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The distribution and local movement patterns of humpback whales in waters off the west coast of Okinawa Island, southwest Japan, were investigated using line transect and photo-identification methodologies. Line transect surveys were conducted from 2011 to 2014 and photo-identification survey from 2006 to 2012. During the surveys, humpback whales aggregated in the areas around Ie and Kerama Islands, and tended to travel along the inshore coast of Okinawa Island when they move locally between those two sites. A total of 496 humpback whales of the known sex were photo-identified (322 males, 75 females and 99 females with a calf). Of these, 24.8% were confirmed moving locally between the sites of Ie and Kerama Islands within the same season. Frequency rates of the local movement for males, females and females with a calf were 41.9, 25.0, and 15.1%, respectively; the frequency of local movement for males was significantly higher than that for females and females with a calf. These results indicate that male humpback whales tend to move more actively between the local breeding sites as compared to females and females with a calf. We speculate that the males search for more opportunities to mate, whereas females with a calf tend to remain in the same areas to nurse their calves. These findings extend our knowledge of the habitat use and reproductive ecology of humpback whales in Okinawan waters, which remain poorly understood.

Detailed knowledge of the population of humpback whales (Megaptera novaeangliae) in Okinawa is important for conservation management in this area; however, information on the spatial distribution of this population is limited. In this study, we investigated the distribution of whales using data on the sighting locations, water depth, and reproductive status of whales collected over 21 years in the area of Kerama and Ie Islands, Okinawa, Japan, one of the breeding grounds in the Western North Pacific. Of 1,402 whales that were photo-identified (856 males, 100 singers, 150 females, and 296 females with a calf), males, females, and singers were mainly distributed in deep offshore waters, while females with a calf were distributed in shallow interisland waters. The results suggest that certain reproductive activities, such as mating behavior or competition among males over females to mate, might occur in the offshore northern waters of Kerama Islands and western waters of Ie Island, while nurturing ...

The species-specific host-recognition system of anemonefish was examined experimentally, with a particular focus on the function of imprinting using naive Amphiprion ocellaris juveniles. Anemonefish parents lay their eggs very close to their host anemone so the eggs are almost always touched by the host's body or tentacles. Here, we demonstrate the embryonic and immediate post-hatching learning of chemical cues via the parents' host in A. ocellaris through a host-exchange experiment with egg batches during hatching. The memory obtained from such imprinting operates at the time when juveniles first search for their hosts. Unexpectedly, innate recognition was found to exist not only in the symbiotic host species but also weakly in two non-partner species. Innate recognition alone is not sufficient. Imprinting via the parents' host complements innate recognition, leading to rigid species-specific host recognition. Imprinting by the parents' single host provides a sufficient cue for reaching the two host species. Furthermore, when combined with imprinting, innate recognition of non-partners serves to supplement the recognition of those species, leading to substitute partnerships that are only observed in some localities. Potential functions of imprinting in the host-recognition system are discussed. The “spare recognition hypothesis” and the necessity of clear distinctions between symbiotic and substitute species are also proposed here.

Expansion of the ‘pharynx’ during breathing or capturing prey in fishes generally involves posteroventral retraction of the hyoid arch. However, the hyoid arch structure of batoid fishes (skates, rays, guitarfishes, and sawfishes) is unique, and how they expand the pharyngeal cavity is poorly understood. To investigate the mechanism of pharyngeal expansion during breathing in the yellow-spotted fanray, Platyrhina tangi, we conducted anatomical and kinematic investigations of the pharyngeal region. Our study revealed that the yellow-spotted fanray and sharks have different skeletal linkage systems for pharyngeal expansion. During pharyngeal expansion in the yellow-spotted fanray, the hyoid bar and branchial apparatus rotate ventrally around the hinge joint between the fifth ceratobranchial cartilage and the pectoral girdle. This pharyngeal expansion mechanism appears to be widespread among batoid fishes and is unique among cartilaginous fishes (sharks, batoids, and holocephalans). Batoid fishes possibly developed this pharyngeal expansion mechanism during early batoid evolution.

Entanglement in fishing gear occurs in endangered manatees and may result in serious injury or death. Such incidents may happen more frequently at night when the animal’s visual sense is limited. In this study, we examined the differences in behavioral response of captive manatees to a net obstacle during light (day) and dark (night) periods. We used a plastic net as the obstacle, and video-recorded the manatees’ behavior. The experiments showed that captive manatees avoided the obstacle during the day more frequently than at night, which suggests that the manatees can perceive the obstacle more readily during light periods. However, there was no difference in the frequency of bumping or actively touching the obstacle between light and dark periods. The results suggest that the manatees can recognize the net obstacle even at night by purposely touching it, but they avoid it less frequently, and that entanglement during light periods may occur during accidental bumping, rather than from a failure to recognize it altogether.

