Eelgrass – An update

Readers of this newsletter will know that the HMCG, CWT and Natural England have a depth of knowledge about eelgrass belonging to the Zostera species. Stella Turk, Pam Tompsett, Roger Covey, Tony Sutton and Kevan Cook have all written about its natural history and distribution within the Helford and other areas of Cornwall. For good basic information about eelgrass the best place to go is the HVMCA leaflet. In addition, Phil Lockley’s film “Jaws of Helford” has some beautiful sequences showing the life amongst the grass.

The devastating affects of the Labyrinthula species of slim mould which greatly reduced Zostra marina within the Helford estuary and destroyed the inter-tidal beds of Zostera noltei and Zostera angustifolia in the past are well documented by Pamela and Tony in their 2000 Report. However there is increasing evidence that the meadows of Zostera are spreading once more and the establishment of the voluntary “No Anchoring Zone” off Grebe Beach in 2000 is felt to have played an important part. Kevan Cook’s article in the Autumn edition 2008 of the HMCG newsletter painted an optimistic picture of the health of Zostera in the Helford and pointed to some evidence that the beds are re-establishing themselves.

In Kevan’s presentation in Gweek in January of this year he explained that there is the possibility that the ever present slime mould will again ravage the beds as it has periodically since the major outbreak on both sides of the Atlantic in the 1930s. In addition eelgrass is vulnerable to the effects of runoff and physical disturbance. So, though there are good reasons to feel happy with progress, there is a need to educate people about the value of eelgrass and explain what can be done to preserve the beds and encourage their growth.

At the moment there is no systematic evidence for the current extent of the beds in the Helford but Tony Sutton is planning to undertake a survey of the transects he used in the 1990s with his students at University College Falmouth. This should establish a new baseline and is certainly a really exciting development.

In addition there is a plan hatched by Abby Crosby to take the cause of Zostera preservation to a wider audience. It is planned to produce articles for the local and boating press to explain the well documented importance of eelgrass beds, to encourage good observation of the no anchor zone, and to alert boat owners to respect the eelgrass beds that exist elsewhere. We will be producing a poster that we hope to be able to display in marinas, sailing clubs, pubs etc which will give basic facts about the species and the no anchor zone. Finally a Power Point presentation will be produced that can be taken to clubs, schools and other interested groups. We want people to appreciate that they can do positive things to preserve eelgrass, wherever it is, and maintain a vital habitat for a rich variety of organisms.

Mike Langshaw, HMCG member and CWT volunteer

Extract from HVMCA newsletter No.42 Spring 2011

Helford Native Oysters

The collection of native oysters for food has long been recorded from coastal and inland archeological sites even as far back as the Iron Age. Near Eastern traders and Roman settlers were familiar with oysters from their Mediterranean use and Turkish pirates were reputed to target succulent Cornish oysters! By the 16th century oysters became marketable here and with an increase in value, ownership rights were established and cultivation techniques evolved. Historically the main British industry developed on the coasts of Kent, Essex, Isle of Wight, Devon and the now abandoned beds in Scotland, whilst in mainland Europe it was chiefly in France and Holland. Until the mid 19th century, oysters were a ‘poor man’s food’ and huge quantities were sold. Now they are regarded as a luxury item!

The Helford River beds came under private ownership through church lands and royalty. Early in the 20th Century MacFisheries and subsequently the Hodges family leased the rights from the Duchy of Cornwall. Some four generations of the family have managed the oyster beds but now, in 2005, changes are taking place with a transfer of the lease to Ben Wright who has experience of marketing oysters in both France and England. (Ben will have more to add in the next newsletter.) Ben aims to regenerate the Duchy Oyster Farm beds whilst respecting conservation issues within a Special Area of Conservation and VMCA and following the advice of bodies such as Natural England, the Environment Agency and the National Trust.

His long-term project is to produce the high quality Native or flat oyster Ostrea edulis and his first job is to test the stock, rake and clean all the beds and identify the most favourable areas for bottom cultivation where the visual impact would be minimal. Motor powered dredgers will be used but, by buying in stock from the Fal, the historic oyster sailboats will also be supported in some measure.

A secondary project will probably include mussels and the Pacific oyster Crassostrea gigas after consultation with Natural England.

Problems with the Bonamia disease in Native oysters, which caused devastation some 25 years ago should be avoided by good husbandry, namely by removing all stock at the end of each year. Pacifics were less affected and would be useful to fill the market demand all year round.

Extremes of temperature, and storms which can cause silting, are natural hazards, whilst physical disturbance of the beds by pleasure boats or water sports enthusiasts cause concern. Accidental pollution of the water is an ever-present and serious threat to this long-established industry and everyone using the river and its shores needs to be extra careful with fuels, sewage and all chemicals. The high quality of water so essential to the successful growth of the Helford oysters is a factor that is also important for the marine wildlife in all its diversity -truly “Commerce, Conservation and Community” in action.

Pamela E Tompsett

Extract from HVMCA newsletter No.31 Autumn 2005

Records of more rare, beautiful and interesting species of the HVMCA

During August 2006, I visited Gillan Creek in search of hemipteran bugs. The creek has extensive stands of sloe (blackthorn) and ivy overhanging the waters edge. The purity of the air and the high humidity in this, and other areas of the Lizard Peninsula, ensures that most of the sloe bushes are richly clad with many different lichens. Gentle beating of these bushes, especially those with Usnea species of lichen, and capturing the falling debris in a net, yielded several small (approx. 3mm) lacebugs.

Examination of these bugs using a 10x-20x magnification binocular microscope reveals their true and amazing beauty. The intricate lace-like reticulations of the pronotum and forewings gives rise to their vernacular name of “lacebugs”. The species here on sloe isPhysetocheila dumetorum.

Further searching of the nearby ivy overhang, revealed another species, even rarer and more beautiful, the ivy lacebug Derephysia foliacea.

Earlier in August down on the muddy sand of the creek where the channel narrows, I had been searching for the obscure sipunculidworm Golfingia vulgaris when I noticed a minute (2mm) bivalve mollusc living in some of the worm tubes. This was Mysella bidentata, the two-toothed Montague shell which lives in a commensulate (= “eating at the same table”) relationship with Golfingia.

Further down the creek, towards the open sea and in cleanish sand, is a large population of the Potato sea urchin Echinocardium cordatum. When these are carefully excavated another slightly larger commensulate mollusc (6-8mm) is often revealed Tellimya ferruginosa(= reddish-brown) attached to the underside spines.

Finally in mid-August Chris and Dillan Bean contacted me regarding an unusual fish caught in nets just off Nare Point. Unfortunately the 32cm fish was member of the Amberjack family. I say unfortunately because the four species of this family found off our coasts are very similar and difficult to identify. After numerous precise measurements were made the fish was identified as the Greater amberjack Seriola dumerili, only the third authenticated record for British waters.

