Selectivity of gillnets in the California Pacific herring roe fishery

Pacific herring, Clupea harengus, landings were sampled during the 1976 season in San Francisco, Tomales and Outer Bodega bays. Fish were sampled according to the type of gear used to catch them - - roundhaul nets (purse seines and lamparas), beach seines, and gillnets.Analysis of the data indicated that gillnets caught largerfish and caught more females than did roundhaul nets. In San Francisco Bay, female herring caught by gillnets had a mean body length of 208 mm (8.2 inches) compared to 179 mm (7.0 inches) for roundhaul nets. The sex ratio was 72% females by gillnets to 55% for roundhaul nets. The larger size and larger number of females caught by gillnets resulted in a much higher ripe roe recovery - - an average of 17.2% compared to 9.8% for roundhaul nets by weight of all samples.Although no definite comparisons of size and sex ratio of fish caught by different types of gear could be made in Tomales Bay and Outer Bodega Bay (because of insufficient sampling), herring in gillnet samples were comparable to those of San Francisco Bay in the two measured characters. (9pp.)