Cultured cetaceans

Dolphin and whale watching has become a blooming activity in the tourism industry in Sri Lanka. Proper scientific data is lacking for the understanding and management of dolphin and whale watching activities particularly in the Southern coast. Based from Mirissa, a shipboard survey was conducted for 43 days from January to May 2012 covering 940 km2 .The diversity and distribution of cetaceans inhabits in the continental shelf and slope were recorded from shipboard sighting data. Their species composition, pod size, behavioral pattern were observed and the distribution pattern was mapped. Total of 8 species of cetaceans were recorded during the study period. They were spinner dolphin ( Stenella longirostris ), bottlenose dolphin ( Tursiops truncates ), melon headed whale ( Peponocephala electra ), fin whale ( Balaenoptera physalus ), killer whale ( Orcinus orca ), short finned pilot whale ( Globicephala melas ), sperm whale ( Physeter macrocephalus ) and blue whale ( Balaenoptera musculus ). Distribution pattern and pod size varied with the species. Out of 6675total sightings, 5382 were spinner dolphins and 843 were bottlenose dolphins. Depth levels showed a significant relationship with different cetacean species (p Sri Lanka J. Aquat. Sci. 20 (1) (2015): 23-33

Long-finned pilot whales and killer whales are widely distributed across the North Atlantic, but few studies have reported their occurrence in Icelandic coastal waters. Here, we use sightings data from research platforms and whale watching tours in six regions of Iceland from 2007 to 2020 to show that the occurrence of long-finned pilot and killer whales varied with region and season. Killer whales were regularly encountered in the south of Iceland during summer and west of Iceland during winter/spring. Long-finned pilot whales were only seen during the summer and were most often encountered in the south, west, and northwest of Iceland. Long-finned pilot whale occurrence in the south of Iceland appeared to increase during the study period but killer whale occurrence showed no noticeable changes. Long-finned pilot whales were sighted often in the areas that were also frequented by killer whales and interspecific interactions were commonly observed when both species co-occurred. Interactions appeared to be antagonistic, with killer whales often avoiding long-finned pilot whales and sometimes fleeing at high speed, similar to what has been described elsewhere in the North Atlantic. In the majority of interactions observed (68%), killer whales avoided long-finned pilot whales by moving away, but in 28% avoidance was at high speed with both species porpoising. This variability in the type of behavioural responses indicates that interactions may be more complex than previously described. We discuss regional trends in long-finned pilot whale and killer whale sightings and potential drivers of the observed interactions.

In this study, we determined the residue levels and patterns of polychlorinated biphenyls (PCBs) and hydroxylated PCBs (OH-PCBs) in the blood from eight species of toothed whales and three species of baleen whales stranded along the Japanese coast during 1999-2007. Penta- through hepta-chlorinated PCB congeners were the dominant homologue groups in all cetaceans. In contrast, specific differences in the distribution of dominant OH-PCB isomers and homologues were found among the cetacean species. In five species of toothed whales (melon-headed whale, Stejneger's beaked whale, Pacific white-sided dolphin, Blainville's beaked whale, and killer whale), the predominant homologues were OH-penta-PCBs followed by OH-tetra-PCBs and OH-tri-PCBs. The predominant homologues of finless porpoise and beluga whale were OH-penta-PCBs followed by OH-hexa-PCBs and OH-tri-PCBs. The predominant OH-PCB isomers were para-OH-PCBs such as 4OH-CB26, 4'OH-CB25/4'OH-CB26/4OH-CB31, 4OH-CB70, 4'OH-CB72, 4'OH-CB97, 4'OH-CB101/4'OH-CB120, and 4OH-CB107/4'OH-CB108 in toothed whales. In three baleen whales (common minke whale, Bryde's whale, and humpback whale) and in sperm whale (which is a toothed whale), OH-octa-PCB (4OH-CB202) was the predominant homologue group accounting for 40-80% of the total OH-PCB concentrations. The differences in concentrations and profiles of OH-PCBs may suggest species-specific diets, metabolic capability, and the transthyretin (TTR) binding specificity. These results reveal that the accumulation profiles of OH-PCBs in cetacean blood are entirely different from the profiles found in pinnipeds, polar bear, and humans.

