Aquaculture can potentially adhere to the standards of the Nature-based Solutions (NbS) framework and contribute to the scaling up of NbS. Thus, this industry may take advantage of ideas that are both environmentally friendly and provide the best social-economic outcomes. The farming industry has recently been in search of added sustainable practices and new possible farming species , which have the potential to increase the availability of nutritious seafood and also promote higher food security. One such approach is the coculture of different species with a focus on positive socio-environmental outcomes , in addition to increased seafood provision.
The US is the top seafood importer in the world and a big consumer of shellfish . Given this opportunity for domestic production, growers, and related seafood businesses (e.g. restaurants) have expressed interest in innovative forms of aquaculture that bridge farming efficiency and marine conservation spheres ( e.g. restorative aquaculture, regenerative aquaculture). At the same time, aquaculture management that increases shellfish quality , and is less time-consuming and less costly for biofouling control is required. Within that context, this work explores the feasibility of coculture of native grazers, Atlantic Purple Sea urchins (Arbacia punctulata) , and the Common periwinkle ( Littorina littorea) , with suspension feed er Eastern oysters (Crassostrea virginica) as two separate projects, and discuss how the approach can fit the framework of NbS.
Using traditional bottom culture cages, and farming bags, different treatments were deployed in selected locations in the Chesapeake Bay area , where oyster culture is common, using a randomized design. Oyster stocking density in farming gear was maintained constant and similar to standard commercial densities in all treatments. Experimental designs involved the collection and use of two different sizes and stocking densities for urchins ; whereas periwinkles were deployed in different coastal culture zones with varying stocking densities . Treatments within projects are being compared in terms of potential effects on farming efficiency, farming management improvement, and species’ conditions and survival. We additionally discuss how the design of grazer-oyster coculture can contribute directly or indirectly as a NbS based on IUCN’s ‘Global Standards for Nature-based Solutions’ (Fig.1) .
Preliminary results show positive effects of the coculture choice upon oyster production relative to the monoculture, such as less biofouling attached to farming gear (Fig. 2), and improved target bivalve species quality (e.g. higher condition index, shell cleanliness), with additional potential environmental outcomes (less use of freshwater in operations, energy) .
Although this research is ongoing and projects are still in the initial phase, grazers could potentially be a useful tool to improve shellfish farming management and bivalve shellfish product quality. Several technical aspects and economic considerations to bring grazers to the seafood market still need to be carefully assessed , but broadly, we expect the advantage of deploying cocultures to be at least two-fold for the farmer: coculture can increase the revenue of the farms with a secondary product and lower farming management costs ; besides potentially being a suitable strategy to small-scale farmers. Moreover , coculture with these grazers uses the same in-use farming space and can be designed to link with marine conservation initiatives , resulting in additional positive environmental outcomes. ¨