[MARMAM] Abstracts - Aquatic Mammals Volume 34, Isssue 3 (2008)

Dagmar Fertl dagmar_fertl at hotmail.com
Thu Nov 6 10:04:55 PST 2008


Dear Marmam and ECS-mailbase subscribers,
 
Apologies to those of you who will get duplicate emails due to cross-posting. The following are abstracts from the most recent issue of Aquatic Mammals, the scientific peer-reviewed journal of the European Association for Aquatic Mammals (EAAM).  Abstracts are presented as a courtesy to the EAAM and the journal editors – Drs. Jeanette Thomas (managing editor; aquaticmammals at gmail.com) and Kathleen Dudzinski (co-editor; kdudzinski at dolphincommunicationproject.org). The journal publishes papers dealing with all aspects of the care, conservation, medicine and science of aquatic mammals. The journal receives support of the Alliance of Marine Mammal Parks and Aquariums and the International Marine Animal Trainers' Association (IMATA). 
 
For more information on the journal, please go to: http://www.aquaticmammalsjournal.org/. 
 
Contact information is provided for the corresponding author for each article. Please do not contact the listserve editors or me for pdfs or copies of the articles.
Thank you for your continued interest in the journal and these postings. 
 
With regards,
 
 
Dagmar Fertl
Ziphius EcoServices
dfertl at gmail.com

http://www.ziphiusecoservices.com
 
Gomes, F.F.A.,* J.E. Vergara-Parente, and S.F. Ferrari. 2008. Behaviour patterns in captive manatees (Trichechus manatus manatus) at Itamaracá Island, Brazil. Aquatic Mammals 34(3):269-276.
 
*Department of Biology, Universidade Federal de Sergipe, 49.100-000 São Cristóvão – SE, Brazil
 
Email: biola_gomes at hotmail.com
 
The Antillean manatee (Trichechus manatus manatus) is distributed along much of the northern and eastern coasts of Brazil, although relatively little is known of the ecology or behaviour of the members of this population. In the present study, the behaviour of seven juvenile manatees earmarked for reintroduction to the wild was monitored using focal animal sampling over a 20-d period at the Aquatic Mammal Centre (CMA/ICMBIO) on Itamaraca Island, Pernambuco. The primary aim of this study was to characterise behaviour patterns, especially individual differences, as a baseline for monitoring during reintroduction. In particular, it was hoped that specific patterns could be identified as a diagnostic reference for the evaluation of an individual’s potential for successful reintroduction. Overall, while resting was the predominant activity of all but one subject, considerable individual variation was recorded in all behavioural categories. In addition, significant differences were recorded between morning and afternoon sessions, with some individuals presenting a given category during only one part of the day. Some of the behaviour patterns, such as circular movement, appeared to be related to anxiety or stress and might be useful for the behavioural diagnosis of individuals earmarked for reintroduction, although it will only be possible to interpret the exact implications following the reintroduction process.
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Maniscalco, J.M.*, D.G. Calkins, P. Parker, and S. Atkinson. 2008. Causes and extent of natural mortality among Steller sea lion (Eumetopias jubatus) pups. Aquatic Mammals 34(3):277-287.
 
*Department of Conservation Science, Alaska SeaLife Center, P.O. Box 1329, Seward, AK 99664, USA
 
Email: john_maniscalco at alaskasealife.org
 
 
The authors studied the causes and extent of mortality in endangered Steller sea lion (Eumetopias jubatus) pups at a small rookery in the northern Gulf of Alaska over seven consecutive summers (2001 to 2007). Mortality among pups up to 2.5 mo post-partum (n = 69) averaged 15.4% (range = 3.8 to 27.8%) and was not dependent on number of pups born. The causes of mortalities varied greatly from year to year, although high surf conditions and killer whale predation accounted for more than half of all deaths. Stillbirths, traumatic injury, and maternal abandonment were individually relatively minor sources of mortality. Causes of mortality were age-dependent. Pups greater than 2 wks old were not washed away by high surf conditions or killed by traumatic injury; whereas pups less than 1 mo old were not subject to predation. The authors also summarize historical observations of pup mortality in this species to compare similarities over time and differences between regions. Current and historic evidence suggests that rates of pup mortality have been higher in the eastern/increasing population of Steller sea lions compared to the western/decreasing population. Therefore, an increase in pup mortality was probably not a major cause of the overall population decline or current lack of recovery.
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Oswald, J.N.*, S. Rankin, and J. Barlow. 2008. To whistle or not to whistle? Geographic variation in the whistling behavior of small odontocetes. Aquatic Mammals 34(3):288-302.
 
