Description of whistles of Irrawaddy dolphins (Orcaella brevirostris) from the waters of Matang,Peninsular Malaysia

The whistles of Irrawaddy dolphins (Orcaella brevirostris) from the waters of Matang, western Peninsular Malaysia are described. Duration, frequency and frequency modulation variables were measured from 163 whistles recorded using a broadband towed hydrophone. Irrawaddy dolphins produced whistles with a mean duration of 0.366 s (S.D. ± 0.217 s). The fundamental frequency of whistles extended from 3040 to 17,123 Hz with low levels of frequency modulation. These dolphins produced whistles that were comparable to those of conspecifics recorded from the waters of Kalimantan, but were generally different from the related Australian snubfin dolphin (O. heinsohni). They also differed from the whistles of the sympatric Indo-Pacific humpback dolphin (Sousa chinensis). Characteristics of Irrawaddy dolphin whistles may be useful in future passive acoustic monitoring studies to investigate differences in sympatric species and their habitat.     

Shark bite injuries on three inshore dolphin species in tropical northwestern Australia

Predation risk has a profound influence on the behavior of marine mammals, affecting grouping patterns and habitat use. Dolphins frequently bear evidence of shark bites, which can provide an indirect measure of predation pressure. Using photo‐identification data, we investigated the prevalence of shark bites on three sympatric species of inshore dolphin, the Australian snubfin (Orcaella heinsohni), Australian humpback (Sousa sahulensis), and Indo‐Pacific bottlenose dolphin (Tursiops aduncus), among four study sites in northwestern Australia. Bite prevalence varied markedly between species, with 72% of snubfin, 46% of humpback, and 18% of bottlenose dolphins exhibiting evidence of shark bites. Binomial logistic regression confirmed a high likelihood of bite presence on snubfin dolphins, and at one particular site for snubfin and bottlenose dolphins. The prevalence of tiger shark (Galeocerdo cuvier) bites on snubfin dolphins was high, and bites attributed to other carcharhinid sharks were observed on all species. While acknowledging methodological differences with other studies, the prevalence of shark bites on snubfin dolphins is among the highest reported for any dolphins, suggesting predation risk represents an important but varying influence thereon. This study provides a baseline for future investigations into the affect of predation risk on the behavioral ecology of these sympatric species.     

SATELLITE-MONITORED MOVEMENTS AND DIVE BEHAVIOR OF A BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS) IN TAMPA BAY, FLORIDA

An adult, female bottlenose dolphin ( Tursiops trucncatus ) was radio tagged and monitored via satellite-based Argos receivers for 25 d from 28 June to 23 July 1990, in Tampa Bay, Florida. A total of 794 transmissions were obtained during 106 satellite passes. A mean of 3.9 (SE = 0.24) locations/day were determined by Service Argos and showed the animal remained in the bay, usually close to the southeastern shore. The dolphin moved at least 581 km at a minimum mean speed of 1.2 (SE = 0.1) km/h. Data from 63, 922 dives were recorded. The animal spent an average of 87.1 (SE = 0.6)% of the time submerged, with a mean dive duration of 25.8 (SE = 0.5) sec. Mean dive duration differed significantly between four periods of the day, as did the mean percent of time spent submerged. During the early morning the animal spent more time at the surface, averaged shorter dives, and was submerged less than other times of day. This is the first study to demonstrate die1 dive cycles in a bottlenose dolphin. Four months after tag loss, the dolphin was photographed with no evidence of necrosis or disfigurement of the dorsal fin. Satellite telemetry was demonstrated as an effective means of documenting the movements and dive behavior of a small inshore cetacean.     

