Integrating multiple lines of evidence to better understand the evolutionary divergence of humpback dolphins along their entire distribution range: a new dolphin species in Australian waters?

The conservation of humpback dolphins, distributed in coastal waters of the Indo‐West Pacific and eastern Atlantic Oceans, has been hindered by a lack of understanding about the number of species in the genus (Sousa) and their population structure. To address this issue, we present a combined analysis of genetic and morphologic data collected from beach‐cast, remote‐biopsied and museum specimens from throughout the known Sousa range. We extracted genetic sequence data from 235 samples from extant populations and explored the mitochondrial control region and four nuclear introns through phylogenetic, population‐level and population aggregation frameworks. In addition, 180 cranial specimens from the same geographical regions allowed comparisons of 24 morphological characters through multivariate analyses. The genetic and morphological data showed significant and concordant patterns of geographical segregation, which are typical for the kind of demographic isolation displayed by species units, across the Sousa genus distribution range. Based on our combined genetic and morphological analyses, there is convincing evidence for at least four species within the genus (S. teuszii in the Atlantic off West Africa, S. plumbea in the central and western Indian Ocean, S. chinensis in the eastern Indian and West Pacific Oceans, and a new as‐yet‐unnamed species off northern Australia).     

Multiple lines of evidence for an Australasian geographic boundary in the Indo-Pacific humpback dolphin (<Emphasis Type="Italic">Sousa chinensis</Emphasis>): population or species divergence?

The taxonomic status of humpback dolphins (genus Sousa, sub-family Delphininae) is unresolved. While the classification of this genus ranges from a single to three nominal species, the International Union for Conservation of Nature and the International Whaling Commission only recognise a ‘two-species’ taxonomy (S. teuszii in west Africa, and S. chinensis in the Indo-Pacific). Under the IUCN (2008), S. chinensis is listed as ‘near threatened’, but is only considered as a ‘migratory’ species in Australia. Taxonomic resolution of the genus Sousa is needed to define particular conservation status and develop appropriate management actions. Using phylogenetic analyses of 1,082 bp of mitochondrial and 1,916 bp of nuclear DNA, we provide multiple lines of genetic evidence for the genetic distinction of S. chinensis in China and Indonesia from S. chinensis in Australia. The separation of Australian Sousa from Sousa of Southeast Asia requires a review of their current conservation status and respective management actions.     

Molecular phylogenetics and population structure of Sousa chinensis in Chinese waters inferred from mitochondrial control region sequences

Phylogenetic analyses of the genus Sousa were carried out across their geographic range and focused especially on the genetic variation patterns and population structure of Sousa chinensis in Chinese waters. The analyses were based on 287-bp of the mitochondrial control region from 122 Indo-Pacific humpback dolphins (Sousa chinensis) and two Atlantic humpback dolphins (Sousa teuszii). All specimens from China grouped together in a well-supported clade with high bootstrap (BS) and Bayesian posterior probability values (BPP), strongly suggesting that only one species of Sousa exists in China. Six haplotypes were identified in 65 individuals from Xiamen and Pearl River Estuary in China. The extremely low level of detected mtDNA genetic diversity strongly suggests a high priority in conservation of Sousa. The highly significant genetic differentiation between the two populations in Xiamen and Pearl River Estuary supports the designation of these two populations as separate management units (MUs) when designing management programs for this species.     

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.     

Living with dolphins: Local ecological knowledge and perceptions of small cetaceans along the Sindhudurg coastline of Maharashtra,India

Two near shore small cetaceans occur commonly along the Maharashtra coast, the Indian Ocean humpback dolphin and Indo Pacific finless porpoise. These cetaceans frequently interact with fisheries in this region due to overlap in space and resource use. Besides stranding records, little ecological information is available about these species from Maharashtra. We conducted 143 semistructured interviews to document local ecological knowledge and community perceptions of small cetaceans in 30 coastal fishing villages in Sindhudurg. Perceptions of finless porpoises were largely neutral, whereas humpback dolphins were negative. A classification regression tree (CART) analysis (root node error: 60%) showed that the annual cost of gear damage was an important predictor variable of humpback dolphin perceptions, followed by occupation (gear type) and age. Entanglements were reported for both species in large and small gill nets, and shore seines. Perceived net damage and catch loss due to humpback dolphins was six times greater than that of finless porpoises. However, finless porpoises were reportedly more frequently entangled in gear than humpback dolphins. We provide an insight into the perceptions of cetaceans in the local community and the fisheries‐cetacean interactions that shape them.     

