RELATIVE ABUNDANCE AND BEHAVIOR OF MARINE MAMMALS EXPOSED TO TRANSMISSIONS FROM THE HEARD ISLAND FEASIBILITY TEST

The Heard Island Feasibility Test source transmitted a hum at 209-220 dB re: 1 mu Pa at 175-m depth, centered on 57 Hz with a maximum bandwi dth of 30 Hz for 1 h of every 3. Experienced marine mammal observers c onducted line-transect surveys and monitored marine mammal behavior vi sually and acoustically in a 70 X 70 km square centered on the transmi ssion site. Thirty-nine groups of cetaceans and 19 of pinnipeds were s ighted from both vessels before the start of transmissions. Thirty-nin e groups of cetaceans and 23 of pinnipeds were sighted during transmis sions. Blue (Balaenoptera musculus), fin (B. physalus), and sperm (Phy seter macrocephalus) whales were sighted during the base line period; blue, sperm, and possibly sei (B. borealis) whales were sighted during the transmission period. More schools of hourglass dolphins (Lagenorh ynchus cruciger) were sighted during transmissions, but fewer groups o f pilot whales (Globicephala melas), southern bottlenose whales (Hyper oodon planifrons), and minke whales (B. acutorostrata). The density of all cetaceans was 0.0157 groups/km(2) before the transmissions and 0. 0166 groups/km(2) during. Antarctic fur seals (Arctocephalus gazella) and southern,elephant seals (Mirounga leonina) were seen, but not in s ufficient numbers to estimate abundance. One blue whale tracked before , during and after a transmission changed respiration and reorientatio n rates, but did not avoid the source detectably. Sperm whales and pil ot whales were heard in 23% of 1181 min of baseline acoustic surveys; but in none of 1939 min during the transmission period. Both species w ere heard within 48 h after the end of the test.