‘I understand the lesson,’ Sherlock said. ‘Can we go back now?’
‘Not yet. Ah still ain’t got my dinner.’ Crowe’s gaze was moving around the surface of the lake, looking for something. ‘Once you know your prey and his habits, you got to look for the signs of his presence. He ain’t just goin’ to pop up an’ announce himself. No, he’s goin’ to skulk around, bein’ careful, and you gotta look for the subtle signs that he’s there.’ His eyes fixed on a patch of water some twelve feet away from the boat. ‘For instance, look over there,’ he said, nodding his head. ‘What do you see?’
Sherlock stared. ‘Water?’
‘What else?’
He narrowed his eyes against the glare, trying to see whatever it was that Crowe had seen. For a moment, a small area of water seemed to dip slightly, like a wave in reverse. Just for a moment, though, and then it returned to normal. And once he knew what he was looking for, Sherlock saw more dips, more sudden and momentary occasions when the surface of the lake seemed to flex slightly.
‘What is it?’
‘It’s called “suckin’”,’ Crowe replied. ‘It happens when the fish – trout, in this case – hang nose-up just below the surface of the water, waitin’ for insect nymphs to float by. Once they see one, they take a gulp of water, suckin’ the nymph down with it. All you see on the surface is that little dip as the water is pulled down and the nymph is sucked below. And that, my friend, tells us where a trout is located.’
He tugged on his fishing rod so that the lure drifted across the surface of the lake, pulled by the line, until it passed through the area where Sherlock had seen the trout sucking nymphs down.