Rain­bows: good or bad?

Si­mon Cooper sees dif­fer­ent shades of the ar­gu­ment

Trout & Salmon (UK) - - First Cast - CHALK TALK

RAIN­BOW TROUT EX­CITE STRANGE pas­sions in chalk­stream fish­ers. Some loathe them with a pas­sion, the catch-record books con­tain­ing such en­tries as, “Lovely day spoilt by too many (ex­ple­tive) RAIN­BOWS.” Oth­ers de­light in the reel-scream­ing ex­u­ber­ance of our North Amer­i­can im­ports. So, as a hum­ble fish­ery man­ager, how do I strad­dle this di­vide? Well, it’s worth ac­knowl­edg­ing from the out­set that rain­bow trout are not en­tirely new to the United King­dom, with the first stock ar­riv­ing in 1859. I’m not sure when they found their way into the chalk­streams, but I sus­pect, with river own­ers of that time be­ing par­tic­u­larly in­no­va­tive, it wasn’t long af­ter­wards. The fish were com­mon by the early part of the last cen­tury in the River Test. An ex­tract from a 1926 catch book, which hangs on the wall of The Grosvenor Ho­tel in Stock­bridge, records that in July an un­named an­gler caught 24 fish: 10 brown trout and 14 rain­bow trout. By way of a brief di­ver­sion, the same record book be­lies the be­lief that the in­ter-war years were a Val­halla of huge fish and dry-fly purists. Our man caught all his fish on wet­flies (Alexan­dra, Red Palmer and Teal & Sil­ver), an av­er­age weight of 1lb 13oz for the browns and 10oz for the rain­bows. The rea­sons most com­monly cited for stock­ing On­corhynchus mykiss is that they are great fight­ing fish and of­fer sport when Salmo trutta is idling his way through the dog days of sum­mer. I can’t pos­si­bly dis­agree with the first as­ser­tion. I sus­pect the sec­ond is a river­ine myth. The real dirty se­cret is cost. Rain­bows are half the price of browns, so you ei­ther save money or get twice the bang for your buck. The case against stock­ing rain­bows seems to me more emo­tional than prac­ti­cal. They are not, which­ever way you cut it, na­tive to the Bri­tish Isles. If man dis­ap­peared to­mor­row, rain­bows would all but van­ish from our is­land within the space of a decade. That would have ap­plied even in the days when we stocked diploid fish, that is to say fish ca­pa­ble of re­pro­duc­tion. For rea­sons not re­ally un­der­stood they rarely breed and we’ve never had brown-rain­bow crosses. To­day, all stocked fish are triploids, that is to say ster­ile fish, and ex­tinc­tion would hap­pen even faster. Triploids are, by the way, cre­ated at the fer­tilised ova stage when the eggs are sub­jected to huge pres­sure in a div­ing air cylin­der, which forces the egg to re­tain a chro­mo­some that is nor­mally ejected dur­ing egg de­vel­op­ment. Hence a triploid has three chro­mo­somes, a diploid two. I do have time for the tra­di­tion ar­gu­ment: chalk­streams are syn­ony­mous with brown trout, the habi­tat man­aged for the past two cen­turies to­wards the goal of fly-fish­ing for our na­tive quarry. But on the other hand, in do­ing so we have grad­u­ally driven out a mul­ti­plic­ity of na­tive fish species that would have oth­er­wise shared the river space. And – this is a philo­soph­i­cal ques­tion – at what point does the im­port be­come the na­tive? We don’t re­gard rab­bits as any­thing other than na­tive but they are only here thanks to the Ro­mans. For more than half the time the River Test has been re­garded as hal­lowed wa­ter, rain­bows have been part of the mix. I think we can be rea­son­ably cer­tain that the found­ing fa­ther of mod­ern dry-fly fish­ing, Fred­eric Hal­ford, came across them (he died in 1913) and I don’t re­call him ful­mi­nat­ing against them. They even have of­fi­cial sanc­tion. The En­vi­ron­ment Agency doesn’t list rain­bow trout as non-na­tive; it al­lows them the same clas­si­fi­ca­tion as brown trout. When you ap­ply for a trout stock­ing li­cence the EA is not pri­mar­ily con­cerned with the species, it cares about size and quan­tity – the biomass, match­ing the vol­ume of fish to the vol­ume of wa­ter. There doesn’t seem to be a habi­tat is­sue; the two types gen­er­ally co-ex­ist in har­mony. Rain­bows: good or bad? They don’t do harm. They cost less. On cer­tain wa­ters the fish­ing will be im­proved. But, and it is a big “but”, they don’t re­ally be­long. There is a com­par­i­son to the shoot­ing world where pheas­ants (ori­gin: China) are no more na­tive than rain­bows, so some shoots have en­tirely aban­doned them, fo­cus­ing on rear­ing the na­tive English par­tridge, which is smaller, faster and harder to hit. These es­tates are flour­ish­ing: there has to be a les­son there. Yes, you per­haps won’t have such a big bag at the end of the day. The sport may have been tougher. But you have been part of some­thing spe­cial. Peo­ple ap­pre­ci­ate au­then­tic­ity. We go fish­ing to get back to na­ture. We ex­pect to catch some­thing that is nat­u­ral. It may be time to say good­bye to rain­bows.

“We fish to get back to na­ture. We ex­pect to catch some­thing nat­u­ral”

An en­try for 1926 in the catch book of the Grosvenor Ho­tel.

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