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1.
Anim Cogn ; 25(5): 1091-1108, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36125643

RESUMO

Thinking flexibly is a skill that enables animals to adapt to changing environments, which enhances survival. Killer whales, Orcinus orca, as the ocean apex predator display a number of complex cognitive abilities, especially flexible thinking or creativity when it comes to foraging. In human care, smaller dolphins and other marine mammals have been trained to think creatively while under stimulus control. The results of these previous studies have demonstrated that bottlenose dolphins, Tursiops truncatus, can create original behaviors in response to an innovative cue. We trained and tested a total of nine killer whales from two different facilities on the innovate concept, using the same methodology. The killer whales ranged in age from 5 to 29 yrs with 4 females and 5 males. The results indicate that the killer whales demonstrated high fluency, originality, some elaboration, and flexibility in their behaviors. Individual variability was observed with younger animals demonstrating more variable behaviors as compared to the older animals. Males seemed to display less complex and lower energy behaviors as compared to females, but this impression may be driven by the age or size of the animal. These results support existing evidence that killer whales are dynamic in their thinking and behavior.


Assuntos
Golfinho Nariz-de-Garrafa , Orca , Feminino , Masculino , Humanos , Animais , Orca/psicologia
2.
PLoS One ; 17(6): e0270523, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35759490

RESUMO

The salmon-eating Southern Resident killer whale (SRKW) (Orcinus orca) population currently comprises only 73 individuals, and is listed as 'endangered' under the Species at Risk Act in Canada. Recent evidence suggests that the growth of this population may be limited by food resources, especially Chinook salmon (Oncorhynchus tshawytscha). We present spatio-temporal bioenergetics model for SRKW in the Salish Sea and the West Coast of Vancouver Island from 1979-2020 with the objective of evaluating how changes in the abundance, age-structure, and length-at-age of Chinook salmon populations has influenced the daily food consumption of the SRKW population. Our model showed that the SRKW population has been in energetic deficit for six of the last 40 years. Our results also suggested that the abundance of age-4 and age-5 Chinook salmon are significant predictors of energy intake for SRKW. We estimated that the annual consumption (April-October) of Chinook salmon by the whales between 1979 and 2020 ranged from 166,000 216,300. Over the past 40 years, the model estimated that the contribution in the predicted SRKW diet of Chinook salmon originating from the Columbia River has increased by about 34%, and decreased by about 15% for Chinook salmon stocks originating from Puget Sound. Overall, our study provides an overview of the requirements and availability of prey for SRKW over the last 40 years, while supporting the hypothesis that SRKW were limited by prey abundance in the study period.


Assuntos
Orca , Animais , Canadá , Dieta , Rios , Salmão
3.
J Acoust Soc Am ; 151(5): 3197, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35649922

RESUMO

Three killer whale ecotypes are found in the Northeastern Pacific: residents, transients, and offshores. These ecotypes can be discriminated in passive acoustic data based on distinct pulsed call repertoires. Killer whale acoustic encounters for which ecotypes were assigned based on pulsed call matching were used to characterize the ecotype-specific echolocation clicks. Recordings were made using seafloor-mounted sensors at shallow (∼120 m) and deep (∼1400 m) monitoring locations off the coast of Washington state. All ecotypes' echolocation clicks were characterized by energy peaks between 12 and 19 kHz, however, resident clicks featured sub peaks at 13.7 and 18.8 kHz, while offshore clicks had a single peak at 14.3 kHz. Transient clicks were rare and were characterized by lower peak frequencies (12.8 kHz). Modal inter-click intervals (ICIs) were consistent but indistinguishable for resident and offshore killer whale encounters at the shallow site (0.21-0.22 s). Offshore ICIs were longer and more variable at the deep site, and no modal ICI was apparent for the transient ecotype. Resident and offshore killer whale ecotype may be identified and distinguished in large passive acoustic datasets based on properties of their echolocation clicks, however, transient echolocation may be unsuitable in isolation as a cue for monitoring applications.


