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... Bottlenose dolphins are found in relatively shallow waters in comparison to other odontocete species (Baird et al., 2003). "Hot spots" of higher risk followed this pattern and were accordingly concentrated along the coast of Maui from Ma'alaea Harbor to Lahaina Harbor. ...
... Pantropical spotted dolphins showed a fairly strong area of overlap with marine debris in the area centered between the islands of Maui, Lana'i, and Kaho'olawe. Spotted dolphins prefer slightly deeper waters than the other odontocete species discussed (Baird et al., 2003), perhaps explaining the second area of high risk for this species in Hawaiian spinner dolphins showed an area of relatively high risk south of Lanai, with smaller low risk areas observed through the species sighting range. Spinner dolphins rest nearshore and in bays during the day and forage offshore at night (Thorne et al., 2012). ...
... Further management measures, particularly those aimed at endangered species such as false killer whales, would incidentally help all species sharing the same habitat. Bottlenose, spotted, and spinner dolphins show evidence of island-associated stocks with limited movement between islands (Baird et al., 2001(Baird et al., , 2003(Baird et al., , 2009Andrews et al., 2010). Although these species are not currently at risk of extinction, recovery potential for Maui populations may be limited due to the relative isolation from other portions of the species' range. ...
Marine debris poses considerable threat to biodiversity and ecosystems and has been identified as a stressor for a variety of marine life. Here we present results from the first study quantifying the amount and type of debris accumulation in Maui leeward waters and relate this to cetacean distribution to identify areas where marine debris may present a higher threat. Transect surveys were conducted within the 4-island region of Maui, Hawai'i from April 1, 2013 to April 15, 2016. Debris was found in all areas of the study region with higher concentrations observed where the Au'au, Kealaikahiki, and Alalakeiki channels converge. The degree of overlap between debris and cetaceans varied among species but was largest for humpback whales, which account for the largest portion of reported entanglements in the 4-island region of Maui. Identifying areas of high debris-cetacean density overlap can facilitate species management and debris removal efforts.
... Despite the high diversity, until recently relatively little research has been undertaken on any species other than spinner dolphins (Stenella longirostris). There has been one long-term multi-species photo-identification effort off the island of Hawai'i, initiated in the early 1980s (McSweeney unpublished, e.g., McSweeney et al. 2005), and since 2000 there have been more dedicated efforts to examine odontocete stock structure and assess population size of various species (Baird et al. 2001Baird et al. , 2002Baird et al. , 2003Baird et al. , 2005). However, efforts have been focused primarily off the eastern-most of the main Hawaiian Islands (off Maui/Lana'i and the island of Hawai'i) with relatively little sampling effort off O'ahu and the islands of Kaua'i and Ni'ihau (Baird et al. 2003; Baird unpublished). ...
... There has been one long-term multi-species photo-identification effort off the island of Hawai'i, initiated in the early 1980s (McSweeney unpublished, e.g., McSweeney et al. 2005), and since 2000 there have been more dedicated efforts to examine odontocete stock structure and assess population size of various species (Baird et al. 2001Baird et al. , 2002Baird et al. , 2003Baird et al. , 2005). However, efforts have been focused primarily off the eastern-most of the main Hawaiian Islands (off Maui/Lana'i and the island of Hawai'i) with relatively little sampling effort off O'ahu and the islands of Kaua'i and Ni'ihau (Baird et al. 2003; Baird unpublished). One species of odontocete, the false killer whale (Pseudorca crassidens), is listed as " strategic " by NOAA Fisheries, as " takes " in the offshore long-line fishery are greater than levels the population is thought to be able to sustain. ...
... Small boat-based field efforts that focused on assessing odontocete populations around Kaua'i/Ni'ihau have been previously undertaken only in May and June of 2003 (Baird et al. 2003). In comparisons with survey efforts around the other main Hawaiian Islands, effort around the islands of Kaua'i and Ni'ihau indicated a relatively high density of bottlenose dolphins (Tursiops truncatus) and rough-toothed dolphins (Steno bredanensis), and relatively low density of pantropical spotted dolphins (Stenella attenuata) and short-finned pilot whales (Globicephala macrorhynchus) (Baird et al. 2003). ...
