LONG HOT SUMMERS; WARM, WINDY, WET WINTERS - its global warming, cry the environmentalists! This may well be true, but despite the predictions of the doom merchants, some of us might consider the spin-off of warmer coastal waters in the UK a benefit. Higher temperatures attract the occasional tropical visitor, ranging from sunfish to leatherback turtles and, according to some claims, even great white sharks.
One species which has been seen in increasing numbers in recent years is the Atlantic or grey triggerfish (Balistes carolinensis) ,which begins to appear along the south and west coasts of the UK in late summer.
If your most memorable encounters with tropical triggerfish involve some nifty defensive swimming and repeated chewing of your fins by angry titans, you might not be thrilled about meeting a related species in our home waters. But grey triggerfish are different.
Until recently I had enjoyed only a fleeting glimpse of one, close to Lands End, and I was delighted to hear from instructors at my local dive shop that several had taken up residence among some wreckage just off Pendennis Point, which is just a few minutes from my home in Falmouth.
Pendennis is a popular sheltered dive site with easy beach access and is very popular with local dive centres, which bring dozens of trainees here every year. The triggers had been seen regularly close to the remains of an old boiler which is used as a target during compass training.
Armed with a bearing and distance, I then had to unearth my compass from ancient diving debris in the garage and try to remember how to use it - we photographers normally follow our cameras! After a few abortive transects I found the boiler, which lay half-submerged in the heavy sand seabed just off the main shore fringing reef.
There was disappointment to begin with - no sign of any triggerfish, but plenty of activity, with a number of large ballan wrasse cruising around the boiler and resting patiently on the seabed.
A few minutes of watching revealed that the wrasse were waiting for the ministrations of a group of rock-cook wrasse - the boiler is the temperate equivalent of a cleaning station, more common in tropical locations, and more than likely the attraction for the triggerfish. So in theory I had only to exercise some patience and my quarry would eventually arrive.
After some 20 minutes, two triggerfish did indeed turn up, and circled warily between the boiler and the reef. It soon became obvious that they were waiting their turn for a manicure.
Eventually, one at a time, they approached the boiler and hung motionless while the rock-cook went to work. They appeared to prefer one side of the boiler where the condenser tubes were exposed. It would provide an escape route if they felt threatened.
This was my cue to begin a slow approach with the camera, all the time being eyed warily by the triggerfish.
I managed to take several shots before they moved off and began to circle the boiler once again on the edge of visibility, so I settled in for another wait.
I felt pretty sure that the fish would return, as one of them had an obvious wound on its dorsal fin to which the rock cook had paid significant attention - too much every now and then, something which caused momentary squabbles between client and beautician.
Patience paid off, and both triggerfish did return. I managed a few more shots as they approached. This pattern was repeated three or four times, and bit by bit they became relaxed in my presence.
These Atlantic triggerfish had been considered a rarity in our waters until only a few years ago, although reports of them along the south coast of England and Wales, and as far north as Nova Scotia on the other side of the pond, date back to the late 1890s.
Over the past 10 years sightings and catches by both amateur and commercial fishermen have increased, and it seems that our warmer summer waters now encourage a regular migration from semi-tropical waters.
They have normally been seen in small groups in shallow water around wreckage or piers and jetties, though there are several reports of schools of several hundred gathering off the south-west coast of Wales in late autumn. These concentrations appear to be in preparation for a migration back to warmer southern waters as our own begin to cool off.
When the autumn gales begin later in the year, it is common to find on beaches, particularly on north-facing coasts, dead fish which have left it too late.
These triggerfish are mostly shellfish diners and there is no shortage of variety in our waters. They will be often be observed eating mussels from both reef and wreckage and also seem to favour winkles, which they pick delicately from kelp fronds before spitting out the remains of the shell.
Juveniles have not been reported so far and it seems unlikely that they spawn in our waters, as this apparently commonly occurs in temperatures of 21C or more.
However, the temperatures off the Cornish coast rose to 19-21C for two or three months this summer, so it may be only a matter of time.
I made several dives to photograph the triggerfish, and usually began the dive with some patient waiting at the boiler for them to make one of their regular visits. The wrasse soon learnt to ignore me, probably assuming that I was waiting for a wash-and-brush-up with them too.
During my idle minutes, I was able to observe the other inhabitants of this isolated community, which had also learnt to regard me with disdain. A large lobster would emerge from the end of the boiler to inspect me at regular intervals, as would scorpionfish, pipefish, tompot blennies and shannies, while numerous inquisitive sand gobies, dragonets and even a plaice would gradually encircle me, obviously expecting something exciting to happen.
A lone, nosy john dory also made several passes through the kelp on top of the boiler in an effort to see what I was up to. They all appeared to be disgruntled that I was not trying to capture their image, though if I had they would, of course, have resumed their usual evasive behaviour!
At least two triggerfish would normally appear, although on one occasion I saw a total of four at a distance, and they would spend up to 20 minutes around the boiler in the cleaning queue. I would then follow them cautiously back onto the reef to watch them feed off the kelp or search among the nooks and crannies in the reef for small crustaceans.
They were unperturbed by my attentions and would repeatedly pause to make inquisitive passes in front of the camera. This gave the best opportunities to shoot them with some natural light at the top of the kelp canopy.
These triggerfish are obviously very happy with their temporary environment, although I have wondered on occasion if they may be suffering from a bit of an identity crisis. On more than one occasion I have seen two of them swimming among a school of grey mullet and keeping up well, despite a very different swimming style.
Whether this behaviour is for protection or amusement is hard to tell, but other than anglers I cant imagine what would predate on the triggerfish.
All this happened last summer, but as autumn gales began to arrive this shallow site would have been repeatedly punished by swell and wave action. I hope these fish moved south again before conditions became too hazardous for them. No doubt others will return this summer as the waters warm again.

Entry to the dive site at Castle Drive is simple, with steps leading from the car park to the waters edge
Two rock-cook wrasse clean the tail of a wounded triggerfish
Inquisitive John Dorys would appear regularly to distract the photographer waiting for the triggerfish


GETTING THERE: Take the A39 to Falmouth, then follow signs for the docks. At a mini-roundabout at the bottom of Melville Road turn right following signs to Pendennis Point. Enter the water via the steps next to the small lay-by car park below the castle on Castle Drive. Following the reef edge to the north-east will bring you to a variety of wreckage, mostly broken up here after World War One.
AIR & NITROX: Cornish Diving 01326 311265; Dive Action 01326 280719; Haven Underwater Centre 01326 250852; Porthkerris Diving Centre 01326 280620; Seaways 01326 375544.
LAUNCHING : Falmouth Bay - Falmouth Watersports Centre (slipway); Maenporth (beach launch).
DAYBOATS: Cornish Diving; Dive Action; Gangy Lady 01326 375458, Patrice 01326 313265; Porthkerris Diving Centre.
FURTHER INFORMATION: Falmouth Harbour Commissioners 01326 312285/314379; Falmouth Coastguard 01326 317575; Falmouth Tourist Board 01326 312300.