Assuntos
Ecolocação , Orca , Animais , Ecótipo , Espectrografia do Som , Vocalização Animal
4.
Environ Toxicol Chem ; 41(9): 2139-2151, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35698926

RESUMO

The northeastern Pacific northern and southern resident killer whale (Orcinus orca) populations are listed as threatened and endangered in Canada, respectively, with persistent, bioaccumulative contaminants, such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), posing threats to their recovery. Concentrations of PCBs and PBDEs in subtidal surface sediments collected from 97 sites along the British Columbia (BC) coast were used to identify their distribution and profiles, and to assess killer whale habitat quality. Victoria Harbour (VH3(site ID: 1) ) sediments exhibited the highest PCB and PBDE concentrations. For PCBs, PCB-138 was found at the highest concentration, followed by PCB-153, PCB-110, PCB-149, PCB-101, and PCB-118. For PBDEs, individual congeners were ranked as follows: BDE-209 > BDE-207 > BDE-206 > BDE-208 > BDE-47 > BDE-99. Principal component analyses (PCA) illustrated the variations in contaminant profiles, with PC1 for PCBs and PBDEs correlated with the octanol-water partition coefficient (log KOW , p < 0.003). Based on the PCA, sediment particle size, total organic carbon (TOC), and water depth at collection were other factors associated with the distribution of PBDEs, while PCB profiles were associated with TOC. Total PCB and PBDE concentrations at 100% and 34% of the sites, respectively, exceeded the recently adopted British Columbia's Ministry of Environment and Climate Change Strategy Working Sediment Quality Guidelines (PCBs 3.7 pg/g dry wt and PBDEs 1000 pg/g dry wt), considered protective of killer whales. Our findings suggest that the legacy of banned PCBs and PBDEs has the potential to constrain the recovery of killer whales as a result of their mobilization from sediments and consequent uptake by marine food webs. Environ Toxicol Chem 2022;41:2139-2151. © 2022 SETAC.


Assuntos
Bifenil Polibromatos , Bifenilos Policlorados , Poluentes Químicos da Água , Orca , Animais , Colúmbia Britânica , Ecossistema , Monitoramento Ambiental , Sedimentos Geológicos/análise , Éteres Difenil Halogenados/análise , Bifenil Polibromatos/análise , Bifenilos Policlorados/análise , Água/metabolismo , Poluentes Químicos da Água/análise , Orca/metabolismo
5.
Sci Rep ; 12(1): 7938, 2022 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-35562583

RESUMO

Accurate diet estimates are necessary to assess trophic interactions and food web dynamics in ecosystems, particularly for apex predators like cetaceans, which can regulate entire food webs. Quantitative fatty acid analysis (QFASA) has been used to estimate the diets of marine predators in the last decade but has yet to be implemented on free-ranging cetaceans, from which typically only biopsy samples containing outer blubber are available, due to a lack of empirically determined calibration coefficients (CCs) that account for fatty acid (FA) metabolism. Here, we develop and validate QFASA for killer whales using full blubber from managed-care and free-ranging individuals. First, we compute full, inner, and outer blubber CCs from the FA signatures across the blubber layers of managed-care killer whales and their long-term diet items. We then run cross-validating simulations on the managed-care individuals to evaluate the accuracy of diet estimates by comparing full-depth and depth-specific estimates to true diets. Finally, we apply these approaches to subsistence-harvested killer whales from Greenland to test the utility of the method for free-ranging killer whales, particularly for the outer blubber. Accurate diet estimates for the managed-care killer whales were only achieved using killer whale-specific and blubber-layer-specific CCs. Modeled diets for the Greenlandic killer whales largely consisted of seals (75.9 ± 4.7%) and/or fish (20.4 ± 2.4%), mainly mackerel, which was consistent with stomach content data and limited literature on this population. Given the remote habitats and below surface feeding of most cetaceans, this newly developed cetacean-specific QFASA method, which can be applied to outer-layer biopsies, offers promise to provide a significant new understanding of diet dynamics of free-ranging odontocetes and perhaps other cetacean species throughout the world's oceans.


Assuntos
Orca , Tecido Adiposo/metabolismo , Animais , Dieta , Ecossistema , Ácidos Graxos/metabolismo , Orca/metabolismo
6.
J Exp Biol ; 225(10)2022 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-35502794

RESUMO

Physio-logging methods, which use animal-borne devices to record physiological variables, are entering a new era driven by advances in sensor development. However, existing datasets collected with traditional bio-loggers, such as accelerometers, still contain untapped eco-physiological information. Here, we present a computational method for extracting heart rate from high-resolution accelerometer data using a ballistocardiogram. We validated our method with simultaneous accelerometer-electrocardiogram tag deployments in a controlled setting on a killer whale (Orcinus orca) and demonstrate the predictions correspond with previously observed cardiovascular patterns in a blue whale (Balaenoptera musculus), including the magnitude of apneic bradycardia and increase in heart rate prior to and during ascent. Our ballistocardiogram method may be applied to mine heart rates from previously collected accelerometery data and expand our understanding of comparative cardiovascular physiology.