Prey preferences of sympatric fin (Balaenoptera physalus) and humpback (Megaptera novaeangliae) whales revealed by stable isotope mixing models

Over‐exploitation of top predators and fish stocks has altered ecosystems towards less productive systems with fewer trophic levels. In the Celtic Sea (CS), discards and bycatch levels have prompted concern about some fisheries, while fin and humpback whales are recovering from centuries of over‐exploitation. A lack of empirical evidence on the preferred diet of some predators such as whales in the CS has hindered the implementation of effective conservation measures using an ecosystem‐based approach to fisheries management. Using a Bayesian framework (SIAR), stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope mixing models were used to assign proportionate diet solutions to fin and humpback whales (skin biopsies) and putative prey items: herring (Clupea harengus), sprat (Sprattus sprattus), and krill (Meganyctiphanes norvegica and Nyctiphanes couchii) in the CS. Krill was the single most important prey item in the diet of fin whales, but one of the least important for humpback whales (albeit based on a small sample of humpback whale samples). Age 0 sprat and herring comprised a large proportion of the diet of both species, followed by older sprat (age 1–2) and older herring (age 2–4). An ecosystem based approach to fisheries management will be required in the CS if we seek effective conservation of both fin and humpback whales, and sustainable fisheries.     

Fine‐scale habitat use in Indo‐Pacific humpback dolphins,Sousa chinensis,may be more influenced by fish rather than vessels in the Pearl River Estuary,China

Shifts in habitat use and distribution patterns in dolphins are often concerns that can result from habitat degradation. We investigated how potential changes to a habitat from human activity may alter dolphin distributions within Lingding Bay in the Pearl River Estuary, China, by studying the relationship between fish choruses, vessel presence and Indo‐Pacific humpback dolphin (Sousa chinensis) detection rates. Analyses revealed temporal and spatial variation within fish choruses, vessel presence and dolphin detection rates. After accounting for any temporal autocorrelation, correlations between fish choruses and dolphin detection rates were also found; however, no relationship between fish choruses and vessel presence or dolphin detection rates and vessel presence were observed. Furthermore, fewer dolphins were detected at sites where fish activity was less intense. Thus fish activity, rather than vessels, may be a key factor influencing the distribution of the dolphins within the estuary. These findings emphasize the risk of potential shifts in habitat use for Indo‐Pacific humpback dolphins due to detrimental changes to prey availability and dolphin feeding grounds from human activity, such as overfishing and coastal developments, within the estuary. This is a critical conservation issue for this dolphin population that is facing intense anthropogenic pressure.     

Using dive behavior and active acoustics to assess prey use and partitioning by fin and humpback whales near Kodiak Island,Alaska

Near the Kodiak Archipelago, fin (Balaenoptera physalus) and humpback (Megaptera novaeangliae) whales frequently overlap spatially and temporally. The Gulf Apex Predator‐prey study (GAP) investigated the prey use and potential prey partitioning between these sympatric species by combining concurrent analysis of vertical whale distribution with acoustic assessment of pelagic prey. Acoustic backscatter was classified as consistent with either fish or zooplankton. Whale dive depths were determined through suction cup tags. Tagged humpback whales (n = 10) were most often associated with distribution of fish, except when zooplankton density was very high. Associations between the dive depths of tagged fin whales (n = 4) and the vertical distribution of either prey type were less conclusive. However, prey assessment methods did not adequately describe the distribution of copepods, a potentially significant resource for fin whales. Mean dive parameters showed no significant difference between species when compared across all surveys. However, fin whales spent a greater proportion of dive time in the foraging phase than humpbacks, suggesting a possible difference in foraging efficiency between the two. These results suggest that humpback and fin whales may target different prey, with the greatest potential for diet overlap occurring when the density of zooplankton is very high.     

Distribution and abundance of Indo‐Pacific humpback dolphins in Leizhou Bay,China

Abstract

The Indo‐Pacific humpback dolphin (Sousa chinensis) is under severe threat in Chinese waters. Only four small populations of this dolphin are known to survive in the East China Sea and South China Sea. We conducted exploratory surveys from June to September 2005, and found a population of humpback dolphins in Leizhou Bay. Thirty‐eight individuals were identified and catalogued, of which 26 were photographed and re‐identified on more than one occasion, and nine were sighted on five or more occasions each. Our preliminary estimate of the size of the Leizhou population is about 237 individuals, second only to the Pearl River estuary population. We suggest that Leizhou Bay has the potential to serve as a “humpback dolphin sanctuary” in Chinese waters.     