Concentrations of serum lipid components, lipid peroxide (LPO) and alpha-tocopherol and electrophoretic patterns of lipoproteins in serum samples obtained from captive marine mammals and terrestrial mammals were compared. Serum concentrations of total cholesterol, free fatty acid, and phospholipid in fish-eating animals were significantly higher than those in manatees and cows. Serum LPO and alpha-tocopherol concentrations in the fish-eating animals were also significantly higher than those in manatees, cows and dogs. Different patterns of densitometric scans of low density lipoprotein (LDL) and a significantly lower percentage of LDL were demonstrated in the dolphins compared with the seals, cow and dogs. The concentration of LPO was significantly correlated with triglyceride and phospholipid concentrations in serum from the dolphins. These results suggest that triglyceride and phospholipid are susceptible to oxidative reaction in fish-eating animals. Evaluation of serum lipids, LPO and alpha-tocopherol concentrations is needed for nutritional husbandry for fish-eating animals.

We examined the incidence of rake mark scars from killer whales Orcinus orca on the flukes of humpback whales Megaptera novaeangliae throughout the North Pacific to assess geo- graphic variation in predation pressure. We used 3650 identification photographs from 16 wintering or feeding areas collected during 1990 to 1993 to determine conservative estimates in the percentage of whales with rake mark scarring. Dramatic differences were seen in the incidence of rake marks among regions, with highest rates on wintering grounds off Mexico (26 vs. 14% at others) and feed- ing areas off California (20 vs. 6% at others), 2 areas between which humpback whales migrate. Although attacks are rarely witnessed, the prevalence of scars demonstrates that a substantial por- tion of animals are attacked, particularly those that migrate between California and Mexico. Our data also suggest that most attacks occur at or near the wintering grounds in the eastern North Pacific. The prevalence of attacks indicates that killer whale predation has the potential to be a major cause of mortality and a driving force in migratory behavior; however, the location of the attacks is inconsis- tent with the hypothesis that animals migrate to tropical waters to avoid predation. Our conclusion is that, at least in recent decades, attacks are made primarily on calves at the wintering grounds; this contradicts the hypothesis that killer whales historically preyed heavily on large whales in high- latitude feeding areas in the North Pacific.

Okinawa Churaumi Aquarium, Ishikawa 424, Motobucho, Kunigamigun, Okinawa 905-0206, JapanThe dugong Dugong dugon is the only strictly marineherbivorous mammal. Dugongs are found as far north asJapan, but they have only been recorded off the coast ofOkinawa Island (26oN, 128oE) since 1970 (Marsh et al.2002).On 9 September 2002, an adult dugong was founddead on the Ushibuka coast (32oN, 130oE), of KyushuIsland (approximately 750 km north of Okinawa Island).It is of primary importance to establish whether thisdugong had inhabited the waters off Kyushu Island orwhether it had moved recently from a more southerlyregion such as Okinawa, because Okinawa is regarded asthe northern limit of the dugong’s habitat.Dugongs feed almost exclusively on various sea-grasses (Aketa and Kawamura 2001). Around OkinawaIsland, feeding trails of dugongs have only been found inseagrass beds (Marsh et al. 2002). At Ushibuka coast,however, macrophyte beds primarily contain macroalgae(Environment Agency 1989), not seagrasses.Naturally occurring stable isotopes of carbon andnitrogen have been used to study the foraging ecology ofseveral marine mammals (Bowen and Siniff 1999). Thenitrogen isotope ratio

Until present, fundamental studies on cortisol secretory patterns have not been conducted in cetaceans. The objectives of this study were: (1) to examine diurnal changes in serum cortisol concentrations in Indo-Pacific bottlenose dolphins Tursiops aduncus and killer whales Orcinus orca , (2) to investigate annual cortisol changes in killer whales, and (3) to investigate the relationship between cortisol and sex steroids (testosterone and progesterone) concentrations in killer whales. Diurnal changes in serum cortisol concentrations were investigated at various intervals in the two species. In Indo-Pacific bottlenose dolphins, serum cortisol levels exhibited the same episodic fluctuations for 24 h as did diurnal terrestrial mammals: cortisol levels were lower at 18:00 h and higher in the early morning. In killer whales, cortisol concentrations continued to decrease until 18:00 h, after which they fluctuated, and then increased in the next morning. Annual changes in cortisol levels were investigated by collecting blood samples every two weeks from two male killer whales and a pregnant female one twice per day (during 09:00–10:00 and 16:00–17:00 h) throughout a one-year period. Regarding sera collected during 09:00–10:00 h from the female, cortisol concentrations showed cyclic changes having about 4-month intervals. In males, cortisol showed higher concentrations in winter and lower concentrations during the summer season. There was a negative correlation between cortisol and progesterone levels in the female and a negative correlation was also observed between cortisol and testosterone in male no. 2. In the female and male no. 1, cortisol levels during 09:00–10:00 h were significantly higher than those during 16:00–17:00 h, and their data are considered to support observations regarding diurnal changes in cortisol levels in the two cetacean species.