As I write it has come to my notice that during the dying days of August vast numbers of young Black bream Spondylissima cantharus have been seen in the Helford River – as one harassed fisherman said, “in plague proportions” . Again this highlights the importance of the HVMCA as a nursery for fish species many of which are of commercial importance. Incidentally the Black bream is known colloquially as the “Old Wife”, does anyone know why?

Dr Paul A Gainey

Extract from HVMCA newsletter No.33 Autumn 2006

The National Trust and The National Coastwatch Institution working together around the Lizard

A Partnership born on the Lizard

The National Coastwatch Institution (NCI) is a voluntary organisation set up in 1994 to restore a visual watch along UK shores after many small Coastguard stations had to close down because of Government cuts. When two fishermen from Cadgwith lost their lives off the Cornish coast below the recently closed lookout, local people decided to restore the visual watch and the first station opened at Bass Point near Lizard village. NCI was born. Others quickly followed suit and by 2006, thirtythree operational stations will be keeping watch around the British Isles.

The National Trust is an independent charity, founded in 1895 for the preservation of places of historic interest or natural beauty. The National Trust is particularly active on the Lizard Peninsula, where they own and manage over 20 miles of spectacular coastline and over 40 buildings for the benefit of the nation. From the sheltered beauty of Frenchman’s Creek on the Helford, to the wild open cliffs of Black Head and Predannack and the busy tourist attractions of Kynance Cove, Lizard Point and Mullion Harbour, all are managed by the Trust for the benefit of conservation and public access.

When the NCI approached the National Trust in 1994 with a view to using the disused Coastguard station at Bass Point as the first NCI station, the Trust were happy to oblige. Not only was this the birth of the NCI, but also the start of a long-term partnership between the two charities.

This year, the National Trust will be converting a further two buildings into Coastwatch Stations.

The small black hut overlooking Cadgwith was originally built as watch house by the coastguard service in about 1875. Later the focus of coastguard activities shifted to the Lizard and this building was reused as a huer’s hut, from where the pilchard lookouts (‘huers’) scanned the sea for shoals of fish. Using a system of semaphore, the huers would direct the small seine boats below in order to encircle and catch the shoals. Today the NCI are reusing the hut for its original purpose, as a Coastwatch station. The station will be manned on regatta days and during other events, keeping a watchful eye over this busy little fishing cove.

At Nare Point, commanding panoramic views across the mouth of the Helford and Falmouth Bay is a disused Cold War MOD observation point. The building was part of a torpedo testing range in Falmouth Bay between 1952 and 1993. Today it forms an important part of the landscape, a guide to navigation, and a link with an all too easily forgotten part of our recent past. It seems fitting that in peacetime, such a building is now being used for saving lives rather than warfare, thanks to the support of the National Trust’s Enterprise Neptune Campaign, and funding from the MoD Veterans Challenge Fund and the Tanner Trust.

It was also at Nare Point that Ealing Film Studios were commissioned to create a replica decoy model of Falmouth station to distract enemy bombing raids during WW2. Little evidence remains today of the simulated railway system except for the original control building and a concrete shelter.

The National Coastwatch Institution is presently recruiting watchkeepers for their newest watch station at Nare Point. Anyone interested in becoming a watchkeeper, or wanting more information about the NCI, is invited to contact Tom Symons 01326 240126. Visual watch-keeping means someone is on scene watching and listening, aware of local conditions even before an incident takes place, providing an accurate picture of events and thus helping to speed rescue. Most of the work of the station is routine surveillance. Watchkeepers must remain vigilant at all times, know how to deal with an emergency and report to HM Coastguard to co-ordinate the various search and rescue services.

They keep watch on potentially vulnerable craft and people; canoeists, sailors and fishermen can easily get into trouble in the unpredictable waters around the Lizard. Watchkeepers also monitor Channel 16, the distress channel, listening out for vessels in distress. Records are kept through logging of all passing vessels, aircraft, walkers etc, as well as giving information to HM customs, police, and harbour authorities.

What doPortable PMA watchkeepers do ?

Watchkeepers must be ready for anything from contacting HM Coastguard in an emergency to informing a local farmer that a sheep is stuck on a ledge. Fishermen and yachtsmen frequently telephone the look-out for local weather conditions before setting out from the safety of the harbour. Walkers too may call in for advice before tackling hazardous coastal paths and dolphin, seal and basking shark sightings are reported to wildlife organisations.

Extract from HVMCA newsletter No.33 Autumn 2006

Bahamas vs The Manacles

Without hesitation most divers would choose to spend a few days in warm Caribbean seas than in cold British waters. No contest surely. Over-there, 30m visibility in azure blue seas teeming with life. Over-here? Well it’s so variable. But even on a good day with our grey-green waters and limited visibility no match for the vibrant West Indies.

In the 1970s I had dived in the Caribbean and been thrilled with the sight of shoals of French grunt and Striped porkfish around wrecks; the parrot fish, angels and Nassau groupers on the reefs. And the invertebrate life was equally colourful and packed: sponges, gorgonians and hard corals, like elkhorn.

Last year I returned to some of the same islands, but it was a Caribbean I hardly recognised. No shoals of French grunt or porkfish greeted me. And where was that icon of West Indian waters, the ubiquitous elkhorn coral? One little bit I spotted and it was bleached and dead.

On what was reckoned to be – by local dive guides – one of the best dives for marine life off south west New Providence Island there were a series of small coral heads, acting as miniature coral reefs with gorgonians, sponges, fire and brain corals. They were populated with just small numbers of reef fish, like blue tang, trumpet, blue chromis and small parrot fish.

The two wrecks we dived had very little marine growth although one was sunk 10 years ago. No fish shoals surrounded them.

This is quite different from Cornish waters where all wrecks appear to have their fish populations. In summer on the Manacle reefs off the Lizard it is possible to see shoals of mackerel and bass along with groups of mullet, cuttlefish, the wrasse family, plus all the invertebrates like jewel anemones, plumose, dead man’s fingers, crabs and lobsters.

What we have, many believe, has diminished over the decades, but nothing like as much as in some parts of the Caribbean.

The national fish of the Bahamas is the Nassau grouper. It occupies a similar role in the Bahamas or West Indies as does cod here. It is one of the most important commercial fish in the West Indies and it is now on the World Conservation Union’s (IUCN) Red List of Endangered Species. Due to over-fishing it has already been eliminated from much of its historic range in the Caribbean.

