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Hal Whitehead - One of the best experts on this subject based on the ideXlab platform.
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galapagos sperm whales Physeter Macrocephalus waxing and waning over three decades
Canadian Journal of Zoology, 2017Co-Authors: Mauricio Cantor, Ana Eguiguren, Godfrey Merlen, Hal WhiteheadAbstract:While population sizes and structures naturally fluctuate over time, rapid within-generation changes are usually driven by habitat quality shifts and/or abrupt mortality. We evaluate how sperm whales ( Physeter Macrocephalus , L. 1758 (= Physeter catodon , L. 1758)) responded to the dynamic habit off the Galapagos Islands over 30 years, relating it to variation in prey availability and whaling operations in the tropical Pacific. In the 1980’s, males and females were commonly sighted foraging and socializing in the northwest of the archipelago. Sightings decreased during the 1990’s; by the 2000’s they became very rare: occasional single foraging males were sighted and females abandoned the archipelago. In the 2010’s, whales return to the southern waters, in large groups with apparently more breeding males and calves. The waxing and waning of Galapagos sperm whales are likely caused by environmental shifts together with ripple effects of whaling. Their patchy prey are influenced by variation in se...
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seasonal occurrence of sperm whales Physeter Macrocephalus around kelvin seamount in the sargasso sea in relation to oceanographic processes
Deep Sea Research Part I: Oceanographic Research Papers, 2014Co-Authors: Sarah N P Wong, Hal WhiteheadAbstract:Abstract Sperm whales (Physeter Macrocephalus) are widely distributed in all oceans, but they are clumped geographically, generally in areas associated with high primary and secondary productivity. The warm, clear waters of the Sargasso Sea are traditionally thought to be low in productivity, however recent surveys have found large numbers of sperm whales there. The New England Seamount Chain bisects the north-western portion of the Sargasso Sea, and might influence the mesoscale eddies associated with the Gulf Stream; creating areas of higher productivity within the Sargasso Sea. We investigated the seasonal occurrence of sperm whales over Kelvin Seamount (part of the New England Seamount Chain) and how it is influenced by oceanographic variables. An autonomous recording device was deployed over Kelvin Seamount from May to June 2006 and November 2006 to June 2007. A total of 6505 hourly two-minute recordings were examined for the presence of sperm whale echolocation clicks. Sperm whales were more prevalent around Kelvin in the spring (April to June: mean=51% of recordings contained clicks) compared to the winter (November to March: mean=16% of recordings contained clicks). Sperm whale prevalence at Kelvin was related to chlorophyll-a concentration four weeks previous, eddy kinetic energy and month. The mesoscale activity associated with the Gulf Stream and the Gulf Stream׳s interaction with the New England Seamount Chain likely play an important role in sperm whale occurrence in this area, by increasing productivity and perhaps concentration of cephalopod species.
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heterogeneous social associations within a sperm whale Physeter Macrocephalus unit reflect pairwise relatedness
Behavioral Ecology and Sociobiology, 2008Co-Authors: Shane Gero, Dan Engelhaupt, Hal WhiteheadAbstract:A good description of a social structure in which individuals live in stable social groups must also capture individual differences in social behaviour in order to understand the selective pressures behind formation and maintenance of those groups. Depending on the evolutionary mechanism acting and the nature of the benefits incurred by individuals, we might expect different patterns of intra-group associations. Female and immature sperm whales (Physeter Macrocephalus, Linnaeus 1758) live in stable and partially matrilineal social units. Using photo identification and sloughed skin sampling for genetic determination of sex and relatedness, we investigated patterns of association within a social unit of sperm whales from the eastern Caribbean. Focus was given to how short-term spatio-temporal associations reflect relatedness among unit members. Contrary to previous findings, we found that the patterns of association among members of this unit were heterogeneous and that individuals had preferred associations or avoidances with specific individuals. Furthermore, these preferred associations correlate with relatedness between individuals, such that individuals associated more with their close relatives when variation in sociability of the individuals is controlled. These results are inconsistent with the simple equivalence model of homogeneous associations between members of a social unit. They indicate intra-unit social complexity, a basis for which seems to be genetic relatedness.
