scholarly journals Circulating inhibin and testosterone during sexual maturation and reproductive seasonality of captive male killer whales (Orcinus orca)

2020 ◽  
Vol 19 (2) ◽  
pp. 209-222
Author(s):  
Hiroshi Katsumata ◽  
◽  
Etsuko Katsumata ◽  
Sukanya Jaroenporn ◽  
Yoko Ueda ◽  
...  
Keyword(s):  
Sexual Maturation ◽  
Killer Whale ◽  
Mature Stage ◽  
Killer Whales ◽  
Pubertal Stage ◽  
Seasonal Breeder ◽  
Northern Atlantic ◽  
Autumn And Winter ◽  
First Time ◽  
Male Killer

The present study aimed to investigate the reproductive biology of male killer whales. Changes in the concentrations of two circulating testicular hormones, inhibin and testosterone, were monitored during sexual maturation of two male Type 1 Eastern Northern Atlantic killer whales over a period of 20 years. The two killer whales grew rapidly at the pubertal stage and reached a plateau at the age of 23 and 20 years, respectively, after which growth slowed down. In the younger male, circulating inhibin was higher in the juvenile than in the pubertal and mature stages; whereas circulating testosterone exhibited the opposite trend. The pubertal period was estimated to last approximately 5 years, from 12 to 17 years of age. In the elder male, circulating testosterone was high from the onset of this study (12 years of age), when the animal also sired successfully for the first time. This finding shows that the male killer whale is possible to sire even if it is not socially matured, if there is opportunity for copulation. During the mature stage, both animals exhibited significantly higher circulating testosterone concentrations in spring compared to autumn and winter; whereas no seasonal change was observed for circulating inhibin. These results clearly demonstrate that the male killer whale is a seasonal breeder, even though it is fertile throughout the year. This is the first study to elucidate the inhibin concentration and secretory source in the male killer whale.

Namu’s Journey

Orca ◽  
2018 ◽  
Author(s):  
Jason M. Colby
Keyword(s):  
Chinook Salmon ◽  
Killer Whale ◽  
Puget Sound ◽  
Washington State ◽  
Killer Whales ◽  
The West ◽  
West Side ◽  
And Behavior ◽  
First Time ◽  
The Brain

The call came by ship-to-shore radio from a Washington State ferry. The skipper on the Seattle-Bremerton route had just spotted killer whales headed south, and he thought Ted Griffin should know. Shouting his thanks, the aquarium owner raced down the dock, leapt into Pegasus, and tore off in the direction of the sighting. Clocked at sixty miles per hour, the shallow-draft runabout may have been the fastest boat on Puget Sound, and it overtook the orcas near Vashon Island. But as Griffin throttled down, he realized to his disbelief that someone else was already chasing them. There, clear as day, was a blue helicopter hovering over the whales. Incensed, Griffin steered Pegasus closer, until he could almost touch the helicopter’s pontoons. Looking up, he spotted a burly man leaning out the cabin door and eying the pod. “Get away from my whales!” Griffin shouted. “Your whales?” the man laughed. “You’ll have to catch them first.” It was the first time Griffin had met Don Goldsberry, ex-fisherman and animal collector for the Point Defiance Aquarium (formerly the Tacoma Aquarium). The two men’s shared pursuit of orcas would soon bind them together. On this day, however, Griffin left feeling a bit embarrassed, having behaved, as he put it, “like a rancher possessive of his herd.” Some part of him knew his quest to capture and befriend a killer whale was becoming unhealthy. He had a struggling aquarium in Seattle and a growing family on Bainbridge Island. Orcas were his obsession, but they weren’t paying the bills. At home, he still talked and laughed with Joan and played with his little sons, Jay and John. But he had whales on the brain. He dreamed of them when asleep and sometimes mumbled about them when awake. With each reported sighting, he dropped everything—to Joan’s increased annoyance. In time, Griffin had come to see patterns in the animals’ migrations and behavior. He noted that they appeared when chinook salmon were running and that they seemed to cling to the west side of Puget Sound when headed south and to the east side when swimming north.