Normally a solitary animal it aggregates in December, January and February to form huge spawning shoals at specific sites throughout the Caribbean. These balls or walls of grouper, numbering up to 100,000, have provided spectacular sights for divers and underwater photographers in the past. Unfortunately these aggregations have also provided a harvest bonanza for fishermen who have been so successful in netting these shoals that the Nassau grouper is now commercially extinct throughout much of the Caribbean. Fishing for Nassau grouper is now banned in many areas during the spawning period. Bermuda banned it 30 years ago, but the Nassau grouper has not returned.

The fear of losing more marine life is leading to the creation of Marine Protected Areas (MPAs) but there is strong resistance from the fishermen. There are proposals for MPAs covering the south western reefs of New Providence Island, Abaco, Walker’s Cay and the Biminis.

Existing MPAs such as the Exumas Cays Land and Sea Park, Pelican Cays National Park at Abaco, and Lucayan National Park at Grand Bahama Island certainly have a lot more marine life and are regarded as having been successful. MPAs are also likely to be proposed here in the UK and are also likely to be fiercely opposed by the fishermen. Still, MPAs will not save elkhorn coral. It is dying because sea temperatures are rising.

Corals flourish in the narrow temperature range 25-29 deg C. When we were diving it was around 30 deg C and that was in October when surface waters would already have started to cool. Bleaching is said to occur when water temperatures reach 32 deg C.

So today it wouldn’t be hard to argue that in good visibility in the summer there is more to see on a Cornish reef like the Manacles than in many parts of the Caribbean. The next question could be: “But for how long”.

Tony Sutton

Extract from HVMCA newsletter No.33 Autumn 2006

Helford’s past seen through its place-names

Places in the past were usually named in a straightforwardly descriptive way, often from the names of people who lived there. Sometimes these descriptions contain valuable clues to the botany, or occasionally the fauna, of the place when it was named. Through tracing the names in historical records we can gain an idea of how old a place- name may be, although we can never be sure how long before its first appearance a name was formed.

The Lizard district is particularly fortunate in having two charters from the Anglo Saxon period. When an Anglo Saxon king made a grant of land, the bounds of the land were often specified in detail; so we have the boundaries of six small estates in the Meneage, in charters dated 969 and 977. These estates were at Lesneage (SW7722), Penare (SW7924), Traboe (SW742l), Trevallack (SW782l), Grugwith (SW7520) and Trethewey (SW7323). The bounds of these estates can give us a glimpse of the landscape, as seen through the eyes of local people over a thousand years ago. In a few cases there are place-names of natural- historical interest.

One boundary-point appearing in the bounds both of Lesneage and Grugwith is Lenbruinn, ‘pool of rushes’ (Cornish lynn ‘a pool’ and broinn, later bronn, ‘rushes’). The larger estate of Lesneage (a name which means ‘the court of the Meneage district’) actually reached to the south of Grugwith, onto Crousa Common, so this pool may have been the large one at SW767199, though the name has not survived. The rushes may have been valued and used, perhaps for thatching or for matting, or for wicks in candles. Another pool in the bounds of Trethewey is Lyncenin ‘pool of ramsons (wild garlic)’, on the stream which forms the parish between St Martin and St Mawgan parishes, probably at SW729233. I have seen ramsons in this area. A third such pool is Poll haescen ‘pool of sedge’, on the boundary of Traboe estate, probably at SW746227, an area where David Coombe noted great tussocks of sedge. One more watery name in these boundaries is Fonton Morgeonec ‘anthill spring’ , in the bounds of Grugwith, evidently a spring distinctive for a very large anthill, or for a number of anthills, close by; this spring was probably somewhere on the stream running to the north of Grugwith. Up on Goonhilly Downs, probably near the Earth Station where five parishes meet, lay Cruc Draenoc ‘thorn-brake barrow, a tumulus either overgrown with thorn trees (probably
blackthorn rather than hawthorn, if so), or lying within a thorn-brake.

Although it does not incorporate a name, the boundary of Penare in 977 is notable because the boundary of the farm was exactly the same in 1840. This means that the hedge forming the boundary (starting at SW797242) is presumably over a thousand years old, though it may have been rebuilt, perhaps many times, during its life, and in this windswept area it certainly does not show the great variety of plant species which we might have expected.

Other names which are not recorded so early are also of interest. North of the Helford River, in Constantine parish, is the farm of Bonallack (SW7126), ‘broombrake’. (The Cornish adjectival ending – ek, often found as – ack, was used to mean place where (a certain type of) plant grows’. Another example of the same name is Menallack, in Mahe parish (SW7431). Both Bonallack and Menallack must have had considerable growth of broom-plants to have gained their names from them. Bonallack is first known in about 1250, and Menallack in 1327, so the broom-brakes must have existed in about 1200 or 1300, at the latest. Both Halliggye in St Mawgan parish (SW7123) and Halligey in St Martin (SW7323) are similarly named from patches of willows (Cornish helyk ‘willow trees’). Perhaps the most surprising name is Carplight, a now ruined farm in Manaccan parish. This name is found as Crupleid in 1199, hut the spelling Crucbleyth in 1327 gives the sense better: ‘wolf’s harrow’ (Cornish cruk ‘harrow’ and bleth ‘wolf’): the farm was presumably named from the earthwork above it (SW749237). At some time before 1199 (again we cannot know how long before) this earthwork must have been known to be frequented by wolves. Less dramatically, the farm of Carnbarges in St Martin parish (SW7424) was named from a rock or tor frequented by buzzards (Cornish bargus ‘buzzard’).

Oliver Padel
St Neot, March 2006

Bibliography

All the Anglo-Saxon charter-boundaries of Cornwall are discussed in detail by Della Hooke, Pre -Conquest Charter-Bounds of Devon and Cornwall (1994), and some of them also by Oliver Rackham, The History of the Countryside (1986).

Details of the Cornish words found in the place-names are given in O. J. Padel, Cornish Place-Name Elements (1985), and a broader introduction to Cornish placenames in Padel, A Popular Dictionary of Cornish Place Names (1988).

Extract from HVMCA newsletter No.33 Autumn 2006

Trigging and the Common cockle

In 2003 byelaws were passed in order to protect the common cockleCerastoderma edule from overexploitation in Cornish estuaries. It is important to maintain a healthy breeding population and it was decided that the recommendation of a minimum collection size of 20mm, about the size of a 20p piece, would assist in this aim together with a ban on harvesting by mechanical means such as suction dredgers.

Although suction dredgers are unlikely to be used in the HVMCA the practice of trigging or cockle collection by hand-raking on Good Fridays has continued and the Helford MC Group members have observed the triggers at work!

