scholarly journals Killer whales are attracted to herring fishing vessels

2020 ◽  
Vol 652 ◽  
pp. 1-13
Author(s):  
E Mul ◽  
MA Blanchet ◽  
BT McClintock ◽  
WJ Grecian ◽  
M Biuw ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Fishery Management ◽  
Killer Whale ◽  
Detailed Knowledge ◽  
Killer Whales ◽  
Fishing Activity ◽  
Fishing Vessels ◽  
Satellite Transmitters ◽  
Core Areas ◽  
The Impact

Marine mammals and fisheries often target the same resources, which can lead to operational interactions. Potential consequences of operational interaction include entanglements and damaged or reduced catches but also enhanced foraging opportunities, which can attract marine mammals to fishing vessels. Responsible fisheries management therefore requires detailed knowledge of the impact of these interactions. In northern Norway, killer whales Orcinus orca are frequently observed in association with large herring aggregations during the winter. We use a combination of biotelemetry and fisheries data to study if, to what extent and at what distances killer whales are attracted to fishing activity. Twenty-five satellite transmitters were deployed on killer whales at herring overwintering and spawning grounds, often near fishing vessels. Over 50% of the killer whale core areas of high usage overlapped with the fisheries core areas, and individual whales spent up to 34% of their time close to active fishing. We used a 3-state hidden Markov model to assess whether killer whale movements were biased towards fishing activities. Of the overall whale movements, 15% (CI = 11-21%) were biased towards fishing activities, with marked heterogeneity among individuals (0-57%). During periods of active fishing, whale movements were biased towards fishing events 44% (CI = 24-66%) of the time, with individual percentages ranging from 0 to 79%. Whales were more likely to be attracted when they were within 20 km. This information can be used in fishery management to consider potential consequences for fishers and whales.

Marine mammals and Japanese long-line fishing vessels in Australian waters: operational interactions and sightings

2006 ◽  
Vol 12 (1) ◽  
pp. 31 ◽  
Author(s):  
Catherine Bell ◽  
Peter Shaughnessy ◽  
Margie Morrice ◽  
Bob Stanley
Keyword(s):  
Marine Mammal ◽  
Marine Mammals ◽  
East Coast ◽  
Fishing Gear ◽  
Killer Whales ◽  
Fishing Vessels ◽  
Long Line ◽  
Target Fish ◽  
Pilot Whales ◽  
Warm Temperate

Observers from the Australian Fisheries Management Authority worked on randomly chosen Japanese long-line vessels in the Australian Fishing Zone (AFZ) between 1980 and 1997. Observer reports (n = 451) were inspected for interactions or sightings of marine mammals. An operational interaction was defined as an activity or behaviour that involved direct contact between a marine mammal and fishing gear, bait, target fish or bycatch, or indications that the marine mammal was feeding. A sighting was defined as the recording of marine mammals that passed the vessel without changing course and/or did not appear to interact with the vessel or its gear. Observers witnessed 23 interactions and made another 44 sightings of marine mammals. A further 24 interactions and sightings were relayed by crew members. Killer whales were reported most frequently: most incidences of fish being damaged, taken or frightened away were attributed to them. Eleven marine mammals were caught: two died, seven were released, and the fate of two others was not recorded. Between 1991 and 1996, when observer coverage was 11.5% overall in the AFZ, the incidence of interactions was 1.71 per million hooks set. The estimated number of interactions in that seven-year period was 157 in the AFZ. Since 1997, the long-line fishery has been conducted by Australian vessels, primarily off the east coast of mainland Australia in warm-temperate waters. A higher proportion of interactions can be expected with killer whales and short-finned pilot whales in these waters, and fewer with seals.

scholarly journals Evidence of killer whale predation on a yearling bowhead whale in Cumberland Sound, Nunavut

