Target Strength of Southern Resident Killer Whales (Orcinus orca): Measurement and Modeling

2012 ◽  
Vol 46 (2) ◽  
pp. 74-84 ◽  
Author(s):  
Jinshan Xu ◽  
Z. Daniel Deng ◽  
Thomas J. Carlson ◽  
Brian Moore
Keyword(s):  
Killer Whale ◽  
Bottlenose Dolphins ◽  
Turbine Blades ◽  
Puget Sound ◽  
Target Strength ◽  
Killer Whales ◽  
Free Swimming ◽  
Active Monitoring ◽  
High Knowledge ◽  
Active Monitoring System

AbstractA major criterion for permitting the deployment of tidal turbines in Washington State’s Puget Sound is management of risk of injury to killer whales from collision with moving turbine blades. An active monitoring system is being proposed to detect and track killer whales within proximity of turbines and alert turbine operators of their presence and location to permit temporary turbine shutdown when the risk of collision is high. Knowledge of the target strength (TS) of killer whales is critical to the design and application of active acoustic monitoring systems. In 1996, a study of the TS directivity of a 2.2-m-long bottlenose dolphin at an insonifying frequency of 67 kHz was performed. Noting that killer whales, which are dolphins, are morphologically similar to bottlenose dolphins and then assuming allometry, we estimated the relative broadside and tail aspect TS of a 7.5-m-long adult killer whale at an insonifying frequency of 67 kHz to be −8 and −28 dB, respectively. We used a three-layer model for plane wave reflection of sound at 200 kHz from the lung of killer whales to estimate their TS. We assessed the accuracy of our killer whale TS estimates by comparing them with TS estimates of free swimming killer whales obtained using a split-beam active acoustic system operating at 200 kHz. The killer whale TS estimates based on the preliminary model were in good agreement with those obtained for free swimming killer whales.

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.

Design and operation specifications of an active monitoring system for detecting southern resident killer whales

2011 ◽  
Author(s):  
Z. Daniel Deng ◽  
Thomas J. Carlson ◽  
Jinshan Xu ◽  
Jayson Martinez ◽  
Mark A. Weiland ◽  
...  
Keyword(s):  
Monitoring System ◽  
Killer Whales ◽  
Active Monitoring ◽  
Active Monitoring System

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.

scholarly journals Estimates of Chinook salmon consumption in Washington State inland waters by four marine mammal predators from 1970 to 2015

2017 ◽  
Vol 74 (8) ◽  
pp. 1173-1194 ◽  
Author(s):  
Brandon Chasco ◽  
Isaac C. Kaplan ◽  
Austen Thomas ◽  
Alejandro Acevedo-Gutiérrez ◽  
Dawn Noren ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Marine Mammal ◽  
Oncorhynchus Tshawytscha ◽  
Interspecific Interactions ◽  
Puget Sound ◽  
The United States ◽  
Washington State ◽  
Killer Whales ◽  
Protected Species ◽  
Annual Biomass

Conflicts can arise when the recovery of one protected species limits the recovery of another through competition or predation. The recovery of many marine mammal populations on the west coast of the United States has been viewed as a success; however, within Puget Sound in Washington State, the increased abundance of three protected pinniped species may be adversely affecting the recovery of threatened Chinook salmon (Oncorhynchus tshawytscha) and endangered killer whales (Orcinus orca) within the region. Between 1970 and 2015, we estimate that the annual biomass of Chinook salmon consumed by pinnipeds has increased from 68 to 625 metric tons. Converting juvenile Chinook salmon into adult equivalents, we found that by 2015, pinnipeds consumed double that of resident killer whales and six times greater than the combined commercial and recreational catches. We demonstrate the importance of interspecific interactions when evaluating species recovery. As more protected species respond positively to recovery efforts, managers should attempt to evaluate tradeoffs between these recovery efforts and the unintended ecosystem consequences of predation and competition on other protected species.

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 Target strength measurement of free-swimming jack mackerel using an indoor large experimental tank

2019 ◽  
Vol 85 (1) ◽  
pp. 2-16
Author(s):  
YOHEI KAWAUCHI ◽  
KENJI MINAMI ◽  
HOKUTO SHIRAKAWA ◽  
KAZUSHI MIYASHITA ◽  
YUKA IWAHARA ◽  
...  
Keyword(s):  
Target Strength ◽  
Jack Mackerel ◽  
Experimental Tank ◽  
Strength Measurement ◽  
Free Swimming

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.

Prey switching by killer whales in the north-east Atlantic: observational evidence and experimental insights

2013 ◽  
Vol 94 (6) ◽  
pp. 1357-1365 ◽  
Author(s):  
Dag Vongraven ◽  
Anna Bisther
Keyword(s):  
Killer Whale ◽  
Large Population ◽  
Tooth Wear ◽  
Killer Whales ◽  
Prey Switching ◽  
Photo Identification ◽  
North East ◽  
The North ◽  
Spawning Stock

Studies in the Pacific have identified distinct killer whale ecotypes that are either specialized mammal- or fish-eaters. The different types have developed hunting strategies that would suggest specialization could be more advantageous than generalism. However, it has been suggested, based on long-term dietary markers of tooth wear and stable isotope values, that lineages in the North Atlantic are generalist, but with individual variation in the proportion of prey types consumed. Here, we present the results of ten years of observational and photo-identification data of a population of killer whales that follows the Norwegian spring-spawning stock of Atlantic herring. Although the whales were predominantly observed while feeding upon herring, one pod of herring-eating whales was also observed interacting with seals. This supports the hypothesis based on the long-term markers, of a degree of specialization, with a small number of groups persistently feeding upon mammals, but switching between herring and seals. We further investigated this prey switching by conducting playbacks of herring-eating killer whale sounds to harbour seals at haul-out sites on the herring spawning grounds. We recorded changes in behaviour consistent with an anti-predator response, suggesting the seals perceived the herring-eating killer whales as a potential predatory threat and had not habituated to their calls. This could be due to the risk of herring-eating killer whales switching to mammalian prey, or the difficulty of discriminating between killer whale pods due to the large population size and number of killer whale call dialects in this population, or a combination of both.

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