This information has been reviewed by Rhiannon Pipkin on behalf of the Group and she has summarised her findings as follows:

“Over the last 10 years the Helford Voluntary Marine Conservation Area Group has carried out a series of informal surveys on Good Friday at the main cockle beds of the Helford Estuary at Bar Beach, Treath and Gillan. These surveys are aimed at providing some monitoring of the number of people trigging and the approximate number of cockles being removed from the beds as a result. The surveys have been spurred on by worries of the cockle populations of the Helford River being in
decline, a view shared by many of the local triggers.

Surveys of 1996, 1999, 2003, 2004 and 2006 have been examined and combined with studies performed by the Environment Agency for the Helford area. Findings indicate the number of people trigging each year to have altered little over the last 10-year period, and the sources of triggers to have remained much the same.

It is estimated that an average of 17-gallons of cockles has been removed from Bar Beach each Good Friday. The surveys of 1996, 1999 and 2006 indicate a 20% decrease in the number of cockles being removed from Bar Beach in the last 10 years, although it is not yet established whether the cockle population has definitely declined. For this to be determined further
survey work is required, measuring the cockle population of the area, and examining the age structure of the beds. New data would be particularly useful to investigate any effect that the 20 mm minimum size for collection has had on the cockle
populations as Jones (2000) suggested that applying this minimum size limit might improve recruitment of
some cockles by 60%.”

I hope that one day we may find resources to repeat the detailed fieldwork in the earlier studies.

Pamela E Tompsett

Extract from HVMCA newsletter No.33 Autumn 2006

“Community, Commerce and Conservation working together” Helford River Sailing Club

Helford’s herons and enigmatic egret

Two of the Helford’s most noticeable birds are the two resident members of the Heron family the Grey Heron (Ardea cinerea) and the Little Egret (Egretta garzetta). Almost the size of a Golden Eagle, the Grey Heron is the most widespread large predatory bird in the UK, equally at home in the remote highlands and islands, rivers and marshes in the English lowlands or in many urban parks. The Little Egret on the other hand, is currently progressing a steady march northwards from the English Channel coast which commenced in the late 1980s.

By the time you read this, I will be undertaking my annual count of the nests of these birds on the Helford for the British Trust for Ornithology (BTO). Started in 1928, the BTO’s Heronries Census is the longest-running single species survey in the world. Quite obviously a mass of data has been gathered over the years that enables the population to be monitored very accurately indeed. The UK population is currently estimated at around 14,200 pairs. This represents a 30% increase since 1978. Helford contributes about 0.1% towards this total! Since the mid 1980s, all the herons on the Helford have congregated to form a single heronry in the mature oak woodland on the western side of Polwheveral Creek. Since that time numbers of pairs have usually been in double figures. Recent counts include (number of pairs in brackets): 2006 (14), 2005 (13), 2004 (12), 2003 (10) – generally very stable numbers. Prior to the mid 1980s there appear to have been smaller heronries scattered across the Helford Estuary – for example at Carne in Gillan Creek.

However, studying some of the statistics surrounding the Little Egret, it almost beggars belief that the species is doing so well. You may well know that the trade in egret feathers in the Victorian and Edwardian fashion industry led directly to the formation of the Society for the Protection of Birds in 1889 (it became ‘Royal’ 15 years later), but are you aware of some of the astonishing figures behind the headline? In the first quarter of 1885, 750,000 egret skins were sold on the London market; in 1887 a single London dealer handled 2 million skins; in 1914 India, 1 ounce of feathers was trading at 10-28 times the equivalent weight of silver. We might think that ‘factory farming’ is a relatively modern phenomenon – it isn’t. To meet the insatiable demand, egret farms developed with pens holding up to 60 pairs. When the eggs hatched, they were removed and hand-reared, causing the birds to lay again. Sometimes pairs had 4 or 5 broods a season. As if this wasn’t bad enough for them, they were themselves plucked four times a year.

Considering that this only took place a century ago, one can only marvel at nature’s rejuvenating powers. From the 1950s the Little Egret colonised westwards across much of Europe arriving in Brittany in 1960. 20 years later they had reached the UK and following a long period of raised hopes by ornithologists, breeding was first confirmed at Brownsea Island in Poole Harbour in 1996. Helford followed a close second the year after. Nature herself can be fickle however. While numbers of pairs nesting at Helford jumped from 5-6 pairs in 2004/5 to 11-12 in 2006, during a visit to Brownsea last year the warden told me that they are now seeing no young fledged due to predation by ravens. Would anyone condone action to protect a new ‘invasive’ species against a long-standing native? The question is rhetorical.

Each year I am surprised how difficult it is to accurately count the nesting pairs. Despite their large size and the fact that they nest early before leaves are out, the nests can be well hidden in the dense ivy that clumps in the canopies of the oaks. It seems to get denser each year. The egrets sit slightly later than the herons. By Flora Day the oaks are bursting and it is a real challenge to pick out the motionless snowy-white birds through the foliage. By that time the heron chicks are well-grown and often standing up in the nests awaiting their next meal.

If anyone fancies experiencing a dawn watch at Polwheveral, the dawn chorus walk at 0630 on Sunday 22nd April will get us quite close. I can’t promise a repeat of last year, though, when on a cold but sunny April morning I had fantastic views of only my second Cornish Osprey fishing below the heronry and then perching alongside it. But you never know……
It will be interesting to see if the number of Egrets overtakes the Herons this year, and to observe if their interactions change as the balance of the two species alters in their breeding colony.

Martin Rule, with thanks to BTO and Birds Britannic

Extract from HVMCA newsletter No.34 Spring 2007

Time to watch out – string jelly’s about

As yet the nearest sighting of these ‘strings of jelly’ to the Helford River has been a record in Falmouth Bay, but it is a species that is likely to make itself felt (literally) more often in the future. Yes, it’s probably another ‘southern’ species extending its range northwards. It is arguably the largest known invertebrate and hitherto there had been no recorded instances in Cornish seas.

So what is this mysterious creature, the common names of which are ‘String Jelly’ or ‘Stinging Hydroid’? Both are descriptive, for it looks like a long piece of unravelling string, and they can sting, as many divers will testify. They are members of the genus Apolemia, the systematics of which are unclear and are thought to be A. uvaria, which was first described in 1815 by Lesuer. They are colonial animals (Siphonophores) related to the Portuguese Man-of-War (Physalia physalia) and the By-the-wind-sailor (Velella velella). In Norwegian seas one of the species is blue in colour and known as ‘Blue Fire’ and is known to have caused the death of fish in a salmon farm. The Cornish examples were all pink, although the colour may not be of significance.