2020 ◽  
Vol 6 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Brent G. Young ◽  
Sarah M.E. Fortune ◽  
William R. Koski ◽  
Stephen A. Raverty ◽  
Ricky Kilabuk ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Killer Whale ◽  
Canadian Arctic ◽  
Bowhead Whale ◽  
Orcinus Orca ◽  
The Arctic ◽  
Killer Whales ◽  
Eastern Canada ◽  
Cumberland Sound ◽  
Potential Impact

Accounts of killer whale (Orcinus orca) predation on marine mammals in the Canadian Arctic are relatively uncommon. Although second-hand reports of killer whale predation events in the Arctic are more common in recent years, these observations are generally poorly documented and the outcome of attacks are often unknown. On 12 August 2016, a floating bowhead whale (Balaena mysticetus) carcass was found off-shore in Cumberland Sound, Nunavut — presumably predated by killer whales that were sighted in the area. Inspection of the carcass revealed injuries consistent with published accounts of killer whale predation on large whales and observations of killer whale predation on bowheads described in Inuit traditional knowledge. The bowhead was male, 6.1 m long in good nutritional condition and estimated between 14 and 16 months old. As a recently weaned yearling, this whale would have been highly vulnerable to killer whale predation. With decreasing summer sea ice making some areas of the Arctic more accessible, the incursion and presence of killer whales in the Arctic is expected to increase. A better understanding of Arctic killer whale predation pressure is needed to predict the potential impact they will have on the eastern Canada–west Greenland bowhead population as well as on other marine mammal prey.

scholarly journals The Whale and the Region: Orca Capture and Environmentalism in the New Pacific Northwest

2014 ◽  
Vol 24 (2) ◽  
pp. 425-454
Author(s):  
Jason Colby
Keyword(s):  
Pacific Northwest ◽  
Killer Whale ◽  
Human Relations ◽  
Killer Whales ◽  
Government Officials ◽  
Marine Predator ◽  
The Pacific ◽  
Principal Source ◽  
Human Perceptions ◽  
The Impact

Although the orca is today widely recognized as a cultural and ecological icon of the Pacific Northwest, historians have ignored the impact of killer whale capture on the development of the region’s environmental values and identity. Between 1964 and 1976, the waters in southern British Columbia and Washington State were the world’s principal source of captive killer whales. The display of orcas by the region’s aquariums transformed human perceptions of this marine predator, and soon aquariums around the world were placing orders for Pacific Northwest killer whales. Yet the expanding capture and export of orcas in the late 1960s and early 1970s raised troubling ecological and moral questions for the region’s human residents. In the context of shifting attitudes toward cetaceans and rising environmental awareness throughout North America, Pacific Northwesters on both sides of the border increasingly viewed orcas as symbols of their region’s shared ecological concerns. The transnational nature of the region’s killer whale pods helped spur not only ecological reflection but also transborder cooperation among activists, scientists, and government officials to study and eventually protect the species. In the process, the shifting human relations with orcas helped redefine the Pacific Northwest.

First record of Norwegian killer whales attacking and feeding on a harbour porpoise

2015 ◽  
Vol 8 ◽  
Author(s):  
A. Mel Cosentino
Keyword(s):  
North Atlantic ◽  
Marine Mammals ◽  
First Record ◽  
Harbour Porpoise ◽  
Sperm Whales ◽  
Killer Whales ◽  
Strait Of Gibraltar ◽  
Cetacean Species ◽  
The North ◽  
Northern Bottlenose Whales

Orcinus orcais a cosmopolitan species and the most widely distributed marine mammal. Its diet includes over 140 species of fish, cephalopods, sea birds and marine mammals. However, many populations are specialised on certain specific prey items. Three genetically distinct populations have been described in the North Atlantic. Population A (that includes the Icelandic and Norwegian sub-populations) is believed to be piscivorous, as is population C, which includes fish-eating killer whales from the Strait of Gibraltar. In contrast, population B feeds on both fish and marine mammals. Norwegian killer whales follow the Norwegian spring spawning herring stock. The only description in the literature of Norwegian killer whales feeding on another cetacean species is a predation event on northern bottlenose whales in 1968. Daily land-based surveys targeting sperm whales were conducted from the Andenes lighthouse using BigEyes®binoculars (25×, 80 mm). The location of animals at sea was approximated through the use of an internal reticule system and a graduated wheel. On 24 June 2012 at 3:12 am, an opportunistic sighting of 11 killer whales was made off Andenes harbour. The whales hunted and fed on a harbour porpoise. Despite these species having overlapping distributions in Norwegian waters, this is the first predatory event reported in the literature.