Influence of environmental and longline fishing operational variables on the presence of killer whales (Orcinus orca) in south-western Atlantic

2012 ◽  
Vol 94 (6) ◽  
pp. 1267-1276 ◽  
Author(s):  
Cecilia Passadore ◽  
Andrés Domingo ◽  
María Szephegyi ◽  
Eduardo R. Secchi
Keyword(s):  
Linear Models ◽  
Killer Whale ◽  
Fishing Effort ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Western Atlantic ◽  
Operational Variables ◽  
Temporal Occurrence ◽  
Occurrence Patterns ◽  
Autumn And Winter

Killer whale (Orcinus orca) is frequently encountered in coastal and high productive pelagic waters, near the shelf break. In the south-western Atlantic Ocean, spatial and temporal occurrence patterns are poorly known. However, the monitoring of the interaction between killer whales and longline fishery suggests that the species is frequent in this region. We analysed the killer whale presence within the Uruguayan pelagic longline fishing zone. Data were collected from 1996 to 2007, during 2189 fishing events, by vessel skippers and on-board observers. We estimated the sighting rate (SR = sightings days/fishing days * 100) for different time scales and in 1 × 1 degree grids. Generalized linear models were used to evaluate the effect of spatial, temporal, environmental and operational variables on the species presence. Killer whales were sighted in 100 fishing days (SR = 4.5%), this occurrence being explained by distance from shore and sea surface temperature, varying among months and fishing boats. Although sightings occurred year round, they were more frequent in autumn and winter, at 150–400 nautical miles (nm) from shore (mean = 250 nm) and in waters with temperatures ranging from 19 to 24°C (mean = 22°C). Sets took place between 19°–40°S and 21°–54°W, while killer whales occurred mostly from 34°–37°S and 48°–53°W. In this region, the high productive Brazil—Malvinas Confluence Zone is located, and concentrates fishing effort and also killer whales.

Validity of puberty self-report in children and adolescents in Ho Chi Minh City

MedPharmRes ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 33-37
Author(s):  
Tam M. Do ◽  
Thanh K. Van ◽  
Huyen TT. Bich ◽  
Thanh TK. Tran ◽  
Minh X. Ngo ◽  
...  
Keyword(s):  
Children And Adolescents ◽  
Sexual Maturation ◽  
Kappa Statistic ◽  
Community Context ◽  
Self Report ◽  
Ho Chi Minh City ◽  
Pubertal Stage ◽  
Perfect Agreement ◽  
Kendall’S Τ ◽  
High Concordance

Background: Puberty is a milestone in child and adolescent development, yet a feasible tool to accurately assess pubertal stage in community context has not been validated in Vietnam. Aim: This study was conducted to validate pubertal self-report among Ho Chi Minh City children and adolescents in comparison with paediatrician’s assessment. Methods: 80 girls and 76 boys aged from 6 to 17 years old from 5 schools in Ho Chi Minh City were recruited. Self-administered questionnaires about sexual maturation were distributed to participants and results were compared with physician’s pubertal examination. Kappa statistic and Kendall’s τ b were used to evaluate validity of the questionnaire. Results: Boys tended to overestimate their development stages while girls tended to underestimate. Fair to almost perfect agreement between students’ reports and paediatricians’ evaluation, along with high concordance was recorded, however younger boys (aged 6-11) showed limited evaluation of their own sexual maturation. Conclusion: This method was inaccurate to evaluate younger boys’ sexual maturation; however, acceptable accuracy in sexual maturation estimation among younger girls and adolescents could allow it to serve as an effective screening tool in community context.

scholarly journals Family feud: permanent group splitting in a highly philopatric mammal, the killer whale (Orcinus orca)

2021 ◽  
Vol 75 (3) ◽  
Author(s):  
Eva H. Stredulinsky ◽  
Chris T. Darimont ◽  
Lance Barrett-Lennard ◽  
Graeme M. Ellis ◽  
John K. B. Ford
Keyword(s):  
Killer Whale ◽  
Group Structure ◽  
Group Living ◽  
Orcinus Orca ◽  
Learning Approaches ◽  
Killer Whales ◽  
Internal Factors ◽  
Individual Fitness ◽  
Leadership Experience

Abstract For animals that tend to remain with their natal group rather than individually disperse, group sizes may become too large to benefit individual fitness. In such cases, group splitting (or fission) allows philopatric animals to form more optimal group sizes without sacrificing all familiar social relationships. Although permanent group splitting is observed in many mammals, it occurs relatively infrequently. Here, we use combined generalized modeling and machine learning approaches to provide a comprehensive examination of group splitting in a population of killer whales (Orcinus orca) that occurred over three decades. Fission occurred both along and across maternal lines, where animals dispersed in parallel with their closest maternal kin. Group splitting was more common: (1) in larger natal groups, (2) when the common maternal ancestor was no longer alive, and (3) among groups with greater substructuring. The death of a matriarch did not appear to immediately trigger splitting. Our data suggest intragroup competition for food, leadership experience and kinship are important factors that influence group splitting in this population. Our approach provides a foundation for future studies to examine the dynamics and consequences of matrilineal fission in killer whales and other taxa. Significance statement Group living among mammals often involves long-term social affiliation, strengthened by kinship and cooperative behaviours. As such, changes in group membership may have significant consequences for individuals’ fitness and a population’s genetic structure. Permanent group splitting is a complex and relatively rare phenomenon that has yet to be examined in detail in killer whales. In the context of a growing population, in which offspring of both sexes remain with their mothers for life, we provide the first in-depth examination of group splitting in killer whales, where splitting occurs both along and across maternal lines. We also undertake the first comprehensive assessment of how killer whale intragroup cohesion is influenced by both external and internal factors, including group structure, population and group demography, and resource abundance.

