ACS Research Committee Report

POPULATION HISTORY OF RIGHT WHALES DETERMINED THROUGH GENETICS OF WHALE LICE
Source: Kaliszewska et al. 2005. Population histories of right whales (Cetacea: Eubalaena) inferred from mitochondrial sequence diversities and divergences of their whale lice (Amphipoda: Cynamus). Molecular Ecology 14: 3439-3456.

Cyamids or “whale lice” are amphipod crustaceans that live as parasites on cetaceans. They spend their entire lives on whales and, because they do not have a free-swimming stage, can only transfer between whales with direct contact. There are three species of cyamid that are distinct for right whales and are not found on any other cetacean. Each of the three cyamid species has a different ecological niche. Cyamus ovalis attaches to right whale callosities, contributing the white color that is used for photo-identification. Cyamus gracilis occupies pits and grooves between callosities. Finally, Cyamus erraticus occupies smooth skin in the genital and mammary slits, as well as opportunistically colonizes wounds. This study looked at whether information about local interactions, large-scale movements, and population history of right whales can be determined from genetic variation in the mitochondrial DNA of cyamids. Samples were taken from right whales in the western North Atlantic, western North Pacific, and three locations in the Southern Hemisphere. Cyamids from individual right whales exhibited high genetic diversity, meaning that there must be cyamid transfer between unrelated whales often enough to make it impossible use whale lice genetics to determine right whale behavioral interactions. All of the cyamid samples taken from right whales in the Southern Hemisphere were so genetically similar that no differentiation could be made between breeding populations. In contrast, there was significant genetic differentiation between cyamids in the Southern and Northern Hemispheres, supporting the view that northern and southern populations have probably been separated for millions of years.    

OBSERVATION OF A FEMALE NORTH ATLANTIC RIGHT WHALE COPULATING WITH TWO MALES SIMULTANEOUSLY
Source: Mate, B., Duley, P., Lagerquist, B., Wenzel, F., Stimpert, A., and Clapham, P. 2005. Observations of a female North Atlantic right whale (Eubaleana glacialis) in simultaneous copulation with two males: supporting evidence for sperm competition. Aquatic Mammals 31(2): 157-160.

It has been hypothesized, based on the relatively large testes size of male right whales, that this species has a mating system based on sperm competition. The testes size varies quite a bit between baleen whale species. Blue whales, the largest species, have testes that average 0.06% of their body mass. Right whales, however, have testes that average 1.3% of their body mass, or one metric ton. Male mammals that exhibit sperm competition generally do not engage in aggressive mating interactions, but rather they compete by producing a high quality and large quantity of sperm. Females in this mating system mate with multiple males. Right whale courtship groups, called Surface Active Groups (SAGs), containing a single female and multiple males are observed year-round. Copulation has been observed in these SAGs, usually with the female lying upside-down at the surface during intromission. On August 11, 2000, the authors witnessed a female right whale in a SAG lying upside-down at the surface with two males copulating with her simultaneously. This event provides strong support for the hypothesis that right whales have a mating system based on sperm competition.    

FORAGING SOUND PRODUCTION IN BOTTLENOSE DOLPHINS
Source: Nowacek, D.P. 2005. Acoustic ecology of foraging bottlenose dolphins (Tursiops truncatus), habitat-specific use of three sound types. Marine Mammal Science 21(4): 587-602.

Bottlenose dolphins produce three different sound types: whistles, echolocation clicks, and burst-pulse sounds. Whistles are frequency-modulated, tonal sounds with a relatively low frequency range. Echolocation clicks are short, broadband pulses with center frequencies that are higher than whistles. Finally, burst-pulse sounds are variable in structure and length. An assumption in bottlenose dolphin acoustic research is that echolocation clicks are used for foraging, while whistles and burst-pulse sounds are used during social interactions; this assumption has recently been questioned. This study investigates the foraging function of three sound types recorded from bottlenose dolphins in Sarasota, Florida. The three sound types used in this study were whistles, echolocation clicks, and “pops,” a hybrid between an echolocation click and a burst-pulse sound. The rate of sound production for all three types was much higher for single animals than for animals in groups. In groups that contained more than two individuals, the rate of sound production was linearly related to the number of animals in the group. Echolocation rate was low during traveling, indicating that although echolocation clicks are used for foraging, they most likely are not as important in navigation, at least in this area. The finding that single dolphins echolocated at a higher rate than animals in a group supports the hypothesis made in previous studies that dolphins may gain information from the echolocation of other group members, thereby negating the need to produce their own echolocation clicks. The rate of pops was higher during foraging behavior, especially for single animals. Previously, pops were thought to be social sounds, but they clearly have a foraging context, as well. The author suggests that pops, as well as echolocation clicks in some cases, could be used for startling fish prey. Whistles were also produced more often by lone foraging dolphins than by foraging groups. The structure of the bottlenose dolphin whistle would not make it well suited to startling fish, so they could instead be used as contact calls or food calls to other dolphins. Dolphins may call conspecifics to alert them to a food resource or to elicit cooperation in foraging and capturing prey.    

