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 Killer whale (Orcinus orca) interactions with blue-eye trevalla (Hyperoglyphe antarctica) longline fisheries

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5306 ◽  
Author(s):  
Paul Tixier ◽  
Mary-Anne Lea ◽  
Mark A. Hindell ◽  
Christophe Guinet ◽  
Nicolas Gasco ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Killer Whale ◽  
Fishing Effort ◽  
Orcinus Orca ◽  
South Eastern ◽  
Operational Variables ◽  
Eastern Australia ◽  
Longline Fisheries ◽  
Fishing Area ◽  
South Eastern Australia

Over the past five decades, marine mammal interactions with fisheries have become a major human-wildlife conflict globally. The emergence of longline fishing is concomitant with the development of depredation-type interactions i.e., marine mammals feeding on fish caught on hooks. The killer whale (Orcinus orca) is one of the species most involved in depredation on longline fisheries. The issue was first reported in high latitudes but, with increasing expansion of this fishing method, other fisheries have begun to experience interactions. The present study investigated killer whale interactions with two geographically isolated blue-eye trevalla (Hyperoglyphe antarctica) fisheries operating in temperate waters off Amsterdam/St. Paul Islands (Indian Ocean) and south-eastern Australia. These two fisheries differ in the fishing technique used (vertical vs. demersal longlines), effort, catch, fleet size and fishing area size. Using 7-year (2010–16) long fishing and observation datasets, this study estimated the levels of killer whale interactions and examined the influence of spatio-temporal and operational variables on the probability of vessels to experience interactions. Killer whales interactions occurred during 58.4% and 21.2% of all fishing days, and over 94% and 47.4% of the fishing area for both fisheries, respectively. In south-eastern Australia, the probability of occurrence of killer whale interactions during fishing days varied seasonally with a decrease in spring, increased with the daily fishing effort and decreased with the distance travelled by the vessel between fishing days. In Amsterdam/St. Paul, this probability was only influenced by latitude, with an increase in the southern part of the area. Together, these findings document two previously unreported cases of high killer whale depredation, and provide insights on ways to avoid the issue. The study also emphasizes the need to further examine the local characteristics of fisheries and the ecology of local depredating killer whale populations in as important drivers of depredation.

Killer whale (Orcinus orca) interactions with the tuna and swordfish longline fishery off southern and south-eastern Brazil: a comparison with shark interactions

2007 ◽  
Vol 87 (1) ◽  
pp. 135-140 ◽  
Author(s):  
Luciano Dalla Rosa ◽  
Eduardo R. Secchi
Keyword(s):  
Killer Whale ◽  
Longline Fishery ◽  
Catch Per Unit Effort ◽  
Killer Whales ◽  
Additional Information ◽  
South Eastern ◽  
Eastern Brazil ◽  
Negative Impacts ◽  
By Catch ◽  
Longline Fisheries

Depredation by cetaceans and sharks on longline fisheries is a global issue that can have negative impacts on both animals and fisheries and has concerned researchers, managers and the fishing industry. Nevertheless, detailed information on depredation is only available for a few regions where the problem exists. With the purpose of evaluating killer whale depredation on longline-caught tuna (Thunnus spp.) and swordfish (Xiphias gladius) in the waters off southern and south-eastern Brazil and comparing it to shark depredation, data sheets were distributed to the captains of tuna vessels in Santos, south-eastern Brazil, between 1993 and 1995. Data on the catch per unit effort (CPUE) of tuna and swordfish and some records of interactions were also obtained from fishing vessel logbooks. Dockside interviews with fishermen and with researchers on board tuna vessels provided additional information. Killer whale and shark interactions were analysed per longline set and per trip. Killer whale interactions occurred from June to February, mainly between June and October, while shark interactions occurred year round. The number of sets and trips involving shark interactions was significantly higher than the number of sets and trips involving killer whale interactions. However, when depredation occurred, the proportion of fish damaged by killer whales was significantly higher than by sharks. Furthermore, killer whales removed or damaged significantly more hooked swordfish than hooked tuna, whereas sharks damaged significantly more hooked tuna than swordfish. This study also shows that cetacean by-catch is experienced by the tuna and swordfish longline fishery in Brazilian waters.

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.

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.

Informatics and Socio-Technical Challenges when Designing Solutions for Integrated eCare

2017 ◽  
pp. 261-289
Author(s):  
Sabine Koch ◽  
Maria Hägglund ◽  
Isabella Scandurra
Keyword(s):  
Integrated Care ◽  
Case Studies ◽  
Health Informatics ◽  
Information Needs ◽  
System Development ◽  
Collaborative Work ◽  
Successful Implementation ◽  
Data Sets ◽  
Technical Challenges ◽  
Definition Of