Assuntos
Balaenoptera , Caniformia , Orca , Acelerometria , Animais , Balaenoptera/fisiologia , Frequência Cardíaca
7.
J Acoust Soc Am ; 151(4): 2521, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35461500

RESUMO

The Arctic Ice Monitoring (AIM) observatory has been maintained on the Chukchi Plateau at 75.1° N 168.0° W nearly continuously since 2003. The AIM site consists of a submerged mooring that, since October 2008, has been instrumented with a passive acoustic recorder to sample ambient sound, with a focus on marine mammal detections in the High Arctic. Year-long data sets for 2009, 2012, and 2014-2020 were analyzed for the presence of signals from Arctic species including bowhead and beluga whales, bearded seals, and walrus. Calls from subarctic ribbon seals were commonly detected in autumn months, suggesting they have expanded their distribution much further northward. Killer whale calls were detected in recent years providing evidence that they have moved further north into the Pacific Arctic. No other subarctic cetaceans were heard. Year-round passive acoustic sampling of sounds produced by marine mammals over a decadal timescale has enhanced our understanding of how climate-driven changes in biodiversity are affecting even the very High Arctic.


Assuntos
Beluga , Baleia Franca , Focas Verdadeiras , Orca , Animais , Regiões Árticas
8.
Mar Pollut Bull ; 178: 113596, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35385819

RESUMO

This introduction to a special issue on approaches to managing underwater noise in Canada provides a brief overview of recent efforts to better understand and reduce anthropogenic underwater noise. Recent programs have aimed to increase understanding of anthropogenic noise in the habitats of highly endangered whales and have supported management actions such as vessel slow downs. Technical workshops have advanced the development of quiet ship design and associated technologies. Collaborative research examined noise levels in the St. Lawrence Estuary and the Arctic Ocean. Efforts to better manage noise have gone beyond shipping: enhanced mitigation measures have been put in place for naval exercises near habitats used by southern resident killer whales, while other work has focused on the identification of appropriate metrics for measuring noise. To coordinate and advance these and other efforts, the Government of Canada is developing a national Ocean Noise Strategy.


Assuntos
Ruído , Orca , Animais , Canadá , Navios , Baleias
9.
J Theor Biol ; 543: 111123, 2022 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-35405202

RESUMO

Two fundamental questions related to menopause that have not been answered are: (1) why does menopause even occur? And, (2) of the more than six thousand known mammals extant today, why human and four whale females are the only ones that are menopausal? Answers to both of these basic questions are provided here on the basis of evolutionary biology. From observational data, it was found that there are three elemental criteria that all menopausal species must fulfill: first, it has to be long-lived (average female lifespan of the species has to be forty years or more); second, it must live in groups; and third, the average female-male lifespan differential has to be at least thirty percent or more. In addition, a corollary criterion for menopause was also established: for a species' females to be menopausal, the Encephalization Quotient (EQ) for the species has to be 2.5 or more. Though humans do not fulfill the third menopausal criterion currently, it has been shown that when the menopausal mechanism first became common in human ancestors, in all likelihood, that principle was conformed to. Of the multitude of mammals around, only a few species satisfy all three menopausal criteria, and hence are the only ones whose females undergo the menopausal process. Many hitherto unanswered questions with respect to menopause, such as, while long and short-finned pilot whales are close to each other both genetically and physiologically, why short-finned females are menopausal while long-finned females are not, why orca females are menopausal while elephant females are not, in spite of both being long-lived, etc., can be answered on the basis of those three criteria. Why there was no selection pressure for males to undergo advanced-age reproductive cessation in those few menopausal species and why the majority of divorces occur in mid-life (40-to-60s) are also explained from a menopausal perspective.