Squalus formosus, a new species of spurdog shark (Squaliformes: Squalidae), from the western North Pacific Ocean

A new species of spurdog, Squalus formosus n. sp., from the lower continental shelf and upper continental slope off the coast of Taiwan and southern Japan, is described. It belongs to the 'highfin megalops group', the members of which share a short snout, high dorsal fins, robust dorsal spines, tricuspid denticles and a white posterior caudal margin. Squalus formosus is most similar to Squalus albifrons, a recently described species from eastern Australia, but differs in some morphological characters and fin colouration. Squalus formosus is sympatric with three other species of Squalus in Taiwanese waters, i.e. Squalus brevirostris, Squalus japonicus and Squalus mitsukurii, and can be readily distinguished from these in the following combination of characters: tall and upright first dorsal fin, with a tall and robust spine, short and bluntly pointed snout, white caudal-fin posterior margin and first dorsal fin with a white anterior margin parallel with dorsal spine. This new species was considered by some authors to be conspecific with Squalus blainville from the eastern Atlantic Ocean, but the results of this study reveal that it is probably endemic to Taiwan and southern Japan.     

Taxonomic revision of the humpback dolphins (Sousa spp.), and description of a new species from Australia

The taxonomy of the humpback dolphin genus Sousa has been controversial and unsettled for centuries, but recent work indicates that there are several valid species. A review of multiple lines of evidence from skeletal morphology, external morphology, coloration, molecular genetics, and biogeography, in combination provides strong support for the recognition of four species of Sousa. These include S. teuszii (Kükenthal, 1892), a species with uniform gray coloration and a prominent dorsal hump, which is found in the Atlantic Ocean off West Africa. The species S. plumbea (G. Cuvier, 1829) has similar external appearance to S. teuszii, but has a more pointed dorsal fin. It occurs in the Indian Ocean from South Africa to Myanmar (Burma). The original taxon, S. chinensis (Osbeck, 1765), is reserved for the species that has a larger dorsal fin with no prominent hump, and largely white adult coloration. It ranges from eastern India to central China and throughout Southeast Asia. Finally, we describe a new species of Sousa, the Australian humpback dolphin, which occurs in the waters of the Sahul Shelf from northern Australia to southern New Guinea. It has a lower dorsal fin, more extensive dark color on the body, and a dorsal “cape.” It is separated from the Indo‐Pacific humpback dolphin by a wide distributional gap that coincides with Wallace's Line.     

<Emphasis Type="Italic">Acheilognathus striatus</Emphasis> (Family: Cyprinidae), a new bitterling species from the lower Yangtze River,China

A new species of bitterling, Acheilognathus striatus sp. nov., is described on the basis of 57 specimens collected from the lower Yangtze River in Jiangxi Province, China. It can be distinguished from all congeners by the following combined characters: a pair of relatively long barbels, slightly longer than half of eye diameter; dorsal fin with three simple and 8–9 branched fin rays, anal fin with three simple and 7–8 branched fin rays; a black longitudinal stripe on body from the base of caudal peduncle, distinctly reaching anteriorly to the vertical line from the origin of dorsal fin, broader in males than in females; a scale distance between the longitudinal stripe and lateral line below the origin of dorsal fin; dorsal and anal fin margined with black band in males.     

Redescription of a rare bothid,Asterorhombus bleekeri (Macleay), and description of a new species ofAsterorhombus from northwestern Australia (Teleostei: Pleuronectiformes)

A rare Australian bothid flounder.Asterorhombus bleekeri (Macleay), is redescribed from the holotype and ten additional specimens from the east coast of Qeensland, Gulf of Carpentaria and Rowly Shoal (Western Australia). The species is transferred fromArnoglossus Bleeker toAsterorhombus Tanaka because of the lack of obvious sexual dimorphism in the interorbital width and pectoral fin length, the lack of rostral and orbital spines, the yellow-white blind side body coloration, and the deeply cleft parhypural and hypural plates. The definition ofAsterorhombus was emended as follows: the first dorsal fin ray continuous with or separated from remaining fin rays and gill rakers slender or stubby, with or without serrations.Asterorhombus osculus sp. nov., formerly briefly described in the literature as unidentified species ofEngyprosopon, was described from eight specimens from the northwestern coast of Australia. The new species is most similar toA. bleekeri in lacking sexual dimorphism, and having the caudal skeleton with deep clefts, two or three rows of teeth on the upper jaw and a pair of conspicuous black spots on the caudal fin, in addition to a similar general appearance, but is distinguished from the latter by shorter gill rakers, a very small mouth and feebly ctenoid scales on the ocular side. Both species clearly differed fromA. intermedius andA. fijiensis in having two (or three) rows of teeth on the upper jaws, slender gill rakers without serrations, first dorsal fin ray continuous with the other fin rays, and a pair of conspicuous black spots on the caudal fin.     