Whistle characteristics of a newly recorded Indo-Pacific humpback dolphin (Sousa chinensis) population in waters southwest of Hainan Island,China, differ from other humpback dolphin populations

Indo-Pacific humpback dolphins (Sousa chinensis) use whistles to communicate with their conspecifics. Little is known about the acoustic repertoire of Indo-Pacific humpback dolphins in waters southwest of Hainan Island, a newly recorded population in 2014. In this study, whistles of Hainan humpback dolphin population were collected by using autonomous acoustic recorders. The fundamental frequencies and durations of whistles were in ranges of 0.71–21.35 kHz and 0.06–2.22 s, respectively. Significant intraspecific differences in duration and frequency of whistles were found between the Hainan population and the other geographically neighboring populations (in Chinese waters) or the population in Malaysia waters. Compared with other Sousa species, significant interspecific differences were also observed. Based on clustering analysis, the whistle parameters of neighboring populations were likely similar to each other. Significant differences were found between humpback dolphins in waters southwest of Hainan Island and those dolphins in the neighboring areas, supporting the hypothesis that this population may be independent. Ambient noise measurements in waters of Hainan Island, Zhanjiang, and Sanniang Bay showed that humpback dolphin populations may use whistles with longer duration, lower frequency, and fewer inflection points for more effective communication to adapt to a noisier environment.     

Cranial morphology and taxonomic resolution of some dolphin taxa (Delphinidae) in Australian waters,with a focus on the genus Tursiops

Phylogenetic relationships in the family Delphinidae have been widely debated. We examined 347 skulls of Tursiops, Stenella, Delphinus, Steno, Lagenodelphis, and Sousa in order to resolve the phylogenetic position of Australian species of Tursiops. Five Tursiops type specimens were included. Cranial morphology was described using 2‐dimensional (2‐D) and 3‐dimensional geometric morphometrics (3‐GM), counts and categorical data. Analyses showed a clear morphological separation of Tursiops, including type specimens, from other genera. The three Stenella species did not cluster together. Stenella attenuata clustered with Delphinus delphis, and Stenella coeruleoalba with Lagenodelphis hosei. Length and width of the skull and rostrum were important discriminators in both methods. For 3‐D data, round vs. angular posterior skull shape distinguished some genera. Taxa that overlapped in the multivariate analyses had different mean tooth counts. Our study challenges genetic studies that identified Tursiops as polyphyletic, with T. aduncus closer to S. attenuata.     

Delineating the fishes of the Clinus superciliosus species complex in southern African waters (Blennioidei: Clinidae: Clinini), with the validation of Clinus arborescens Gilchrist & Thompson, 1908 and Clinus ornatus Gilchrist & Thompson, 1908, and with descriptions of two new species

The Clinus superciliosus complex comprises six closely related species. Three of the species were originally recognized by Gilchrist and Thompson as two distinct species, Clinus superciliosus (Linnaeus, 1758) and Clinus ornatus Gilchrist & Thompson, 1908, and a variety, Clinus superciliosus var. arborescens Gilchrist & Thompson, 1908. A number of other authors described various similar species, which subsequently were all synonymized with Clinus superciliosus. A further species, Clinus spatulatus Bennett, 1983, an obligate estuarine dweller, is known only from the Bot, Kleinmond, and Klein river estuaries in the Western Cape, South Africa. Two further species, Clinus musaicus sp. nov. (discovered while searching for C. ornatus specimens) and Clinus exasperatus sp. nov. , are herein described: the first is currently known from False Bay and the west coast of the Cape Peninsula, whereas the second species is known from only two specimens just east of False Bay. Clinus ornatus and Clinus arborescens Gilchrist & Thompson, 1908 are recognized as a valid species, and can be distinguished from C. superciliosus and C. spatulatus on the basis of meristic values, form of the orbital cirrus, position of the dorsal‐fin crest, taste bud number and pattern, diet, and coloration. All extant types of C. superciliosus are examined as specimens, or photographs and radiographs, and their validity and identification are assessed. Genetic analysis of mitochondrial and nuclear DNA supports species differentiation. A key is provided for the species complex. Furthermore, the variable coloration of four of the species, probably related to the substrate the larvae settle upon, and the increase in the number of vertebrae, and fin‐ray and spine number, with decreasing water temperature is discussed. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society 2012, 166 , 827–853.     

