Reporting Form here.
This project is funded by the National Aquarium Limited at Plymouth and is supported by Seasearch.