An adult humpback whale, possibly greater than 12 metres in length, has been sighted in the Firth of Clyde this week – the fifth such whale to be seen off western Scotland in the past month, compared with a usual total of just one or two per year. The whale was sighted off Tighnabruaich in the Kyles of Bute on 6 July. On 8 July it surfaced alongside the Scottish Ocean Youth Trust’s yacht, spouting and swimmingly strongly in a northward direction into Loch Fyne. The whale was observed breaching out of the water and lob-tailing – a dramatic manoeuvre…