There are few studies on the ecology of whales in underwater except for small whales (Baird, R., 1996, Otani, S., 1998). It is hoped that through the use of Autonomous Underwater Vehicles (AUVs) new knowledge about whales can be gained. The whale makes sounds, and especially the humpback whale (Megaptera novaeangliae) makes a specific sound called “a song”. We started our project to develop the technology for AUVs to follow and observe humpback whales by analyzing their songs and locating them underwater.A small size passive SONAR was designed, fabricated, and fitted on the AUV AQUA EXPLORER 2000. An observation experiment was conducted in March 2001 off the Kerama Islands, Okinawa. Prior to our studies, there were no examples of AUV observations on whales anywhere in the world. This experimental observation was conducted as a joint project of the Underwater Technology Research Center at the Institute of Industrial Science in the University of Tokyo, KDDI Co. Research Institute, and the Okinawa EXPO Aquarium. The AUV succeeded in detecting a humpback whale underwater and approaching it within 50m in this experiment.

Lacaziosis, formerly called lobomycosis, caused byLacazia loboi, is a zoonotic mycosis found in humans and dolphins and is endemic in the countries on the Atlantic Ocean. Although the Japanese coast is not considered an endemic area, photographic records of lacaziosis-like skin lesions were found in bottlenose dolphins (Tursiops truncatus) that were migrating in the Goto Islands (Nagasaki Prefecture, Japan). We diagnosed 2 cases of lacaziosis in bottlenose dolphins captured simultaneously at the same coast within Japanese territory on the basis of clinical characteristics, cytology, histopathology, immunological tests, and detection of partial sequences of a 43 kDa glycoprotein coding gene (gp43) with a nested-PCR system. The granulomatous skin lesions from the present cases were similar to those found in animals from endemic areas, containing multiple budding and chains of round yeast cells and positive in the immune-staining with anti-Paracoccidioides brasiliensisserum which is a fungal species related toL. loboi; however, thegp43gene sequences derived from the present cases showed 94.1% homology toP. brasiliensisand 84.1% toL. loboi. We confirmed that the causative agent at the present cases was different genotype ofL. loboifrom Amazon area.

We conducted an ultrasonographic experiment on a pregnant manta ray, Manta alfredi (Chondrichthyes, Batoidea). This study showed how the embryo of the live-bearing elasmobranchs respires in the body of the female. In the embryonic stage, the manta ray embryo takes in uterine fluid by buccal-pumping. After birth, the manta ray shifts its respiratory mode from buccal-pumping to ram-ventilation. The rapid reduction of the spiracle size in the young manta ray may reflect this shift of respiratory mode. Unlike mammals or some carcharhinid sharks that acquire oxygen through a placenta and umbilical cord, the manta ray embryo does not have a direct connection with the mother. Thus, the manta ray embryo obtains oxygen by buccal-pumping of the uterine fluid, in the same way that the embryos of egg-laying species obtain oxygen from the water in the egg case. This finding extends our understanding of the diversity of embryonic respiratory systems in live-bearing vertebrates.

MIWA SUZUKI1, TERUO TOBAYAMA2, ETSUKO KATSUMATA2, SENZO UCHIDA3, KEIICHI UEDA3, MOTOI YOSHIOKA4, AND KATSUMI AIDA1. 1 Graduated School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, 113-8657, Japan (miwa@marine.fs.a.u-tokyo.ac.jp), 2 International Marine Biological Research Institute (Kamogawa Sea World), Higashi-cho, Kamogawa, Chiba, 269-0041, Japan, Okinawa Expo Aquarium, Motobu-cho, Okinawa, 905-0206, Japan, a Faculty of Biosources, Mie University, Kamihama-cho, Tsu, Mie, 514-8507, Japan.

Des observations de requins captifs ont permis d'apporter de nouveaux elements dans l'etude du processus de retournement de l'intestin valvulaire. Comparaison anatomique de la position de l'estomacopylorique, la longueur et le type de valve intestinale dans differentes especes d'elasmobranches afin de donner des bases morphologiques aux mecanismes d'eversion gastrique