Oyster habitats Collapsed across Europe, mostly due to over fishing, in the 18 and even 1700’s. Fast-forward, and in the last ten years oyster restoration has escalated throughout Europe from just one or two restoration sites to over 50.
So where do the oysters for restoration come from if the habitats are gone?
Restoration projects rely on the production of oyster larvae from remnant broodstock animals. These are then either grown-on in aquaculture farms or settled onto substrates such as shell before being transferred out to the restoration sites. This is where the bottle-neck is. The production of oyster larvae and ‘spat’ (settled baby oysters) is sporadic and only available from a hand full of commercial sources in the UK and across Europe. In the last two years in the UK restoration projects have not been able to get hold of the required numbers.
Pond production, where larvae are produced in shallow ponds with plankton rich water is an agricultural process to produce baby oysters. The practice goes back as far as Roman times but is used successfully today on the basis that, with several ponds, each year some will succeed and others will not. The process requires good husbandry skills and appropriate land close to the water but it is not high-tech and is therefore inexpensive to operate.
Ponds local to restoration sites also does not have the same biosecurity risks of transferring partially grown oysters across country with possible invasive species and diseases hitch-hiking their way with them.
Overall, pond production beside the Firth of Forth, where Scotlands biggest oyster beds used to be, is a cost-effective way to secure the supply chain for restoration on the East coast.
Professor Bill Sanderson of Heriot Watt University in support of Balanced Horizon, and our Forth Marine Hatchery project wrote this article.