Assuntos
Menopausa , Orca , Animais , Evolução Biológica , Biologia , Feminino , Humanos , Masculino , Mamíferos , Menopausa/genética , Orca/fisiologia
10.
J Acoust Soc Am ; 151(3): 1651, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35364953

RESUMO

Long-term passive acoustic monitoring of cetaceans is frequently limited by the data storage capacity and battery life of the recording system. Duty cycles are a mechanism for subsampling during the recording process that facilitates long-term passive acoustic studies. While duty cycles are often used, there has been little investigation on the impact that this approach has on the ability to answer questions about a species' behavior and occurrence. In this study, the effects of duty cycling on the acoustic detection of southern resident killer whales (SRKW) (Orcinus orca) were investigated. Continuous acoustic data were subsampled to create 288 subsampled datasets with cycle lengths from 5 to 180 min and listening proportions from 1% to 67%. Duty cycles had little effect on the detection of the daily presence of SRKW, especially when using cycle lengths of less than an hour. However, cycle lengths of 15-30 min and listening proportions of at least 33% were required to accurately calculate durations of acoustic bouts and identify those bouts to ecotype. These results show that the optimal duty cycle depends on the scale of the research question and provide a framework for quantitative analysis of duty cycles for other marine species.


Assuntos
Orca , Acústica , Animais , Espectrografia do Som , Vocalização Animal
11.
Curr Biol ; 32(8): R375-R377, 2022 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-35472428

RESUMO

A newly discovered fossil dolphin shows that modern killer and false-killer whales evolved from fish-eating ancestors. While today both species occasionally feed on large warm-blooded prey, including seals and other whales, this diet specialization has evolved only recently.


Assuntos
Focas Verdadeiras , Orca , Animais , Apetite , Dieta , Baleias
12.
J Acoust Soc Am ; 151(2): 1380, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35232073

RESUMO

Climate-driven changes are affecting sea ice conditions off Tasiilaq, Southeast Greenland, with implications for marine mammal distributions. Knowledge about marine mammal presence, biodiversity, and community composition is key to effective conservation and management but is lacking, especially during winter months. Seasonal patterns of acoustic marine mammal presence were investigated relative to sea ice concentration at two recording sites between 2014 and 2018, with one (65.6°N, 37.4°W) or three years (65.5°N, 38.0°W) of passive acoustic recordings. Seven marine mammal species were recorded. Bearded seals were acoustically dominant during winter and spring, whereas sperm, humpback, and fin whales dominated during the sea ice-free summer and autumn. Narwhals, bowhead, and killer whales were recorded only rarely. Song-fragments of humpback whales and acoustic presence of fin whales in winter suggest mating-associated behavior taking place in the area. Ambient noise levels in 1/3-octave level bands (20, 63, 125, 500, 1000, and 4000 Hz), ranged between 75.6 to 105 dB re 1 µPa. This study provides multi-year insights into the coastal marine mammal community composition off Southeast Greenland and suggests that the Tasiilaq area provides suitable habitat for various marine mammal species year-round.


Assuntos
Baleia Franca , Baleia Comum , Orca , Acústica , Animais , Groenlândia , Mamíferos
13.
Proc Natl Acad Sci U S A ; 119(13): e2114932119, 2022 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-35312354

RESUMO

SignificanceAcoustic signals travel efficiently in the marine environment, allowing soniferous predators and prey to eavesdrop on each other. Our results with four cetacean species indicate that they use acoustic information to assess predation risk and have evolved mechanisms to reduce predation risk by ceasing foraging. Species that more readily gave up foraging in response to predatory sounds of killer whales also decreased foraging more during 1- to 4-kHz sonar exposures, indicating that species exhibiting costly antipredator responses also have stronger behavioral reactions to anthropogenic noise. This advance in our understanding of the drivers of disturbance helps us to predict what species and habitats are likely to be most severely impacted by underwater noise pollution in oceans undergoing increasing anthropogenic activities.


Assuntos
Ruído , Orca , Animais , Medo , Comportamento Predatório , Som
14.
Curr Biol ; 32(8): 1843-1851.e2, 2022 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-35259339

