ACS Research Committee Report

BOTTLENOSE DOLPHIN MUD PLUME FEEDING
Source: Lewis, J.S. and Schroeder, W.W. 2003. Mud plume feeding, a unique foraging behavior of the bottlenose dolphin in the Florida Keys. Gulf of Mexico Sci. 21(1): 92-97.

Bottlenose dolphins throughout the world exhibit a wide variety of feeding styles. These behaviors differ depending on human activity, environmental variables, and other factors. For instance, bottlenose dolphins in some areas focus on fisheries by-catch when foraging, while others living in shallow, estuarine habitats, and intentionally strand while chasing prey. In the lower Florida Keys, another unique feeding style, mud plume feeding, has been discovered. This behavior was first witnessed in 1999 and since then has been seen more than 186 times. The first sign of this feeding activity is a thick cloud of sediment that rises to the surface and grows in size linearly. The feeding dolphin can sometimes be seen moving just ahead of the mud plume. After a few seconds, the mud plume stops growing in size and then the dolphin lunges through it, creating a great deal of surface disturbance. It is thought that the dolphin creates the mud plume with a purposeful downward motion of the tail near the bottom. The exact prey species being used in this feeding behavior was not determined, but in many cases fish were seen jumping in front of lunging dolphins or out of the plume. The mud plume may help the dolphin concentrate prey, which may use the plume either for protection or for foraging possibilities.    

CULTURAL CLANS IN SOUTH PACIFIC SPERM WHALES
Source: Whitehead, H. and Rendell, L. 2004. Movements, habitat use and feeding success of cultural clans of South Pacific sperm whales. J.Anim.Eco. 73: 190-196.

Female and juvenile sperm whales are usually found in pods of about 20 animals, which are often split into two or more long-term social units. As the whales socialize, they produce stereotyped patterns of clicks, called codas. Codas produced by sperm whales in social units off the Galapagos Islands could be categorized into three distinct acoustic "clans". Each clan has a distinctive coda repertoire and members of the same acoustic clan were usually found in the same social unit. Groups of sperm whales tended to be aggregated within hundreds of km of other groups of the same clan. There were two acoustic clans studied in this area; these clans differed in habitat use, movement patterns, and defecation rates. One, referred to as the "Regular", clan was found in shallower water and moved in more convoluted paths; the other, "Plus-one", clan was found in deeper water and moved in straighter paths. The defecation rate differed between clans and also between years. This difference may be due to divergent prey types or ingestion rates. In addition, the distribution and movement patterns of each clan may be more adaptive in certain years, but less adaptive in others, depending on the climatic and environmental conditions. Therefore, the behavior of the sperm whale clans may be more reliant on cultural transmission than on environmental variables.   

NORTH ATLANTIC RIGHT WHALE CALVES
Source: New England Aquarium right whale team

Six North Atlantic Right Whale Calves Seen So Far on the Southeastern United States Calving Grounds    

PATERNITY AND POLYGMY IN HUMPBACK WHALES
Source: Cerchio, S., Jacobsen, J.K., Cholewiak, D.M., Falcone, E.A., and Merriweather, A.D. 2003. Paternity, polygamy and alternative mating tactics in humpback whales from the 15th Biennial Conference on the Biology of Marine Mammals held in Greensboro, North Carolina, December 2003.

Humpback whales use the Revillagigedo Archipelago in Mexico as a mating and calving ground. The sex ratio of the whales in this area is two to three males for every one female. Within humpback whales, there is strong competition amongst males for mating access to females, and consequently, variable reproductive success. Whales in the Revillagigedo Archipelago were biopsy sampled for genetic and subsequent paternity analyses. There were two methods used to identify paternity of calves: one was considered "conservative" and the other "relaxed". In both methods, the paternity assignments differed significantly from random. Most males (47) could only be assigned paternity of one calf, but several males were assigned two (5) or even three (3) paternities. Overall, it was only 37% of males that accounted for all calves sampled. This finding suggests that the majority of males are not successful in siring offspring. Assigned fathers were observed in a variety of behavioral types, such as escorting mother/calf pairs, actively competing with other males, and singing, indicating more than one successful mating strategy.    