Development of intentional stranding hunting techniques in killer whale (Orcinus orca) calves at Crozet Archipelago

1995 ◽  
Vol 73 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Christophe Guinet ◽  
Jérome Bouvier
Keyword(s):  
Growth Curve ◽  
Parental Investment ◽  
Killer Whale ◽  
Elephant Seal ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Juvenile Female ◽  
Adult Females ◽  
Social Transfer ◽  
High Degree

This paper describes the trend in the practice of what we interpret to be the "intentional stranding" hunting technique of two juvenile female killer whales (Orcinus orca), A4 and A5, belonging to pod A on the beaches of Possession Island, Crozet Archipelago. Pod A was composed of three adult females, A2, A3, A6, and one adult male, A1. A2 is A4's mother and A3 is A5's mother. The year of birth and thus the probable age of the two juveniles were estimated from their growth curve determined by means of a photogrammetric technique. These observations indicate that at Crozet Archipelago, juvenile killer whales first practiced intentional stranding on their own when they were 4–5 years old. Their first attempt to capture elephant seal pups by means of this technique was observed when they were 5–6 years old. However, 5- to 6-year-old juveniles still needed the assistance of an adult female to return to the water with their prey. This study indicates that learning hunting techniques needs a high degree of skill and requires high parental investment to reduce the associated risk. Furthermore, social transfer, through apprenticeship, is probably one of the mechanisms that enables the high degree of adaptability observed in killer whales.

scholarly journals A long post-reproductive lifespan is a shared trait among genetically distinct killer whale populations

2021 ◽  
Author(s):  
Mia Nielsen ◽  
Samuel Ellis ◽  
Jared Towers ◽  
Thomas Doniol-Valcroze ◽  
Daniel Franks ◽  
...  
Keyword(s):  
Social Structure ◽  
Killer Whale ◽  
Demographic Data ◽  
Reproductive Period ◽  
Substantial Variation ◽  
Killer Whales ◽  
Reproductive Conflict ◽  
Demographic Patterns ◽  
General Prediction

The extended female post-reproductive lifespan found in humans and some toothed whales remains an evolutionary puzzle. Theory predicts demographic patterns resulting in increased female relatedness with age (kinship dynamics) can select for a prolonged post-reproductive lifespan due to the combined costs of inter-generational reproductive conflict and benefits of late-life helping. Here we test this prediction using >40 years of longitudinal demographic data from the sympatric yet genetically distinct killer whale ecotypes: resident and Bigg’s killer whales. The female relatedness with age is predicted to increase in both ecotypes, but with a less steep increase in Bigg’s due to their different social structure. Here, we show that there is a significant post-reproductive lifespan in both ecotypes with >30% of adult female years being lived as post-reproductive, supporting the general prediction that an increase in local relatedness with age predisposes the evolution of a post-reproductive lifespan. Differences in the magnitude of kinship dynamics however, did not influence the timing or duration of the post-reproductive lifespan with females in both ecotypes terminating reproduction before their mid-40s followed by an expected post-reproductive period of ~20 years. Our results highlight the important role of kinship dynamics in the evolution of a long post-reproductive lifespan in long-lived mammals, while further implying that the timing of menopause may be a robust trait that is persistent despite substantial variation in demographic patterns among population.

scholarly journals Mitigating killer whale depredation on demersal longline fisheries by changing fishing practices

2014 ◽  
Vol 72 (5) ◽  
pp. 1610-1620 ◽  
Author(s):  
Paul Tixier ◽  
Jade Vacquie Garcia ◽  
Nicolas Gasco ◽  
Guy Duhamel ◽  
Christophe Guinet
Keyword(s):  
Killer Whale ◽  
Collaborative Work ◽  
Dilution Effect ◽  
Killer Whales ◽  
Fleet Size ◽  
Operational Variables ◽  
Definition Of ◽  
Longline Fisheries ◽  
Technical Solutions ◽  
Fishing Practices