RESUMO

The killer whale (Orcinus orca) and false killer whale (Pseudorca crassidens) are the only extant cetaceans that hunt other marine mammals, with pods of the former routinely preying on baleen whales >10 m in length and the latter being known to take other delphinids.1-3 Fossil evidence for the origins of this feeding behavior is wanting, although molecular phylogenies indicate that it evolved independently in the two lineages.4 We describe a new extinct representative of the killer whale ecomorph, Rododelphis stamatiadisi, based on a partial skeleton from the Pleistocene of Rhodes (Greece). Five otoliths of the bathypelagic blue whiting Micromesistius poutassou are associated with the holotype, providing unexpected evidence of its last meal. The evolutionary relationships of R. stamatiadisi and the convergent evolution of killer whale-like features were explored through a broad-ranging phylogenetic analysis that recovered R. stamatiadisi as the closest relative of P. crassidens and O. orca as the only living representative of a once diverse clade. Within the clade of Orca and kin, key features implicated in extant killer whale feeding, such as body size, tooth size, and tooth count, evolved in a stepwise manner. The tooth wear in Rododelphis and an extinct species of Orcinus (O. citoniensis) are consistent with a fish-based diet, supporting an exaptative Pleistocene origin for marine mammal hunting in both lineages. If correct, predation by the ancestors of Pseudorca and Orca did not play a significant role in the evolution of baleen whale gigantism. VIDEO ABSTRACT.


Assuntos
Orca , Animais , Comportamento Alimentar , Filogenia , Comportamento Predatório , Baleias
15.
Biol Lett ; 18(2): 20210328, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35104426

RESUMO

Fisheries can generate feeding opportunities for large marine predators in the form of discards or accessible catch. How the use of this anthropogenic food may spread as a new behaviour, across individuals within populations over time, is poorly understood. This study used a 16-year (2003-2018) monitoring of two killer whale Orcinus orca subantarctic populations (regular and Type-D at Crozet), and Bayesian multistate capture-mark-recapture models, to assess temporal changes in the number of individuals feeding on fish caught on hooks ('depredation' behaviour) of a fishery started in 1996. For both populations, the number of depredating individuals increased during the study period (34 to 94 for regular; 17 to 43 for Type-D). Increasing abundance is unlikely to account for this and, rather, the results suggest depredation was acquired by increasing numbers of existing individuals. For regular killer whales, a plateau reached from 2014 suggests that it took 18 years for the behaviour to spread across the whole population. A more recent plateau was apparent for Type-Ds but additional years are needed to confirm this. These findings show how changes in prey availability caused by human activities lead to rapid, yet progressive, innovations in killer whales, likely altering the ecological role of this top-predator.


Assuntos
Orca , Animais , Teorema de Bayes , Pesqueiros
16.
Mar Pollut Bull ; 174: 113301, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35090284

RESUMO

Motorized vessels are a major source of anthropogenic noise and can have adverse effects on species relying on sound for communication and feeding. Monitoring noise levels received by endangered southern resident killer whales (SRKWs) requires knowing the number, distance, and speed of surrounding vessels, including small boats that do not have Automatic Identification Systems (AIS). A method for estimating their speed is required to predict received noise levels and compliance with vessel regulations. We compared theodolite and photogrammetry methods to estimate the number, distance, and speed of vessels in SRKW Salish Sea summertime critical habitat. By treating AIS as "truth", we found photogrammetry-derived ranges and speeds were more variable than theodolite estimates. Error in photogrammetry-derived speeds increased with range. Overall, we found time saved in the field using photogrammetry was more than offset by long analysis time. Theodolite data were relatively easy to collect, and produced accurate and precise results.


Assuntos
Orca , Animais , Ecossistema , Ruído , Navios
17.
Mar Pollut Bull ; 174: 113124, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34915419

RESUMO

The habitat of the endangered southern resident killer whale (SRKW) overlaps major international shipping lanes near the Port of Vancouver, British Columbia. Shipping is a dominant source of underwater noise, which can hinder SRKW key life functions. To reduce environmental pressure on the SRKWs, Vancouver Fraser Port Authority offers incentives for quieter ships. However, the absence of a widely accepted underwater radiated noise (URN) measurement procedure hinders the determination of relative quietness. We review URN measurement procedures, summarizing results to date from two Canadian-led projects aimed at improving harmonization of shallow-water URN measurement procedures: One supports the International Organization for Standardization (ISO) in the development of a URN measurement standard; the other supports the alignment of URN measurement procedures developed by ship classification societies. Weaknesses in conventional shallow-water URN metrics are identified, and two alternative metrics proposed. Optimal shallow-water measurement geometry is identified.


