Population dynamics of the European native oyster in a Marine Conservation Zone exposed to unregulated harvesting

Abstract

The implementation of closed zones as fishery management tools have been shown to be successful in the augmentation of habitat restricted species. A concerted restoration effort is currently being focused on the European native oyster throughout its natural range. This has been accompanied by an increase in oyster prices. In 2018 a native oyster for restoration purposes cost 80 pence sterling by 2021 the price had increased to £3.50. It is likely that these price increases have led to harvesting pressure on established wild populations. A number of recovering Ostrea edulis assemblages in Strangford Lough Northern Ireland are located within a closed zone which has been in operation since 2008. This research investigated the effectiveness of this restricted area in regards to protecting O. edulis assemblages. The study revealed that within policed regions of the restricted area the population increased from an estimated 1000 oysters in 2004 to >88,000 in 2021. Furthermore, the age structure and population dynamics differed considerably from non-policed areas which still experienced harvesting. The research supports the use of closed zone legislation as a conservation tool with developing O. edulis populations. As newly restored populations become established, rising market prices will place these under increased harvesting pressure. The use of closed zones may offer a means of protecting these emergent populations.