Where we are


Guernsey Sea Farms is based in Guernsey, an independent island of the Channel Islands. The island is located in deep water and is biologically isolated with France and UK with no native populations of oysters or mussels.  With excellent  seawater quality and a favourable climate GSF is ideally situated for the culture of oysters.

We have a unique location in an old granite quarry, connected to the sea by a sluice gate which can be selectively opened for seawater exchange. This allows us to manipulate conditions to optimise growth.  

Guernsey Sea Farms was set up in the early 1970’s as an oyster nursery mainly supplying the oyster farming industry in France.  It later ran into difficulties and it was only when Mark and Penny Dravers built the hatchery in 1983 that the business become properly secure and profitable. 

There have been many changes over the years with both markets and production.   TBT, a toxic antifouling paint used in the 60’s and 70’s,  was responsible for two big changes in the business.  French oyster growers realised that the paint was responsible for poor growth and lack of fecundity in gigas oysters and it was banned from use.  Cleaner seas and estuaries resulted in huge natural settlements of oysters which meant that France no longer needed oyster seed from Guernsey.  So, soon after setting up the new hatchery, GSF had to find different markets for its seed!  

However it was work on the effects of TBT  by laboratories in the UK and CEFAS in particular, that led to GSF becoming the main supplier of oysters and other marine organisms for toxicity testing. 

There have been many changes in the market for shellfish seed over the years and the hatchery became an important producer of clam seed (Tapes philippinarum) for a while.  We have also produced scallops (Pecten maximus)  and abalone (Haliotis tuberculata) in the past but both remain pre-commercial.  We have also operated two ongrowing or farming sites in Guernsey( Rocquiane and Mielette bays) sending part grown oysters to Scotland.  

In recent years we have focussed only that hatchery and nursery production of oysters (Crassostrea gigas), both diploid and triploid. We have improved our stock quality and capacity by large scale production of micro-algae over 300m3/day in innovative floating tanks. Our nursery is highly efficient with one man able to grade 20 million seed or 1 tonne every 2 weeks as well as packing despatches. Our energy use and carbon footprint is probably the lowest in the industry thanks to 90% heat recovery in the hatchery and the floating pontoon paddle wheel which typically pumps 20 m3/minute on less than 0.5kw power. 

Finally we maintain strict biosecurity to remain free of the OsHV1muvar virus and Vibrio aesturianus that we have seen severely impact French and Irish farms.