Volume 43 - Issue 6


AM 43.6 Cover 100dpi

Abstract: Emigration of individual animals is an important biological phenomenon that depends on both populations and ecosystem attributes. Off Mikura Island, a long-term identification survey of individual Indo-Pacific bottlenose dolphins has been conducted since 1994 using an underwater video system. Between 1994 and 2014, 277 individual dolphins were identified by this survey, with 41 individuals emigrating from Mikura Island during this period. Adults emigrated significantly more often than younger age classes. The sex and age classes of emigrants in 2008 and 2010 (the years with the greatest amount of emigration) differed, suggesting that social relationships within a population may affect emigration. Emigrants were observed among the Izu Island Chain and in Chiba, Shizuoka, Mie, and Wakayama Prefectures. The greatest distance dolphins emigrated from Mikura Island was 390 km to Tanabe in Wakayama Prefecture. Some individuals were observed to have emigrated to several areas during the period. The most frequent destination was Toshima Island, one of the Izu Islands Chain, where emigrants have been observed to reproduce. Emigrant groups were composed exclusively of individuals from Mikura Island; there were no immigrants to the Mikura Island area during the 20-y period of observation, although six emigrants eventually returned to their original range. Future studies of social relationships and habitat use by emigrants will reveal more about the reasons dolphins leave their habitats.
Key Words: emigration, long-distance movement, Japan, Indo-Pacific bottlenose dolphin, Tursiops aduncus
Document Type: Research Article
DOI: https://doi.org/10.1578/AM.43.6.2017.585
Page Numbers: 585-593

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Abstract: Ethograms, or categorized lists of behavioral descriptors, are fundamental research tools in the study of animal behavior and are essential to the overall understanding of the behavioral ecology of a species. With specific definitions of activity state categories and behavioral event types, the behavior of a species can be described, quantified, and compared across populations. We present the first ethogram for bottlenose dolphins (Tursiops truncatus) in Ireland based on sighting records collected during 256 surveys (2014-2016) in the Shannon Estuary. The ethogram consists of 11 activity states and 45 behavioral events. The most frequently recorded activity state was Travel (52%), while the most frequently recorded behavioral events were Slow travel (40% of sightings), Surface rush (28% of sightings), and Leap (28% of sightings). The ten least frequently recorded behaviors were seen in only 10% of total sightings with < 8 records each. A video test for multiple researchers to assess inter-observer reliability in behavioral data recording demonstrated the validity of this study’s behavioral data and the efficacy of the ethogram in its applicability to other studies. Validity (percentage agreement = 88.1 ± 7.0) and reliability (Fleiss’ Kappa = 0.81) scores were high across 24 test participants (12 trained and 12 untrained), but results indicated that those with prior training scored significantly higher. Furthermore, we investigate the presence/absence of behaviors recorded in other studies of bottlenose dolphins. This ethogram and behavioral discussion serve to describe and compare quantita-tive data on the behavior of bottlenose dolphins in Ireland for the first time and provide a strong basis for further research.
Key Words: ethogram, repertoire, bottlenose dolphin, Tursiops truncatus, Shannon Estuary, Special Area of Conservation
Document Type: Research Article
DOI: https://doi.org/10.1578/AM.43.6.2017.594
Page Numbers: 594-613

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Document Type: Short Note
DOI: https://doi.org/10.1578/AM.43.6.2017.614
Page Numbers: 614-617

