Native Oyster

The native or flat oyster (Ostrea.edulis) is a filter feeding, bivalve mollusc. They live on the seabed in relatively shallow coastal waters and estuaries (from the lower shore to 80m). They prefer habitats sheltered from strong wave action which tend to be muddy, but require something hard for larval settlement - usually shells or stones. All native oysters start out as males, and throughout their lives change back and forth from male to female. In Britain, breeding normally takes place in the summer. It reaches maturity at about 3 years old. The average reproductive size for the oyster is about 5cm. Oysters can reach a shell length of up to 11cm, and occur in variable shapes. Native oysters have a rough shell that is yellow, pale green or brown in colour, sometimes with bluish, pink or purple markings. The two halves of a native oysters shell are different shapes. The left shell is concave and fixed to the substratum, the right being flat with rougher edges and sitting inside the left, acting as a lid. Inner surfaces of both valves or shells are smooth and usually pearly, white or bluish-grey, often with darker blue areas.The shell shape is a good way to distinguish native oysters from Pacific oysters, which were introduced to the UK in 1926, and which prefer intertidal habitats. Native oysters have rounder shells with smoother edges, while their Pacific relatives have a more elongated shell with deeply waved edges. A single female native oyster can produce 2 million eggs. Although usually up to about 11cm long, native oysters can grow to more than 20cm and can live as long as 20 years.

 

The harvesting of native oysters in the the Fal Estuary for commercial purposes is an activity with more than two centuries history.  And it is the last remaining commercially viable native oyster fishery in the UK.

Despite the decline in the native oyster fisheries seen in the past for which Bonamia, pests, competition from slipper limpets chemical contaminants and TBT had contributed, the small fishery using sailing dredgers and hand dredging has continued in Carrick Roads (Walmsley and Pawson, 2007). 

Since 2014 the fishery has been managed by Cornwall Inshore Fisheries and Conservation Authority (CIFCA), they have carried out annual surveys of the fishery since 2021.

 

2024 saw the highest number of oysters surveyed in the time series, remaining high and stable into 2025.

Landings of native oysters declined in the winter of 2018 /2019 due to decreased demand for oysters from traditional French markets. large numbers of oysters (11,000 tonnes ) were placed on lays to grow on that season. There was an increase in landings of queen scallops which allowed the fishery to remain profitable. 

According to the detailed annual surveys carried out by Cornwall IFCA the stocks of oysters within the restricted area of the Fal fishery fluctuate but appear healthy and on an overall increasing trend. A stock assessment is not carried out but overal picture over the last two years is of increased distribution and density of oysters on the beds, 2024 saw the highest number of oysters surveyed in the time series, remaining high and stable into 2025. During those years, there has been a decline in the amount of scallops Mimachalmys varia and Aequepecten opercularis (marketed as Queen scallops).

 

Stock is assesed via route 2 scoring - there is no concern for fishing pressure and in light of increased stocks and landings there are no concerns for biomass.  Stock rating is now 0.25. Landings are low partly due to poor markets. No detailed stock assessment is carried out but detailed annual surveys by CIFCA show that the stock density on the oyster beds fluctuate. The unique nature of this sail and oar fishery means it is unlikely to collapse. 

The Truro River oyster fishery (producing Fal Oysters) is unique in its management, in that oysters can only be harvested using sail and oar power and dredges can only be hauled by hand. This is the only fishery of its kind and the overall effect has been to limit the fishery by making it more inefficient. In the recent article by Long et al (see references) this is argued to be the cause of the long-term success of this fishery in comparison to other less sustainable fisheries. The fishery has recently become the responsibility of Cornwall Inshore Fisheries and Conservation Authority. The 2016 Regulatory order for Fal Fishery modernised the regulation from the old fishery bye-laws and reduced the area which can be fished taking away the southern area of the fishery where the fishery overlapped with protected mearl beds and seagrass beds. Additionally an exclusion zone was also introduced around an area of seagrass found off Penarrow point. The minimum size of oysters which can be removed from the fishery was increased in 2025 following a vote by the Fal Fisheries Comittee made up of Oysterfishermen. Oysters that can be removed from the fishery are those which can hang on a ring of 72mm diameter and oysters which pass through the ring must be put over the side of the boat back onto the fishery, or put onto oyster lays. Oyster lays are areas on the very low shore set aside for oysters to be stored. There is a closed season for oyster fishing between 1st April and 30th September inclusive.  All dredges used must be licensed (Licence fee is currently £165 per year). Dredging can only be carried out between the hours of 9am and 3pm on weekdays and 9am and 1pm on a Saturday - there is no dredging allowed on a Sunday. The dredges themselves are limited to a maximum width of 1.2m, and the dredge must not have teeth, tines or other digging projections. The dredge must not exceed a weight of 20kg. These restrictions combined with the fact that only manual handling of dredges is allowed restricts the impact of the dredges on the seabed and makes this method of dredging far more sustainable than scallop dredging or oyster dredging under power. Fal Fisheries Regulations amended 2025. 

 

Classification of bivalve mollusc Production areas in England and Wales, Sanitary Survey Report) Fal estuary(lower) and Percuil river 2012 CEFAS Kershaw and Campos

COUNCIL REGULATION (EC) No 510/2006 on protected geographical indications and protected designations of origin “Fal Oyster”