Scientists reveal fish are older than you might think

Many of the most sought-after carp are older than the anglers fishing for them - and the world’s oldest fish lived to the grand old age of 226.

The remarkable science of ageing fish has revealed some stunning facts regarding how long it takes them to reach full size and exactly how long they can live, none more so than the Japanese koi carp Hanako, which lived three times the average human lifespan.

But counting growth rings on scales helps scientists and fishery managers understand far more than just the age of the fish. For example, it reveals details of a fish’s growth rates, helping paint a picture of how much food is available in the fishery, how much predation there is, whether the habitat is suitable, and whether the fish are stressed.

And, by taking scale samples regularly, it becomes easy to distinguish when and where there are good and bad year classes of fish, which in turn reveals the fisheries likely to produce outsized specimens, or good bags of specimen-sized fish.

“Big-fish anglers would be interested in the Environment Agency’s fish ageing data ¬ I know I am,” said fisheries consultant Bruno Broughton, who has been studying fish ages for more than 30 years.

“Study of fish ages reveals when and where each species is peaking, meaning the capture of a big fish could be on the cards. This is why anglers in the know have been collecting scales from fast-growing fish for decades, enabling them to predict when the fishery will be at its zenith,” he added.

But, because scales only continue to grow so long as the fish grows, it becomes hard to age a fish once it has reached its maximum size. This means that it is anglers who have ultimately taught scientists just how long-lived some species can be!

According to records chub, bream and tench can, in extreme cases, live to ages approaching 30 years, while one Leney-strain Redmire common carp named Raspberry survived to around 70 years of age.

Perhaps the most impressive fish-ageing statistic is that your rod licence fee helps pay EA scientists to collect and age over 50,000 fish scales every year as part of regular surveys. All the data is available to anglers and clubs wanting to learn more about their fisheries.

“Fish-ageing data is vital for highlighting strong year-classes of fish. We use it for the fishery management advice we give to angling clubs and to determine where environmental conditions and river habitats are having positive or negative impacts on fish populations and their growth rates,” explained Justin Mould, fisheries technical officer for Anglian central area.