Is competition healthy? maybe not for our Strumble Porpoises...

 Hi Cliff,

 

Lloyd just said that you wanted a little report of yesterday’s survey. Sadly, don’t have any good photos but can give you the info!

We had a pod of around 20 common dolphins feeding quite a way out for the first half of the survey. We then had around 4 feeding porpoises coming relatively close but were elusive and deep diving. In the last 15 minutes of the survey, we were watching some odd splashing very close to the cliff and were shocked to see a large tuna leap from the water!

But I do Nadia !☺ (taken by Ken from the Cartlett Lady back in August 2017)...and its set me off thinking! we only started recording Bluefins about seven or eight years ago out in the Celtic Deep. We only started seeing Common Dolphins inshore since 2000-2001andthen only onceor twice in the summer. Nw we see them all year round and often in big numbers of 60+

 

Porpoise numbers at Strumble seem to be declining since the days when we regularly experienced  what my old mate Elfyn Pugh termed "Porpoise soup".On a slow count, i might often register 40 or more individual surfacing porpoises, as I scanned across from the Lighthouse to Mackerel Rock, about 150 degrees.Since 2000 Common dolphins have started to appear at Strumble at first once or twice inthe summer but now in good numbers all year round.

That would hardly ever happen these days in fact I can remember when I last saw anything resembling "Porpoise Soup".So what has changed in the past couple of decades that might affect Porpoise numbers at Strumble? 

So far as I can remember there are fewer commercial potting fishermen, Boat traffic is no more frequent There used to be both the conventional Ferry and the fast cats, but the fast cats are long gone so less ferry traffic. So far as i can tellm if anything, there has been less anthropogenic (human)  disturbance in recent years than occured 20 years ago.

So, what if any changes have occured to the Strunble dynamic that might impact on Porpoise numbers.

The answer may well be competition from other species such as Common Dolphins and in the past year or so, Bluefin Tuna  that have infiltrated what used to be our porpoises happy hunting grounds....