Whales from space: Four mysticete species described using new VHR satellite imagery

Large‐bodied animals such as baleen whales can now be detected with very high resolution (VHR) satellite imagery, allowing for scientific studies of whales in remote and inaccessible areas where traditional survey methods are limited or impractical. Here we present the first study of baleen whales using the WorldView‐3 satellite, which has a maximum spatial resolution of 31 cm in the panchromatic band, the highest currently available to nonmilitary professionals. We manually detected, described, and counted four different mysticete species: fin whales (Balaenoptera physalus) in the Ligurian Sea, humpback whales (Megaptera novaeangliae) off Hawaii, southern right whales (Eubalaena australis) off Península Valdés, and gray whales (Eschrichtius robustus) in Laguna San Ignacio. Visual and spectral analyses were conducted for each species, their surrounding waters, and nonwhale objects (e.g., boats). We found that behavioral and morphological differences made some species more distinguishable than others. Fin and gray whales were the easiest to discern due to their contrasting body coloration with surrounding water, and their prone body position, which is proximal to the sea surface (i.e., body parallel to the sea surface). These results demonstrate the feasibility of using VHR satellite technology for monitoring the great whales.     

From the southern right whale hunting decline to the humpback whaling expansion: a review of whale catch records in the tropical western South Atlantic Ocean

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Polytypy of the genus <Emphasis Type="Italic">Zanclorhynchus</Emphasis> (Zanclorhynchinae: Congiopodidae): Description of the new species <Emphasis Type="Italic">Z. сhereshnevi</Emphasis> sp. n. from the Indian sector of the Southern Ocean

New species Zanclorhynchus chereshnevi sp. n. has been described. The type series of the new species has been sampled along the shores of Prince Edward Islands (46°55′ S 37°58′ E) in the Southern Ocean at the depth of 170 m. The new species differs from the another representative of the genus, Z. spinifer, by weak arming of the first dorsal fin and the head and by the body proportions and coloration.     

Genetic and morphological discrimination of three species of ninespined stickleback Pungitius spp. (Teleostei,Gasterosteidae) in France with the revalidation of Pungitius vulgaris (Mauduyt, 1848)

The taxonomy of French ninespined sticklebacks (Pungitius spp.) has long been controversial. To clarify the taxonomy in this group, we use mitochondrial (COI) and nuclear (RNF213) sequence markers, as well as morphological data. In France, both genetic markers discriminate three evolutionary lineages. Morphological analysis on fresh and type specimens supports the different lineages and the existence of three species in France. Pungitius pungitius, occurring in the North of France and Rhone basin, is characterized by specimens longer than 35 mm SL, by a flat head with a straight or slightly concave snout, typically 9–10 dorsal spines, 10–11 dorsal soft rays, 9–10 anal soft rays, 0–12 scutes on the caudal peduncle with a keel reaching the last anal‐fin ray, longer pelvic fin, post‐dorsal and caudal peduncle lengths, and a slim caudal peduncle (caudal peduncle depth/length 11.8%–21.9%). Pungitius laevis, occurring in France, in the English Channel basins and Loire drainage, differs from the other species by a head rounded with concave snout in specimens longer than 35 mm SL, accentuating the impression of fleshy lips, 0–4 scutes on the caudal peduncle and a higher caudal peduncle depth/length ratio (15.7%–34.5%). Finally, Pungitius vulgaris, endemic to the Vienne River and rivers of south‐western France as far north as the Garonne estuary, is differentiated by a rounded head with a straight or slightly convex snout, the absence of scutes on the caudal peduncle and by having 11 pectoral‐fin rays. Our data confirm the existence of a hybridization zone in the North of France between P. pungitius and P. laevis. As a result, Pungitius lotharingus is invalid, as it was described based on hybrid specimens. A lectotype for P. laevis was designated because the syntypes included hybrids. This revision provides new perspectives for evolutionary biology studies and will have consequences for Pungitius conservation in France.     

