Fishing pressure on trout is now part of everyday life on many Spanish rivers. Finding a reach where you can fish a full session without meeting another angler—or simply wait beside a glide in solitude—has become increasingly difficult.
The days when long journeys on secondary roads turned a river 200 kilometres away into a genuine expedition are gone. Better roads, better communications and easier access have put almost any river within a few hours of almost anyone. There are more of us fishing, for better or worse, yet we have not always turned that growth into better management or healthier rivers.
How fishing pressure changes trout behaviour
Crowding does more than spoil the sense of escape many anglers look for. At certain times and on certain reaches, a supposedly relaxing day can feel more stressful than a day at the office. Sharing a short stretch with fifteen other anglers certainly feels that way to me. It is why I deliberately seek out less-frequented water or choose methods that may produce fewer fish and demand more effort. Thankfully, walking for an hour still discourages plenty of people.
But angling pressure also affects the fish. The issue is not only the number of anglers who may want to put trout in the pan; repeated human presence can alter how trout use the river. The question at the heart of this article is simple: how far does fishing pressure affect trout feeding at the surface?
Autumn on the regulated rivers of Castilla y León
For several years, catch-and-release fishing was extended until 15 October on regulated waters in Castilla y León. Many of us saw that extension as an opportunity to fish beats we had missed in the permit draw, or rivers whose summer flows had made them difficult during the main season.
Once the heat eased and the flows began to stabilise, the conditions looked ideal. Trout were preparing to spawn and hatches could still be abundant. In those early years it was unusual not to find at least a few fish rising in the glides. The fishing was often lively, with plenty of trout and a reasonable chance of a genuinely large fish. There was regular surface activity; if a dry fly failed, a dry-dropper rig usually found an answer.
I still remember a caption in a well-known Spanish fishing magazine: “Autumn, solitude in abundance.” Several seasons have passed since then, and time has not stood still on our rivers. Fishing the major regulated rivers of Castilla y León in September and October now often means crowds. The Esla, Porma, Órbigo and Carrión have all been caught up in the rush to make the most of the final weeks.
The equation has changed. Good flows and substantial hatches no longer guarantee rising fish. Perhaps the influx of anglers, combined with nearly six months of accumulated pressure, has much to do with it. Whatever the precise cause, it is no longer unusual to spend an entire day without seeing more than the occasional rise.
When limiting access changes what anglers see
Until fairly recently, the social sport-fishing reaches of Castilla y León—Escenarios Deportivos Sociales, or EDS—functioned in practice much like open catch-and-release water, except for a handful of days reserved for competitions and other organised events. Because anyone could fish them at almost any time, some became extraordinarily crowded. The busiest are now managed through a permit system that limits daily attendance.
I remember counting more than fifty anglers on the Carrión EDS, with three or four people working every glide. It could still be entertaining fishing. Small trout were active on the surface and often selective about what they took, but the average size was tiny. On one morning, after passing twenty other anglers, I caught two dozen finger-length trout on a mayfly pattern I had tied—one I later realised was almost identical to Joaquín Herrero’s famous Carriona.
Once permits began to control access, the most striking change was not simply the amount of surface activity but the quality of the trout appearing in it. Fish of every size began to be caught on top. The larger trout were probably there all along; indeed, good fish sometimes appeared during the evening rise. They simply did not show themselves while the river was being disturbed throughout the day. A mature trout needs a degree of calm before it will settle into a feeding rhythm, and that reach rarely offered it.
Asturian sea trout under constant pressure
Anyone who has fished Asturias during the sea-trout season—on the Cares-Deva, Sella, Narcea or Eo—knows what a heavily pressured river looks like. I will leave aside the number of anglers who can gather around a pool during the evening rise and describe a scene that has become increasingly familiar.
You arrive at the river and the only movement is people climbing in and out of the water. Someone is wading waist-deep, casting at nothing obvious and sending waves across the pool. The sea trout seem to have vanished. If you are lucky enough to find a small group feeding, the fish rising are usually the smaller ones. Meanwhile, genuine torpedoes lie tight to the stones on the riverbed, scarcely moving.
Walk upstream past a managed beat or a closed reach and the contrast can be revealing. The same classes of fish may be present, yet there they feed freely, with large and small sea trout rising together. The problem is brutally simple: we do not give the bigger fish time to settle. How can a mature sea trout commit to feeding at the surface when anglers have occupied its pool from seven in the morning until eleven at night? It needs an exceptionally safe opportunity before it will come up.
Do we want to fish—or fish better?
Anyone who lives beside a heavily fished river and sees it outside the season will recognise the pattern. Once the anglers disappear and the trout are left undisturbed, fish may rise in conditions—and to hatches—far poorer than those that produced almost no surface activity during the season.
Our presence changes a river in more ways than we sometimes imagine. Habitat deterioration may be the most obvious effect, but changes in trout behaviour should not be ignored. Feeding at the surface is probably one of the moments when a fish feels most exposed. Trout need calm and a sense of security before they will hold high in the water and rise repeatedly.
Any unfamiliar presence can interrupt that behaviour. If the disturbance is repeated—and repeatedly associated with danger, being hooked and handled—the fish may change their habits. Later experimental work on angled trout has likewise examined how fish adjust their behaviour to changing levels of angling pressure; readers interested in the science can consult this University of Glasgow research paper.
That brings me to the question I added in 2020: do we prefer simply to fish, or would we rather fish better? Perhaps fishing pressure on trout should be the next major management issue on our rivers.
Álvaro G. Santillán
Originally published in the Spanish magazine Líneas Vivas in 2008. Translated and updated for Focus on the Fly. Explore more of our fly-fishing photography.