Attention was first drawn to the ‘String Jelly’ by Rory Goodall, when he saw the strange creatures between Penzance and the Scillies. He informed Joana Doyle, Marine Officer of Cornwall Wildlife Trust, and Ray Dennis, who maintains the marine sightings database for Cornwall. Ray subsequently arranged for Dr Paul Gainey, a local marine expert, to see this phenomenon. He describes them as being present in tens of thousands, varying in length but mostly about 25cms long, but some extended specimens up to 2m in length. Some were seen releasing minute reproductive jellyfish (medusae). String jellies are known to form chains up to 20m or more in length. Each long chain is headed by a small buoyancy bladder (the equivalent bladder in Portuguese Man-of-War is shaped like a Cornish pasty), but the long string is very fragile and is soon broken up into shorter lengths, all of which are reproductively viable.

These short lengths have been described as like ragworms, and I now realise that some stinging strands previously reported to me were probably this species, but never has it been seen in such numbers as in 2007!

Stella Turk

Large Helford Sea-hares – Aplysia depilans

On Tuesday 16th October 2007 Tony Sutton was diving on the eelgrass bed at 5.7m depth in the Helford VMCA when he came across some exceptionally large greenish brown sea-hares (35cm) which attracted his attention. When he returned a few days later with his camera he was able to take some excellent pictures which indicated the species Aplysia depilans. Confirmation of this identification was established by Dr Paul Gainey when one of the animals was taken briefly from the water.

The commonest species of sea-hare in our shallow water is Aplysia punctata which can reach some 20cm extended length but is more usually below 10cm. They are typically found on the sea-bed grazing on algae, often amongst eelgrass where they leave their yellowish pink egg strings during the autumn-spring breeding season.
Sea hare A. depilans photograph by Tony Sutton
Sea hare A. depilans with eggs photograph by Tony Sutton

More impressive are the other, much less common, species Aplysia depilans and Aplysia fasciata the former is known to reach 30cm and the latter can be even larger at around 40cm. Both are associated with the warmer seas of the Channel Islands, Atlantic France and the Mediterranean as well as Madeira and West Africa where A. fasciata in particular can be observed swimming more freely than our A. punctata. Two large parapodial lobes and the broad “slug-like” body pulsate rhythmically carrying the animal through the water with a flapping motion.

Tony was fortunate to find some animals with egg masses. Could this be linked to the significantly warmer sea temperatures of recent years? In 1976, the Opisthobranch expert, T E Thompson, remarked that it is not known whether Aplysia depilans ever breeds in British waters.

Recent reports of large sea hares from other sites include Poole Harbour – one weighing 1.5kg Aplysia fasciata still swimming happily, grazing on sea lettuce   Ulva lactuca at the National Marine Aquarium and producing egg masses. Four more, probably of the same species, were caught and released in Poole by local fishermen. The Blue Reef Aquarium, Newquay has also received one. Other reports, some of which could have been of either of the larger species, have been received from Mevagissey, Falmouth, Beesands, Tor Cross, Nos Mayo, Devon and St Helier, Jersey.
Sea hare A. depilans photograph by Tony Sutton

How can you tell the difference between the two larger species by the shore – not easily and dissection seems inappropriate. Try looking, especially underwater, at the two large parapodial lobes mentioned above which are free all the way to the end of the body in Aplysia fasciata but in Aplysia depilans they are joined rather high posteriorly – see Tony’s photos. The oral tentacles at the front are more frilled in A. fasciata. Try to take photos that show these characteristics! These are not easy to see if you find something looking like a large lump of gelatinous liver on the shore but could be seen if a freshly stranded animal was placed in a bucket of sea water.

All sightings of these larger species would be of great interest and Dr Paul Gainey would try to visit any find within range or as far as practicable Tel: 01326 372 840.

Dr Pamela E Tompsett

Extract from HVMCA newsletter No.35 Autumn 2007

Maritime and marine emergency planning

There is a constant programme of European funded initiatives underway, many of which relate to the health of our marine and maritime environments. The initiatives are invariably partnerships between counties, regions or countries. The Cycleau project was a good example of this work which was carried out in Cornwall.

A project which is due to finish at the end of October is the EROCIPS project (Emergency Response to Oil, Chemical and Inert Pollution) which involved Devon and Dorset County Councils as well as Pembrokeshire CC, Northern Ireland, Brittany and so on. One of the investigative aspects of the project was to look at risks from shipping in the Western Approaches. This included research on the number, size and scale of shipping movements carrying hazardous cargo, together with aspects of the coastline which would be impacted in the event of an incident. Coastal types, access, fisheries, scientifically listed and protected areas etc were all studied.

At a late stage in the project the contractor asked if Cornwall could supply data to populate and properly finish the study. With great, and speedy, assistance from Cornwall Sea Fisheries, the Environment Agency and others, together with data we had already collated for our Beach Clean up guidelines, I was able to supply the required data by the almost impossibly short deadline. As this newsletter goes to press I am waiting for the final EROCIPS report to be published.

Separately I am reviewing the former Fal Emergencies plan which is designed to provide a co-ordinated response to maritime emergencies, other than oil pollution. A review meeting in July saw representatives from all of the ‘blue light’ agencies, Falmouth Port, Harbour Masters, Defra (Transec), Port Health Authority and CCC Emergency Planning staff working together to update the plan. One major outcome from this meeting was the inclusion of the Helford estuary fully into the new Fal Bay and Estuaries Maritime Emergency Plan. Scenarios which would be covered by this multi-agency response plan include collisions, groundings, sinking, fire, disease outbreak, major pollution of the watercourse and dangerous goods related incidents which are beyond the routine capabilities of the harbour authorities or public services. Individual agencies are submitting their own segments of the plan. I hope that the plan will be completed and in place before the end of the year.

Finally, many of you will remember John James, Emergency Planning Manager, from Cornwall County Council, who was instrumental in early support for the HVMCA. John has just retired. I am sure that you will join me in wishing John a long and happy retirement.

Martin Rawling
Emergency Planning Officer
Cornwall County Council

Cornish lobsters – new tagging study

Cornish shellfishermen are being asked to look out for tagged lobsters in their catches over the next couple of years, as part of a new study by Cornwall Sea Fisheries Committee. Up to 2000 lobsters, mainly undersized, will be tagged in an attempt to gather more information on their movements and growth rates. This work, which is being funded by the Fishmongers’ Company, will help to build up a clearer picture of local lobster stocks.

The blue or orange plastic tags which are printed with a unique CSFC number, are inserted into the muscle tissues between the carapace and the tail, leaving two streamers visible outside the shell. Fishermen are being encouraged to record the position (Lat/Long), depth and date on which the lobster was caught, and the number and colour of the tag, before returning the lobster to the sea. If possible, they are also asked to measure the carapace size. Special recording forms and a limited number of plastic vernier callipers are available from the CSFC office for this purpose. All returned forms and any other records of the tagged lobsters will be entered into a draw with a prize of £50.