*Scripps Institution of Oceanography, University of California at San Diego, San Diego, CA 92038, USA
 
Email: oswald.jn at gmail.com
 
Whistles are used by odontocetes to varying degrees. During a visual and acoustic survey of dolphin abundance in the eastern tropical Pacific Ocean (ETP), whistles were heard from 66% of single species schools and from 98% of mixed species schools. In contrast, whistles were heard from only 24% of single species schools and 23% of mixed species schools during a survey of temperate waters off the western United States. The most common species encountered in the ETP were Stenella coeruleoalba, S. attenuata, and Tursiops truncatus, all of which whistled frequently. The most common species encountered in the temperate study area were Delphinus delphis, Phocoenoides dalli, Lissodelphis borealis, and Phocoena phocoena, only one of which whistled (D. delphis). Why do small odontocete species living in the ETP whistle more frequently than those living in colder waters farther north? Six hypotheses are explored: (1) predator avoidance, (2) group size, (3) school composition, (4) behavior state, (5) temporal variation, and (6) anatomical differences. Multivariate logistic regression with whistling as the dependent variable and group size, school composition, time of day, presence of a beak, and study area as independent variables showed that all variables were significant (p < 0.001). An explanation of the aggregation of whistling species in the tropical study area and nonwhistling species in the temperate study area is likely found in some combination of the hypotheses discussed.

 
 
Hauser, D.D.W.*, C.S. Allen, H.B. Rich, Jr., and T.P. Quinn. 2008. Harbor seals (Phoca vitulina) in Iliamna Lake, Alaska: Summer diet and partial consumption of adult sockeye salmon (Oncorhynchus nerka). Aquatic Mammals 34(3):303-309.
 
School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA 98195, USA
Current Address: 78 Marine Drive, Logy Bay, Newfoundland A1K 3C7, Canada (DDWH)
 
Email: donna.hauser at gmail.com
 
This study assessed the summer diet and consumption patterns of harbor seals (Phoca vitulina) resident in Iliamna Lake, Alaska. The authors predicted that adult sockeye salmon (Oncorhynchus nerka), a seasonally abundant and nutrient-rich prey source, would dominate diets when available and that seals would preferentially consume the most energetically profitable portion of salmon carcasses. Diet was examined by identifying hard parts of prey found in harbor seal scats, and consumption patterns were measured by collecting carcasses of harbor seal-killed sockeye salmon along island spawning grounds. Salmonids were present in 98% of scats that contained identifiable prey, followed by petromyzontids, osmerids, cottids, coregonids, and gasterosterids. The carcass surveys provided evidence of selective consumption patterns of sockeye salmon body parts. Harbor seals consumed the bodies of nearly all (96.6%) male salmon collected, leaving little but the head. In contrast, the belly and eggs were consumed in 63.6% of the female samples, and the entire body was eaten in only 31.3% of females. The harbor seals in Iliamna Lake thus took advantage of the seasonally abundant adult sockeye salmon by consuming them selectively and as a high proportion of their diet, but they also consumed smaller resident fishes, which presumably sustain them during the rest of the year.
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 Jefferson, T.A.* and S.K. Hung. 2008. Effects of biopsy sampling on Indo-Pacific humpback dolphins (Sousa chinensis) in a polluted coastal environment. Aquatic Mammals 34(3):310-316.
 
