Due to contraceptive pills being flushed down toilets and drains, a dramatic effect is taking place in British rivers, wherein male fish are mutating to females due to waste chemicals found in the waters.
A leading ecotoxicologist has called for stricter controls on chemicals and warns that there could be other “sub-lethal” effects taking place.
Professor Charles Tyler of Exeter University is one of many scientists that are increasingly concerned about waste substances found in water.
Although some can be found originating from industrial processes, others are drugs taken by people that are then passed through the body and into sewers.
A major study that took place in 2008 discovered that nearly 25 per cent of male roach fish taken from 51 sites on English rivers showed signs of turning female.
Speaking in conversation with The Independent, Professor Tyler said:
If you look in terms of what gets into a fish’s liver or gonad, the analysis of the chemicals it contains is a bit of a blueprint in terms of what’s flushed down the toilet.
“We’re starting to establish not just effects on gender, but that they can also affect other physiological processes in the fish as well.”
It is not well understood just what effect chemicals are having on the natural environment but studies have been able to show that at least 200 cause feminisation in fish.
This leads to males from breeding successfully but according to Professor Tyler, “it depends how feminised they’ve become.”
This means that populations can reduce over time, which could be hard to spot, as many effects do not actually kill the fish.
Professor Tyler shall be presenting his findings at the 50th Anniversary Symposium of the Fisheries Society in the British Isles at Exeter University from July 3 to 7.
Other research discussed at the event will include the destruction of coral reefs and how the sounds that the reefs produce are making fish become lost in the water.