HORIZONTAL ANGULAR DISCRIMINATION BY AN ECHOLOCATING BOTTLENOSE DOLPHIN TURSIOPS TRUNCATUS

ABSTRACT

A bottlenose dolphin was tested on its ability to echoically discriminate horizontal angular differences between two arrays of vertical, air-filled, PVC rods. The blindfolded dolphin was required to station in a submerged, vertically-oriented hoop, 2 radial metres from the stimuli, and indicate whether an array with four rods (S+) was to the left or the right of an array with two rods (S-), by pressing a corresponding paddle. The angular separation between the rods within each array (θ_w) was maintained at 2 degrees but the angular separation between the two arrays (θ_b) was varied to produce angular differences (δθ = θ_b-θ_w)ranging from 0.25 degrees to 4 degrees. A modified method of constant stimuli was used to test for angular discrimination ability, and yielded a psychometric function having a 75% correct threshold of 1.6 degrees. This threshold fell between the passive listening minimum audible angle thresholds of 0.9 degrees for click signals and 2.1 degrees for a pure tone signal (Renaud & Popper 1975). Analyses of response times, number of clicks and inter-click intervals failed to detect any significant adaptive behaviour occurring as the task became more difficult. These results help to define angular resolution capabilities of dolphin sonar that may play an important role in representing spatial information in the dolphin's environment.     

Chloroplast genome sequence confirms distinctness of Australian and Asian wild rice

Cultivated rice (Oryza sativa) is an AA genome Oryza species that was most likely domesticated from wild populations of O. rufipogon in Asia. O. rufipogon and O. meridionalis are the only AA genome species found within Australia and occur as widespread populations across northern Australia. The chloroplast genome sequence of O. rufipogon from Asia and Australia and O. meridionalis and O. australiensis (an Australian member of the genus very distant from O. sativa) was obtained by massively parallel sequencing and compared with the chloroplast genome sequence of domesticated O. sativa. Oryza australiensis differed in more than 850 sites single nucleotide polymorphism or indel from each of the other samples. The other wild rice species had only around 100 differences relative to cultivated rice. The chloroplast genomes of Australian O. rufipogon and O. meridionalis were closely related with only 32 differences. The Asian O. rufipogon chloroplast genome (with only 68 differences) was closer to O. sativa than the Australian taxa (both with more than 100 differences). The chloroplast sequences emphasize the genetic distinctness of the Australian populations and their potential as a source of novel rice germplasm. The Australian O. rufipogon may be a perennial form of O. meridionalis.     

The reliability of pigment pattern‐based identification of wild bottlenose dolphins

Long‐term studies often rely on natural markings for individual identification across time. The primary method for identification in small cetaceans relies on dorsal fin shape, scars, and other natural markings. However, dorsal fin markings can vary substantially over time and the dorsal fin can become unrecognizable after an encounter with a boat or shark. Although dorsal fins have the advantage in that they always break the water surface when the cetacean breathes, other physical features, such as body scars and pigmentation patterns can supplement. The goal of this study was to explore the use of dorso‐lateral pigment patterns to identify wild bottlenose dolphins. We employed photographic pigment matching tests to determine if pigmentation patterns showed (1) longitudinal consistency and (2) bilateral symmetry using a 30 yr photographic database of bottlenose dolphins (Tursiops aduncus). We compared experienced dolphin researchers and inexperienced undergraduate student subjects in their ability to accurately match images. Both experienced and inexperienced subjects correctly matched dolphin individuals at a rate significantly above chance, even though they only had 10 s to make the match. These results demonstrate that pigment patterns can be used to reliably identify individual wild bottlenose dolphins, and likely other small cetacean species at other sites.     