MINKE WHALES NEAR JAPAN AND KOREA
Source: Lavery, S., Dalebout, M.L., Funahashi, N., Young-Woon, M., and Baker, C.S. 2003. Genetic evidence for multiple stocks of minke whales threatened by hunting and bycatch in coastal waters of Japan and Korea from the 15th Biennial Conference on the Biology of Marine Mammals held in Greensboro, North Carolina, December 2003. .

Minke whale meat from Japanese and Korean markets was surveyed using genetic techniques. There are two known stocks of minke whale off of Japan. The "J" stock is found in the Sea of Japan and is protected from whaling due to its small population size. The "O" stock is found offshore, is presumably more abundant, and is the primary target of Japanese whaling. Japan also allows the killing of entangled or by-catch whales for commercial sale; these animals are presumably of the "J" stock. Japanese by-catch remained consistent until 2001, when it increased four times; it increased again in 2002. Between the two years, about 450 whales were killed "accidentally." Minke whale meat is sold in the Japanese and in the Korean market. Meat sampled in Japan was biased towards males; in contrast, meat sampled in Korea was biased towards females. In addition, there were three "J" stock mitochondrial DNA haplotypes identified in these samples. The ratio of these haplotypes differed between the Japanese and Korean markets, indicating that they may come from different coastal stocks. There may be a coastal population on the eastern and one on the western shore of Japan, as well as one on the coast of Korea. This population structure may increase vulnerability to coastal minke whale stock decline.    

FEEDING AND VOCAL BEHAVIOR OF BLUE WHALES
Source: Calambokidis, J., Oleson, E., McDonald, M., Burgess, B., Francis, J., Marshall, G., Bakhtiari, M., and Hildebrand, J. 2003. Feeding and vocal behavior of blue whales determined through simultaneous visual-acoustic monitoring and deployment of suction-cup attached tags from the 15th Biennial Conference on the Biology of Marine Mammals held in Greensboro, North Carolina, December 2003. .

Blue whales off the coast of California and Mexico were studied using Crittercam (a suction-cup attached tag with a video recorder), acoustic tags, and a digital tag that records sound, depth, and pitch and roll of the whale. The tags indicated that the blue whales made deep dives below deep krill (shrimp-like crustaceans) layers and took vertical upward lunges into the prey. There appeared to be less feeding and less deep diving at night. The maximum dive depth of a tagged animal was 300m, deeper than had been previously recorded. Blue whale calls were made consistently at a depth of 15-20m, even if the animal was diving deeper. All of the sampled callers were male. The callers were divided into two types: "Regular" and "Irregular". Regular callers were usually solitary and traveled in a straight line. Irregular callers were more common and were usually pairs of whales containing a female and a trailing male.   

THREE FORMS OF KILLER WHALES IN ANTARCTIC WATERS
Source: Pitman, R. and Ensor, P. 2003. Going with the floe: three forms of killer whales in Antarctic waters from the 15th Biennial Conference on the Biology of Marine Mammals held in Greensboro, North Carolina, December 2003. .

There were three forms of killer whales identified by morphological (physical) characteristics. Type A animals look like "typical" killer whales from throughout the world; they have medium sized eye patches that are oriented parallel to their body axis. They primarily hunt minke whales in open water and have a mean pod size of 13.6 animals. Type B animals have a larger (twice as large) eye patch that is oriented parallel to their body axis and a "cape" of white behind their dorsal fin. These animals have smaller group sizes, on average 12 members, and hunt primarily seals in pack ice. Type C animals have a narrow, forward- slanted eye patch, a "cape", smaller pectoral fins, and commonly have diatoms. They form much larger groups, on average 46 animals, and have only been documented hunting toothfish in the pack ice. Further analyses have to be conducted to determine whether these killer whales are genetically distinct and may actually be three different species.