LIVE CAPTURE OF LARVAL BILLFISHES: DESIGN AND FIELD TESTING OF THE CONTINUOUS ACCESS NEUSTON OBSERVATION NET (CANON)

摘要

Basic research on larval billfish biology and ecology has been hampered by difficulties with species identification, the capture of live specimens, and their survival after capture (Richards, 1974; Post et al., 1997; Serafy et al., 2003). Whereas, genetic techniques are helping to resolve the identification problems (McDowell and Graves, 2002; Hyde et al., 2005; Luthy et al., 2005), obtaining live, uninjured billfish larvae for scientific study remains a serious obstacle (Idrisi et al., 2003; Serafy et al., 2003). To date, the most successful effort to collect live istiophorid larvae, and to subsequently maintain them in captivity, was conducted by Post et al. (1997). They sampled over a 2-yr period off Miami, Florida with a circular, 1 m diameter plankton net with 1 mm mesh. By limiting their neuston tow duration to 2 min or less, overall larval istiophorid survival immediately after collection was 30%.