A DWARF FORM OF THE SPINNER DOLPHIN (STENELLA LONGIROSTRIS) FROM THAILAND

A very small form of the spinner dolphin has been found to inhabit the Gulf of Thailand. Ten specimens taken incidentally in a local shrimp fishery differ from specimens of this species collected elsewhere in body size and shape, skull size and shape, number of teeth and numbers of thoracic and lumbar vertebrae. Four cranially adult males were 129–137 cm long, well below the ranges for the Indian Ocean, western Pacific, central Pacific, eastern Pacific and Atlantic. The skull is also very small. Tooth counts and vertebral counts average lower than in other series. The color pattern is not significantly different from that of spinner dolphins in the central and western Pacific, Atlantic and Indian Oceans but differs from that of the small eastern spinner of the eastern Pacific. The Gulf of Thailand specimens are morphologically separable from all other specimens, but it is to be expected that when larger samples are available there will be some overlap. The dwarf form may overlap in body and skull size with small spinner dolphins taken incidentally in a gillnet fishery for sharks off northern Australia. The geographic range of the dwarf spinner may be restricted. The size and status of the population and the impact of the shrimp fishery are unknown and should be investigated. The dwarf spinner may have an ecology different from that of other spinners, feeding mainly on reef-associated and benthic organisms rather than mesopelagic animals.     

AXIAL MUSCULATURE IN THE DOLPHIN (TURSIOPS TRUNCATUS): SOME ARCHITECTURAL AND HISTOCHEMICAL CHARACTERISTICS

In view of the supposition that a dolphin can swim faster than would be predicted based on its physical features and presumed muscle power potential, studies were initiated to reevaluate the assumptions made in reaching these conclusions. Several previous studies have shown that the architectural and histochemical properties of a skeletal muscle dictate its force, velocity and displacement properties. This study examined the muscle fiber lengths and tendon arrangements of the dorsal and ventral axial muscles in dolphins ( Tursiops truncatus ). Fiber type and fiber size distributions were determined to reflect the general biochemical characteristics of the musculature. The dorsal muscles had a higher mean fiber length (167 Vs. 90 mm) and the range within and across different dorsal muscles was less (141–199 vs. 37–185 mm) than in the ventral muscles. Both the dorsal and ventral muscles consisted of an overall mean of 50 percent slow twitch and 50 percent fast twitch fiber types. The fast twitch fibers were 67 percent larger (2,200 vs. 1,317 μ m ²) than the slow twitch fibers in the ventral and 38 percent larger (1,213 Vs. 879 μm²) in the dorsal muscles. In addition, the mean cross sectional area of the fibers in the ventral muscles was approximately 65 percent greater (1,750 vs. 1,072 μm²) than those in the dorsal muscles. The shorter, larger-diameter fibers of the ventral musculature give it a greater potential for force production for a given amount of muscle mass. In contrast, the dorsal muscles appear to be designed to optimize velocity and displacement, ( i.e. , longer fibers). These findings contribute to the information necessary for the determination of the power potential of the musculature of the dolphin.     

<Emphasis Type="Italic">Chelidoperca tosaensis</Emphasis>, a new species of perchlet (Serranidae) from Japan and the Philippines,with geographic range extension of <Emphasis Type="Italic">C</Emphasis>. <Emphasis Type="Italic">stella</Emphasis> to the northwestern Pacific Ocean