At this stage, lobsters are being tagged in Mounts Bay (blue tags) and from Port Isaac Bay to Bude (orange tags). In future years it is hoped to extend this programme to other areas but as lobsters are capable of moving many miles, it is still possible that some of the Mounts Bay lobsters may find their way into Falmouth Bay and up to the Helford.

Sam Davis, Senior Fishery Officer, who is carrying out the tagging, said that, “As a result of our recent shellfish stock survey and from talking to local fishermen, we identified a need for more detailed information on our lobster stocks. The skippers involved have been really positive about this work and we have already received two reports of tagged lobsters within a few days of the project starting”.

Further information on this work can be found on the CSFC website www.cornwall.gov.uk/seafisheries, in the  Research and Environmental section and recording forms can be obtained from the CSFC office or from fishery officers.

Extract from HVMCA newsletter No.35 Autumn 2007

The Lizard Peninsula Heritage Trust

The Lizard Peninsula Heritage Trust, a registered charity formerly known as ‘Friends of the Lizard’ from its origins in 1997 until 2005, has published a new promotional leaflet with grant-aid from Kerrier District Council’s Community Grant budget. The leaflet sets out the Trust’s evolving wide interest in all matters that contribute to the natural, historic and man-made environment of the Lizard Peninsula, with the twin aims of seeking their protection and enhancement, while promoting their understanding and enjoyment.

Chairman of the Trust, David Richardson from Coverack, said “This general leaflet is the first in this year’s publications series. Subsequent titles will include ‘Conservation Areas’ and ‘Historic Buildings’, followed by ‘Archaeology’ and ‘Parks & Gardens’ probably in the following year. We hope that it will give both residents and visitors a brief introduction to the very special environmental qualities of the Lizard Peninsula, but also an insight to our aims and objectives.”

Kerrier District Council’s portfolio holder for Leisure, Arts & Culture, Cllr Loveday Jenkin, said “We are delighted to have supported this publications initiative by the Lizard Trust, which will increase the public’s awareness of this unique part of Kerrier’s area. It is important that we all work together to protect and enhance our environmental heritage.”
Kerrier’s community grant scheme offers grants of up to £2000 to support community groups that aspire to the Council’s Community Strategy and the work of the Environment team. The grants are designed to increase participation in cultural activities, sport/active recreation, encourage increased use of Kerrier’s open spaces and support the aspirations of Parish and Town plans. For further information or an application form, please contact Kerrier’s Regeneration team on 01209 614061 or by email at regeneration@kerrier.gov.uk.

The leaflet, with membership details, will be freely available at various public outlets in Helston and the Lizard area, or by contacting David Richardson on 01326 280058 or by Email at d813richardson@btinternet.com

David Richardson
Coverack TR12 6TP
Chairman, Lizard Peninsula
Heritage Trust
Registered Charity No 1092934

Extract from HVMCA newsletter No.36 Spring 2008

Rock Crevice Fauna

Having recently become very much more interested in the beetles, Coleoptera, of Cornwall, I have looked for some that actually live between high and low water marks, inhabiting rock crevices where, presumably, small pockets of trapped air enable them to survive when the tide is in.

In summer 2006 several visits were made to the shores between Prisk Cove and The Bar, Helford Passage to look for the two particular small beetles Aepus robinii and Aepus marinus – no common names. My first visit to Prisk Cove involved moving ‘slabs’ of loose rock to reveal the sand-filled rock crevices below. This specialised habitat revealed a whole variety of different animals – centipedes, gastropds (snail like molluscs) and mites to name but a few. A short search of one crevice yielded a pale, yellow-brown 2-3mm beetle. This was Aepus robiniicharacterised by eyes protruding slightly from the side of its head and smooth, lobed wing cases with 3 or 4 very long stiff hairs on each.

Also present in the crevice were large numbers of the familiar grey-blue collembola (springtails) Anurida maritima, often seen as ‘rafts’ in rock pools, on which the beetles probably feed. Aepus robinii is a Nationally Scarce (B) species with a more southern European distribution extending from southern Britain along the Atlantic coast of France and Spain to the Mediterranean area.Although the second and somewhat rarer A. marinus was not found then, two other interesting and rare species, the pseudoscorpionNeobisium maritimum and the bizarre and somewhat obscure Echiuran worm Thalassema thalassemumwere found sharing the same habitat as A. robinii. The greatly enlarged and pincer-like second pair of appendages of Neobisium maritimumgive it a superficail appearance of a tail-less scorpion, hence the name pseudo-scorpion. N. maritimum is about 3mm long and is a rich olive-brown in colour. This Nationally Scarce (A) species is perhaps nowhere more common in Britain than on the Cornish coastline.

Thalassema thalassemum, an obscure, unsegmented ‘worm’ also prefers mud and sand filled crevices especially on the lower shore. The main body is 2-3 cm long with an extensible proboscis 1 – 20 cm long, tapering to a point, altogether a rather strange animal! A provisionally Nationally Scarce species it occurs northwards from the Mediterranean to southern Britain where they are relatively common in Cornwall and Devon but very rare elsewhere.

The second Aepus beetle, A marinus, was later found on or about the high water mark between the Ferryboat Inn and The Bar. Whereas this does occur as part of the rock crevice fauna its preferred habitat is under stones lying flat on fine sand or shingle. This Nationally Scarce (B) and Biodiversity Action Plan (BAP) species has a much more restricted distribution range extending from southern Norway along the English Channel to northern Brittany. About the same size and colour as A.robinii it has greatly reduced, non-protruding eyes, and square-cut downy wing-cases.
Since the original search for the above species they have been found in good numbers throughout the search area, yet a further piece of evidence of the importance of the Helford Estuary, and near confines, for rare and interesting species!
N.B. After removing the loose ‘slabs’ of rock and examining the rock crevices beneath, each slab was replaced carefully in exactly the original position.
Dr Paul A Gainey

Extract from HVMCA newsletter No.36 Spring 2008

Green Tourism beside the Helford River

The Budock Vean Hotel, three times winner of Cornwall’s Hotel of the Year Award and Gold Award Winner for Green Tourism, celebrated the New Year with two new eco-tourism awards.

The Budock Vean achieved Gold in the Sustainable Tourism Initiative of the Year category of the Cornwall Tourism Awards 2007. Judges were impressed by the Budock Vean’s strong sustainability ethos where care for the environment was clearly at the heart of operations.

The level of commitment and thoroughness of sustainable practices shown by the hotel to reduce their environmental impact was highlighted as an example to other businesses in the tourism industry.

