Up to 30 minke whales were spotted recently feeding off Eigg in what has been described as one of the largest gatherings of the species recorded around the Hebrides.
The remarkable gathering was witnessed towards the end of last month during a specialist 10-day cetacean research expedition, ‘In Search of Giants’, operated by small-ship cruise operator Hebrides Cruises, which set out from Oban to explore some of Scotland’s most remote waters in search of whales and other marine wildlife.
Marine scientist Dr Conor Ryan and guide and crew member Dan Wagstaff estimated that between 20 and 30 minke whales were feeding within a visible area of around a four-mile radius off Eigg.
Groups of seven and eight whales were recorded, with further whales feeding in the distance, and multiple sightings from the evening were reported to the Hebridean Whale and Dolphin Trust’s Whale Track recording scheme.
Dr Ryan said gatherings of this size are rare, although not unprecedented in the Hebrides, and described the density of whales encountered off Eigg as “exceptional”.
He said: “The feeding behaviour itself is typical, but the densities were exceptional.
“I describe baleen whale feeding like the ‘supermarket effect’: lots of food in one place gathers lots of individuals, which might be completely unrelated and only together for a short period while the food is abundant.
“We witnessed the rapid formation and breakdown of these feeding frenzies when we were on the water that day, with the minke whales dramatically lunge-feeding on shoals of fish alongside shearwaters and auks.”
Dr Ryan said similar densities have been reported to the Hebridean Whale and Dolphin Trust’s Whale Track scheme off Ardnamurchan and the Cairns of Coll in recent years, but confirmed that the Eigg encounter could be described as one of the largest gatherings recorded around the Hebrides.
The specialist expedition was developed to explore the former whaling grounds west of St Kilda and investigate which of the great whale species hunted in these waters during the 20th century can still be found there today. Its timing and search area were informed by historical whaling research recently published by Dr Ryan and colleagues at the Scottish Association for Marine Science.
After visiting St Kilda, Elizabeth G headed west to the edge of the continental shelf, where the seabed rapidly falls from around 200 metres to depths of 1,000 metres and beyond. After around 20 miles of searching the shelf edge, the expedition encountered a fin whale mother and calf. The mother was estimated to be around 20 metres long, with her calf measuring approximately 10–11 metres.
The pair were observed in waters once hunted for great whales, including fin whales.
Later in the expedition, two humpback whales were spotted in the Minch among feeding minke whales, before the gathering of up to 30 minkes off Eigg provided a dramatic final wildlife encounter.
Other sightings during the 10-night expedition included a basking shark, bottlenose dolphins, grey seals and a wide variety of seabirds.
Emma Fairbairns, director and shore manager of Hebrides Cruises, said: “In Search of Giants is a very special expedition for us because it combines the experience of exploring some of the wildest and most remote waters around Scotland with a genuine research purpose.
“To finish this year’s expedition surrounded by so many feeding minke whales off Eigg was an extraordinary sight and something everyone on board will remember.”
The expedition took place aboard Elizabeth G, which has its own connection to the history being explored. The vessel was formerly a rescue boat serving the large Norwegian fleet which fished for herring and hunted whales in Shetland and the Outer Hebrides. Today, she carries guests and researchers into the same waters to observe and record their marine wildlife.
Hebrides Cruises is a family-run small-ship cruise operator based in Oban. Its three vessels – Elizabeth G, Emma Jane and Lucy Mary, take a maximum of 10 or 12 guests on wildlife and adventure cruises throughout the Inner and Outer Hebrides and Scotland’s west coast with each cruise having a dedicated wildlife guide on board.