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 Impact of mechanized clam dredging on the discarded megabenthic fauna on the Catalan coast (NW Mediterranean)

2021 ◽  
pp. 1-9
Author(s):  
Marc Baeta ◽  
Claudia Rubio ◽  
Françoise Breton
Keyword(s):  
Small Scale ◽  
Fishing Activity ◽  
Lethal Damage ◽  
Catalan Coast ◽  
Nw Mediterranean ◽  
Chamelea Gallina ◽  
Level Scale ◽  
Nw Mediterranean Sea ◽  
The Impact ◽  
Partial Damage

Abstract There is an important small-scale fishery using mechanized dredges and targeting clams (mainly wedge clam Donax trunculus and striped venus clam Chamelea gallina) along the Catalan coast (NW Mediterranean Sea). This study evaluated for the first time the discards and impact of mechanized clam dredging on the Catalan coast. To this end, three surveys were performed on board standard clam vessels (September and November 2016 and January 2017). Surveys were conducted in the three main clam fishing areas (Rosas Bay, South Barcelona and Ebro Delta). The composition of discards and the impact caused to discarded species was assessed using a three-level scale (undamaged; minor or partial damage; and lethal damage). Our study revealed that a large proportion of the catch (between 67–82% weight) is discarded. Even though about 63% of the discarded species were undamaged, 11% showed minor or partial damage and 26% lethal damage. Infaunal and epifaunal species with soft-body or fragile shells were the most impacted by the fishing activity (e.g. the sea urchin Echinocardium mediterraneum (~89%) and the bivalve Ensis minor (~74%)). Our results showed different levels of impact by target species and fishing area.

scholarly journals Natura 2000 sites and fisheries in German offshore waters

2008 ◽  
Vol 66 (1) ◽  
pp. 155-169 ◽  
Author(s):  
Søren Anker Pedersen ◽  
Heino Fock ◽  
Jochen Krause ◽  
Christian Pusch ◽  
Anne L. Sell ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Fishery Management ◽  
Conservation Status ◽  
Natura 2000 ◽  
Management Measures ◽  
Favourable Conservation Status ◽  
Management Plans ◽  
Natura 2000 Site ◽  
Environmentally Sound ◽  
Fishing Impacts

Abstract Pedersen, S. A., Fock, H., Krause, J., Pusch, C., Sell, A. L., Böttcher, U., Rogers, S. I., Sköld, M., Skov, H., Podolska, M., Piet, G. J., and Rice, J. C. 2009. Natura 2000 sites and fisheries in German offshore waters.–ICES Journal of Marine Science, 66: 155–169. The principal objective of sites selected as part of Natura 2000 is to achieve or maintain a favourable conservation status of habitats and species named in the EU Birds and Habitats directives. In the German exclusive economic zone, the habitat types protected by this legislation are sandbanks and reefs; protected species include marine mammals, seabirds, and specific migratory fish species. The ICES project Environmentally Sound Fishery Management in Protected Areas (EMPAS) aims to answer two questions: (i) To what extent do specific fishing activities significantly threaten attainment of the conservation objectives of the Natura 2000 sites? (ii) What management measures would reduce these conflicts and how effective would they be at helping to ensure the favourable condition of these sites? Assessments of fishing impacts on Natura 2000 sites require basic data on the conservation status of individual habitats and species, as well as data for fine-scale distributions of ongoing fishing activities. This paper describes and discusses the process used by the EMPAS project in developing fishery-management plans for each Natura 2000 site in German offshore waters.

