Aug12

Basking in the Sun with Breaching Sharks & Porpoise Calves

Categories // Hebrides Wildlife Officer

Basking in the Sun with Breaching Sharks & Porpoise Calves
Spectacular view of a breaching basking shark from CalMac Isle of Lewis during a survey on 6th August 2019 

Calm conditions have provided some spectacular sights in the Herbrides over the past few weeks! 

We’ve had some great weather for whale watching here in the Hebrides in recent weeks. Not just because the sunshine has occasionally put in an appearance but mainly because we have had low winds most of the time.  I seem to spend my life checking out the wind forecasts because that really determines how easy it is to spot any marine mammals that are out there and makes it easier and more comfortable for the guests and passengers to come out on deck and enjoy the wildlife with me.  We have had some days where it has been a mill pond out on the water and that always gets me very very excited.  Even if little else turns up you are pretty much guaranteed sightings of harbour porpoise and seals when it is like that.  The calm conditions mean that their tiny fins, or in the case of curious seals – heads, can be seen some distance away from the ferry.

What has been noticeable in these conditions is how many harbour porpoise there are in the area, and also how many of them have calves in tow at the moment.  These tiny marine mammals really are wonderful animals and face many struggles each day from entanglement in fishing gear, to attacks from bottlenose dolphins, to the constant need to feed due to the cold temperate waters they reside in that puts them on an “energetic knife edge”. 

These past few weeks there have been porpoise everywhere!  I really shouldn’t be surprised as a large part of the area that I work in has been designated as a harbour porpoise Special Area of Conservation (SAC) by Scottish Natural Heritage.  Their population is generally in decline across most of its range and they are classed as Vulnerable on the IUCN Red List.  But here in the Hebrides the population is strong and the Minch and Inner Hebrides is a very important habitat for them.  And the fine conditions have allowed us to record them, particularly those with young, and also to simply enjoy their presence around the ferries.

But the area is also a hotspot for the much larger minke whales and basking sharks.  It is deemed so important an area for them that there are also plans in place to designate a marine protected area here for their protection.  It is currently out to public consultation and Marine Scotland are asking the public to comment.  I will be having my say.  If you go to  https://consult.gov.scot/marine-scotland/four-new-marine-protected-areas/consultation/ you can too but you will need to do so by 30th August when the consultation closes.  It is worth bearing in mind that as our Head of Science and Conservation points out, these sites always need to be properly managed in order to actually have any teeth:  https://www.orcaweb.org.uk/our-work-orca-news/item/41-new-marine-conservation-zones

At the moment, until the data for the year has been analysed, this is purely anecdotal, but it certainly seems that minke whale sightings from our surveys and Wildlife Officer programme in the region have been greater in number than last year.  Of course, even for a whale that can reach 9 meters in length, the calm conditions have made recording them more easy and that might have been the deciding factor.  But ORCA’s protocols and effort based data collection will take the conditions into account when working out numbers. 

I’ve also had some basking shark sightings.  Including a fabulous moment during a dedicated survey this week this week when one actually breached right out of the water.  The huge splash that was created at first suggested that it was probably a minke whale performing but second, third and fourth breaches confirmed the almost bizarre shape that a basking shark makes as the gentle giant flies through the air.  This is not a regular occurrence and something that we were very privileged to see.  Scientists don’t really know why this occurs and it has been estimated that a breech by a basking shark expends 50% more calories than it would for a similar sized white shark so there has to be a specific reason to exert so much energy.  It certainly isn’t doing this to feed but perhaps it has something to do with breeding and finding a mate.  We know so little about these sharks but it is believed that there is possibly courtship behaviour taking place within the proposed MPA and perhaps its future designation would encourage further research into these fascinating creatures.       

 Andy

ORCA Wildlife Officer – The Hebrides