Considerable uncertainty exists regarding population structure and population sizes of most species of odontocetes in the Hawaiian Islands. A small-boat based survey for odontocetes was undertaken off the islands of Kaua‘i and Ni‘ihau in October and November 2005 to photoidentify individuals and collect genetic samples for examining stock structure. Field effort on 24 days covered 2,194 km of trackline. Survey coverage was from shallow coastal waters out to over 3,000 m depth, though almost half (47%) was in waters less than 500 m in depth. There were 56 sightings of five species of odontocetes: spinner dolphins (30 sightings); bottlenose dolphins (14 sightings); short-finned pilot whales (6 sightings); rough-toothed dolphins (5 sightings); and pantropical spotted dolphins (1 sighting). One hundred and five biopsy samples were collected and 14,960 photographs were taken to document morphology and for individual photo-identification. Photographs of distinctive individuals of three species (bottlenose dolphins, 76 identifications; rough-toothed dolphins, 157 identifications; short-finned pilot whales, 68 identifications) were compared to catalogs of these species from a survey off Kaua‘i and Ni‘ihau in 2003, as well as from efforts off O‘ahu, Maui/Lana‘i and the island of Hawai‘i. Within- and between-year matches were found for all three species with individuals previously identified off Kaua‘i and Ni‘ihau, though no matches were found with individuals off any of the other islands. This suggests site fidelity to specific island areas, and population structure among island areas for all three species. Movements of photographically identified bottlenose dolphins were documented between deep water areas off the islands of Kaua‘i and Ni‘ihau, as well as between shallow (<350 m) and deep (>350 m) waters. A lack of sightings or reports of false killer whales off Kaua‘i or Ni‘ihau during our study, combined with documented movements among the other main Hawaiian Islands, suggest that there is no “resident” population of false killer whales that inhabits waters only off Kaua‘i or Ni‘ihau
... The distribution of cetaceans within deep water environments is linked to the physical characteristics of their habitat (Baird et al., 2003;Certain et al., 2008). Habitat selection can be well described by using features like distance to nearest coast, water depth, and sea bottom slope (Cañadas et al., 2002;Ingram & Rogan, 2002), which can be derived from GPS position data. ...
... Different species' abundance was significantly correlated to water depth, distance to coast and sea bottom slope. Similar findings involving small odontocetes were made e.g. in Ireland (Ingram & Rogan, 2002), the Mediterranean Sea (Cañadas et al., 2002), the Bay of Biscay (Certain et al., 2008), and the Hawaiian archipelago (Baird et al., 2003;Webster et al., 2005). The results indicate that different species use different parts of the same general and relatively unstructured habitat. ...
... The results indicate that different species use different parts of the same general and relatively unstructured habitat. Habitat partitioning within areas used by several cetacean species also was evidenced in regions like the Azores (Quérouil et al., 2008), Hawaii (Baird et al., 2003), and others (see review in Bearzi, 2005). ...
... Additionally, results of analyses of odontocete distributions in relation to depth and residency of some odontocete populations around certain islands are discussed as it is relevant to interpreting sighting data. More information on the purpose of these surveys can be found in Baird et al. (2001 Baird et al. ( , 2002 Baird et al. ( , 2003 Baird et al. ( , 2004 Baird et al. ( , 2005). ...
... Thus higher-densities close to the islands may represent reproductively-isolated " resident " populations of animals, rather than aggregations of individuals from a broader oceanic population. In addition, information available on interchange among islands and genetic differentiation within the main Hawaiian Islands suggest that for bottlenose dolphins (Baird et al. 2002Baird et al. , 2003 Martien et al. 2005) and probably rough-toothed dolphins (Webster et al. 2005) there may be little or no movements among island areas. Insufficient information is available to assess whether this is true for short-finned pilot whales, pantropical spotted dolphins, beaked whales or sperm whales, though both false killer whales (Baird et al. 2005) and melon-headed whales (Huggins et al. 2005) have been documented moving among islands within the main Hawaiian Islands. ...
