Sei whale at Firths Voe, Mossbank

Updated: ID confirmed as Sei whale (Balaenoptera borealis) by Dr Tom Jefferson, an acknowledged world cetacean expert and a visiting scientist at the Southwest Fisheries Science Center, NOAA Fisheries in the USA. (NOAA is the National Oceanic and Atmospheric Administration, a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere). Dr Jefferson very kindly confirmed the species following a request from the cetacean expert I contacted; and I have appended his statement below.

Dr Tom Jefferson said:

‘Yeah, I think (this is a) sei whale. I don’t know how reliable the color of the baleen plates really is, and I would be very reluctant to make an ID based only on that. But, a much more telling feature here is rostrum shape. This whale has a rostrum with a downturned tip, which is very characteristic of seis, and I have never seen it on minkes. I would say I’m 100% sure (this) one is a sei whale’.

Other additions/ updates to original post:

Date of previous confirmed Shetland sighting: 27th August 1993
Additional information about items used in making ID added
Additional details about sightings added
Additional general information about this species added

On 1 September I received a notification that there was a Minke whale in Firths Voe and it seemed to be hanging around. By lunchtime I had decided to go to try and see it because I had only seen 2 Minke whales previously and both had stranded and died meaning my experience of them was both limited and rather sad. So the chance to see a live and healthy Minke whale was one I couldn’t miss; the weather was good and I hoped to get some photos too.

I got to Mossbank as quickly as I could and found my friend George watching the whale; he had first let me know of its presence. I was very hurried because I had to get back to work; it was humid and still and the midges were awful – but the visibility was good and the whale wasn’t far offshore, often swimming in circles or up and down between 20 and 50 metres away. It was large and dark and I particularly noted its long, dark body, though I didn’t see its tail fluke above the water. I only saw 2 or 3 blows whilst I was there, these were fairly low and bushy – but not particularly powerful. It was a quite distinctive sound that carried in the still air.

The whale was feeding and, as it swam through the water it created quite a series of waves that rolled up against the rocky shore; there were 3 or 4 seals anxiously watching from a safe distance – though they were never in any danger from this animal. It fed in two ways, firstly in an upright form, powering forward at quite a good speed with its mouth open and just the pointed top of its head and front part of its baleen out of the water. It would then dive just below the surface and repeat that before arching its back, showing its dorsal fin and then going beneath the surface. The other way it fed was far more dramatic because the whale was on its side and showed its huge mouth, much of its baleen, its eye, throat grooves and pectoral fins – in this mode it became clear just how much the throat expands as it ploughs through the water scooping up water and whatever it was feeding on.

All too soon and, regrettably, I had to go. The consequence of that was, not only was I in too much of a hurry to get all the photos I wanted (the blow and a fluke shot are the ones I most regret not waiting for), but also I completely forgot about taking any video. None of this seemed too much of an issue at the time – I was just glad to get photos of what I thought was a healthy Minke whale!

It was a few days before I could process and review the images but when I started looking at them it was soon obvious this wasn’t like the two Minke whales I had seen previously; it was much larger, appeared dark all over (apart from the light colour under the throat that included some striking pink blotches) and some of the things I noticed at the time started to become quite obvious. The dorsal fin was larger and more upright, the pectoral fins were dark on top and underneath – both the two previous Minkes I had seen had light patches underneath and this is confirmed by the Evans and Cawardine guides I consulted. I estimate the whale to be in the region of 15m long, though that’s no more than a guess because I never saw more than a glimpse of body behind the dorsal fin and I didn’t see the blow holes and dorsal fins out of the water at the same time, though they came tantalisingly close on a number of occasions; this is, apparently typical of this species. I also didn’t see the tail stock or fluke.

I reviewed a number of websites to see if there were any definitive ID features and kept coming back to the pectoral fins, Minkes’ fins should have white bands underneath, though apparently this is variable. Coupled with the size (even if my estimate is wrong, I’m quite clear it was much larger than either Minke I had seen before), the colour, movements, all dark pectoral fins and strongly sickle shaped dorsal fin it seems to me that we saw a Sei whale.

At exactly the same time I was reaching my conclusion, George had received word back from Neil, a mutual friend much more experienced in identifying whales than I and he had concluded it was likely to be a Sei whale from George’s photos. Over the next few days I sought further opinion with the result that Sei whale is the confirmed ID of this animal.

Additional information that became known to me during those few days concerned the blow, the colour of the baleen plates and the rostrum (the beak-like upper jaw). Apparently, the blow of a Minke is seldom visible at all, even when heard, so the fact that it was visible at all was more important than I realised. Also, I later found out that, when leaving the Voe 2 days later the whale gave one large blow that was clearly visible from quite a distance; this information was recorded by another observer. In the case of the baleen plates, these are generally black in Sei whale and cream coloured in Minke whale. Finally, as noted above by Dr Jefferson, the distinctive rostrum is quite different to that found on the Minke and was decisive in identifying this animal.

One other thing that seems to be noted for this species is skimming for small prey, which may explain why it seemed to spend quite a lot of the time I saw it on its side, mouth open, before gently slipping just below the surface. In fact, this initially caused me some concern because I have witnessed other cetaceans swimming on their side that perished very shortly afterwards – though these were dolphins and a pilot whale.

Sei whales were hunted and, in common with other large whales, their population was heavily depleted, however it would seem that Sei whales have recovered somewhat more successfully from hunting than other large baleen whales. Their status is listed as “Vulnerable” by IUCN (International Union for the Conservation of Nature).

Images are here:

2 Responses to “Sei whale at Firths Voe, Mossbank”

  1. george graham (@gm4zhl) Says:

    Great write up to your blog Austin, just been reading about the Sei Whale, and it says that it never raises its tail flukes, which is a pity as we were so close to it..


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