CCAMLR

Larval fishes were obtained from 0-50 m bongo net and stratified 0-200 m Nansen net samples collected in the western Bransfield Strait region during four RACER program cruises, December, 1986, through March, 1987. Three nototheniid species, Nototheniops larseni, Notothenia gibberifrons, and Trematomus scotti, numerically dominated the total catch. Two typically abundant species in this area, Pleuragramma antarcticum and Notothenia kempi, were relatively uncommon. Depth related catch differences appear to be responsible for substantial shifts in species abundance relations between the two types of net hauls. Gear differences, the restricted geographical coverage, and between year variability in hydrographic conditions may explain species dominance differences between the RACER samples and prior surveys in the Antarctic Peninsula area.
Largest abundances occurred during January in the vicinity of Gerlache Strait and island shelf areas; larvae were infrequently collected in Drake Passage waters. Individual species demonstrated different distributional patterns suggesting that water mass influence, larval depth distribution, and behavioral differences may be involved.
Estimated January-March growth rates for Nototheniops larseni (0.06 mm day-1) and Trematomus scotti (0.05 mm day-1) are similar but low compared to that of Notothenia gibberifrons (0.12 mm day-1).

Field research activities conducted aboard the NOAA Ship Surveyor during the 1989 austral summer in waters adjacent to the Antarctic Peninsula and South Georgia are described. Operations included 1) ice seal studies in Gerlache Strait, 2) ichthyoplankton survey around South Georgia, 3) benthic survey for fish and invertebrates around South Georgia, 4) measurements of air and surface water C02 content, 5) detailed bathymetric mapping, 6) pelagic bird and marine mammal observations, 7) sampling for fish age and growth studies, 8) hydroacoustic survey for krill around Elephant and King George Islands, 9) net sampling for krill in association with the hydroacoustic survey, 10) sampling for larval krill and associated measurements of sea surface temperature and chlorophyll-a, 11) observations of bird densities associated with krill distribution, and 12) collection of cephlapod specimens.

The hydroacoustic survey found a high krill abundance in the Elephant Island area (a “superswarm" not unlike 1981) and a very low abundance in the King George Island area compared to last years survey. The total biomass in the vicinity of Elephant Island estimated from 200 kHz survey data was 940 k tons with only 34 k tons in the King George Island/Bransfield Strait. The survey results apply to 6,057 nm2 near Elephant Island and 5,454 nm2 in the Bransfield Strait. The “superswarm” was estimated to contain 975 k tons of krill and covered approximately 200 nm2.