CONSERVATION ISSUES - JULY 2006

Basking Sharks were being regularly seen around Cornwall during June, particularly around West Penwith. Where Fred found several feeding in one place he put out his plankton net, and brought me some samples, to find out what they were feeding on. In the little jars, one could see several little creatures, smaller than pin heads, jumping about, so the next step is to catch one of these and get it onto a microscope slide and place a cover slip over it.

In the early samples I found Copepods, creatures I find in nearly every plankton sample I have examined, I also found Mysids and Euphausids, these I have seen less often. Plankton brought to me on Thursday 15th June, was however more exciting, for I found creatures I had never seen before. I am unable to identify them down to a species, but I can put them into groups known as Pagurid and Coenobitid Larvae, for these have very distinctive eyes. Some Copepods do not have eyes and when they do, it is usually only one, but sometimes two, and they appear as just black spots, as is the case with most Mysids, Euphausids and numerous other larvae. What is so different about the Pagurid and Coenobitid Larvae is that the eyes have little facets like the eyes of bees and flies.

I made drawings of the creatures I examined under the microscope, but could not find an exact match with any of the drawings in a book I have of Marine Plankton. However the book only covers a few dozen species; but how many different species are there in the sea? 

I understand that the mouth of Fred’s plankton net is about 2 ft diameter, Idon’t know how many minutes the net was towed through the water, but the little jars contained about 50 little creatures each, and  it amazes me that the largest fish in the sea, the Whale Shark and the Basking Shark, can not only survive, but grow to such a massive size, on such a meagre diet. It just indicates the countless numbers of these creature that inhabit the oceans, and shows why the two sharks spend most of their lives ploughing through the water with their mouths wide open!  

There were 207 reported sightings of Basking Sharks around Cornwall during June, mostly around West Penwith, but the odd ones turned up from as far east as Trevose Head on the north coast and Whitsand Bay on the south.

On 23rd June there were at least 100 Basking Sharks between Marazion and Cape Cornwall. Bottlenose Dolphins were reported 34 times from Porthtowan on the north coast to Mounts Bay on the south. 16 single Ocean Sunfish were seen from Crackington Haven on the north coast to Falmouth on the south. 12 reports of Harbour Porpoise were seen from Helford to Pendeen and Common Dolphins were seen 4 times, the biggest pod being about 30. There were 4 reports of single Minke Whales off Cornwall and a pod of 3 off the Scilly Isles. There were 2 reports of single Pilot Whales and one of a Risso's Dolphin off Cot Valley 

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