*Southwest Fisheries Science Center, NOAA Fisheries, 8604 La Jolla Shores Drive, La Jolla, CA 92037, USA
 
Email: sclymene at aol.com
 
We conducted a biopsy sampling study of Indo-Pacific humpback dolphins (Sousa chinensis) in Hong Kong between October 2004 and January 2006. Humpback dolphins were sampled with a Barnett Ranger RX-150 crossbow. In total, 87 shots were taken at ranges of 8 to 28 m, and 36 tissue samples were collected. The hit rate was 56.3%, and the success rate was 41.4%. There was a better chance of hitting the dolphin with the dart when animals were closer to the shooter (all hits were at < 23 m distance). Humpback dolphin reactions to the procedure were mostly slight, with a few moderate reactions but no extreme ones. Humpback dolphins reacted similarly to hits and misses, and their reaction can best be characterized as a startle response. All reactions were short-term, and there was virtually no evidence of long-term impacts on behavior, social organization, or distribution patterns. Wounds appeared to heal well and were healed over with tissue in < 21 d. When conducted carefully by experienced persons, biopsy sampling of humpback dolphins can be done safely and effectively.
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Vila, A.R.*, C. Campagna, M. Iniguez, and V. Falabella.  2008. South American sea lions (Otaria flavescens) avoid killer whale (Orcinus orca) predation. Aquatic Mammals 34(3):317-330
 
Wildlife Conservation Society, CC794, (8400) Bariloche, Río Negro, Argentina
 
Email: alevila at speedy.com.ar
 
South American sea lions (Otaria flavescens) are predictably preyed on by killer whales (Orcinus orca) at their breeding colonies in Peninsula Valdes, Argentina. Captures occur in shallow waters along the coastline. Killer whales strand in the surf where sea lion pups practice their swimming skills. Being slow and apparently unaware of danger (nonvigilant), pups are the most vulnerable prey (87% of captures). Adult sea lions escaped most attacks by increasing their swimming speed, changing directions swiftly, grouping, and hauling out of the water. In our observations, predator avoidance behaviours were contextual and based on the presence of killer whales and the degree of risk in the areas used by sea lions during their movements between rookeries. Swimming speed increased in sites where the risk of predation was highest and when killer whales were present. Vigilance and escape manoeuvres were recorded at these dangerous sites, characterized by deeper water and a sloping beach, which allowed the killer whales to strand or approach the coast safely. Predictability of the killer whales in space and time facilitates the South American sea lions in developing a reliable antipredation behaviour. Killer whales become more proficient at being predators, and adult sea lions become better at avoiding being preyed upon as they accumulate experience. The inexperience of the sea lion pups is the currency that sustains the killer whale’s high rate of take.**********************
Simard, P.* and S. Gowans. 2008. Group movements of white-beaked dolphins
(Lagenorhynchus albirostris) near Halifax, Canada. Aquatic Mammals 34(3):331-337.
 
*University of South Florida, College of Marine Science, 140 7th Avenue South,St. Petersburg, FL 33701, USA

 
Email: psimard at marine.usf.edu
 
 
Movement patterns of animals are important in understanding their role in the environment (e.g., foraging, residency) and may provide insight into an animal’s life history and social structure. Movement is particularly important for animals where resources are highly temporally and spatially variable such as in the marine environment. Groups of white-beaked dolphins (Lagenorhynchus albirostris) were tracked at sea near Halifax, Nova Scotia, Canada, during the early summer months from 2003 to 2005. Twelve groups were followed for 20 min or more, and GPS positions of the research vessel when within approximately 10 m of the dolphins were used to determine group movements. For each group, movements were quantified by determining the straight-line bearing, swim speed, and directional deviation (the degree of deviation from straightline travel). Spearman’s correlations were calculated between these variables and day, time, mean water depth, bathymetric variability, dolphin group size, and number of young dolphins in the group. Significant negative correlations were found between bathymetric variability and swim speed (rs = -0.839, p = 0.001) and between bathymetric variability and directional deviation (rs = -0.608, p = 0.036). A significant positive relationship was found between directional deviation and mean water depth (rs = 0.755, p = 0.005). This indicates a tendency for dolphin groups to vary their direction of travel more frequently in areas with lower bathymetric variation and deeper water and to increase their swim speed in areas of lower bathymetric variation. A significant positive relationship was also found between group size and swim speed (rs = 0.880, p < 0.001). A possible explanation is that these dolphins are altering their movement patterns and group size in relation to foraging activities. 
Trimble, M.* and R. Praderi. 2008. Assessment of nonmetric skull characters of the franciscana (Pontoporia blainvillei) in determining population differences. Aquatic Mammals 2008, 34(3):338-348.
 
