East coast
Dolphins on the increase.
A recent study recorded sightings of six different species in an area stretching from North Northumberland to Whitby North Yorkshire and beyond down to the Humber. The species recorded were Harbour Porpoise, Common Dolphin, Bottlenose Dolphin, Risso's Dolphin, Long-finned pilot whales and White-Beaked Dolphin.
Rising water temperature and the abundance of food, such as herring and mackerel, now available are thought to be among the factors responsible for the increased numbers of whales and dolphins being reported from some parts of the North Sea.
White beaked dolphins were the most frequently-sighted species, including one particular sighting of a school - or group - of around 250 dolphins, 25 miles off Cullercoats
Local fishermen have also confirmed that they see large schools of dolphins migrating to and from the central North Sea at the start and end of summer.
Numbers of white-beaked dolphins tend to build up in late summer, often associated with aggregations of mackerel or herring. They are the commonest dolphin in the North Sea, ranging over wide areas particularly in the northern and central parts.
Perhaps the most surprising statistic revealed by the study was the number of sightings of Risso's dolphin - a flat-nosed dolphin which can grow to up to 3.8 metres in length - which accounted for 12 per cent of the total sightings. Risso's dolphins are primarily a warm water species, with few records from the North Sea, so that could indicate that the North Sea is getting warmer.
The sightings of common dolphin also support this theory, because they are more usually found off the South West of England, where the waters are warmer, extending in midsummer to the west coast of Scotland, but rarely into the North Sea, but in recent years, sightings have become more regular.
A local fisherman says the presence of Risso's dolphins in the North Sea could also be because of an increase in the numbers of squid, which are an important food source for Risso’s, as well as for White-beaked and common dolphins and the Long-finned pilot whale. .
The survey reported fairly standard behaviour in most cases, which helps us to be confident of the identification process. For example, Harbour Porpoise are a shallow water species, most commonly found swimming slowly close to the coast, and most of the sightings of them fitted this pattern of behaviour.
It was also recorded, more varied activity among white-beaked dolphins, Risso's dolphins and common dolphins. These species had more interaction with vessels, such as following the boat, rubbing on the hull, or even trying to score the occasional fish that escaped from the nets as they were being hauled in
Following up on the Dead Harbour Porpoise story we brought you, nothing and no one has been caught. In connection with their deaths
Dolphin Care UK suspects that pair trawling, where two boats stretch out a net between them, could be responsible for the deaths of these porpoises. They then become a bycatch to the fishermen who would simply dump them overboard.
The practice is illegal in British waters, but still practiced by some foreign trawlers beyond the 12-mile limit around the UK. We must catch the people responsible for these deaths and we must do it soon, Before any more die.
See more about bycatch:Bycatch