Periodic small-boat surveys were undertaken around the main Hawaiian Islands from February 2000 through February 2005, primarily to collect genetic samples and photo-identify odontocete cetaceans. A dataset of 529 odontocete sightings exists from these surveys, representing 16 different species. While the dataset is useful to note where certain species have been seen and document features such as group size and depth preferences, there are a number of biases and limitations of the dataset that must be taken into account for other analyses. There are both inter-annual and seasonal biases in survey effort. While some species are probably resident to the islands and numbers are unlikely to vary seasonally, others may use the area regularly only during certain seasons (e.g., striped dolphins, Risso's dolphins), and thus are probably under-represented in the dataset. Information is not available to assess inter-annual variability in any of the species' use of the area around the main Hawaiian Islands. Survey effort was geographically biased (by region and by depth), and particular depth preferences have been documented for most species of Hawaiian cetaceans. Thus the likelihood of documenting species will depend to a large degree on the water depths surveyed, which varied among islands and among years. Sighting probability varies among species based on dive durations, body size, group size, and surface behavior; it is likely that long-diving and/or cryptic species such as beaked whales, sperm whales, and dwarf and pygmy sperm whales are under-represented in the dataset. Additionally, given the overall low density of cetaceans in Hawaiian waters, and the low sighting rates of some species in particular, a strong small sample size bias exists for areas around Kaua'i, Ni'ihau, and O'ahu; off those areas the small amount of survey coverage relative to sighting rates for some species suggests these species are not likely to have been recorded frequently even if they may use the area on a regular basis.
... killer whales (Pseudorca crassidens) can be successfully photo-identified by the notches on their dorsal fins, with individuals remaining recognizable over periods of more than 20 years. Much of our knowledge about the species' population structure is derived from the extensive and ongoing photo-id studies conducted in Hawaiian waters (e.g.Baird et al. 2003. More limited studiesexist from Costa Rican (Acevedo-Guitíerrez et al. 1997) and West-African waters (e.g. ...
... However, given that only 8 samples from 1 group of dolphins from Kauai/ Niihau were available (Table 1), there were not enough data to draw strong conclusions about the relationship between this region and other regions. Lack of samples from Kauai/ Niihau was not due to lack of sample effort (Baird et al. 2003;), rather pantropical spotted dolphins appear to be much less common in that region (Figure 1;Table 1). Baird et al. (2013) reported that pantropical spotted dolphins were likely the most abundant odontocete in the inhabited Hawaiian Islands during their 13-year study and made up over 22% of sightings near Hawaii, 4-islands area, and Oahu but only 3.9% of sightings off of Kauai/Niihau. ...
Understanding gene flow and dispersal patterns is important for predicting effects of natural events and anthropogenic activities on animal populations. In Hawaii, most species of odontocetes are managed as single populations. Recent exceptions include false killer whales, spinner dolphins, and common bottlenose dolphins, for which studies have shown fidelity to individual islands or groups of islands. Our study focused on pantropical spotted dolphins. We analyzed mitochondrial control region and 11 microsatellite loci from 101 individuals from 4 areas: Hawaii, Maui/Lanai, Oahu, and Kauai/Niihau. We examined F ST , F′ ST , R ST , Jost‘s D , and Φ ST and used TESS to estimate number of populations and assignment probabilities. Our results support genetic differentiation among Hawaii, Maui/Lanai, and Oahu and suggest that pantropical spotted dolphins near Kauai/Niihau are likely transient and in low numbers. Between island regions, F ST for microsatellites ranged from 0.016 to 0.045 and for mtDNA, from 0.011 to 0.282. F ′ ST , ranged from 0.098 to 0.262 for microsatellites and 0.019 to 0.415 for mtDNA. R ST and Φ ST showed similar results to F ST for microsatellites and mtDNA respectively, and Jost‘s D fell between F ST and F ′ ST . TESS supported 3 populations, and greatest mean assignment probability by island region ranged from 0.50 to 0.72. The private alleles method indicated migration rates among regions from 1.49 to 3.45, and effective population size of the island of Hawaii was estimated to be 220. There was no strong evidence to support sex-biased dispersal or group fidelity. Considering this study in the larger context of other odontocete population studies and studies of connectivity, we suggest genetic differentiation may be mediated by behavior adapted to differing habitat types and niches.
... False killer whale sighting locations during 2000-2004 boat-based surveys (+)(Baird et al. ) and 1993(Baird et al. -2003 ...
