The air has been hot long enough for the whole surface to be warm. There is no water sensor here, so we cannot tell you the depths are safe — only that they are the most likely place to find a few cool degrees if the water is deep enough. On the big reservoirs and Highland lochs the cool layer sits at four to ten metres, but late-summer oxygen losses can narrow it. On shallow club fisheries under five metres there is no refuge. Fish dawn and dusk only or rest the venue. Barbless hooks. Land it fast. Wet hands. No air shots. If a fish swims off slowly, rolls, or needs more than half a minute to revive, stop. That is the welfare signal — not the temperature.

• DepthDeep waters: a fast sinker to four to ten metres, but watch the colder deeps for poor oxygen late in the season. Shallow fisheries: no refuge. First light, last light, or come back another day.
• TimingTwo hours after dawn and the hour before dark. Nothing else. The real stop signal is the fish on release — if recovery is slow, stop.