Fishing Lines: Bitter Pill for fish to swallow

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THE NEWS that Britain's male fish are changing sex should solve, at a stroke, the problem of our declining birth-rate.

In scientific circles, the disclosure this week that male carp and trout are developing female characteristics because they have been drinking Pill-polluted water is nothing new. A decade ago, hermaphrodite roach were found next to a large sewage outfall. And back in the early 1970s, there were rumours that Norfolk eels were exhibiting strange sexual reactions. (Eels love sewage outlets, which is where the highest concentrations of water with added oestrogen will be found.)

The Department of the Environment instigated secret research into this aberrant behaviour. It stayed under wraps because the water authorities, eager for privatisation, felt that revelations about the transsexual quality of their product might not exactly encourage investors.

Rumours about those earlier findings have just been confirmed by the Directorate of Fisheries Research and a team from Brunel University. They found that the quantities needed to induce such deviant reactions are minute. Although we're talking about concentrations of under one part in 1,000 billion, levels at which even the most advanced analysis techniques cannot detect the hormones, fish are affected for several miles below sewage outfalls.

One of the biggest surprises to scientists has been that fish are affected at all. Chalk another one up for Darwin: we share enough genetic elements with perch, chub and gudgeon for our hormonal chemicals to affect their life. But invertebrates such as dragonfly larvae and water-fleas are too far removed to be similarly affected.

But drinking tap-water and eating trout is not going to turn us all into a nation of Julian Clarys. Although the hormones will filter into tap-water, the quantities are so minuscule that they will have no effect.

Several species of marine fish, particularly wrasse, have the ability to change sex when there is a shortage of females. This ingenious survival mechanism is a way of ensuring that there are always enough females to perpetuate the species. However, this is believed to be the first instance of freshwater fish exhibiting such behaviour.

The immediate assumption is that turning fish into hermaphrodites could have a severe impact on reproduction. But the whole thing may actually result in better fishing.

Female fish, you see, are always the larger of a species. Male pike, for example, rarely exceed 10lb while females can weigh more than 40lb. The same weight imbalance is true in all species.

Now imagine a water where most fish are female. It follows that they will grow larger and therefore be more attractive to catch. Already fishermen are mixing amino acids, essential oils and high-protein additives into a doughy food mix that has resulted in huge growth spurts. One particular carp at Wraysbury, Middlesex, was caught last July weighing 47lb. The fish, nicknamed Mary, was 49lb 4oz in October and more than 50lb when taken again in December.

A far easier solution will be for anglers to snaffle those contraceptive Pills, break them up and add them to the groundbait mix.

With more than four million anglers, mostly male, the implications are enormous. Sexual risks are certain to be taken as all those Pills disappear from circulation to catch and create bigger fish. If only 1 per cent of this unsafe sex results in unexpected pregnancies, that represents 40,000 more babies.

Neat, eh? You have to admire the Government's cleverness in providing better fishing and addressing the slumping birth-rate in one subtle manoeuvre. And to think I worried about catching male eels wearing make-up.