Under the 1994 amendments to the Marine Mammal Protection Act (MMPA), the National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (USFWS) are required to publish Stock Assessment Reports for all stocks of marine mammals within U.S. waters, to review new information every year for strategic stocks and every three years for non-strategic stocks, and to update the stock assessment reports when significant new information becomes available. This report presents stock assessments for 13 Pacific marine mammal stocks under NMFS jurisdiction, including 8 “strategic” stocks and 5 “non-strategic” stocks (see summary table). A new stock assessment for humpback whales in American Samoa waters is included in the Pacific reports for the first time. New or revised abundance estimates are available for 9 stocks, including Eastern North Pacific blue whales, American Samoa humpback whales, five U.S. west coast harbor porpoise stocks, the Hawaiian monk seal, and southern resident killer whales. A change in the abundance estimate of Eastern North Pacific blue whales reflects a recommendation from the Pacific Scientific Review Group to utilize mark-recapture estimates for this population, which provide a better estimate of total population size than the average of recent line-transect and mark-recapture estimates. The ‘Northern Oregon/Washington Coast Stock’ harbor porpoise stock assessment includes a name change (‘Oregon’ is appended to ‘Northern Oregon’) to reflect recent stock boundary changes. Changes in abundance estimates for the two stocks of harbor porpoise that occur in Oregon waters are the result of these boundary changes, and do not reflect biological changes in the populations. Updated information on the three stocks of false killer whales in Hawaiian waters is also included in these reports. Information on the remaining 50 Pacific region stocks will be reprinted without revision in the final 2009 reports and currently appears in the 2008 reports (Carretta et al. 2009). Stock Assessments for Alaskan marine mammals are published by the National Marine Mammal Laboratory (NMML) in a separate report. Pacific region stock assessments include those studied by the Southwest Fisheries Science Center (SWFSC, La Jolla, California), the Pacific Islands Fisheries Science Center (PIFSC, Honolulu, Hawaii), the National Marine Mammal Laboratory (NMML, Seattle, Washington), and the Northwest Fisheries Science Center (NWFSC, Seattle, WA). Northwest Fisheries Science Center staff prepared the report on the Eastern North Pacific Southern Resident killer whale. National Marine Mammal Laboratory staff prepared the Northern Oregon/Washington coast harbor porpoise stock assessment. Pacific Islands Fisheries Science Center staff prepared the report on the Hawaiian monk seal. Southwest Fisheries Science Center staff prepared stock assessments for 9 stocks. The stock assessment for the American Samoa humpback whale was prepared by staff from the Center for Coastal Studies, Hawaiian Islands Humpback National Marine Sanctuary, the Smithsonian Institution, and the Southwest Fisheries Science Center. Draft versions of the stock assessment reports were reviewed by the Pacific Scientific Review Group at the November 2008, Maui meeting. The authors also wish to thank those who provided unpublished data, especially Robin Baird and Joseph Mobley, who provided valuable information on Hawaiian cetaceans. Any omissions or errors are the sole responsibility of the authors. This is a working document and individual stock assessment reports will be updated as new information on marine mammal stocks and fisheries becomes available. Background information and guidelines for preparing stock assessment reports are reviewed in Wade and Angliss (1997). The authors solicit any new information or comments which would improve future stock assessment reports. These Stock Assessment Reports summarize information from a wide range of sources and an extensive bibliography of all sources is given in each report. We strongly urge users of this document to refer to and cite original literature sources rather than citing this report or previous Stock Assessment Reports. If the original sources are not accessible, the citation should follow the format: [Original source], as cited in [this Stock Assessment Report citation].