Assuntos
Ruído , Orca , Animais , Colúmbia Britânica , Ecossistema , Navios
18.
Sci Rep ; 11(1): 20284, 2021 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-34645878

RESUMO

Killer whales (Orcinus orca) are top predators throughout the world's oceans. In the North Pacific, the species is divided into three ecotypes-resident (fish-eating), transient (mammal-eating), and offshore (largely shark-eating)-that are genetically and acoustically distinct and have unique roles in the marine ecosystem. In this study, we examined the year-round distribution of killer whales in the northern Gulf of Alaska from 2016 to 2020 using passive acoustic monitoring. We further described the daily acoustic residency patterns of three killer whale populations (southern Alaska residents, Gulf of Alaska transients, and AT1 transients) for one year of these data. Highest year-round acoustic presence occurred in Montague Strait, with strong seasonal patterns in Hinchinbrook Entrance and Resurrection Bay. Daily acoustic residency times for the southern Alaska residents paralleled seasonal distribution patterns. The majority of Gulf of Alaska transient detections occurred in Hinchinbrook Entrance in spring. The depleted AT1 transient killer whale population was most often identified in Montague Strait. Passive acoustic monitoring revealed that both resident and transient killer whales used these areas much more extensively than previously known and provided novel insights into high use locations and times for each population. These results may be driven by seasonal foraging opportunities and social factors and have management implications for this species.


Assuntos
Acústica , Ecolocação/fisiologia , Monitoramento Ambiental/métodos , Transdutores , Vocalização Animal/fisiologia , Orca/fisiologia , Alaska , Animais , Ecótipo , Geografia , Oceanos e Mares , Dinâmica Populacional , Análise de Regressão , Estações do Ano , Especificidade da Espécie
19.
J Anim Ecol ; 90(11): 2692-2703, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34553382

RESUMO

Environmental forces can create spatially synchronous dynamics among nearby populations. However, increased climate variability, driven by anthropogenic climate change, will likely enhance synchrony among spatially disparate populations. Population synchrony may lead to greater fluctuations in abundance, but the consequences of population synchrony across multiple scales of biological organization, including impacts to putative competitors, dependent predators or human communities, are rarely considered in this context. Chinook salmon Oncorhynchus tshawytscha stocks distribute across the Northeast Pacific, creating spatially variable portfolios that support large ocean fisheries and marine mammal predators, such as killer whales Orcinus orca. We rely on a multi-population model that simulates Chinook salmon ocean distribution and abundance to understand spatial portfolios, or variability in abundance within and among ocean distribution regions, of Chinook salmon stocks across 17 ocean regions from Southeast Alaska to California. We found the expected positive correlation between the number of stocks in an ocean region and spatial portfolio strength; however, increased demographic synchrony eroded Chinook salmon spatial portfolios in the ocean. Moreover, we observed decreased resource availability within ocean fishery management jurisdictions but not within killer whale summer habitat. We found a strong portfolio effect across both Southern Resident and Northern Resident killer whale habitats that was relatively unaffected by increased demographic synchrony, likely a result of the large spatial area included in these habitats. However, within the areas of smaller fishing management jurisdictions we found a weakening of Chinook salmon portfolios and increased but inconsistent likelihood of low abundance years as demographic synchrony increased. We suggest that management and conservation actions that reduce spatial synchrony can enhance short-term ecosystem resilience by promoting the stabilizing effect multiple stocks have on aggregate Chinook salmon populations and overall resource availability.


Assuntos
Ecossistema , Orca , Animais , Pesqueiros , Salmão
20.
Mar Pollut Bull ; 173(Pt A): 112976, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34563959

RESUMO

Disturbance from underwater noise is one of the primary threats to the critically endangered southern resident killer whales (SRKWs). Previous studies have demonstrated that SRKWs spend less time feeding when vessels are present. In 2018, we measured the effects of a voluntary vessel slowdown action in SRKW critical habitat to assess whether ship speed (and related source level) affects foraging behaviour. Observations of SRKWs and ships were collected from land-based sites on San Juan Island, WA, USA, overlooking the Haro Strait slow-down area. Exploratory analyses found little support for a linear relationship between ship speed and SRKW behaviour, but strong support between received noise level from ships and the probability of SRKWs engaging in foraging activity. Reducing ship speed, and therefore ship noise amplitude will help decrease the probability of ship noise disrupting SRKW foraging activity and may help to increase the proportion of accessible salmon.


Assuntos
Orca , Animais , Ecossistema , Ruído , Salmão , Navios
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