From 1991-2002 data on the presence and distribution of cetaceans in the Greek Seas have been systematically collated in a database (821 sightings and 715 strandings). Data originated from dedicated surveys, stranding reports, opportunistic sightings and published or unpublished photographic and video documents. Twelve cetacean species have been recorded. Seven of them are permanently present and commonly observed in one or more of the Greek Seas: striped dolphin, common bottlenose dolphin, short-beaked common dolphin, Cuvier’s beaked whale, sperm whale, Risso’s dolphin and fin whale. In addition, the harbour porpoise is present locally in the Thracian and northern Aegean Seas. The humpback whale, false killer whale and common minke whale are occasional Mediterranean species that were sighted or stranded infrequently; the Sowerby’s beaked whale is an accidental species that was found floating dead only once. Five other species (white whale, Blainville’s beaked whale, long-finned pilot whale, killer whale, blue whale) have been erroneously included in the Greek cetacean fauna in the past due to wrong assumptions, false identifications or lack of supporting evidence. The occasional occurrence of pilot and killer whales in the Greek Seas should still be regarded as unconfirmed. The distributional range, stranding numbers and sighting frequencies of sperm whales, Cuvier’s beaked whales and short-beaked common dolphins in the Greek Seas indicate that their local ‘sub-populations’ are among the most important in the entire Mediterranean Sea. Harbour porpoises in the Thracian and northern Aegean Seas are important from a conservation perspective since this species does not inhabit any other part of the Mediterranean Sea.

Interspecific relationships in density among a whale community in Antarctic feeding grounds were examined using the sightings data derived from the systematic surveys conducted between 1978/1979 and 1987/1988. A clear difference in densities against the physiographic variables (the sea floor-slope type) was identified between baleen whales and toothed whales. Densities of sperm whales and ziphiids were low in the waters over the continental shelf where minke whales' densities were highest. This led to an apparent negative correlation in the density between minke and sperm whales, and minke whale and ziphiids. A significant positive correlation in density between minke and blue whales was identified. No association in density between minke and humpback whales was observed. Distribution of killer whales shows strong positive correlation with that of minke whales. The positive correlation existed between minke and blue whales, and minke and killer whales even when the effect of environmental variables was excluded. Analysis also revealed that the environmental variables, including physiographic variables, are major factors affecting the distributions and density of whales, especially between baleen whales and toothed whales.

This work compiles a decade (2001-2010) of marine mammal sightings in the Malpelo Fauna and Flora Sanctuary (FFS) and the area between the island and mainland coast. Four separate sources of data were consulted, which used visual searching during cruising efforts while Malpelo’s surrounding waters were surveyed from a vantage point. Seven species were identified in the FFS: October and November were the months with higher species richness. Tursiops truncatus had the highest encounter rates (17.78 groups/100 h), followed by Megaptera novaeangliae (1.62) and Stenella attenuata (0.88). These species were usually within 6 km from the island. Other species seen around the island include Stenella coeruleoalba, Delphinus delphis, Stenella longirostris and Zalophus wollebaeki. On the other hand, thirteen species were identified during cruises, and March and April were the months with the highest species richness. Megaptera novaeangliae had the highest encounter rate (5.94), followed by T. truncatus (3.30), S. attenuata (3.08), D. delphis (3.08) and S. coeruleoalba, Globicephala macrorhynchus and Orcinus orca, each one with 0.66. Other species seen during the cruises include Steno bredanensis, Pseudorca crassidens, Grampus griseus, Peponocephala electra, Physeter macrocephalus and Ziphius cavirostris. Megaptera novaeangliae were associated to the continental shelf, T. trunctaus and D. delphis to oceanic waters, and S. attenuata to both the continental shelf and oceanic waters. Delphinus delphis was more abundant in intermediate waters, during the first trimester (January-March), while T. truncatus was the most abundant species around the Sanctuary during all seasons, suggesting that is the same population. The latter was also the only species found all year round in both zones (around the island and in oceanic waters), and encounter rates did not change across years. Megaptera novaeangliae had a seasonal presence (mostly June to November) with a higher abundance during the third trimester (July-September), both around Malpelo and the transect. The presence of humpback whales calves suggests that Malpelo is used for reproductive purposes. This new information about the marine mammals found in Malpelo FFS and the area between the island and the continent contributes to the understanding of these species in Colombian waters.

