Juvenile Bycatch

Juvenile bycatch is the capture of immature, pre-spawning fish below the size of first reproduction, a form of growth and recruitment overfishing that lowers future yield and spawning biomass. It is common in small-mesh trawls, beach seines, and drifting-FAD tuna sets, where undersized bigeye and yellowfin are taken before they grow to marketable weight. Managers counter it with minimum mesh sizes, minimum conservation reference sizes, bycatch reduction devices, sorting grids, and area or seasonal closures over nursery grounds. Reducing juvenile catch raises yield-per-recruit and protects the stock’s reproductive output, a core objective of size-selective gear regulation.