Over the summer and autumn I’ve enjoyed the thrill of watching two humpback whales feeding and breaching off the Sands of Forvie National Nature Reserve in Aberdeenshire. Is this a one-off or are we seeing a wider population recovery in Scottish Waters?
Herman Melville, the author of Moby Dick, described the humpback as “the most gamesome and lighthearted of all the whales, making more gay foam and whitewater generally than any of them”. This, of course, made them more obvious to whalers and they were hunted to the brink of extinction for their meat and oil. When finally, in 1982, the International Whaling Commission (IWC) introduced a moratorium on commercial whaling, the North Atlantic population had fallen from an estimated 112,000 to a few thousand individuals. They were on the edge of local extinction, even though in the North Atlantic, they were protected since 1955.
What followed is one of the few ecological success stories in a world where the diversity of animal and plant species is in rapid decline and the rate of extinctions is higher than ever. In most areas, humpbacks have recovered to their pre-exploitation population size with annual increase rates of about 7-10% recorded off Australia, Southern Africa and South America. However, there is no evidence of recovery for populations in some areas such as off the Pacific islands, where there may be as few as 2,000 animals.
Humpback whales in the North Atlantic have similarly recovered and nowadays there’s an estimated 20,000. The recovery has been strongest in the western North Atlantic whereas it’s less certain in the eastern North Atlantic. This includes UK waters.
Although the humpback is one of the most studied of whales, we still know relatively little of their habits. The eastern North Atlantic population, which feeds largely in arctic waters off Norway and Iceland, is thought to migrate mainly to the Cape Verde islands with a few heading to the Caribbean breeding grounds, home to most humpbacks from the western North Atlantic.
But in British Isles and Norway things are changing. With the recovery of herring and mackerel stocks, humpbacks are now present both in summer and winter, competing with other whales and dolphins.
So what does this mean for Scotland? The map below, produced by the Sea Watch Foundation, shows a peak in sightings in the last two years compared to previous years.
Humpback whales are not common in British waters, but are increasingly seen off the west coast of Ireland and in northern Scotland in summer, possibly on their way between summer northern feeding grounds around Iceland and northern Norway and winter breeding grounds off the coasts of NW Africa.
Alternatively, there may be humpbacks roaming the region year-round. Since the 1980’s, there have been regular sightings from Shetland, the northern Irish Sea, and in the western approaches to the English Channel. Some of these have been in winter, as is the case of the 2012 sightings of a humpback whale off the Aberdeenshire coast from December to March.
All this points to an increase in humpback presence in Scottish waters but we need further research to verify if there is a true upward trend and to establish the origin of ‘our’ humpbacks. This will provide important information on which to safeguard any recovery.
For the two ‘Aberdeenshire’ whales, I sent photographs of their tail flukes to the University of the Atlantic, in Maine, USA. Here, they maintain a catalogue of over 8000 photos of tail flukes which are the equivalent of fingerprints for whales. Each whale has a diagnostic coloured fluke, with different configurations of pale and dark areas on the undersides, and with additional features such as abrasions and wear to the fluke margin, it all adds up to a sure-fire ID for most whale individuals.
Neither of the ‘Aberdeenshire’ whales were in the US catalogue which is not surprising given they are probably from the eastern Atlantic population. However, neither were they in the UK-wide catalogue of fluke and fin images from the 1970s to the present, maintained by the Sea Watch Foundation, although some of the other individuals have been recorded moving between Aberdeenshire, the Moray Firth and Shetland as well as into the southern North Sea.
Dr Kevin Robinson, Director of the Cetacean Research & Rescue Unit, based in Banff, Aberdeenshire, has a licence from SNH to obtain DNA samples from humpbacks in Scottish waters. This will tell us which cohort of the North Atlantic population these come from, which will allow us to better plan for their management.
Speaking of management, a recent 2016 IWC paper presents a worrying picture. The summary findings, based on recorded entanglements of humpbacks between 1992-2016, concludes that Scottish inshore waters are unlikely to sustain a population of humpback whales. This is because they currently act as a major source of entanglement, mainly with crab and lobster creels. Rescue responses to six of the 12 entangled whales resulted in successful disentanglements, although their long-term survival remains unknown. Three of the 12 entanglement cases were fatal. The conclusion of the modelling showed that Scottish waters currently act as a mortality sink for humpbacks.
Efforts are underway to establish a Scottish Parliamentary Working Group, made up of fishing, welfare and conservation bodies. This would look at the extent of the entanglement problem and make recommendations to mitigate it. It has to be said that fishermen have been at the forefront of efforts to save whales from entanglements, as much to conserve the whales as to save their gear. It seems a win : win so hopefully the Group will be set up early in 2017.
Meanwhile, I continue to enjoy the two humpbacks off the Aberdeenshire coast. Last week, they decided to spend time off Aberdeen City’s beach and surprised this surfer photographed by Walter Innes. Later the whale made gay foam and whitewater, breaching further out in the bay. Herman Melville would have been pleased.
My thanks to Dr Peter Evans, Director of the Sea Watch Foundation and his staff for their help with the blog and to Walter Innes and the BDMLR for permission to use their photos.
Ron Macdonald was formerly SNH’s Head of Policy and Advice.
For more information about Forvie NNR visit the Reserve website.