The Cornwall Sustainability Awards 2007 also named the Budock Vean as Medium Sized Business Winner for its best practices of sustainable solutions that help save the planet and make economic sense.

Second generation owners Martin and Amanda Barlow have made considerable efforts over the past seven years to run the hotel in an environmentally friendly way to benefit their native Cornwall.

Recent initiatives are inventive and varied and include:

• the use of a granular organic fertiliser combined with mycorrhizal fungi to feed the gardens and the nine hole golf course.
• a clever UV dechlorination system which recycles every three weeks 10,000 litres of wastewater from the pool and the hot tub to water the gardens and the golf course every three weeks.
• waste water and sewage discharge occurs to enzyme-activated septic tanks and feeds an alder bed. This is a core part of a strategy to ensure that the Budock Vean does not pollute the Helford River as a result of business activities.
• The Budock Vean is totally committed to purchasing as many products and services as possible from Cornish and in particular local based suppliers. In 2007, the hotel spent approx £3 million with suppliers and 75% of this total spend was with suppliers within the county.
• Over 25 native species of trees and wildflowers have been re-introduced and the nesting boxes accommodate bats and wild birds.

The word is spreading and the Budock Vean has been listed in the top 50 greenest hotels in the UK and short listed in the Virgin responsible Tourism Awards. Martin Barlow was recently invited to advise hoteliers in the Isles of Scilly on best environmental practices.

The Barlows agree that ‘going green’ will never jeopardise their guests feel good factor and believe that the Budock Vean is its own best advert for the eco approach in this highly competitive industry. Guest repeat and recommended stays account for 64% of the bookings year on year.

And as for the future? Budock Vean is committed to becoming less oil dependant and plans are in hand to make the hotel estate a mini generator of energy rather than purely a user.

For further information visit www.budockvean.co.uk.
Martin and Amanda Barlow – owners Budock Vean Hotel

Extract from HVMCA newsletter No.35 Autumn 2004

Spider crabs – the wildebeest of our waters

Whilst many of us enjoy the odd crab sandwich (or maybe more), far fewer people have sampled the delights of spider crab, despite its delicious sweet flesh and great abundance around our coasts. Perhaps because of this perceived lack of commercial interest, there has been very little targeted research into spider crabs within the UK. By contrast, a great deal of effort has been put into researching these animals in Spain where the major European fisheries are, and also in France, the Channel Islands and Ireland.

There are numerous spider crab species found across the world from Chile to the Lebanon, with the heavy weight title going to a species found in Japan whose leg span can reach over 4 ft! In the waters of Cornwall and in the Helford, there will be both the commercially targeted spiny spider crab which can range in size from 50mm to 200mm along the length of its body, as well as the ‘true’ spider crabs which are delicate little creatures often only 10mm long.

Male spiny spider crabs have a triangular, flattened body with large claws, whilst the females are rounder and have a curved flap underneath their body in which they store their eggs. Generally they have one brood of eggs per year although up to four broods have been reported. Usually these berried (egg bearing) females are not landed as their eggs clog up the tank filters in the lorries in which they are transported to mainland Europe.

Unlike many other crabs, spider crabs do not moult every year. Once they reach their ‘teenage’ phase in their second year, the females have a terminal or final moult, after which they do not grow any further. The males have one additional moult during which they grow their distinctively larger claws which are essential for defence and for successful mating. In a few cases, mutations occur resulting in crabs which have half male and half female characteristics, locally called ‘halfies’ in Cornwall and ‘strangers’ or a more non-pc term further up the south coast! In the population, there will be a range of different sized crabs which may all be of a similar age and they can live for up to 8 years. One interesting piece of recent research has used the rate at which their claws erode as they walk about the seabed, as a way of estimating their age. Younger crabs have pointed black claws whilst the older crabs are walking about on worn out stumps!

They have a complex lifecycle during which they undertake mass migrations annually from our coastal waters to deeper offshore and back again, like the wildebeest of our waters. The juveniles live in shallow rocky areas where they feed on a variety of animal and seaweed species. In order to hide from predators, they decorate their shells with seaweed and sponges and some species are known as ‘decorator’ crabs. The local name for these juveniles is ‘commandoes’, after soldiers’ habit of wearing camouflage on their helmets. Some adults also carry often large numbers of a parasitic sea anemone on their legs.

Once they need to moult, spider crabs will seek shelter and have been recorded in eelgrass beds, ripping up the eelgrass fronds. Newly moulted crabs are bright reddy orange in colour with very sharp spines. In Cornish waters, females will migrate into shallow sandy areas to mate in April and May and they are often found on the seabed in huge mating aggregations of hundreds of animals. It is at this time of the year that they are caught in pots and nets all around Cornwall but especially on the north coast. In the winter, they migrate offshore again and in Falmouth Bay, a number of local vessels from Helford and Cadgwith catch the larger male crabs which command a good price and are a welcome boost to winter earnings.

Once regarded as an unmarketable nuisance by inshore fishermen, common or spiny spider crabs now make up over 30% of crustacean shellfish landings into Cornwall. The overwhelming majority of these crabs are exported alive in vivier lorries to France and Spain as sadly, there is very little domestic demand for them at present. Both male and female crabs are eaten but the males tend to be larger, with more claw meat and therefore more marketable. Often, merchants will not accept the smallest females and this has led to an approach to Cornwall Sea Fisheries Committee to undertake some research into spider crab stocks during 2008, with the aim of investigating the merits of raising the minimum legal size from 120mm to 130mm, the same size as the males (or jacks).

Sam Davis, Fisheries Officer, CSFC

Extract from HVMCA newsletter No.36 Spring 2008

The history of Cornish seaweed observers

One of the delights of dabbling in rock pools is to meet scuttling crabs, glistening anemones, darting fish and a whole range of amazing shells. All of these are set amongst a colourful array of seaweeds, red, green and brown, which provide shelter and food for so much of our marine fauna both on rocks and fringing our creeks.

Over 640 British seaweed species have been identified; some 400+ occur in Cornish waters and nearly 300 different species have been found within the Helford VMCA. Who are the people that have made these discoveries?

The very first published work on British seaweed was prepared in Cornwall. This is not so surprising when the geographical position of Cornwall is considered, together with its rias, different aspects and varied geology, offering a multitude of rock pools. Indeed experts on the study of marine Algae, such as Dr Juliet Brodie in the Natural History Museum have recently extolled the richness of the far South West of Britain. It follows that Cornwall has attracted national specialists for many of the faunal, floral and fungal groups. However, John Stackhouse went a step further and adopted a small west-facing cove in Mounts Bay and built Acton Castle so that he could have easy access to what has become known as Stackhouse Cove (SW5428). His illustrated work on Nereis Britannica was first published in 1797.

