Helford Conservation Cruise
Sunday, 11th July 2010
Once again, the weather was kind, producing a warm, dry and wind-free day. With 95 passengers on board, plus tanks containing a variety of live fish, crabs and other creatures, the Enterprise boat headed to the mouth of the estuary and around into Gillan Creek, in sight of St Anthony church. The National Trust owns two small properties on the south bank, one containing Bronze Age barrows and an Iron Age cliff castle. Looking seaward there was a clear view of Nare Point and its observation post, now occupied by Coastwatch, but, during WWII, part of a testing range for air-drop torpedoes. Adjacent land had been used as a decoy site, with troughs of combustible material designed to delude enemy night bombers that they were hitting Falmouth Docks. The observation post sits on a raised beach. At a higher level is another and much more widespread plateau surface which forms the flat top of the Lizard Peninsula. This is a wave-cut platform, about 5 million years old. Uplift of the land, which raised it to its present elevation, caused the rivers to become incised, accounting for the steep sides of the Helford and other valleys.
The boat now re-entered the Helford and made its way up-river. The rocky shores on either side are made of shales, siltstones and sandstones, laid down on the bed of a deep sea about 380 million years ago. Subsequently, at about 300 million years, the rocks were compressed into E-W trends, which govern the line of the Helford, and intruded by mineralised granites. Very much later came the Ice Age. From about 600,000 years ago ice sheets dominated the northern continents, advancing and retreating four times with corresponding falling and rising of sea level. At maximum fall, sea level was 400 feet (120m) lower than today and when the ice finally withdrew, 17,000 to 7,000 years ago, sea level rose quickly, flooding the Cornish valleys to produce ‘rias’. The rivers and tributaries regraded to the new, higher base level, lost energy and dumped their sediment in their valleys. The Helford and its creeks are arms of the sea, stocked with marine, not freshwater, creatures. Penetrating far inland they provide sea-going routes for trade and leisure, whilst their muddy and sandy sediments are vital to marine and birdlife.
Heading up-river, David Muirhead mentioned the Durgan fish cellars, where pilchards had been salted and packed, and then told us about various fishing boats, interspersed among numerous leisure craft in the moorings between Helford and Helford Passage. At the height of the mackeral boom, hand-lining boats were landing 20,000 tons a week. Nowadays the fleet concentrates on net fishing , not trawling, for monkfish, turbot, ray and other species; and pot fishing for edible and spider crabs, crawfish and lobsters. Cornwall Sea Fisheries Committee administers regulations out to the 6 miles limit. Within the river, boat fishing for bass is not allowed from May to January, although shore fishing is permitted.
The fine weather had brought out canoeists and anglers and, perhaps for this reason, bird life had so far been in short supply. But in a quiet stretch near Mawgan Creek there was a treat as a flock of about 20 redshank wheeled away ahead of us and a pair of shelduck with 6 ducklings were seen. Andrew Tompsett discussed the Helford’s varied bird life and pointed out occasional egrets in trees and a pair of swans. Picking up the commentary, Abby Crosby explained the concept of the Your Shore project, a 3-year programme under the aegis of the Cornwall Wildlife Trust to enhance the activities of five Cornish VMCAs through education, school activities and volunteer involvement in marine conservation.
The boat had now reached Gweek and turned in front of the Seacore quay, where a large drilling platform was moored. Although now based in Falmouth, this international drilling contractor still uses its original Gweek base for some repairs and refitting. Pamela Tompsett noted that Gweek had long been a commercial port, with important boat building in the 1840s, several quays serving the hinterland and today a boatyard servicing leisure craft. Returning past the National Seal Sanctuary and a bed of Spartina grass, a favoured shelter for young bass, Ken McMullen told us about the National Trust property of Tremayne, which had been given to the Trust by the Trelowarren Estate. Much of the work involves managing the ancient woodlands, dominantly sessile oak, which are important habitats for bats and other species. The boathouse is occupied again this year by barn owls. Tremayne quay, a pleasant spot for a picnic, was built in 1846 in anticipation of a visit by Queen Victoria which didn’t materialise. Farther downstream is the National Trust’s property on the side of Frenchman’s Creek with, on the corner, the house built by ‘Powders’ Thorburn, a colourful character, artist, author and (alleged) gun smuggler.
We headed up Polwheveral Creek to the heronry, just south of Scott’s quay which had formerly been used to ship granite from Constantine quarries. There were a few herons in the trees and others flapping lazily overhead. More obvious were the startlingly white little egrets, about 20, which share the heronry although nesting later. Andrew explained that the egrets, moving north from Europe, had first nested in 1997 and are now established. This year’s count at the heronry gave 12 heron and 7 egret nests.
At the next location, the oyster farm in Porth Navas Creek, Abby told us that the Helford has been famous for oysters for centuries. Early leases were issued by the Bishop of Exeter. In more recent times the fishery was operated successively by four generations of the Hodges family and currently it is run by Ben Wright on a Duchy lease. Production is mainly of the native oyster, both from the Helford and brought in from the Fal for fattening and cleansing. Some quicker-maturing Pacific oysters are also reared. Oysters are vulnerable to predators such as starfish and crabs, and parasites, and last year were affected by the algal bloom which also caused problems for other species. Water quality is extremely important, since oysters are destined for human consumption, and Helford waters are very clean, category B and sometimes category A.
Moving out of the creek and back to Helford Passage, Abby noted the vessels of the Helford River Childrens’ Sailing Trust and talked about the various conservation designations which protect the Helford: AONB, SAC and SSSI. Particular mention was made of the eelgrass beds off Durgan, an environment ‘like an underwater meadow’ which is a haven for young bass. She expressed thanks to the captain and crew of Enterprise Boats, Nick Bailey for use of his pontoon, the National Trust and Derek Goodwin for tanks and live exhibits, the speakers and to the passengers for supporting the cruise and helping to make it a success.