The impact of dietary protein:carbohydrate balance on lifespan and reproduction in Protaetia brevitarsis (Coleoptera: Scarabaeidae: Cetoniinae)

2021 ◽  
pp. 1-8
Author(s):  
S.-H. Kim ◽  
H. Park ◽  
W. Kim ◽  
J.-H. Song ◽  
S.J. Roh ◽  
...  
Keyword(s):  
Reproductive Performance ◽  
Egg Production ◽  
Detailed Knowledge ◽  
Reproductive Senescence ◽  
Egg Hatchability ◽  
Edible Insect ◽  
Age Related ◽  
Medicinal Value ◽  
Egg Production Rate ◽  
The Impact

The establishment of efficient and sustainable production of industrially important insects necessitates the detailed knowledge of the optimal mixture of macronutrients required for maximising their performance and fitness. The white spotted flower chafer, Protaetia brevitarsis (Coleoptera: Scarabaeidae: Cetoniinae), is one of the most important edible insects in East Asia with high nutritional and medicinal value. Here, we report how the ratio of protein to digestible carbohydrate (P:C) in the diet influenced lifespan and reproductive performance in the adults of P. brevitarsis. Throughout their lifespan, beetles were fed ad libitum one of five diets with differing P:C ratio (0:1, 3:7, 1:1, 7:3, 1:0). Both lifespan and the number of eggs produced over the lifetime were maximised at the P:C ratio of 3:7 and declined as the ratio deviated away from this optimal P:C composition. Beetles fed a diet containing only protein (P:C 1:0) not only had the shortest lifespan but also exhibited substantially reduced lifetime egg production compared to those fed the other diets. However, the effects of dietary P:C ratio on daily egg production rate and egg hatchability were marginal. The number of eggs produced at each age stage peaked at the age of week 2 and then gradually declined with increasing age, showing the sign of reproductive senescence. Age-specific egg production was higher in beetles confined to three intermediate P:C ratios (3:7, 1:1, 7:3) than those confined to two extreme P:C ratios (0:1, 1:0) throughout their lifespan. The speed of age-related decrease in reproductive performance was the slowest at P:C 3:7. Our data have implications for optimising the production of this edible insect with emerging economic importance.

Mistuning and Damping of a Radial Turbine Wheel. Part 1: Fundamental Analyses and Design of Intentional Mistuning Pattern

2021 ◽  
Author(s):  
Alex Nakos ◽  
Bernd Beirow ◽  
Arthur Zobel
Keyword(s):  
High Stress ◽  
Forced Response ◽  
Experimental Investigations ◽  
Detailed Knowledge ◽  
Turbine Wheel ◽  
Operation Conditions ◽  
Radial Turbine ◽  
Influence Coefficients ◽  
Modes Of Vibration ◽  
The Impact

Abstract The radial turbine impeller of an exhaust turbocharger is analyzed in view of both free vibration and forced response. Due to random blade mistuning resulting from unavoidable inaccuracies in manufacture or material inhomogeneities, localized modes of vibration may arise, which involve the risk of severely magnified blade displacements and inadmissibly high stress levels compared to the tuned counterpart. Contrary, the use of intentional mistuning (IM) has proved to be an efficient measure to mitigate the forced response. Independently, the presence of aerodynamic damping is significant with respect to limit the forced response since structural damping ratios of integrally bladed rotors typically take extremely low values. Hence, a detailed knowledge of respective damping ratios would be desirable while developing a robust rotor design. For this, far-reaching experimental investigations are carried out to determine the damping of a comparative wheel within a wide pressure range by simulating operation conditions in a pressure tank. Reduced order models are built up for designing suitable intentional mistuning patterns by using the subset of nominal system modes (SNM) approach introduced by Yang and Griffin [1], which conveniently allows for accounting both differing mistuning patterns and the impact of aeroelastic interaction by means of aerodynamic influence coefficients (AIC). Further, finite element analyses are carried out in order to identify appropriate measures how to implement intentional mistuning patterns, which are featuring only two different blade designs. In detail, the impact of specific geometric modifications on blade natural frequencies is investigated.

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.

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