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Abstract: Ammonium urate nephrolithiasis has been reported in common bottlenose dolphins (Tursiops truncatus) managed under human care but rarely occurs in free-ranging dolphins. In terrestrial mammals, including human beings, consumption of purine-rich seafood may predispose to urate urolith formation because purines are metabolized and excreted in urine as urate ions. Dolphins consume a piscivorous diet, but the purine content of their diet is unknown. Free-ranging dolphins consume live, temperate-water fish, whereas managed dol-phins consume frozen, stored, and thawed cold-water species that dolphins would probably not encounter in the wild. Purine metabolite concentrations vary with species and cold storage methods, so the purine intake of managed and free-ranging dolphins may differ. The concentrations of eight purine metabolites were measured in fresh frozen fish species commonly consumed by free-ranging dolphins and in seven frozen, stored, and thawed fish and squid species commonly consumed by managed dolphins. Total purine content was cal-culated for two model diets typically consumed by managed dolphins and a model diet reported to be consumed by bottlenose dolphins in Sarasota Bay, Florida. Total and individual purine metabolite concentrations differed significantly (p < 0.05) among individual species and among model diets. The mean total purine content of model managed dolphin diets was twice that in the model free-ranging dolphin diet. Inosine and IMP were measured because they can convert to hypoxanthine during frozen storage. Hypoxanthine concentrations were higher relative to inosine and IMP in managed species after frozen storage than in unstored free-ranging species (p < 0.05). These differences may explain the higher prevalence of ammonium urate nephrolithiasis in some managed dolphins compared to free-ranging dolphins and implies that the purine intake of some managed dolphins can be decreased by altering the proportions of species fed. Further research is needed, however, to determine whether such a change prevents ammonium urate nephrolith formation in dolphins.
Key Words: diet, kidney stones, ammonium urate nephroliths, IMP, inosine, hypoxanthine, purines, bottlenose dolphins, Tursiops truncatus
Document Type: Research Article
DOI: https://doi.org/10.1578/AM.43.6.2017.618
Page Numbers: 618-628

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Document Type: Short Note
DOI: https://doi.org/10.1578/AM.43.6.2017.629
Page Numbers: 629-634

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Abstract: Many recent studies have demonstrated that the health of bottlenose dolphins (Tursiops truncatus) can serve as an important indicator of hazards in the marine environment. A convenient and accurate way to get a “snapshot” of a dolphin’s health is to compare biological and physiological measurements to known reference intervals (RIs), which are ranges of values often considered normal or healthy. Measurements that fall above or below RI thresholds are usually considered abnormal and may indicate a health concern. Biological and physiological parameters of individuals sampled during field health assessments are often compared to RIs, but this is usually conducted post-fieldwork, following veterinary evaluation and biological sampling, which limits the ability to quickly diagnose problems and immediately perform more telling tests. The objective of this study was to develop a mobile application (app) that allowed instantaneous comparison of bottlenose dolphin morphometrics (i.e., length, mass, and girth) to previously published body condition RIs in situ. Furthermore, for bottlenose dolphins with mass and girth within normal ranges, the mobile app was programmed to compare field measurements to newly derived percentiles (25th, 50th, and 75th). The app was developed using MIT App Inventor 2© software. Functions were validated using historical and simulated data and were field tested during a bottlenose dolphin capture-release health assessment to evaluate feasibility for field use and to gain information for feature enhancements. An app that can rapidly evaluate body condition will significantly enhance veterinary evaluations of bottlenose dolphins (in the wild and under human care), as well as enhance epidemiologic studies of population health as coastal environments become increasingly stressed from pollution and other anthropogenic disturbances.
Key Words: cetacean, marine mammal, health, technology, length, mass, girth
Document Type: Research Article
DOI: https://doi.org/10.1578/AM.43.6.2017.635
Page Numbers: 635-644

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Document Type: Short Note
DOI: https://doi.org/10.1578/AM.43.6.2017.644
Page Numbers: 644-648

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Document Type: Short Note
DOI: https://doi.org/10.1578/AM.43.6.2017.649
Page Numbers: 649-654

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Document Type: Short Note
DOI: https://doi.org/10.1578/AM.43.6.2017.655
Page Numbers: 655-660

