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... though we have some understanding of the species that can be encoun- tered in this area, we still lack information on their use of this unique habitat. Fiordland extends from Milford Sound in the North to Preservation Inlet in the South (Fig. 1). The terrestrial portion of the area comprises Fiordland National Park, covering a land area of 12 524 km 2 . The fiord complex is composed of 14 fiords. The main oceanographic feature of fiords is the presence of a low-salinity layer topping the marine stratum. The presence of this layer depends on several variables, particularly ...
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... species were infrequently observed by the sighting network in Fiordland waters (Table 5 and Figs 10 and 11). Common dolphins were observed only during summer months (3 sightings, Table 6) and at the entrance of fiords (Figs 10 and 11). Both sightings in Doubtful Sound were in the gut area (Fig. 10). No description allowed to distinguishing which species of common dolphin is present in Fiordland. Southern long-finned pilot whales (Globicephala melaena edwardi) were sighted at the entrance of Dusky Sound and in Doubtful Sound, in the vicinity of Elizabeth Island (Figs 10 and 11). Only two sighting records were available for that ...
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... description allowed to distinguishing which species of common dolphin is present in Fiordland. Southern long-finned pilot whales (Globicephala melaena edwardi) were sighted at the entrance of Dusky Sound and in Doubtful Sound, in the vicinity of Elizabeth Island (Figs 10 and 11). Only two sighting records were available for that species. ...
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... Elizabeth Island (Figs 10 and 11). Only two sighting records were available for that species. In both cases the group size was small (1 and 5 individuals) which is uncommon for the species. These sightings are the first official record of this species in Fiordland. A group of 10 orcas was observed travelling south at the entrance of Milford Sound (Fig. ...
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... whales were observed on two occasions in the vicinity of Dagg Sound during winter 1996 and 1998 (Fig. 11). Surprisingly, humpback whales were observed during summer and winter, seasons when they are supposed to be at, respectively, their feeding and breeding grounds (Table 6). A group of six whales was encountered inside Doubtful Sound as far as the entrance of Crooked Arm in January 1998 (Fig. 10). A solitary minke whale (Balenoptera ...
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... vicinity of Dagg Sound during winter 1996 and 1998 (Fig. 11). Surprisingly, humpback whales were observed during summer and winter, seasons when they are supposed to be at, respectively, their feeding and breeding grounds (Table 6). A group of six whales was encountered inside Doubtful Sound as far as the entrance of Crooked Arm in January 1998 (Fig. 10). A solitary minke whale (Balenoptera acutorostrata) was sighted off Ferguson Island, Doubtful Sound in October 1997, constituting the first official record of this species in Fiordland. Finally, only a solitary southern right whale was seen during this 3-year observation period in Milford Sound in June 1997. Southern right whale - - 1 ...
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... only a solitary southern right whale was seen during this 3-year observation period in Milford Sound in June 1997. Southern right whale - - 1 - Figure 11. Sighting records along the Fiordland coast, 1996-99. ...
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... of bottlenose dolphins in Milford and Doubtful Sounds are not included. For sightings of infrequently seen species in Doubtful Sound see Fig. ...
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... contributed by differences from expected sighting frequency in quadrats 2, 3, and 4 (Table 7). Bottlenose dolphins tended to spend more time in these quadrats than would be expected if sightings were evenly distributed among quadrats. They also tended to spend more time along the northern shore, especially in the vicinity of Dale Point (Table 8, Fig. 12) and in the middle of the fiord (Table ...
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... the chance of finding dusky dolphins in Milford Sound was not equally distributed over the fiord (n = 89, χ 2 = 60.26, p < 0.0001). Most sightings occurred in quadrat 1 (25.8%, n = 89). Tables 10 and 11 and Fig. 13 also show ...
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... dolphins appeared to be present year-round in Milford Sound (Fig. 14). The number of sightings was generally lower during winter and spring but the sighting effort during these months is too low to draw any firm conclusions from this result (Table ...
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... of dusky dolphins indicate that the dolphins are mainly present in Milford Sound during summer months ( Fig. 15 and Table 13). However the low sampling effort outside the summer season made it impossible to test this ...
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... preference for the northern shore of the middle portion of the fiord seemed to be consistent during summer and autumn (Tables 7, 8 and 9; Figs 16 and 17). The middle of the fiord seemed to be also preferred during winter and spring, but more data are needed for a thorough statistical analysis (Figs 18 and 19). ...
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... median group size was 32 individuals (Fig. 21). No spatial analysis of group size frequency distribution could be performed because the sample size was too low (n = ...
