Identification of Eggs and Spawning Zones of Hairtail Fishes Trichiurus (Pisces: Trichiuridae) in Northern South China Sea, Using DNA Barcoding

Commercially important hairtails, Trichiurus spp., are widely distributed throughout China’s marine waters. Because eggs of these species difficult to identify and the taxonomy group has recently been resolved, their spawning grounds in northern South China Sea (SCS) not well known. We identified three ( T. japonicus , nanhaiensis brevis ) using DNA barcodes spring late summer–autumn ichthyoplankton surveys 2019 SCS. Egg distributions reveal that occur mainly from central southern Beibu Gulf, along Hainan Island, waters off Pearl River Estuary, egg densities higher than summer-autumn. Spawning commonly occurs continental shelf, shelf slope (over seabed depths 42–380 m), shallow water. Considering salinity temperature data, we found were associated with specific water masses. In spring, occurred at Gulf mass (CSBGWM) surface (SCSWM). While summer-autumn, SCSWM. Our findings occurrence spatial temporal distribution determined by hydrological conditions.