* Cetáceos Uruguay, Sección Etología, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo C.P. 11400, Uruguay
 
Email: mica.trimble at gmail.com
 
The franciscana (Pontoporia blainvillei) is a small endemic dolphin of the Atlantic coast of Brazil, Uruguay, and Argentina that presents conservation problems because of its incidental mortality in nets of artisanal fisheries throughout its entire distribution. An important step in managing small cetaceans is to define the populations involved because each identified population requires evaluation and treatment as a separate unit. Since 1991, morphological and genetic differences among franciscanas of different regions have been detected. Nonmetric characters (i.e., coded by discrete states and also known as qualitative traits) have been employed for the analysis of population differentiation of more than 50 mammal species because it has been assumed that they are exposed to minimum selection pressure. The aim of this study was to identify potentially useful nonmetric skull characters of the franciscana for comparison among individuals from different locations in order to investigate geographic variation in these traits and to determine their frequencies in individuals of the Uruguayan coast. Twenty-six characters were examined for 115 skulls belonging to the cetacean collection of the National Museum of Natural History and Anthropology (Montevideo, Uruguay). The potential existence of character dependence on body length, sex, and time period was examined. A total of 12 characters were excluded from subsequent analyses: seven were not sufficiently variable, four were dependent on body length, and one showed sexual dimorphism. Only 14 characters were remaining, and their frequencies were calculated. None of them was dependent on time period. Due to the low number of potentially useful nonmetric skull characters found in this study, the utility of this technique as an additional tool for franciscana population assessment is uncertain. The authors give some general methodological recommendations for use of nonmetric characters in population differentiation studies.
 
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Weir, C.R. 2008. Short-finned pilot whales (Globicephala macrorhynchus) respond to an airgun ramp-up procedure off Gabon. Aquatic Mammals 34(3):349-354.
 
1 Ketos Ecology, 4 Compton Road, West Charleton, Kingsbridge, Devon TQ7 2BP, UK
2 Department of Zoology, School of Biological Sciences, University of Aberdeen, Tillydrone Avenue,
Aberdeen, AB24 2TZ, UK
 
Email: c.r.weir at abdn.ac.uk; Caroline.Weir at ketosecology.co.uk
 
The ramp-up is a standard procedure within the offshore geophysical industry for mitigating the potential impacts of seismic airgun sound on marine mammals. However, the efficiency of the ramp-up as a mitigating procedure is poorly documented. In March 2008, a pod of 15 short-finned pilot whales (Globicephala macrorhynchus) was monitored before, throughout, and following a 30-min ramp-up procedure during a 2-D seismic survey off Gabon. No change in behaviour was apparent during the initial period of the rampup. However, 10 min into the ramp-up procedure (at airgun volume of 940 cu3), the nearest whale subgroup turned sharply away from the airguns. Subsequent behaviour included milling, tailslapping, and a 180° change of course to travel in the opposite direction from the seismic vessel. The observation described here suggests that pilot whales did initially demonstrate an avoidance response to the ramp-up. However, the movement away from the source was limited in time and space. Recommendations are made for further research into the efficiency of the ramp-up procedure for marine mammal mitigation.
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Dendrinos, D., A.A. Karamanlidis, S. Kotomatas, V. Paravas, and S. Adamantopoulou. 2008. Report of a new Mediterranean monk seal (Monachus monachus) breeding colony in the Aegean Sea, Greece. Aquatic Mammals 34(3):355-361.
 