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... shoreline contains many cusps and bays, which may facilitate predation, while the southern shore is more even. Dolphins also seem to prefer narrowing areas such as Dale and Copper Points (Figs 3 and 12). These places may also facilitate the capture of pelagic, schooling prey. ...
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... dolphins are often encountered in Dusky and Breaksea Sounds (Fig. 11) and this fiord system may support a resident population. When comparing group size of bottlenose dolphins in this fiord with those in Doubtful and Milford Sounds, it is found that the largest fiord (Dusky/Breaksea Sound) seems to have the smallest median group size. This could be due to a biased sampling effort and a limited sample ...
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... There is some evidence that corroborates the other inshore locations highlighted as important in this study for several species v www.esajournals.org (Childerhouse et al. 1995, Lusseau and Slooten 2002, Benoit-Bird et al. 2004, Barlow et al. 2018), but in most cases, there are no published summaries of species richness. This lack of information reflects the species-specific, localized studies that dominate cetacean research in New Zealand, which is largely focused on immediate conservation issues (Baker et al. 2019). ...
Many cetacean species are at risk from anthropogenic disturbances including climate change, pollution, and habitat degradation. Identifying cetacean hotspots for conservation management is therefore required. Aotearoa–New Zealand waters are used by 53% of the world’s cetacean species and are a global cetacean diversity hotspot. Using geographic predictions of cetacean taxa, we aimed to identify important areas within New Zealand waters using two methods: estimates of cetacean richness and a spatial prioritization analysis. For both methods, we investigated how varying levels of uncertainty in predictions of the taxa’ occurrence layers would affect our interpretation of cetacean hotspots. Despite some marked spatial differences in distribution of important areas for cetacean diversity, both methods, across all uncertainty scenarios, highlighted six distinct deep offshore regions as important habitat. Generally, inshore areas had lower richness estimates than offshore areas, but these remain important for conservation for species with limited ranges (e.g., the endemic Māui and Hector’s dolphins), and in some places had similar richness values to offshore hotspots. Furthermore, inshore hotspots had lower uncertainty in predicted taxa distribution and richness estimates. The use of two different uncertainty estimates allows the integration of distributional information from differing sources (different modeling methods with varying numbers of cetacean records) to be integrated in a robust and conservative way. Identification of cetacean hotspots with varying levels of uncertainty provides a robust and efficient step toward prioritizing areas for conservation management in a participatory process.
... Acoustic detections have also been documented in the Southern Ocean during summer, autumn and winter (December-August; Fig. 4; Appendices S10-S13). In 40 non-standardised studies (Appendix S18), fin whales were not detected in only four locations at latitudes higher than 30°north or south: the Black Sea (Notarbartolo di , Dede & Tonay 2010, the North Indian Ocean , and in fjords in eastern Canada (Diemer et al. 2011) and New Zealand (Lusseau & Slooten 2002). The northernmost observations of fin whales in the Pacific Ocean were made in the southern Chukchi Sea, at approximately 70°N, between June and August (Figs 4 and 5; Appendices S10-S17). ...
The global distribution of fin whales B alaenoptera physalus is not fully understood. Existing maps can be divided into two conflicting categories: one showing a continuous global distribution and another showing an equatorial hiatus (gap in the global distribution) between approximately 20° N and 20° S . Questions also remain about the seasonal distribution of fin whales.
To explore the suggested equatorial hiatus and seasonal distribution patterns, we synthesised information on fin whale distribution in the post‐whaling era (1980–2012) from published literature, publicly available reports and studies conducted by various organisations. We created four seasonally stratified maps showing line‐transect density estimates, line‐transect survey effort, acoustic detections, and sightings.
An equatorial hiatus in the global distribution of fin whales during the post‐whaling era is supported by numerous line‐transect surveys and by the rarity of equatorial acoustic detections and sightings, and corroborated by whaling era reports, morphological analyses, and genetic analyses.
Our synthesis of post‐whaling era data is consistent with results from other studies indicating that fin whales are more abundant at higher latitudes during warmer months and more abundant at lower latitudes (although these latitudes are still greater than 20°) during colder months. However, our synthesis and results from other studies also indicate that some fin whales in both hemispheres remain in higher latitudes (50°–60° north or south) during colder months and in lower latitudes (to approximately 20°–30° north or south) during warmer months, indicating that seasonal fin whale movements differ from the seasonal migrations of blue whales B alaenoptera musculus and humpback whales M egaptera novaeangliae .