厦门湾中华白海豚潜在生态廊道识别及人类活动干扰评估

生态廊道具有维持或恢复生态连通性的功能，对于连接生物栖息地、保护物种多样性具有重要意义。现有的生态廊道研究主要集中于陆地，而海洋生态系统具有水体广泛连通、缺乏直观的景观斑块等特点，导致海洋生态廊道的研究成为长期以来的科学难题。以栖息地位于厦门湾的国家一级保护动物中华白海豚（Sousa chinensis）为对象，尝试基于物种分布模型和最小成本路径分析法建立海洋生态廊道的识别方法。研究采用物种分布模型识别厦门湾内中华白海豚的适宜生境分布区和节点，并利用模型产出的生境适宜性结果生成海洋中的阻力表面，模拟计算节点与节点间在阻力表面上的最小成本路径，从而生成物种扩散网络。研究结果显示，厦门湾中华白海豚的分布主要受到航道距离、到岸线距离和叶绿素浓度三项因素的影响，主要适宜生境位于西海域至九龙江口和大嶝海域。潜在的核心生态廊道面积93.19km²，次级生态廊道面积170.41km²，九龙江口-鼓浪屿南侧-黄厝-大小嶝岛沿线可能是厦门湾中华白海豚的主要迁移路线。在此基础上，从用海空间重叠和桥梁影响两方面开展了人类活动对廊道的干扰评估。评估结果显示旅游活动和航运活动可能是中华白海豚生态廊道的主要影响来源，其中核心廊道受旅游活动影响更大，次级廊道受航运活动的影响更大。此外，厦门岛北部的桥梁亦可能会影响中华白海豚生态廊道的连通性。研究创新性地提出了海洋生态廊道的空间定量化识别方法并成功应用于厦门湾中华白海豚研究，研究结果可为我国海洋生物多样性保护、海洋保护区的空间规划等领域提供新的科学工具。     

Comparative anatomy of the dorsal hump in mature Pacific salmon

Mature male Pacific salmon (Genus Oncorhynchus ) demonstrate prominent morphological changes, such as the development of a dorsal hump. The degree of dorsal hump formation depends on the species in Pacific salmon. It is generally accepted that mature males of sockeye (O. nerka ) and pink (O. gorbuscha ) salmon develop most pronounced dorsal humps. The internal structure of the dorsal hump in pink salmon has been confirmed in detail. In this study, the dorsal hump morphologies were analyzed in four Pacific salmon species inhabiting Japan, masu (O. masou ), sockeye, chum (O. keta ), and pink salmon. The internal structure of the dorsal humps also depended on the species; sockeye and pink salmon showed conspicuous development of connective tissue and growth of bone tissues in the dorsal tissues. Masu and chum salmon exhibited less‐pronounced increases in connective tissues and bone growth. Hyaluronic acid was clearly detected in dorsal hump connective tissue by histochemistry, except for in masu salmon. The lipid content in dorsal hump connective tissue was richer in masu and chum salmon than in sockeye and pink salmon. These results revealed that the patterns of dorsal hump formation differed among species, and especially sockeye and pink salmon develop pronounced dorsal humps through both increases in the amount of connective tissue and the growth of bone tissues. In contrast, masu and chum salmon develop their dorsal humps by the growth of bone tissues, rather than the development of connective tissue.     

How to contend with paraphyly in the taxonomy of the delphinine cetaceans?

Molecular phylogenetic analyses conducted over the past 15 yr have consistently had difficulties resolving relationships among the cetacean species in the subfamily Delphininae. In addition, paraphyly of the genera Tursiops and Stenella in these molecular phylogenies has been a recurrent problem since the first appearance of such a phylogeny in 1999, suggesting that these genera do not accurately reflect the evolutionary relationships of the species they contain. Morphological analyses have not resolved the issues. The genera in Delphininae originated in the 19th Century on questionable morphological grounds. The species were nearly all originally described in the genus Delphinus of Linnaeus. Recent molecular phylogenies based on various mitochondrial and nuclear DNA markers have suggested a wide range of possible relationships among these taxa, and several authors have suggested synonymizing all the taxa (Lagenodelphis, Stenella, Sousa, and Tursiops) under Delphinus. Until molecular and/or morphological analyses adequately sort out relationships in this very recently radiated group, one possible solution indeed would be to merge all the delphinine genera with Delphinus. Implications of such a move and alternatives are discussed.

Editor's Note: Papers from past Norris Award winners have primarily been a revised or reduced version of the actual presentation given as a plenary talk at the biennial conference. Dr. Perrin requested being allowed to take a topic from his presentation and expand on it to present a set of ideas in the form of an essay that could pass the rigors of the peer‐review process. As a result, this Norris Award paper has undergone peer‐review and has taken longer than usual for a Norris Award paper to appear in the journal following its presentation at the biennial conference. It also has co‐authors, with varying opinions on the issues discussed in the essay, to cover appropriately and more thoroughly those components of the paper that required additional expertise. I believe this approach has produced an excellent, thought‐provoking essay and is an approach that should be available to future Norris Award winners if they so choose to take it. Since this essay is meant to elicit dialogue, comments are welcome and will be considered for publication in Letters to the Editor.