In the 19th century, extensive, annotated collections were formed by R. W. Smitham and R. V. Tellam, and two large albums of pressed specimens are in the Royal Cornwall Museum, Truro. Some years ago these were loaned to J. H. Price, then in the Botany Dept of the Natural History Museum. R. V. Tellam published a list for East Cornwall in the Penzance Natural History and Antiquarian Society and in the same year (1884) and in the same publication John Ralfs included a list for West Cornwall.

The published compilation taking account of all previous sources for the 19th and 20th centuries, including the compilation by E. M. Holmes is in The Victoria History of the Counties of England (1906). J.H. Price himself made extensive lists and collections from many Cornish shores. He undertook extensive recording on the shores of the Lizard peninsula and published this in two parts in Cornish Studies No 7 (for 1979) and No. 8 (for 1980). One co-author was a Museum colleague, S. Honey and the other was C. E. Hepton who made previous records available as well as taking part in fresh field work. Also included are the Helford surveys initiated by the Helford VMCA by Pamela Tompsett and the Cornish Biological Records Unit arranged by Stella Turk.

2003 saw the publication of a national Atlas and Seaweed Checklist for Britain and Ireland by Gavin Hardy and Michael Guiry but this unfortunately missed many records from Cornwall and as is the way of published checklists there are many more additions needed immediately.

In 2006 the HVMCA Group published The Marine Algae of the HVMCA, a checklist with records of the date and place of seaweeds found. Geographically the Helford River fits comfortably within a single kilometre square on the Ordnance Survey map. So this is assuredly the place to state that this square arguably has more species of seaweed than any other British square.

If you have a beginners interest in seaweeds, the various and readily available Pocket Guides are helpful. More precise identification information can be found on-line and in detailed publications from the Natural History Museum and Field Studies Council.

Dr Juliet Brodie will be visiting Cornwall again at the lowest tidal cycle in June 2009 and there will be opportunities to join her workshops. Please email Pamela petomp@bioscope.demon.co.uk if you are interested and wish to book a place.

Stella M Turk and Pamela E Tompsett

Extract from HVMCA newsletter No.37 Autumn 2008

Up all night (but not partying): UK’s first marine BioBlitz

Already cold and wet, zipping up my wetsuit for the third time that day at three am was not quite what I envisaged when my colleague Jason Birt suggested we hold a marine Bioblitz. However, the underwater sights that we encountered during the subsequent dive more than made up for such inconveniences. A popular way of involving the public in scientific activities, the Bioblitz came to life in New York in 1996, the general idea being that scientists, students and the public would come together for twenty four hours to map the biodiversity of a set area, commonly parks. In recent years the idea has gained in popularity and spread across the globe, however until now no one in the UK has been inspired enough (some might say crazy) to organise an overnight marine event. Jason’s inspiration came from reading the book The Highest Tide by Jim Lynch and I was coerced into helping make his dream a reality.

After many months of planning Maenporth was chosen and a date set. Holding an event that includes a Friday the 13th may seem a little inauspicious for some but the day was well enjoyed by all involved. Activities ranged from SeaSearch dives to acoustic recording of bats and birds along with rock pooling, insect netting and much much more. Starting on the sunny afternoon of the 12th of June, staff and students from Falmouth Marine School and Seafans Scuba School worked round the clock to catalogue and photograph as many living organisms found as possible. Work to identify all the species photographed is ongoing with initial estimates suggesting that over 200 species were found, some of the images of which can be found at www.bioblitz.org. uk, along with further details of the event.

This year’s event was held as a trial run with carefully limited numbers of participants, however following the event’s success planning for a bigger summer 2009 event is just beginning. The aim for this next event is to involve a much wider audience, especially members of the public and students from a range of colleges and universities in Cornwall, along with as many local experts as possible. Our ideal would be to find a site within the Helford where there is a wide range of habitats with access suitable for both students and the public. We envisage the event to be held during June. If you know of any such site, have any identification skills to offer or would like to be involved in any way feel free to contact me on 01326 310310 or trudy.russell@ falmouthmarineschool. ac.uk.

Trudy Russell Technician and Lecturer at Falmouth Marine School

Extract from HVMCA newsletter No.37 Autumn 2008

Duchy Oyster Farm Update

Over the last two years the Duchy Oyster Farm has farmed the non-native Pacific oyster on the beds of the Helford. Pacific oysters were introduced to the UK under licence in the 1970s and introduced to the Helford and Percuil rivers in 1974 in collaboration with the Ministry of Agriculture and Fisheries. Pacific oysters are classed as a “non-susceptible” species, which means that they do not carry and are immune to the diseases and risks, which affect native species. In light of increasing sea temperatures, there has been growing concern that Pacific oysters will continue to spawn in UK waters in increasing numbers. The Duchy of Cornwall is now one of the first UK operators to adopt the cultivation of non-spawning triploid Pacific oysters on a large scale, therefore preventing any spread of the non-native species. The Duchy Oyster Farm has additionally spent time relaying native oysters onto the Helford beds, and if growth and results are as hoped, 2008 will be the first year that real Helford native oysters once again will be able to be sold to the country’s leading restaurants and hotels – albeit in a limited number!

Further plans of the Duchy Oyster Farm include a proposed demarcation zone for cage cultivation and fishermen’s store pots. Cages act to hold bags of oysters that are deployed sub-tidally. The proposed demarcation zone lies between Bosahan Point and The Voose. This is an area that has traditionally been used by local fishermen for their store-pots. The proposed zone is intended to accommodate oyster cages as well as the fishermen’s store-pots. The Duchy Oyster Farm for this purpose has liased with David Muirhead, as chairman of the Cadgwith Helford and District Fishermen’s Society, in order to get feedback from the local fishermen. The Oyster Farm will additionally liaise with individual fishing boats, and has undergone a voluntary consultation with users of the river. It will still be possible for boats to navigate within the zone, and for it to be accessed by all other river users at all time. By demarcating the area with navigation markers and on charts, the Duchy Oyster Farm hopes to be able to use smaller pick-up buoys which can be camouflaged in a dark grey or green colour as opposed to having to use large fluorescent marker buoys, designed primarily to be seen by river-users by way of their size and colour. The ultimate objective is to do away with surface markers altogether. With this in mind, the Duchy Oyster Farm are actively researching options such as the use of GPS and divers to locate and help retrieve cages as well as techniques and hardware for sub-surface marker and recovery systems, thereby reducing the visual impact on the river. It is hoped that this demarcation will help with safety and navigation within the Helford River.

Ben Wright & Rhiannon Pipkin

Extract from HVMCA newsletter No.37 Autumn 2008