Our maps of global fin whale distribution provide a comprehensive picture of current knowledge and highlight important geographical and temporal data gaps. Surveys should be conducted within the identified data gaps in order to increase fine‐scale spatial and temporal knowledge of distribution patterns, improve fin whale taxonomy, and identify areas of elevated fin whale densities that may require management of threats, such as ship strikes.
... Since T-PODs were moored together on the same mooring, we assumed that a larger number of positively identified click trains reflected a more effective setting (dos Santos & Almada, 2004). Acoustic detections of species other than bottlenose dolphin are unlikely in Doubtful Sound, as no other cetaceans are resident in the area and sightings of others are very rare (Lusseau & Slooten, 2002; personal observation). ...
Autonomous acoustic data loggers can provide useful data on habitat use and activity patterns of vocalizing cetaceans. One type, the T-POD, uses filters that can be set to match the click characteristics of the target species. We used wideband acoustic recordings to document typical click spectra of bottlenose dolphins in Doubtful Sound, New Zealand, in order to develop T-POD settings optimal for that population. T-PODs at these settings made between 8 and 33 times as many detections as accompanying T-PODs set as in other studies of this species, confirming the value of optimizing settings for a particular dolphin population. Maximum detection range was 1313 m, and mean range of first detection was 593 m. Of 45 groups observed within 500 m of the T-POD, 47% were detected acoustically. Effective detection radius was estimated at 266 m (95% CI 222–317 m).
... We possess information concerning the distribution of the Doubtful/Thompson Sound sub-population, the Dusky/Breaksea Sound sub-population and the Northern Fiordland sub-population (Williams et al., 1993; Bräger and Schneider, 1998; Schneider, 1999; Lusseau and Slooten, 2002; Currey and Rowe, 2008). We can thus estimate the minimum extent of occurrence and provide a reasonable estimate of the overall extent of occurrence despite possessing only patchy sightings data for the Northern Fiordland population outside Milford Sound (Lusseau and Slooten, 2002). Hence we were able to assess or infer the appropriate threat classification for criteria under each category. ...
Numerous globally abundant species are exposed to human impacts that threaten the viability of regional populations. Assessing and characterising the risks faced by these populations can have significant implications for biodiversity conservation, given the ecological importance of many such species. To address these risks, the IUCN is starting to conduct assessments of regional populations in addition to species-level assessments of conservation status. Here, we demonstrate a threat assessment process that is robust to uncertainty, applying the IUCN criteria to a regional population of bottlenose dolphins in Fiordland, New Zealand. We compiled available population-specific information to assess the population under the five Red List criteria. We estimated there were 205 Fiordland bottlenose dolphins (CV = 3.5%), using current estimates of abundance for two sub-populations and stochastic modelling of an earlier estimate for the third sub-population. Population trajectory and extinction risk were assessed using stochastic age-structured Leslie matrix population models. The majority of model runs met the criteria for classification as critically endangered (C1: 67.6% of runs) given the number of mature individuals (123; CV = 6.7%) and the predicted rate of population decline (average decline: 31.4% over one generation). The evidence of isolation of the population confirms this was an appropriate regional classification. This approach provided an assessment that was robust to uncertainty.
... In addition to the population in Doubtful Sound, two further resident populations have been described. One ranges among seven of the Northern Fiords, whereas the second lives year-round in Dusky and Breaksea Sounds (Bräger andSchneider 1998, Lusseau andSlooten 2002). These locations are less accessible than Doubtful Sound, and consequently, are less studied. ...
Sexing cetaceans usually requires time-consuming observation, or genetic sexing via biopsy sampling or skin swabbing. We developed a method to determine the sex of bottlenose dolphins (Tursiops sp.) in Doubtful Sound, Fiordland, using laser-metric dorsal fin photographs. From dorsal fin photographs of 43 bottlenose dolphins of known sex (25 females, 18 males) we analyzed the shape, proportion of fin area covered in scarring and epidermal lesions, and the number of fin nicks. Males had significantly higher rates of scarring (P < 0.001) and dorsal fin nicks (P < 0.01) than females, whereas the severity of epidermal lesions was higher in females (P < 0.05). A logistic regression applied to all measured variables, and measurements of dorsal fin size, indicated that the proportion of dorsal fin scarring (P < 0.001), number of fin nicks (P < 0.01), and dorsal fin surface area (P < 0.01) were significant variables and together correctly predicted the sex of 93% (40/43) of the dolphins. The classification function may not be applicable to other populations due to geographic variation in bottlenose dolphin morphology and social structure. The method is quick and noninvasive to apply, and further increases the value of dorsal fin photo-identification pictures.