KILLER WHALE ATTACKS ON MINKE WHALES
Source: Ford, J.K.B., Ellis, G.M., Matkin, D.R., Balcomb, K.C., Briggs, D., and Morton, A.B. 2005. Killer whale attacks on minke whales: prey capture and antipredator tactics. Marine Mammal Science 21(4): 603-618.

This study describes nine incidents of predation or attempted predation of minke whales by transient killer whales in the waters of British Columbia, Washington, and southeastern Alaska. There are two “ecotypes” of killer whales in the study area: transients and residents. The transient killer whales studied here are almost exclusively mammal-eating and much of their diet is made up of pinnipeds (seals and sea lions) and small odontocetes (toothed whales). The amount of predation of baleen whales by killer whales is not well documented and is in some debate amongst the scientific community. In the nine events described in this study, all involved a single minke whale; four were fatal attacks, four minke whales escaped, and one whale stranded on shore and later died. A total of 33 killer whales were involved in these attacks. Large whales under attack employ a variety of antipredator tactics, including physically defending themselves using their size, seeking refuge near shore, or fleeing at high speeds. In four cases described here, the minke whales fled at high speed for up to an hour before the killer whales aborted the chase. In order for this strategy to be successful, the minke whale must have a superior endurance and speed than the killer whales. Killer whales have been documented to swim at higher speeds than minke whales, but apparently can not always sustain such speeds. In three cases, the minke entered a shallow bay or harbor, where it was entrapped and killed by the killer whales or stranded and died on shore. It is unclear whether moving into shallow water was an antipredator tactic or was accidental during attempts to flee. In no case did minke whales that were surrounded by killer whales make any attempt to defend itself. It appears that minke whales’ only defense is to outrun the killer whales. In contrast, other baleen whale species, including humpback, gray, and right whales, have been previously witnessed to engage in aggressive behaviors to ward off attacks by killer whales. The baleen whale species above are generally slower than minke whales, however, and would most likely be unable to use fleeing as a means of escape from attacking killer whales. Other fast-moving baleen whales, such as Bryde’s and blue whales, react to attack in similar ways as the minke whales. Killer whales in this study attacked by ramming, using their bodies to push the minkes beneath the surface, and by biting the tail and tail stock. In all observed cases, the killer whales ate only the tongue, skin, and a small portion of the blubber. In the minke whale chases and attacks documented here, adult males tended to trail behind the adult females and juveniles. The larger overall size, as well as the larger dorsal and pectoral fin size may make these males less efficient at swimming at high speeds, causing them to fall behind during the chase. Although nine cases of minke attacks were documented here, the overall occurrence of minke predation is relatively rare. The most important prey for killer whales in the region is harbor seals, which are also the most abundant marine mammal species.    

FISHING GEAR INVOLVED IN THE ENTANGLEMENTS OF HUMPBACK AND RIGHT WHALES
Source: Johnson, A., Salvador, G., Kenney, J., Robbins, J., Kraus, S., Landry, S., and Clapham, P. 2005. Fishing gear involved in entanglements of right and humpback whales. Marine Mammal Science 21(4): 635-645.

Entanglement in fixed fishing gear, such as lobster pots and gill nets, is a significant cause of injury and mortality to humpback and North Atlantic right whales. Right whales, in particular, are still in decline in spite of being protected from whaling for over 70 years. Part of the reason for this decline is human-caused mortality. Studies of the whale scarring has found that over 50% of humpback whales and over 70% of right whales have scars from entanglement. In this study, records of known entanglements were examined, especially focusing on incidents in which the entangling gear was recovered. Five entanglement variables were examined: entanglement outcome (at last sighting), gear type, part of gear, line type, and point of attachment of entangling gear. A total of 61 entanglements, including 31 right whales and 30 humpback whales, were analyzed. Four right and three humpback whales died; five right whales were deemed potentially dead; 12 right and 20 humpback whales were alive and gear free; six right and five humpback whales were alive and still entangled; and two humpback and two right whales had unknown outcomes. Gear type was determined in 45% of right and 73% of humpback entanglements. Right whales were found to be entangled in pot gear 71% of the time and gill net gear 14%. Humpback whales, on the other hand, were entangled in pot gear 41% of the time and gill net gear 50%. The part of the gear that entangled the animal could only be identified in just over half of the cases. Fifty-six percent of entanglements of both species involved buoy line. Sinking buoy line was found on more entangled animals than floating buoy line. Over 85% of ground line entanglements were floating line. The most common point of attachment for right whales was the mouth, whereas for humpbacks it was approximately equal between the mouth and the tail.   