To support optimal monitoring and enforcement investment, management aimed at minimizing disturbance to wildlife requires an understanding of how regulatory compliance might vary spatially as well as across species and human-user groups. In the Salish Sea, humpback whales (Megaptera novaeangliae) and two ecotypes (southern resident and Bigg's) of killer whales (Orcinus orca) now interact with a large and growing number of small commercial and recreational vessels that partake in whale watching. Those vessels often approach close to cetaceans and thus pose risk via collision, marine noise and pollution, exposure to which may result in disturbance, injury and death. The primary management tool for mitigating impacts is minimum distance regulations. Compliance, however, is poorly understood. We examined commercial and recreational small vessel compliance with viewing distances across two seasons (June–September 2018 and 2019) in over ≈404 h of on-water observation. Overall vessel compliance was nearly 80%, but several distinct patterns emerged. Recreational boats were significantly more likely to violate distance regulations and boaters were more likely to be non-compliant around killer whales. Compliance did not vary with day of week or time of day. Spatially, non-compliance was concentrated in waters closer to coastal communities. Collectively, these patterns suggest that optimal enforcement could be targeted to identify areas of high non-compliance, especially for killer whales, with effort spread across days and times. Finally, we discuss how investments in education could target recreational boaters at a time when multiple and interacting stressors are accumulating in the Salish Sea.

Data are presented on the distribution, measurements and weights, ecology, and other aspects of the biology of 12 species of cetaceans, one pinniped, and the manatee in Florida waters. Most of the records are for the period from 1953 through June 1963, although some for earlier years are included. Records of cetaceans based on strandings or specimens washed onshore, dead specimens seen or collected in offshore waters, and skeletal materials from beaches include a probable one of the little piked whale (Balaenoptera acutorostrata) 1 of the humpbacked whale (Megaptera novaeangliae), 3 of the goose-beaked whale (Ziphius cavirostris), 7 of the pygmy sperm whale (Kogia breviceps), 2 of the sperm whale (Physeter catodon), 1 of the rough-toothed dolphin (Steno bredanensis), 18 verified or probable records of the short-finned pilot whale (Globicephala macrorhyncha), 17 verified or probable records of the bottle-nosed dolphin (Tursiops truncatus), 2 of the common dolphin (Delphinus delphis), and 1 of the long-beaked dolphin (Stenella longirostris). The latter is the second record of this species in Florida waters and apparently the third for North America. Observations on living cetaceans include 16 and possibly 18 verified or probable records for the Atlantic right whale (Balaena g. glacialis), 1 for the humpback whale, 2 for the killer whale (Orcinus orca), 3 and a possible 4th for the short-finned pilot whale, and 10 for the bottle-nosed dolphin. The sight record of the humpback whale apparently constitutes the first record of this species in the Gulf of Mexico. External, skeletal measurements, or both, of Florida specimens of Megaptera, Kogia, Physeter, Steno, Globicephala, Tursiops, Delphinus, and Stenella longirostris are given. One pinniped record obtained was of the California sea lion. (Zalophus californianus), and another probably also refers to this species. Both undoubtedly involve animals escaped from captivity. One individual apparently moved approximately 100 miles from where it escaped in about 10 days . Twenty-five records of dead manatees (Trichechus manatus) and 5 sight records are summarized. Of the former, 10 individuals had apparently been killed by cold, 3 by boats, and 2 by shooting. The cause of death of the remainder is unknown, although the death of 7 individuals in the Fort Myers area in the spring of 1963 coincided with a red tide epidemic in the Gulf to the north. Further evidence of the occurrence of seasonal movements in Florida manatee populations is presented.