... The bottlenose dolphins of Fiordland (44°30', 168°E; 46°10'S, 166°40'E) are thought to be the World's southern-most resident groups of bottlenose dolphins (Bräger & Schneider 1998). They are found in three separate populations within Fiordland (Bräger & Schneider 1998; Lusseau & Slooten 2002). One population ranges among the fiords and bays of the northern Fiordland coast. ...
... Dusky Sound is the most remote and the most data deficient of the three Fiordland populations. Currently, published information concerning the population is limited to opportunistic surveys of the southern fiords that suggest bottlenose dolphins are resident in the fiord, at least in spring and summer (Bräger & Schneider 1998; Lusseau & Slooten 2002). ...
1. The bottlenose dolphin of Dusky Sound (Tursiops sp.) are a little studied group at the southern limit of the species range, while the neighbouring bottlenose dolphins of Doubtful Sound have been declining, and are subject to potential impacts from tourism and habitat change.
2. We applied photo identification census and capture- recapture techniques to estimate dolphin abundance in both Doubtful and Dusky Sounds. Further we applied laser photogrammetry and a sex prediction model derived from the population in Doubtful Sound to assess the likely sex ratio in Dusky Sound.
3. In Doubtful Sound, there were 56 (CV=1.3%) bottlenose dolphins, representing no net change in population status over the past 12 months. Four of five individuals missing from last year were under 4 years of age. Survival of newborns in the first year of life was 50%, confirming the importance of calf survival in population health.
4. In Dusky Sound, there were 102 (CV=0.9%) bottlenose dolphins, the first abundance estimate for this population. We did not encounter any individuals from Doubtful Sound in Dusky Sound (or vice versa) suggesting little or no interchange between populations.
5. We predicted the sexes of 79 individuals (representing 98- 99% of adults and sub-adults) in Dusky Sound. When our predictions were corrected for animals of known sex, the resulting sex ratio was 35 males to 44 females, not significantly different to an expected 1:1 ratio (G = 1.02, d.f. = 1, P = 0.312).
6. High resighting rates of individual dolphins suggest the population may be resident, similar to Doubtful Sound. However the clear seasonal shift in distribution observed in Doubtful Sound was absent from Dusky Sound. We discuss the consequences of our findings for the future management of the Fiordland bottlenose dolphins.
The bottlenose dolphins of Fiordland, New Zealand, live at the southern limit of the species’ worldwide range. They are exposed to impacts from tourism and habitat modification, particularly in Doubtful Sound, and their conservation requirements are presently unclear. Dolphin abundance was estimated in Doubtful Sound using photo- identification census and capture-recapture techniques (56 individuals; 95% CI: 55- 57), detecting a decline of 34-39% over 12 years among adults and sub-adults (>3 years old). The cause of this decline was investigated via demographic modelling in Doubtful Sound and a comparative assessment of population status in Dusky Sound.
Capture-recapture modelling of photo-identification data compiled since 1990 yielded a constant adult survival rate marginally lower than prior estimates for wild bottlenose dolphins (!a(1990–2008) = 0.9374; 95% CI: 0.9170-0.9530). Survival of calves (<1 year old) declined to an unsustainable level that is thought to be the lowest recorded for wild bottlenose dolphins (!c(2002–2008) = 0.3750; 95% CI: 0.2080-0.5782) coincident with the opening of a second tailrace tunnel for a hydroelectric power station. Reverse-time capture-recapture modelling detected declines in recruitment (f(1994–2008) = 0.0249; 95% CI: 0.0174-0.0324) and population growth (!(1994–2008) = 0.9650; 95% CI: 0.9554- 0.9746) over time consistent with the decline in calf survival (<1 year old) and a separate reduction in juvenile survival (1 to 3 years old) reflecting cumulative impacts.
Dolphin abundance was estimated in Dusky Sound using photo-identification census and capture-recapture techniques (102 individuals; 95% CI: 100-104) providing no evidence of interchange with Doubtful Sound. A comparative assessment of health status between Doubtful and Dusky Sounds revealed skin lesioning was more severe in Doubtful Sound, particularly among females, and newborn calves appeared to be smaller and were born over a shorter period: factors that may contribute to the low levels of calf survival in Doubtful Sound. The Fiordland bottlenose dolphins were assessed under IUCN Red List regional criteria. The small size of the population (205 individuals; 95% CI: 192-219) combined with the projected rate of decline in stochastic matrix models (average decline: 31.4% over one generation) resulted in a recommended classification of Critically Endangered.