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Abstract: Human activity can greatly influence the behavior and distribution of bottlenose dolphins (Tursiops truncatus). This project focused on the distribution and behavior of bottlenose dolphins in the Drowned Cayes, Belize. Prior to the 2000s, the area was relatively undeveloped and undisturbed and had minimal human activity. Since 2000, fish camps, small resorts, and cruise ship tourism have flourished in the area. This has caused an increase of over 800,000 visitors from 1998 to 2006. Boat-based survey data were collected from 2005 to 2015 and compared to results from surveys conducted in 1999-2000. Total dolphin observation time as a percentage of total survey time was 17.2% in the 1999-2000 dataset and 10.8% in the 2005-2015 datasets. This decrease in observation time suggests that the dolphin population in the Drowned Cayes has decreased since the late 1990s. However, these values could be influenced by survey methods. In 2015, cruise ship presence in the area was also recorded. Eighty-nine percent of the total observation time for 2015 occurred on days for which there were zero cruise ships present, suggesting that dolphins may be avoiding the area when cruise ships are present. Foraging was the most frequently observed behavior in both 1999-2000 and 2005 to 2015 suggesting that the Drowned Cayes is used as a foraging area. That said, the percent of foraging activity was significantly higher in 1999-2000 (86.3%) than in 2005 to 2015 (57.4%), having dropped by 28.9%. Interestingly, there was a 23.6% increase in traveling behavior between 1999-2000 (9.2%) and 2005 to 2015 (32.8%). These behavioral changes could potentially be linked to increased human activity or other unidentified factors. Examining observed changes in behavior increases knowledge of this species in the study area and can provide insight for improved local management of this small dolphin population.
Key Words: Belize Barrier Reef Lagoon System, ecotourism, behavior, cruise ships, mother–calf pairs, Swallow Caye Wildlife Sanctuary, conservation, human impacts, bottlenose dolphin, Tursiops truncatus
Document Type: Research Article
DOI: https://doi.org/10.1578/AM.43.6.2017.661
Page Numbers: 661-672

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Document Type: Short Note
DOI: https://doi.org/10.1578/AM.43.6.2017.673
Page Numbers: 673-681

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Document Type: Short Note
DOI: https://doi.org/10.1578/AM.43.6.2017.682
Page Numbers: 682-690

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Abstract: Harbor porpoises (Phocoena phocoena) were rarely seen in San Francisco Bay prior to 2008 despite numerous marine mammal search efforts beginning in the 1970s. The species inhabited the bay historically before they were functionally extirpated by the early 1940s. Their disappearance correlated with increased anthropogenic disturbances such as dredging, shoreline construction, World War II military defenses, and environmental impacts from industrialization. After observing porpoises throughout the central San Francisco Bay from 2008 to 2010, we documented the porpoises’ occurrence by means of a visual count from the Golden Gate Bridge. From 2011 to 2014, we spent 288 h counting porpoises from that unique platform, resulting in 2,698 porpoise group sightings recorded in all months of the year. Group size averaged 2.15, and the maximum group size was 16 animals. Calves comprised 10% of all porpoises sighted and were also seen throughout the year. Porpoises were observed on 96% of 169 survey days, and an average of 34.37 ± 29.19 were seen per day. Porpoises can now be seen in the central bay daily throughout the year. Stranding records for the bay reflected the general pattern of the porpoises’ decades-long absence and their reappearance. Potential reasons for the porpoises’ return include decreased water and noise pollution, improved water quality, and increased marine productivity that created conditions in the bay that were favorable for porpoises.
Key Words: San Francisco Bay, cetacean, extirpation, habitat reoccupation, recovery, recolonization, ecosystem resilience, harbor porpoises, Phocoena phocoena
Document Type: Research Article
DOI: https://doi.org/10.1578/AM.43.6.2017.691
Page Numbers: 691-702

Free Vol. 43, Iss. 6, Stern

Document Type: Obituary
DOI: https://doi.org/10.1578/AM.43.6.2017.703
Page Numbers: 703-704


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