Managing the ‘capture’ in capture-based aquaculture to safeguard marine fishes and their fisheries

Abstract

After global capture fisheries plateaued in the 1990s and many stocks were classified as overfished, aquatic food production systems expanded into various forms of aquaculture to meet growing needs. In support of wild resource management, aquaculture is often considered to be part of the solution to overfishing. Aquaculture is broadly classifiable as capture-based or hatchery-based (CBA and HBA) and documented as ‘aquaculture’ in FAO statistics, as distinct from wild capture. Yet, in practice, the separation is often unclear. Aquaculture involves many ‘hybrid’ activities that continue to place pressure on wild populations, e.g. for seed and feed supplies. This wild-dependence is poorly reflected in global statistics and in the management and policies around aquaculture operations. One clear example involves wild seed supply for CBA. The often-implicit assumption that the early life-history stages supplying many CBA operations are essentially limitless due to an assumed high early natural mortality is rarely justifiable in practice. The CBA of fishes, in particular, depends on the supply of post-settlement to late pre-reproductive phase young, taken across a wide size/age range that is typically unmanaged. Lack of clarity around commonly used terminology, such as “ranching” and ‘seed’, obscures linkages to wild populations further hampering moves towards sustainability.