Abstract Odontocete depredation on longlines involves socioeconomic and conservation issues with significant losses for fisheries and potential impacts on wild populations of depredating species. As technical solutions to this conflict are limited and difficult to implement, this study aimed to identify fishing practices that could reduce odontocete depredation, with a focus on killer whales (Orcinus orca) interacting with Patagonian toothfish (Dissostichus eleginoides) longliners off the Crozet islands. Data collected by fishery observers from 6013 longline sets between 2003 and 2013 allowed us to statistically detect the significant influence of five operational variables using GLMMs. The probability of interactions between vessels and killer whales was decreased by (i) the number of vessels operating simultaneously in the area: the limited number of depredating killer whales may induce a dilution effect with increased fleet size, and (ii) depth of longline sets: vessels operating in shallow waters may be more accessible to whales that are initially distributed on peri-insular shelves. The cpue was negatively influenced by (iii) length of longlines: longer sets may provide killer whales access to a greater proportion of hooked fish per set, and positively influenced by (iv) hauling speed: increased speed may shorten the time during which toothfish are accessible to whales during hauling. The time it takes for killer whales to reach vessels was positively correlated to (v) the distance travelled between longline sets with an estimated threshold of 100 km beyond which whales seem to temporarily lose track of vessels. These findings provide insightful guidelines about what fishing strategy to adopt given these variables to reduce killer whale depredation here and in similar situations elsewhere. To a greater extent, this study is illustrative of how collaborative work with fishermen in a fully controlled fishery framework may lead to the definition of cost-limited and easy-to-implement mitigation solutions when facing such human-wildlife conflict.

scholarly journals The genus Hyalomma Koch, 1844. I. Reinstatement of Hyalomma (Euhyalomma) glabrum Delpy, 1949 (Acari, Ixodidae) as a valid species with a redescription of the adults, the first description of its immature stages and notes on its biology

2006 ◽  
Vol 73 (1) ◽  
Author(s):  
D.A. Apanaskevich ◽  
I.G. Horak
Keyword(s):  
South Africa ◽  
Ixodid Tick ◽  
Valid Species ◽  
Immature Stages ◽  
Large Herbivores ◽  
Hyalomma Marginatum ◽  
Hyalomma Rufipes ◽  
Autumn And Winter ◽  
First Time ◽  
Preferred Hosts

For nearly 50 years the ixodid tick Hyalomma marginatum turanicum, reputedly introduced into South Africa on imported Persian sheep, has been considered identical to the Asian Hyalomma (Euhyalomma) marginatum turanicum Pomerantzev, 1946. Comparisons of this tick with the Asian H. (E.) m. turanicum and other subspecies of Hyalomma (Euhyalomma) marginatum, however, reveal that it is an old taxon, namely Hyalomma rufipes glabrum Delpy, 1949. It is hereby reinstated as Hyalomma (Euhyalomma) glabrum, and its adults are redescribed and its immature stages described for the first time. The preferred hosts of its adults are large herbivores such as zebras, gems bok and eland, on which it occurs during summer. The preferred hosts of its immature stages are scrub hares and ground-frequenting birds, on which it is present during autumn and winter. Data on its distribution and possible disease relationships are also provided.

The sighting of pygmy killer whales (Feresa attenuata) in the southern Bay of Biscay and their association with cetacean calves

2002 ◽  
Vol 82 (3) ◽  
pp. 509-511 ◽  
Author(s):  
A.D. Williams ◽  
R. Williams ◽  
T. Brereton
Keyword(s):  
Killer Whale ◽  
South Atlantic ◽  
First Year ◽  
Bay Of Biscay ◽  
Killer Whales ◽  
The South ◽  
Tropical Waters ◽  
New Born ◽  
Close Proximity

The pygmy killer whale Feresa attenuata is a poorly understood species that occurs in tropical and warm sub-tropical waters worldwide. The true range of these animals is not well established and there have been reports of them in temperate waters of the South Atlantic and Pacific Oceans. At 1746 h on 24 April 1997 at 45°15′76″N 30°56′54″W the first of two groups of small robust cetaceans were observed by experienced cetacean observers during a survey carried out aboard the P&O Portsmouth cruise ferry ‘Pride of Bilbao’. At 1820 at position 45°25′96″N 40°00′94″W on the same day a second group of animals of this species was encountered. In both cases the cetaceans were in close proximity to cetaceans with new born or first year calves. Identification information was recorded by the observers and the animals were identified as pygmy killer whales. These records represent the first in the Bay of Biscay and the most northerly records for this species.

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