Chelidoperca tosaensis is described as a new species based on 84 specimens from Japan and the Philippines taken from depths of 60–302 m. The species can be distinguished from all known congeners by having the following combination of characters: scale rows between lateral line and base of spinous dorsal fin 3; pored lateral-line scales 37–42 (modally 39); scale rows in longitudinal series 39–43 (modally 40); no longitudinal dark stripe or row of dark blotches on body side. The new species is additionally characterized by having a combination of numerous, scattered, yellow spots on dorsal and anal fins with red streak or cluster of reddish spots over bases of about 4–6th dorsal-fin spines; large ocellated red spot with pinkish white border present on membrane between opercular spines; pelvic fin with middle area yellow with whitish spine, and whitish first, second and fifth soft rays; caudal fin with about three transverse rows of yellow spots centrally and posteriorly, two fan-shaped rows of red blotches on basal third, and a pair of white blotches with a pair of yellow blotches between white blotches on the base. Diagnostic characters of Chelidoperca stella, previously known only from its type locality in the Andaman Sea, are updated based on 12 specimens from Taiwan, the Gulf of Tonkin, Vietnam and the Philippines. These specimens represent the first records of the species from the Pacific Ocean.     

Resource partitioning in sympatric delphinids: space use and habitat preferences of Australian snubfin and Indo-Pacific humpback dolphins

1. Many species of delphinids co-occur in space and time. However, little is known of their ecological interactions and the underlying mechanisms that mediate their coexistence. 2. Snubfin Orcaella heinsohni, and Indo-Pacific humpback dolphins Sousa chinensis, live in sympatry throughout most of their range in Australian waters. I conducted boat-based surveys in Cleveland Bay, north-east Queensland, to collect data on the space and habitat use of both species. Using Geographic Information Systems, kernel methods and Euclidean distances I investigated interspecific differences in their space use patterns, behaviour and habitat preferences. 3. Core areas of use (50% kernel range) for both species were located close to river mouths and modified habitat such as dredged channels and breakwaters close to the Port of Townsville. Foraging and travelling activities were the dominant behavioural activities of snubfin and humpback dolphins within and outside their core areas. 4. Their representative ranges (95% kernel range) overlapped considerably, with shared areas showing strong concordance in the space use by both species. Nevertheless, snubfin dolphins preferred slightly shallower (1-2 m) waters than humpback dolphins (2-5 m). Additionally, shallow areas with seagrass ranked high in the habitat preferences of snubfin dolphins, whereas humpback dolphins favoured dredged channels. 5. Slight differences in habitat preferences appear to be one of the principal factors maintaining the coexistence of snubfin and humpback dolphins. I suggest diet partitioning and interspecific aggression as the major forces determining habitat selection in these sympatric species.     

A simple laser photogrammetry technique for measuring Hector's dolphins (Cephalorhynchus hectori) in the field

The ability to measure and age individuals within a population has many important applications, for example, for examining growth and determining size class. We developed a simple photogrammetric system using two parallel lasers and a digital camera, in order to measure dorsal fin dimensions of free-ranging Hector's dolphins. Laser dots were projected onto the fin, providing scale, thus allowing measurement as well as simultaneous photo-ID of 34 individuals from fin nicks and other marks. Multiple measurements (≥5) were available for six individuals; these resulted in mean CVs of 3.71% for fin length and 3.76% for fin height. Errors due to variations in angle and measurement were quantified via photography of a fiberglass Hector's dolphin model. Allometric measurements and age data were collated from 233 autopsied Hector's dolphins. Using these data, fin length was found to be a better predictor of total length (females r²= 0.732, males r²= 0.678) than fin height. Gompertz age/length growth curves were fitted to these individuals. Linear regressions were used to estimate total length for 34 individuals from laser-metrically estimated fin base length. Individuals were then assigned one of three age categories. This system shows promise as a noninvasive way of measuring individuals, while allowing simultaneous photographic identification.     

