Tackle and Tactics
Not as foul as they seem.
In April 1986 I wrote a short story headlined ‘Anti-fouling paints could put fish at risk!’ warning of the threat, posed by (then) modern protective coatings, to marine life. That my fears had been firmly grounded was proved by the subsequent government ban on paints containing Tributyl Tin (TBT). Of course I felt pleased about the reduction in the level of pollution in our seas, estuaries and rivers but there was no reason for complacency.
Already, I thought, the paint-company boffins would be working overtime to produce the next generation of poisonous pigments which could harm marine plants and animals in their youngest and most vulnerable stages.
Since every angler is, quite rightly, concerned about his or her future sport I thought that it might be appropriate to remind us of the details of anti-fouling paints in general and to point out why we should continue to be vigilant.
Just think back for a moment to the last occasion when you were collecting soft or peeler-crabs for cod, flounder or bass baits. When you turned over that big rock and all those prime crustaceans scuttled for the nearest cover, there must have been one or two vulnerable specimens with broken claws and battle-scars among them. For sure the old shell-backs would sport a rich encrustation of off-white barnacles and little whirly Spirorbis worm tubes. How did all their pals avoid being decorated in the same way?
Of course, the answer is that they shed their skins. The younger the crab the more quickly it will grow and the more often it will need to shed its shell and with it the build up of encrusting rubbish. Each year the seaweeds, mussels, barnacles, tube worms, sponges, sea squirts and hydroids, which clothe every suitable rock surface, release countless billions of larvae. All of these specks of drifting life are bent on finding a place to settle and to live out their lives.
For secure attachment these creatures have developed some of the most efficient glues and cements known to man. Variations of barnacle cement are probably holding the fillings in your teeth at this moment. Once any sort of fouling plant or animal has taken a grip it takes some shifting.
A settling larva is not fussy whether it lands on a rock, a crab, a sea urchin, a limpet, a winkle, a fish or even a whale. I have already mentioned how crabs and other crustacea, avoid being fouled by regularly shedding their shells, but why aren’t all the other creatures plastered in ‘barnacles’? No doubt animals like crabs, prawns, squat-lobsters and lobsters spend a good deal of time scraping and preening themselves but most of the others do not have claws and pincers to groom their exteriors with.
Soft-bodied creatures, including many fish, produce copious amounts of slime so that anything which settles on their skin will slide or slough off. In addition some of them have other defences. Anemones have lethal stinging cells with little poisonous darts or grasping, twisting coils. The slime of some sea slugs, such as the aptly-named sea lemon, contains strong sulphuric acid, a real deterrent to lodgers. Hard-cased animals have more of a problem. Starfish for example, have tough skins armed with little snapping jaws like miniature pairs of scissors or a parrot’s beak. These tiny defences are constantly in action. Sea urchins have a great variety of similar but more elaborate jaws, some on stalks and all ceaselessly snapping. Snails and limpets may often live on exposed rocks where even the toughest foulers are unable to survive.
Despite all these precautions many sea creatures acquire miniature jungles during their lives. The effort of carrying a load of unwanted guests must be considerable and, no doubt, many die as a result of the wasted energy. Even huge whales have to put up with the drag caused by giant barnacles specially designed to cling to their leathery hides.
Little wonder, in the light of what I have said, that the multi-million pound industries of merchant shipping, fish farming, yacht racing and boating not to mention the world’s navies, have a lot to lose when there super smooth hulls and pipes are covered in crud. It may matter little to you whether you need an extra pull on the oars to reach your fishing mark, but to the country which has invested billions to win the America’s cup, half a dozen goose barnacles can make all the difference between a financial bonanza and bankruptcy.
When ocean-going ships were made of wood they were armoured with copper sheets to keep out shipworms, gribbles and the like. In years gone by copper-based paints were the only recourse for anyone wanting to reduce the amount of growth on the hull of their boat. Now copper is pretty poisonous metal and there can be little doubt that it kills and maims much marine life but, compared to the innovative TBT paints, it was positively harmless.
Tiny concentrations of Tributyl Tin, only 0.000000001 grams per litre of sea water “next to bugger all” as one of my pals expressed it --- cause terrible deformities in shellfish. Yet as recently as 1975 the government believed that it was safe to permit 20 times as much as the above amount to be present in solution in our coastal waters! In the early months of 1986 regulations were introduced to prevent the sale of the most vicious forms of TBT paints. Shortly afterwards the Royal Yachting Association produced a leaflet telling its members how to use anti-fouling paints safely.
As it became clear that TBT was much more dangerous to fish and shellfish than at first thought, the sale of such paints was banned altogether and its use became illegal. It took a year or two before the hulls of boats ceased to leach out their poisons - in the meantime government scientists have kept a wary eye on any new products being formulated.
It would be reassuring to know that the carnage caused by TBT will never be repeated, and that the paint people might come up with a more acceptable solution, like a boat that “sheds it skin” or is too slippery to foul? It seems likely that the damage done to fresh and salt water by TBT will by now have been made good. We may have lost a few year-classes of oysters, dog whelks and even some fish but time is a great healer.
Although it's now twenty years since I wrote about the need for new antifouling strategies the internet is still full of bright but almost untried ideas. Barnacles are the main problem and probably account for half of the reported fouling organisms. Their fouling causes huge increases in roughness and raises fuel costs of shipping by as much 40%. Once attached, dislodging these little crustaceans is almost impossible because, as I've already said, they secrete one of the strongest adhesives known to man.
Huge amounts are spent annually on attempts to deter barnacle larvae from settling. Naturally occurring chemicals with antifouling properties are being tested for this purpose. Limpets graze barnacle larvae and algae off intertidal rocks but do not inhabit ship-fouling communities. Mediterranean limpets have been transplanted onto metal plates in an attempt to reduce settlement. Some silicone paints (presumably a bit like the surface of Teflon pans) are known to deter attachment but they aren't very efficient. By incorporating tiny cylinders of carbon, each a thousand times thinner than a human hair, into paints, scientists have created a material that they hope will stop organisms sticking to hulls. It is said that such 'Nanotubes, "disrupt the paint surface at the molecular level so the glue molecules cannot operate effectively". In theory When the ship moves the organisms will be swept away. I won't be holding my breath!
If you have any comments or questions about fish, methods, tactics or 'what have you.'get in touch with me by sending an E-MAIL to - firstname.lastname@example.org