SOCIAL INTERACTIONS OF HUMPBACK WHALE MOTHER/CALF PAIRS
Source: Sardi, K.A., Weinrich, M.T., and Connor, R.C. 2005. Social interactions of humpback whale (Megaptera novaeangliae) mother/calf pairs on a North Atlantic feeding ground. Behaviour 142: 731-750.

This study focuses on humpback whales in the southern Gulf of Maine, including Stellwagen Bank and Jeffreys Ledge off the Massachusetts’ coast, during the years 1984 through 1998. Association patterns of whales in groups containing a mother/calf pair were analyzed based on the associates’ age and sex class, as well as the mother’s reproductive history. Mother/calf pairs demonstrated an overall preference for associating with adult (over seven years of age) males. In years when the same females were not accompanied by a calf, they had a preference for adults of either sex and for male sub-adults (between five and seven years of age). Associations of females were also combined for all years that they had calves versus years without a dependent calf and there were distinct differences. In years with and years without a calf, females often associated with adult males. However, in years with a calf, there was an increase in associations with juvenile (between one and four years of age) males. This apparent preference of mother/calf pairs to associate with juveniles has not been previously documented and there are several possible explanations. One explanation is that the juvenile initiates the association by approaching the mother/calf pair. In other mammals, juvenile females have been observed to approach calves, presumably to acquire parenting experience. In this study, however, it is the juvenile male humpbacks that were observed with mother/calf pairs more often. Perhaps these males are afforded an opportunity to play or socialize with the calves by approaching the pair. It is also possible that both mother/calf pairs and juveniles are using sub-optimal habitats to feed and they simply associate at random with other whales in the area. Juveniles may be out-competed by adults in more productive areas and mothers may be attracted to the habitats in this study because they are beneficial to the calf for a variety of reasons, including shallow water, relative protection from high seas, or other factors. The reproductive history, including number of previous calves, calving rate, and whether or not she became pregnant in the following breeding season, did not appear to have an impact on association patterns. The relative positioning of all members of groups containing a mother/calf pair were also analyzed to determine if positioning is random or if the mother keeps herself between her calf and other whales. Mothers were observed in a surface position between their calves and other members of the group significantly more often, both in duration and in surfacing frequency, then expected by random. The positions of individuals in the group were not fixed; associates shifted their position often. Interactions between mother and juvenile associates sometimes appeared aggressive, with the juvenile trying to approach the calf and being rebuffed by the mother. Mothers appeared to act protective of their calves by using their bodies as a physical barrier against other group members.   

NORTH ATLANTIC RIGHT WHALES IN CRISIS
Source: Kraus, S.D., et al. 2005. North Atlantic right whales in crisis. Science 309: 561-562.

In spite of international protection from commercial whaling since the 1930s, the North Atlantic right whale is still one of the most endangered large whales in the world. The current population estimate is approximately 350 individuals, but the population is still in decline at an estimate 2% per year. This population has been prevented from recovering due to a low reproductive rate and recently declining survival probabilities, especially for reproductively active females. Most known right whale mortalities are due to ship collisions and entanglements in fishing gear. Between 2004 and 2005, there have been eight recorded right whale deaths, including six adult females (three with near-term fetuses). Three of these whales were killed by ship collisions; one by a fishing gear entanglement; one by a probable ship strike; two were offshore and could not be examined thoroughly; and one calf stranded alive on a beach and later died. The loss of this many right whales is unprecedented in 25 years of studying the species. The estimated mortality rate for this species is 4%, which would be approximately 14 whales per year. In the last 20 years, an average of 2.4 dead right whales have been reported each year, indicating a detection rate of 17%. The eight deaths in the last two years is 2.9 times higher than the average annual mortality and if the detection rate has remained constant, could mean that as many as 47 right whales died during this period. The calf production rate has increased in the last five years from an average of 12 calves per year up until 2000, and an average of 23 between 2001 and 2005. This increase in birth rate will mean little, however, if the mortality rate continues at such a high level. The authors urge immediate changes to the management of right whales, focusing on reducing human-induced mortality.