Morphometric Analysis and Identification on Specific Metric Characters Pertaining Growth of the Osteobrama cotio of the Brahmaputra, Barak and Teesta River of North Eastern Himalayan River Systems

The variations of morphometric features and the identification of the characteristic features involved in growth variation of Osteobrama cotio were studied from three Eastern Himalayan River Systems: The Brahmaputra, Barak and Teesta River systems. Altogether 220 specimens of different sizes were analysed. Each morphometric character including total length of 220 individuals ranging from 47 to 86 mm and the standard length (SL) from 31 to 65 mm, were recorded. We tested the hypothesis that the body proportion changes gradually rather than abruptly by fitting the linear and quadratic regression curves against the SL of each metric character. The subpopulation from all the locations appeared to be relatively uniform in all of the characters examined. Out of the nine metric characters examined, all the eight characters (head length, snout length, eye diameter, body depth, pre dorsal length, post dorsal length, dorsal fin length and caudal fin length) demonstrated the allometric growth of the fish as described by quadratic regression, except anal fin character which is isometric in growth.     

Echinogobius hayashii, A new genus and species of gobiidae

Echinogobius hayashii, a new genus and species of Gobiidae is described, based on 11 specimens from Japan and Australia. This genus is distinguishable from all other gobiid genera in having the following combination of characters: first spine of first dorsal fin hard and straight, about 1.5 times second spine in thickness; first spine of second dorsal fin hard, with similar thickness as first soft ray of second dorsal fin, supported by two normally-sized pterygiophores; snout convex; preopercular spine absent; predorsal scales absent; all scales cycloid. The species occurs between 1–20 m in clear water on clear sandy bottoms influenced by fast tidal currents. Based on our observations, it is not associated with an alpheid shrimp.     

Bibarba bibarba: A new genus and species of Cobitinae (Pisces: Cypriniformes: Cobitidae) from Guangxi Province (China)

A new genus of Cobitinae, Bibarba gen. n., and a new species, B. bibarba sp. n., were discovered and are described for the Chengjiang River, a tributary of the Hongshuihe River in Guangxi Province of southern China. This river region is characterized by a Karst landscape, and the river that is inhabited by the new genus is a slowly moving stream with arenaceous and cobblestone beds. The new genus resembles Cobitis Linnaeus, 1758 (subfamily Cobitinae) in the shape and pigmentation pattern of their body, the absence of scales on their head, and the presence of a suborbital spine, but differs from it by a single Lamina circularis on the third pectoral fin ray instead of on the base of the second pectoral fin ray; two pairs of barbels (one rostral pair and one maxillo-mandibular pair) instead of three pairs of barbels (one rostral pair, one maxillary pair, and one maxillo-mandibular pair); a relatively thick and short suborbital spine with a strong medio-lateral process instead of a suborbital spine without or with a weakly formed medio-lateral process as in Cobitis; and the lack of a black stripe extending from the occiput through the eye to the insertion of the rostral barbel. The first two characters have not been reported in any other genus of the subfamily Cobitinae. A morphometric character analysis based on PCA reveals differences between B. bibarba and C. sinensis in body size, barbel length, interorbital width, pectoral fin length in males, and the position of the dorsal and ventral fins. Type specimens of the new species are kept in the Freshwater Fishes Museum of the Institute of Hydrobiology at the Chinese Academy of Sciences in Wuhan, Hubei Province.     

ECOLOGY, BEHAVIOR AND SOCIAL ORGANIZATION OF THE BOTTLENOSE DOLPHIN: A REVIEW

The authors review the literature on bottlenose dolphin ecology, behavior and social organization, focusing on data collected on free-ranging animals. Most bottlenose dolphins studied to date have had definable home ranges, and behavioral, morphological and biochemical information indicates discrete stocks in some areas. Bottlenose dolphins appear to form relatively permanent social groups based on sex and age. Mother—calf bonds are long-lasting. Movement patterns are extremely variable from location to location but are relatively predictable at any given site. Food resources are one of the most important factors affecting movements. Bottlenose dolphin behavior is very flexible, and these dolphins are generally active day and night. Feeding peaks in the morning and afternoon have been observed at several sites. Social behavior is an important component of daily activities. Sharks are the most significant predator on bottlenose dolphins in most areas, but captive and wild studies show that dolphins and sharks frequently live in harmony as well. Human activities may be helpful, harmful or neutral to bottlenose dolphins, but interactions with humans are frequent for these coastal cetaceans.