People often assume that science is filled with those ‘Eureka!’ moments. That serendipity is the mother of all scientific discovery. Well, after over ten years of being a marine biologist I can safely say that this is simply not the case, at least not in my experience. There have certainly been some chance discoveries and surprise moments in my career so far, but every single one of these has come after a protracted period of, often tedious, targeted study and painstaking research. It would be very easy to make the ‘eureka’ assumption of the latest piece of research that I have been involved in – the first ever match of a UK humpback whale to Arctic feeding grounds.
Humpback whales, Megaptera novaeangliae, have been found around the UK for as long as humans have walked its shores. Archaeological traces of humpback whale remains have been found in Neolithic sites in the Orkneys and in Bronze Age settlements of the Outer Hebrides1. We should perceive the humpback whale to be as much a part of British wildlife as our magnificent red deer, our secretive badger or even the breath-taking basking shark. Yet somehow it remains firmly in the ‘occasional foreign visitor’ category for most people. Perhaps this is because, throughout much of our recent history, its population has suffered from intense commercial whaling pressure2.
It is maybe because of this induced rarity that the increased sightings of humpback whales over the past two decades has been greeted with such fanfare, often making it in to regional and national media3. In Scotland, humpback whales have been appearing increasingly often, and consistently over the past three years, in the Firth of Forth. In 2017, thanks to growing awareness of the richness of marine mammal biodiversity in the region, the Forth Marine Mammals (FMM) group was formed. FMM is a community project based around the Firth of Forth that reports live sightings of marine mammals to its members via social media, allowing people to increase their own chance of a sighting and also to share images of encounters.
Since 2017 humpback whales have been appearing in the Firth of Forth between January and March each year. This consistent timing of their appearance soon got local people pondering, “could these whales be the same individuals each year?”, “Where do these whales go when they aren’t in the Firth of Forth?”. Thankfully, owing to the markings found on the underside of a humpback whales fluke, or tail, individuals can be identified in a process known as ‘photo-ID’4 and this can begin to provide an answer to these questions.
The volunteers of FMM quickly became citizen scientists and began trying to match all the incredible photographs of their whales both between years and to whales that had been sighted elsewhere. Facebook, Instagram and Google Image searches were all fair game in their search for potential fluke matches. One incredibly industrious volunteer, Lyndsay McNeil, discovered that one whale, named ‘Sonny’, had visited the Firth of Forth in both 2017 and 2018. This was amazingly important, as it showed that these whales were visiting the Firth of Forth intentionally and that there must be some purpose to their visit. Then, thanks to many hours of work, Lyndsay made another match, this time of a whale sighted in the Firth of Forth in 2018 and in the remote Norwegian archipelago of Svalbard in the Arctic in 2017. This was the first time ever that an individual whale had sighted in both UK waters and its Arctic feeding grounds. The whale was named ‘VYking’ after its distinct Y-shaped marking on its tail.
This was a significant discovery and provided an important piece of the jigsaw that is the lives of these incredible marine mammals. Being part of the FMM, myself and my two co-authors, Emily Cunningham and Katie O’Neil, realized the significance of this hard-won discovery and were keen to not only investigate further but to make sure this information was recorded in the scientific literature. We started by confirming the matches with independent viewers, all of whom were experts in cetacean photo-ID. We then sent the best images of all whales individually identified to a wide selection of international photo-ID catalogues to see if any other matches could be made – none came up. Our research into the literature threw up more questions than answers, as is usually the case. Why have the whales only started appearing just recently? Why do the whales come to the Firth of Forth? Where do they head afterwards?
In this post-commercial whaling era, we are seeing many humpback whaling populations recover around the globe5. Unfortunately, we simply do not have the data to know for sure if this is the case for the population we find in UK waters, that of the North-East Atlantic. In fact, we don’t even know if this is a single population as no population genetic studies at an appropriate scale have ever been carried out. I have reason to believe that if such a study were commissioned then it might in fact reveal at least two populations. But if the local population is recovering then that is one possible explanation for their appearance in the Firth of Forth, they could be re-colonizing old habitats or exploring new ones as their population grows. Equally we could be seeing a range shift due to changing environmental conditions, possibly as a result of climate change. For now, and until further data is collected, we simply do not know.
Our current level of understanding is also lacking in why the Firth of Forth is so special. It is possible that the improvement in our river systems, as a result of EU directives, has increased the availability of prey fish in the Firth of Forth due to improved water quality, thus making it viable as a feeding area for humpback whales. Again, without further research this is currently guesswork.
Humpback whales are renowned for their extremely long-distance migrations between high latitude feeding areas and low latitude breeding areas6. It is also known that in other parts of the world some juvenile humpback whales either make stop-offs along their migration at ‘service stations’ to rest and feed7 or make only partial migrations to mid-latitude locations8. It is highly probable that the Firth of Forth serves either or both of these purposes. Although the maturational status of the whales observed here is unknown, they do not appear to be fully grown adults and the identification of a nearby stranded individual as a juvenile male adds weight to this idea. Until either new photo-ID matches show up or a satellite tagging study is undertaken we may not know the answer.
We muse about these questions, and others, in our recent publication in Marine Biodiversity Records. This study couldn’t have taken place without all the hard work and dedication of the Forth Marine Mammals group and we want to thank each one of them for their contributions. A personal thank you also goes to my co-authors, for their hundreds of hours of input and for battling through three rounds of peer-review. This is a great example of citizen science and we hope to continue to support them in their discoveries of the secrets of the lives of these humpback whales in the years to come. One thing is for sure, there still remains plenty to be discovered.
The full paper can be found here.
1Buckley, M., Fraser, S., Herman, J., Melton, N.D., Mulville, J. and Pálsdóttir, A.H., 2014. Species identification of archaeological marine mammals using collagen fingerprinting. Journal of Archaeological Science, 41, pp.631-641.
2Tønnessen, J.N. and Johnsen, A.O., 1982. The history of modern whaling. University of California Press.
3Rare sighting of humpback whale off coast of Cornwall. BBC News. 03/08/2019. https://www.bbc.co.uk/news/av/uk-england-cornwall-49219571/rare-sighting-of-humpback-whale-off-coast-of-cornwall
4Wells RS. Identification methods. In: Würsig B, Thewissen JGM, Kovacs KM, editors. Encyclopedia of marine mammals. Academic press; 2017. p. 503–9.
5Katona, S.K. and Beard, J.A., 1990. Population size, migrations and feeding aggregations of the humpback whale (Megaptera novaeangliae) in the western North Atlantic Ocean. Report of the International Whaling Commission (Special Issue 12), pp.295-306.
6Stevick, P.T., Neves, M.C., Johansen, F., Engel, M.H., Allen, J., Marcondes, M.C. and Carlson, C., 2010. A quarter of a world away: female humpback whale moves 10 000 km between breeding areas. Biology letters, 7(2), pp.299-302.
7Bortolotto, G.A., Kolesnikovas, C.K.M., Freire, A.S. and Simões-Lopes, P.C., 2016. Young humpback whale Megaptera novaeangliae feeding in Santa Catarina coastal waters, Southern Brazil, and a ship strike report. Marine Biodiversity Records, 9(1), p.29.
8Swingle, W.M., Barco, S.G., Pitchford, T.D., Mclellan, W.A. and Pabst, D.A., 1993. Appearance of juvenile humpback whales feeding in the nearshore waters of Virginia. Marine Mammal Science, 9(3), pp.309-315.
Dr. Daniel M Moore 