Killer whales (Orcinus orca) have only infrequently been reported from Hawaiian waters, and most of what is known about killer whales worldwide comes from studies in coastal temperate waters. Here we present 21 records of killer whales from within the Hawaiian Exclusive Economic Zone between 1994 and 2004. Killer whales were recorded nine months of the year, most around the main Hawaiian Islands. Although there were more records than expected during the period when humpback whales are abundant around the Islands, there is likely an increase in sighting effort during that period. Killer whales were documented feeding on both a humpback whale and cephalopods, and two species of small cetaceans were observed fleeing from killer whales. Although it is possible that there are both marine mammal–eating and cephalopod-eating populations within Hawaiian waters, it seems more likely that Hawaiian killer whales may not exhibit foraging specializations as documented for coastal temperate populations. Saddle...

Pilot Whales: Globicephala melas and G. macrorhynchus

This study presents a detailed seasonal comparison of the abundance and distribution of cetaceans within 100‐150 nmi (185‐278 km) of the California coast during 1991 and 1992. The results of a shipboard line‐transect survey conducted in July‐November 1991 (“summer”) were compared to those from aerial line‐transect surveys conducted in March‐April 1991 and February‐April 1992 (“winter”). Using a confidence‐interval‐based bootstrap procedure, abundance estimates for six of the eleven species included in the comparison exhibited significant (α= 0.05) differences between the winter and summer surveys. Pacific white‐sided dolphins (Lagenorhynchus obliquidens), Risso's dolphins (Grampus griseus), common dolphins (Delphinus spp.), and northern right whale dolphins (Lissodelphis borealis) were significantly more abundant in winter. The abundance of blue whales (Balaenoptera musculuss) and gray whales (Eschrichtius robustus) reflected well‐documented migratory patterns. Fin whales (B. physalus) were significantly more abundant during summer. No significant differences in seasonal abundance were identified for Dall's porpoises (Phocoenoides dalli), bottlenose dolphins (Tursiops truncatus), killer whales (Orcinus orca), sperm whales (Physeter macrocephalus), or humpback whales (Megaptera novaeangliae). Significant north/south shifts in distribution were found for Dall's porpoises, common dolphins, and Pacific white‐sided dolphins, and significant inshore/offshore differences were identified for northern right whale dolphins and humpback whales.

Summary form only given. Cetacean abundance in the eastern tropical Pacific is based on large-scale line-transect surveys covering 6% of the world ocean. Cruises using 2 vessels for 4 months each were carried out in 8 years between 1986 and 2000. Thirty cetacean species were recorded, over 1/3 of the world total. Abundance is estimated with a modified line-transect analysis, using covariates to model the detection process, with precision evaluated by bootstrap. Aerial photography from a ship-based helicopter is used to improve estimates of school sizes. Based on the most recent estimates, the most abundant dolphins are short-beaked common dolphins (2.86 million) followed by spotted (1.62 million), spinner (1.06 million), and striped (1.04 million) dolphins. Spotted and spinner dolphins were formerly the most abundant, but populations have been reduced by incidental catch in the yellowfin tuna fishery. The most abundant baleen whales in this tropical area are Bryde's whales (11,900). Among the larger toothed cetaceans, the most abundant are short-finned pilot whales (430,000) and sperm whales (minimum of 17,000). Sperm whales have been reduced in abundance by whaling in the past. Killer whales occur evenly throughout the area, while migratory blue and humpback whales are clumped at certain locations. The abundance of pilot and Bryde's whales increased significantly over the period 1986-2000; the abundance of other species did not change significantly.

