Optimization of off‐bottom spat collectors for restoration and production of the European flat oyster (Ostrea edulis) in Dutch coastal waters

Abstract

Efficient spat collection is essential to both the successful restoration and cultivation of the European flat oyster (Ostrea edulis). The results of four different experiments investigating larval abundance, and the use of seven different types of suspended spat collectors in seven locations in the SW Netherlands were compared. These different types included Chinese hats, Vexar mesh, PVC tubes, and four types of bivalve shells. Larval abundance, and timing of peaks in abundance for both O. edulis and the non‐indigenous Pacific oyster (Crassostrea gigas) varied between locations and years. The most successful spat collectors were sacks of bivalve shells. In general, most spat were observed on collectors deployed 1–2 weeks after the peak in larval abundance was detected. Fouling was heavy and may have prevented larval settlement on collectors deployed too early. Suspended sacks of bivalve shells show great promise as O. edulis spat collectors intended for reef restoration purposes but may need further development for cultivation application.

Identifying knowledge gaps for successful restorative aquaculture of Ostrea edulis: a bibliometric analysis

“…Cluster one (green) had eight articles that dealt specifically with restoration. Sub-clustering was not possible due to the small number of papers Many aspects fell into this cluster: from the need of having high enough densities for successful reproduction ( Eagling et al , 2018 ), and the seed collection stage ( Colsoul et al , 2020 ; Rodriguez-Perez et al , 2020 ; van den Brink et al , 2020 ) to the suggestion that soft interventions such as protecting areas with a gravelly seabed may be a way to aid a natural come back in areas were a remaining natural population may be present even if in few numbers ( Kerckhof et al (2018) ). The need to consider infection in restoration procedures was also part of this cluster ( Sas et al , 2020 ).…”

“…One common theme that emerged between the two was seed harvesting or production, an issue affecting aquaculture that relies mostly on wild seed collection but also affects restoration programmes that rely on active ‘seeding’ of often large quantities of oysters. Within this theme, two papers ( Colsoul et al , 2021 ; van den Brink et al , 2020 ) appeared in both searches. van den Brink et al (2020) deals with the identification of the optimisation of collection, both in terms of collector types and methodology (e.g., timing), showing how ‘natural’ substrates (shell) would be optimal but raising questions related to the ‘economic viability’ of using this method for aquaculture purposes, which usually employs artificial collectors that simplify the process of detachment for the second phase of cultivation.…”

“…Within this theme, two papers ( Colsoul et al , 2021 ; van den Brink et al , 2020 ) appeared in both searches. van den Brink et al (2020) deals with the identification of the optimisation of collection, both in terms of collector types and methodology (e.g., timing), showing how ‘natural’ substrates (shell) would be optimal but raising questions related to the ‘economic viability’ of using this method for aquaculture purposes, which usually employs artificial collectors that simplify the process of detachment for the second phase of cultivation. Colsoul et al (2021) provide a comprehensive review of seed production research in general, starting from the general biology of the species, identifying the stressors, and then looking at the history of production technologies, going into detail on seed production in polls, ponds and hatcheries.…”

Sea bed disturbance increases flat oyster recruitment for low to moderate stock densities

“…However, there was no difference in the number of oyster spat observed, with no live spat observed in either treatments in 2012 and 2013, and 12 spat recorded in 2014 on non‐harrowed plots with three on harrowed plots, showing that harrowing made no difference to spat settlement (Bromley et al, 2016). As flat oysters can display high interannual variation in both spatfall timing and abundance (van den Brink et al, 2020), the authors point out their result could be down to bad luck in working in poor spat years, but it could also be that the shelf budget was not limiting oyster spatfall success in this system.…”

Recruitment of Oysters by Different Collection Devices at a Longline Shellfish Farm in the Central Adriatic Sea

“…Many trials have been carried out using different substrates to obtain oyster spats from the natural field. The most commonly used substrates to recruit oysters include empty bivalve shells (cultch), rope, coco rope, hemp rope, ribbon, Chinese hats (or coupelles), tubes, and tiles (sometimes covered with quicklime) [17][18][19][20][21]. Most of these substrates have been scientifically tested in hatchery or field conditions [7].…”