Why choose our seed?

Guernsey Sea Farms has been producing disease free oyster seed for over 35 years.  We supply Crassostrea gigas seed to a worldwide market and with excellent air connections, deliveries can be made within 48 hours. With many years experience in oyster farming we have much knowledge to impart and welcome all enquiries. Contact us if you have any questions which haven’t been covered in our pages or visit our useful links page

Disease free

Isolated from other regions of shellfish production, Guernsey Sea Farms has long had a reputation of supplying disease free oysters. Our seed is tested for disease by independent laboratories on a regular basis. We supply to areas which are particularly sensitive to the spread of disease and, in the EU and UK, to “non-designated areas” which are free of the OsHV-1 virus


We follow strict procedures and protocols to ensure biosecurity

Robust records

We have a robust and accurate record system for all our seed which enables us to trace back to the original broodstock and can answer any enquiries about particular batches of seed


Frequent washing and grading means the oysters are well sorted and clean


Water and algae supply in the nursery is carefully monitored and managed to ensure the supply of strong and healthy oyster seed


We are the only hatchery producing triploid seed in the UK and every batch of triploids is verified by our in-house Flow Cytometer. Find out more about Triploid oysters here

Suggestions for Stocking & Husbandry


Smaller seed need to be graded more frequently than larger seed, for example we recommend every 4 to 6 weeks in the growing seasons for G7 seed, whereas G13 can be graded just once a year. As a rule of thumb we say that it is only necessary to grade when more than 50% by weight (30% by number) will make the grade – otherwise it is an unnecessary stress.


We recommend turning every 4 weeks in growing season.

Stocking in bags or poches

As a general rule, use bags with a mesh size that is half or just over half the size of mesh the seed has been graded on. For example G7 seed should not go into anything larger than a 4mm mesh and G10 seed into anything no bigger than a 6 mm bag. This will allow seed to sit on mesh and prevent it from healing in. On the other hand it is advisable to use as large a mesh as possible to allow for a free flow of water through the oysters. Growth rate can be significantly reduced using small mesh. It is important to move up mesh sizes as soon as growth allows.

NB stocking levels will depend on time of year/ expected growth of stock and frequency of grade.