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

It's hard to tell just how imperilled killer whales are. With several different forms – some of which may even be different species – it's unclear which are at serious risk and which are less vulnerable. But one group is definitely in jeopardy. ‘The southern resident killer whale population was listed as endangered in the United States in 2005’, says Jennifer Tennessen from the National Oceanic and Atmospheric Administration (NOAA), USA and the decline of Chinook salmon in the Pacific Northwest – which are consumed by the population of ∼75 whales – is believed to be one of the causes. While shipping also poses a risk to the animals, NOAA has been monitoring them for a decade and one of the scientists’ main goals was to estimate how much fish the charismatic whales capture. But, with the majority of pursuits occurring beneath the waves, Tennessen and her colleagues needed to develop a technique based on the animals’ manoeuvres that would allow them to identify when the mammals were successful.Heading into the Salish Sea, between Vancouver Island, British Columbia and Washington State, Tennessen and her colleagues – Marla Holt, Candice Emmons, Brad Hanson, Jeff Hogan and Deborah Giles – attached tags to 21 whales to record their sounds and underwater movements. Then the team followed the animals, noting where they surfaced and what they were up to, in addition to retrieving the remains of any meals. ‘Fieldwork is one of the most exciting yet simultaneously challenging aspects of the research’, says Tennessen, describing how she and her colleagues tracked the animals from small inflatable boats in all conditions.Safely back on shore, Tennessen and Holt began looking for patterns in the movement recordings that correlated with the tell-tale echolocation clicks produced by the whales when closing in on a fish. ‘Once a fish has been detected, the killer whale angles its body steeply downward, begins a descent to depths of about 50–300 m, and then remains underwater for about 7–10 min while pursuing the fish’, says Tennessen, adding that they abruptly roll on their sides and change direction frequently during a pursuit. Incorporating details of these signature manoeuvres into a computer program, Tennessen and Holt were able to identify successfully 126 occasions when the killer whales intercepted a tasty fish.However, when the team categorised all of the deep dives that they had recorded, they were surprised that some of the dives were unsuccessful and Tennessen explains that this was unexpected ‘because diving deep costs significant energy and it was thought that the payoff was a captured fish’. The team also compared the number of successful hunts, according to their movement signatures, with how often they observed the killer whales dining at the surface and discovered that some of the animals appear to consume their prey before reaching the surface; ‘underscoring…that surface observations alone can misrepresent the actual number of fish being captured’, says Tennessen. Most surprisingly, the team realised that the males were diving more than the females and that they were more successful. ‘[This] suggests that males may need to forage more in order to meet their greater metabolic needs’, she says.So male and female killer whales are not equal when it comes to hunting and now the team is eager to find out how the noise generated by shipping and other vessels affects the enigmatic mammals while searching for salmon beneath the waves.

Social imitation learning is an essential skill that humans use to achieve social acceptance, increase awareness in unknown situations or to achieve cultural adaptation. In this work we address the problem of social imitation learning in a many-to-one learning scheme (group of humans to robot), where humans do not necessarily have teaching roles. Contrary to common imitation learning approaches based on one-to-one learning schemes with two agents (human teacher and robot student), our approach is inspired by social learning theory and consists in performing human behavior modeling by observing multiple humans while discovering common behavioral patterns. We propose a common framework for social behavior feature extraction that can be used to collect essential information of various social behaviors such as multi-person trajectory and multiple-body pose. Considering the fact that social imitation learning is shaped by stimuli of others' behavior and the more individuals define the behavior, the more likely to engage in it; our modeling approach also considers a social force model that triggers social behavior learning when observing a group of people. Finally, collective behavior modeling is achieved by feature clustering using a Gaussian Mixture Model approach. Experimental results show that our approach is suitable for social human behavior modeling in situations such as emergency evacuation and Japanese style greeting (bowing).