The central role of eHealth to enable the successful implementation of integrated care is commonly acknowledged today. This is easier said than done. To provide correct, understandable, and timely information at the point of need and to facilitate communication and decision support for a network of actors with different prerequisites and needs are some of the big challenges of integrated care. This book chapter focuses on the specific challenges related to informatics and socio-technical issues when designing solutions for integrated eCare. Methods for requirements elicitation, evaluation, and system development using user-centred design in collaborative environments involving a variety of stakeholders are presented. Case studies in homecare of older patients, in the care of stroke patients, and regarding citizen eHealth services in general illustrate the application of these methods. Possible solutions and pitfalls are discussed based on the experiences drawn from the case studies. To address the main informatics and socio-technical challenges in integrated eCare, namely informatics-supported collaborative work and to provide coordinated continuity for the patient, top-down activities such as health informatics standardisation, and bottom-up activities resulting in the definition of concrete patient journey descriptions, interaction points, information needs (that can be transformed into standardised data sets), as well as visualisation and interaction patterns need to go hand in hand.

Paediatric polymyositis and dermatomyositis

2013 ◽  
pp. 1021-1032
Author(s):  
Clarissa Pilkington ◽  
Liza McCann
Keyword(s):  
Controlled Trial ◽  
Collaborative Work ◽  
Assessment Tools ◽  
Inflammatory Myopathies ◽  
Double Blind ◽  
Drug Treatments ◽  
Adults And Children ◽  
Associated Malignancy ◽  
Subjective Study ◽  
Definition Of

Juvenile polymyositis and dermatomyositis are inflammatory myopathies that affect muscle. Dermatomyositis also affects skin, and can have many extramuscular manifestations. Inflammatory myopathies are uncommon in childhood, with dermatomyositis occurring more than polymyositis. For this reason, published research has concentrated on juvenile dermatomyositis. The spectrum of disease severity ranges from mild cases that can recover completely without treatment, to multisystem inflammation that can be fatal. Treatments have improved over the decades, reducing mortality from 30% before the era of steroids, to less than 1% in the present day. Juvenile cases of dermatomyositis differ from those seen in adulthood, without tendency for associated malignancy, and a far greater incidence of calcinosis. Calcinosis can be deposited as small calcinotic lumps or as sheets of calcinosis. It is very difficult to treat and causes extensive morbidity, and depending on where the calcinosis is deposited, it can cause severe disability or even death. Over the last decade, international collaborative work has concentrated on developing disease activity and assessment tools for both adult and juvenile forms of myositis. This will enable more subjective study of these rare diseases in multinational cohort studies, and enable clinical trials to investigate drug treatments. This work led to the first international double-blind placebo controlled trial of treatment in both adults and children with dermatomyositis (using rituximab as the drug). Further international collaboration has led to the development of core outcome variables, a definition of disease flare, and classification criteria.

Trust in Virtual Communities

2008 ◽  
pp. 2500-2504
Author(s):  
Eun G. Park
Keyword(s):  
Virtual Communities ◽  
Virtual Community ◽  
Integrated Approach ◽  
Future Research ◽  
Trust Building ◽  
Web Based ◽  
Trust Establishment ◽  
Cultural Aspects ◽  
Definition Of ◽  
Technical Solutions

Trust is one of the key factors that emerged as a significant concept in virtual communities. Trust is so complicated that it is hard to define in one standardized way. Trust issues have evolved into two major ways in the fields of virtual community and security. Among a huge literature concerning trust in virtual communities, a majority of literature addresses technical solutions on trust-building by providing new Web-based applications. They range from human users authorization, semantic Web, agent technologies and access control of network to W3C standardization for content trust and security. Some examples include AT&T’s Policymaker or IBM’s Trust Establishment Module (Blaze, Feigenbaum, & Lacy, 1996; Herzberg, 2000). Only a minority deals with understanding the concept of trust and sources of trust-building from social and cultural aspects. It appears to miss the essence of trust in virtual communities, although an integrated approach is needed for building trust in communication and the use of virtual communities. This article aims to present the definition of trust and relevant concepts for recognizing sources of trust-building in virtual communities. This article also presents future research implications for further development on trust and trust-building in virtual communities.

A Basic Definition of E-Collaboration and its Underlying Concepts

2011 ◽  
pp. 48-53 ◽  
Author(s):  
Ned Kock
Keyword(s):  
Collaborative Work ◽  
Basic Definition ◽  
Broad Definition ◽  
Processing Power ◽  
Electronic Collaboration ◽  
Computer Mediated ◽  
Common Task ◽  
Main Components ◽  
Definition Of ◽  
Electronic Technologies

Electronic collaboration (e-collaboration) is operationally defined here as collaboration using electronic technologies among different individuals to accomplish a common task (Kock & D’Arcy, 2002; Kock, Davidson, Ocker, & Wazlawick, 2001). This is a broad definition that encompasses not only computer-mediated collaborative work but also collaborative work that is supported by other types of technologies that do not fit most people’s definition of a “computer.” One example of such technologies is the telephone, which is not, strictly speaking, a computer—even though some of today’s telephone devices probably have more processing power than some of the first computers back in the 1940s. Another example of technology that may enable e-collaboration is the teleconferencing suite, whose main components are cameras, televisions, and telecommunications devices.

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