MOm/Hellenic Society for the Study and Protection of the Monk Seal, Solomou Street 18, 10682 Athens, Greece
 
Email: a.karamanlidis at mom.gr
 

Identifying and effectively protecting the last remaining Mediterranean monk seal (Monachus monachus) populations and their habitats is a key priority for the survival of this critically endangered species. Following the opening of a restricted naval area at the island of Gyaros in the central Aegean Sea, Greece, the authors initiated efforts to verify the existence and assess the status of the species in the area. Using established monk seal habitat suitability criteria and survey techniques, the authors aimed to identify suitable habitat and document possible pup production of the species in this new area. Throughout the coastline of the island eight coastal caves were located, three of which were considered suitable for resting and pupping, while the remaining five were considered suitable for only resting. Pup production was recorded during the 2004, 2005 and 2007 pupping seasons and a minimum of ten, four and seven pups were identified respectively. In addition, mother – pup associations and interactions on three open beaches, a behavior that has not been observed in this species in the Mediterranean Sea recently, were recorded. This newly discovered colony, with relatively high natality compared to other breeding sites in the Mediterranean Sea and the rare use of open beaches, is of outstanding conservation value and is in urgent need of effective protection.
Fahrni Mansur, E.*, B.D. Smith, R. Mansur Mowgli, and M.A. Abu Diyan. 2008. Two incidents of fishing gear entanglement of Ganges River dolphins (Platanista gangetica gangetica) in waterways of the Sundarbans Mangrove Forest, Bangladesh. Aquatic Mammals 34(3):362-366.
 
*Bangladesh Cetacean Diversity Project, Shonadanga R/A, Khulna, Bangladesh
 
Email: mowgliz at gmail.com
 
Incidental mortality in fishing gear, especially gillnets, is considered among the most severe threats to the endangered Ganges River dolphin (Platanista gangetica gangetica). However, almost no information is available about actual interactions of the species with fisheries. An emaciated adult Ganges River dolphin was found stranded on Katka Beach where the eastern Sundarbans mangrove forest of Bangladesh meets the Bay of Bengal. The dolphin had a piece of fine-thread, mono-filament, 5-cm mesh-size gillnet, used to catch hilsa (Tenualosa ilisha) in large rivers and coastal areas, wrapped tightly around its rostrum. It also had a thicker strand, double-filament, 2.5- to 3.5-cm meshsize gillnet, used to catch medium-size fin fishes in large rivers and small creeks, entangled in its teeth at the end of the rostrum. The dolphin was disentangled and released. In another incident, the carcass of a nonlactating female Ganges River dolphin was also retrieved from a local fishing boat in the northeast portion of the Sundarbans. The dolphin had become entangled in a long-line fishing gear very similar to the rolling hooks used in the Yangtze River that have been cited as among the primary factors contributing to the probable extinction of the baiji (Lipotes vexillifer). These incidents confirm that Ganges River dolphins are vulnerable to being accidently killed by becoming entangled in gillnets and long-lines. These events also indicate the importance of monitoring mortality rates and establishing a protected area network in channel segments where the species occurs in relatively high numbers.
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Evans, W.E. 2008. Historical perspectives: A short history of the Navy’s Marine Mammal Program. Aquatic Mammals 34(3):367-380.
 
evans1930 at sbcglobal.net
 
No abstract provided. Dr. William Eugene Evans is a world-renowned marine mammal acoustician and ecologist with special interest in marine mammal management and conservation biology. He worked with the Navy for many years and provides a brief synopsis on the history of the U.S. Navy’s Marine Mammal Program.
 
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Cockcroft, V.* 2008. Book Review: Whales and dolphins off the Southern African Subregion. Peter B. Best. Cambridge University Press, Cambridge, UK, 2007. Aquatic Mammals 34(3):381.
 
*Centre for Dolphin Studies, Nelson Mandela Metropolitan University, P.O. Box 1856, Plettenberg Bay, 6600, South Africa
 
Email: info at dolphinstudies.co.za 

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