Huge Shadows in the Water
Michelle looks at the heritage of the Highland basking shark fishing industry
Running into the school one of the pupils eagerly began to tell us about what he had just seen on the way to class “I saw a basking shark” he excitedly shouted.
“Wow a basking shark that's amazing!” I said
“It was huge” he continued.
I knew basking sharks (Cetorhinus maximus) could be seen in the Sound of Sleat but in all my time living in that area I hadn't spotted one. However, all this was about to change, a few nights later while sitting in the college common room I happened to glance out of the window and there, just offshore, I saw them, huge shadows in the water below. Grabbing my camera, I ran downstairs outside and down to the beach where I gazed awestruck as they slowly circled.
I could see their huge size from the tip of their snout to the tip of their tail, their dorsal fin predominant in the middle. I scrambled down the shore to get as close as possible to these majestic animals that were once a common sight around the west coast of Scotland but which for many years became scarce because they possessed something that humans required.
Basking sharks, belong to the group of sharks known as mackerel sharks that also include great white, porbeagle, thresher and megamouth sharks.
Now why would basking sharks, the second largest fish in the world after the whale shark, be hunted you might wonder? The answer to that is in their liver. It contains a substance called squalene which has been used as a lubricant in the aviation industry, as fuel for lamps, as a vitamin supplement, in cosmetics and even did the tempering process of high-grade steel.
In the years between 1946 and 1986, 77, 204 basking sharks were taken by fisheries in Scotland, Ireland and Norway. A single basking shark of average size could contain 4-500 kilogrammes of oil within its buttery coloured liver making up roughly a quarter of its entire body weight, with an adult basking shark being up to 40ft or 12m in length and weighing up to 6 tonnes.
Basking sharks are however very slow to grow and mature, living for between twenty and a hundred years, the males don’t reach maturity until 12-16 years old and the females not until they are 20 years old, because of this, the basking shark fishery around the UK had a big detrimental impact on basking shark numbers in the area. The last Scottish fisherman gave up hunting these creatures in 1995 with the basking shark becoming protected UK waters in 1998.
I watched for over an hour that evening as the sun began to lower in the sky as the sharks unconcerned about my presence on the shore continued to circle and feed in the plankton rich water. What’s amazing is that during the time I was watching them feed each of the basking sharks I saw that evening would have filtered 6000 litres of or approximately an Olympic sized swimming pool of water through their 27000 gill rakers, (the comb like structures used to filter plankton).
Not too far from where I had my close encounter with the basking sharks in the Sound of Sleat was where the Author of “The Ring of Bright water”, Gavin Maxwell machine-gunned his first basking shark in the 1940’s and from where several sharks were killed and dragged into Mallaig harbour nearby. After that first hunt, Gavin Maxwell decided to set up a basking shark fishery on the Island of Soay in Loch Scavaig with his partner.
Though Maxwell’s fishery only lasted a few years on Soay from 1945-49, so many sharks were killed that there was over 16 tonnes of shark flesh in the pickling tank, which unfortunately had begun to rot and became infested with maggots due to the insufficient strength of the pickling solution. It gave off an awful stench, the slipway ran pink with the plankton from the sharks stomachs and the harbour red with blood. Today, all that remains of the island’s fishery is a few ruins standing as a memorial to the Sharks that were killed and processed there.
Much has changed since the 1940’s and even more since basking sharks became protected in UK waters in 1998. We have discovered new products that mean their oil is no longer needed and understand much more about our impact on the oceans, but basking sharks are still being hunted around the world for their fins used in shark fin soup. One basking shark can yield 90kg of fins and fetch around £540 per kilogram.
Basking sharks are also unfortunately caught as bycatch in fishing nets. With slow growth and maturity rates and a likely gestation of three and a half years, every shark is incredibly precious in ensuring the species survives into the future.
A more hidden but just as serious threat to basking sharks and all marine life in general is that of microplastics. As filter feeders, any small pieces of plastic within the water column are likely to be ingested along with the shark’s planktonic food and copepods.
We still have so much to learn about basking sharks such as where they give birth, only one female has ever been seen giving birth and she was caught and killed.
How far can they travel? Do they stay in one area and move up and down the water column or migrate to follow their food supply? Through satellite tags we are starting to get some answers. We now know that they don’t hibernate but hang out in deeper water offshore in winter and that they are capable of diving over 3000ft, and a few have even been recorded as reaching 5000ft, is it in these dark waters that they give birth?
Imagine if these amazing creatures slip from the earth before we really get to know them, imagine if in the future no child will run excitedly into nursery to tell of the huge animal he saw just off the shore. Imagine that our children’s children will only be able to look at a photo in a book or watch a short video, the way we do with the thylacine today. Imagine no more lampreys parasitising the sharks before returning to Scotland’s rivers to breed.
Today, the sight of basking sharks feeding in the waters off Scotland serves as a reminder of nature's resilience and the importance of preserving such magnificent species but we must not get complacent as the oceans span the world and what one country does within its own waters directly affects all marine wildlife.
Michelle Melville is High Life Highland’s Heritage Ranger, is passionately dedicated to preserving Scottish natural and cultural heritage. A skilled artisan, Michelle excels in a range of hand crafts from carving and weaving to stained glass creation and needle felting. Her talent in these crafts forms a vital part of her role in engaging and inspiring communities to be inspired by their environment, and learn new skills and gain in confidence.