Mr Otter

I was fishing upstream of the Dorchester, last night. Fished upstream to not far from where some years ago you will recall we built an otter holt. At about 8.45pm I was approaching the river bends near the holt, when I saw an otter on my bank, clearly fish eating. I approached quietly but I must have alerted the otter because it turned quickly and dived into the river, its long pointed tail clearly seen as it became submerged. I sat down and just watched, about ten minutes later on the opposite bank I could see the otter’s head only, moving upstream then downstream again, feeding. About 30 yards upstream I was using a mayfly spinner, a fish took and I measured it to be 12.5 inches long. Then I noted a gash along its flank / lateral line, had Mr Otter been at work??