The Sindhudurg coast in Maharashtra, India, supports diverse fisheries and is a vital habitat for the Indian Ocean humpback dolphin Sousa plumbea , a species found nearshore along the west coast of India. Here, dolphins cause economic losses to fishermen by competing for catch and damaging fishing gear. Dolphins are also affected by entanglement in or ingestion of parts of fishing nets. There is a need for a systematic assessment of the distribution of risks to dolphins and the specific fisheries most impacted by interactions with dolphins. To bridge this information gap, we (1) analysed the behaviour and locations of dolphin groups in the absence and presence of fishing vessels (2012-2015) and (2) mapped the spatial overlap of dolphins and fishing vessels (2014-2015) to determine high-risk areas for dolphins. We observed 175 dolphin groups, of which 75 groups (43%) engaged in foraging behaviours. Dolphins occurred in approximately 50% (164 km ² ) of the total survey area, and fishing vessels were observed in 100% of the total survey area (333 km ² ). The proportion of dolphin groups engaged in foraging behaviours was significantly higher when fishing vessels were present compared to when absent. Gillnet (55%) and trawl (32%) accounted for the majority of observed fishing vessels when dolphins were present. Gillnet vessels had a 95% spatial overlap with dolphin habitat, and trawl and purse-seine vessels each had 86%. We identified 8 high-risk areas that were within ~500 m of the coastline, coinciding with high-density dolphin habitat near estuaries. These results have the potential to inform marine mammal conservation and fishery management in Sindhudurg.
In Dwarf Sperm Whale, Kogia simus, has been recorded in tropical and warm temperate waters world-wide. This species is rarely observed at sea, and little is known of its biology. Insufficient information is available to classify its world-wide status, though they are infrequently taken directly and indirectly in various fisheries. In Canada, the only confirmed record is of a single stranded animal from Vancouver Island. British Columbia, though they are likely found in Canadian waters more frequently. There are no obvious threats to its status in Canadian waters where the species list not at risk.
Field studies begun in 1970 and continuing to date have identified at least 3 adjacent resident Tursiops truncatus populations (or communities) along the central W coast of Florida, using photo-identification, mark-recapture techniques, behavioral observations, radio-tracking and brief captures. Males travelling between populations appear to be vectors for genetic exchange. For the Sarasota population, an annual recruitment rate to age 1 of 0.048 was countered by a minimum mortality rate of 0.010 and a mean annual loss rate from other causes of 0.029. Immigration was infrequent, with a mean annual rate about 0.02. Mean fecundity rate was 0.144. Because of the prolonged period of association between mothers and calves, there were nearly 6 times as many mother-calf pairs as mothers with young of the year. -from Authors
Summarises results of a sighting survey around the Solomon Islands between 28 November and 11 December 1993. No blue whales Balaenoptera musculus were observed. Fourteen schools (23 animals) of Bryde's whales Balaenoptera edeni and seven schools (12 animals) of sperm whales Physeter macrocephalus were sighted. Small cetacean species were also observed. All the Bryde's whales involved four cases of mothers and calves. Some Bryde's whale individuals were observed in association with large shoals of pelagic fishes and sea birds. -from Authors
Small boat surveys were organised off the Society Islands (French Polynesia), with 2–3 active ob-servers on board. Sampling was done with Beaufort 4 sea state or less, cruising at 10 km/h mostly on engine power, from March 1996 to May 1999. The area of study extends over 400 km from Tahiti at the southeast, to Maupiti at the northwest, and was divided into 4 sectors: the lagoon area, the inshore stratum (<10 km from the barrier reef) of the Windward and Leeward Islands, and the offshore stratum. For a seasonal analysis the survey data were divided into a September–November period and a March–May period. A sighting rate and a relative abundance index (individual/km of effort) was estimated for delphinids, for each stratum and each period. Mean and variance estimates were computed with Distance 2.2 software. Some 134 sightings were obtained during a total effective effort of 6482 km, including 5222 km with sea state less than Beaufort 3. The humpback whale (Megaptera novaeangliae) was observed 35 times, the sperm whale (Physeter macrocephalus) and the dwarf sperm whale (Kogia simus) once, two species of beaked whale (Mesoplodon densirostris and Ziphius cavirostris) were observed 8 times, and seven species of delphinid were sighted 91 times, in order of decreasing frequency: Stenella longirostris, Steno bredanensis, Globicephala macrorhynchus, Peponocephala electra, Lagenodelphis hosei, Tursiops truncatus and Grampus griseus. The inshore strata had relative abundance indices of 0.258 delphinid/km (Windward Islands) and 0.219 delphinid/km (Leeward Islands), while only 0.021 delphinid/km were found in the offshore stratum. Cetaceans in general favour the inshore waters. An index of 0.123 delphinid/km was found during the March–May period, compared to 0.345 during the September–November period. Factors influencing the distribution of cetaceans are dis-cussed and comparisons given with results obtained in other archipelagos and the eastern tropical Pacific.