ACS Research Committee Report

FEEDING VOCALIZATIONS OF HUMPBACK WHALES
Source: Cerchio, S and Dalheim, M. 2001. Variations in feeding vocalizations of humpback whales (Megaptera novaeangliae) from Southeast Alaska. Bioacoustics 11:277-295.

The authors analyzed vocalizations produced by humpback whales on their feeding grounds in southeast Alaska. Each call contained a short, frequency-modulated introduction and conclusion and a longer body with little frequency modulation. The calls were produced in a stereotyped series. There was little variation within a series of calls, but there was significant variation between series. Overlapping series of calls, presumably produced by two different animals, did vary significantly, indicating the presence of individually specific calls. The authors present two possible explanations for this individual difference. The first is that these calls include individually specific information; the second is that the different calls may maximize prey herding effects when whales are feeding together.    

COMMON DOLPHIN DEATHS INVESTIGATED
Source: LA Times March 23rd, 2002. "Death of dolphins investigated."

On March 22nd, three common dolphins washed up on the southern California coast, bringing the total number of stranded marine mammals to 22. This is the largest stranding since 1994. Scientists suspect that a toxin called domoic acid is to blame. Domoic acid has never before been determined to be toxic to dolphins, but it has been connected to other marine mammal deaths before. Humpback and blue whales, as well as pinnipeds have been found to be susceptible; in 1998, it killed over 400 sea lions off the California coast. The toxin is found in blooms of single-celled organisms and it moves up the food chain through filter feeders such as sardines and finally into marine mammals. Tissue samples from the stranded dolphins have been sent out and the laboratory tests will confirm the cause of death.    

HUMPBACK WHALE CALF DEATH OBSERVED
Source: Honolulu Star Bulletin Monday March 11th, 2002. "Scientists witness whale calf's death."

On February 28th, 2002, scientists from the Hawaii Whale Research Foundation, Kewalo Basin Marine Mammal Lab, and Center for Whale Studies documented a calf's death. The calf was estimated to be 15 feet long and approximately 27 days old. The calf appeared to have some sort of spinal deformity in front of the dorsal fin, causing difficulty in swimming. The tail flukes and pectoral flippers appeared weak. The calf had rapid and labored breathing. It spent most of its time resting on its mother's rostrum and was even pushed to the surface by its mother on several occasions. Once the calf finally died, the mother continued to try to push it to the surface and lift it up on her head. She remained within 200 yards of the calf for a half hour after it died. Researchers were able to collect a skin sample from the calf, but were not granted permission to bring the carcass on shore for necropsy. It is estimated that up to 15.25% of calves do not survive until the feeding season, but calf deaths are very rarely witnessed.    

CETACEAN EVOLUTION
Source: the following is a brief summary of several articles examining the evolution of living cetaceans and the attempt to discover their "sister" taxa, from a talk by Philip D. Gingerich.

Cetacean evolution is continually being examined and altered according to new findings. Most taxonomists agree that they evolved from an ungulate type ancestor. Which particular type, however, has been under debate, based on both molecular and structural arguments. Until now, existing molecular evidence supported evolution from an artiodactyls (a family of even-toed ungulates), while fossils supported evolution from a mesonychian (a family of odd-toed ungulates). Fossils recently uncovered in Pakistan now show both molecular and structural evidence that cetaceans are more likely from the artiodactyl family, rather than the mesonychians as was previously thought. Basically, this means that the closest ancestor to the cetaceans is a predecessor of the modern hippo. There are still missing links, of course, and scientists feel that neither the mesonychians nor the hippotamids/artiodactyls are the sister group of the cetaceans. However, Theweissen believes that cetaceans and artiodactyls are two branches of a larger group, or clade, called the cetariodactyls. The mesonychians are not included in this clade because of morphological differences.