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comparison of two computer assisted photo identification methods applied to sperm whales Physeter Macrocephalus
Aquatic Mammals, 2005Co-Authors: Bas W P M Beekmans, Hal Whitehead, Ruben Huele, Lisa Steiner, Adri G Steenbeek, Whale Watch AzoresAbstract:Two computer-assisted photo-identification methods for sperm whales (Physeter Macrocephalus), namely the Highlight method (Whitehead, 1990) and the Europhlukes method (based on Huele et al., 2000), were compared. Performance was measured in terms of speed and accuracy. A test set was constructed containing two photographs of each of 296 individuals. The test set was divided into three classes of photographic quality and three classes of pattern distinctiveness. Both programs met requirements for rapid matching; the mean extraction times were 74.2 and 90.1 s per image for the Highlight and the Europhlukes methods, respectively. The two methods performed similarly with respect to accuracy. Accuracy improved by using higher-quality photographs or photographs representing more distinctive flukes. Still, even when using only the higher-quality photographs, 12.4% of the matches were not included in the top nine of the list of potential matches by the Highlight method compared to 14.0% for the Europhlukes method. The rate of failure to find the true match in the top nine was only 3.3% when both methods were used together, however. It is, therefore, recommended that for improved matching, both methods should be used in tandem or that an integrated program, which combines the two methods, should be developed.
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the diet of galapagos sperm whales Physeter Macrocephalus as indicated by fecal sample analysis
Marine Mammal Science, 2000Co-Authors: Sean C Smith, Hal WhiteheadAbstract:Fecal samples were collected while following sperm whales (Physeter Macrocephalus) off the Galapagos Islands, Ecuador. They contained 133 upper beaks and 164 lower beaks of cephalopods. Analysis of the lower beaks suggests that the sperm whales fed primarily on three genera of cephalopods; Histioteutbis (62%), Ancistrocbeirus (16%), and Octopoteutbis (7%). The beak dimensions indicate that the cephalopods ranged in mantle length from 5 to 54 cm and in mass from 12 to 650 g. Fecal samples varied significantly between five study years and over different parts of the study area, but the number of beaks collected per sample did not correlate significantly with defecation rate (a measure of feeding success). Using beak material from fecal samples gives a biased estimate of sperm whale diet, reducing the frequencies of very small and very large cephalopods. However, all other available methods of assessing sperm whale diet also possess biases.
Nikoletta Diogou - One of the best experts on this subject based on the ideXlab platform.
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sperm whale Physeter Macrocephalus acoustic ecology at ocean station papa in the gulf of alaska part 1 detectability and seasonality
Deep Sea Research Part I: Oceanographic Research Papers, 2019Co-Authors: Nikoletta Diogou, Daniel M Palacios, Sharon L Nieukirk, Jeffrey A Nystuen, Evangelos Papathanassiou, Stelios Katsanevakis, Holger KlinckAbstract:Abstract Sperm whales Physeter Macrocephalus produce loud, stereotypical click sequences and are an ideal species to be studied with passive acoustic techniques. To increase our limited knowledge of sperm whale occurrence patterns in remote and inaccessible locations of the North Pacific, we analyzed a five-year-long (June 2007–April 2012) acoustic data set recorded at Ocean Station PAPA (OSP; 50°N, 145°W) in the Gulf of Alaska (GOA). Firstly, we assessed the sperm whale detection performance of the Passive Aquatic Listener (PAL), and secondly, we investigated temporal patterns of sperm whale presence at OSP. The PAL proved highly efficient, with above 50% probability of detecting more than two sperm whales, a condition met for over 50% of the recordings. Results indicated that sperm whale clicks were recorded year-round, with a clear seasonal pattern. The number of detections during the summer months was approximately 70% higher compared to winter. An ambient noise analysis showed that differences in detection rates were likely not driven by seasonal changes in ambient noise levels. The average propagation range of sperm whale clicks ranged between 7 and 8 km between summer and winter, with slightly decreased detection distances observed in winter. Seasonal shifts in the intensity of the Alaska Current and the latitudinal oscillations of the North Pacific Transition Zone results in changes in water mixing, transport of nutrients and the concentration of prey such as squid, which likely drives sperm whale distribution.
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Sperm whale (Physeter Macrocephalus) acoustic ecology at Ocean Station PAPA in the Gulf of Alaska – Part 1: Detectability and seasonality
Deep Sea Research Part I: Oceanographic Research Papers, 2019Co-Authors: Nikoletta Diogou, Daniel M Palacios, Sharon L Nieukirk, Jeffrey A Nystuen, Evangelos Papathanassiou, Stelios Katsanevakis, Holger KlinckAbstract:Abstract Sperm whales Physeter Macrocephalus produce loud, stereotypical click sequences and are an ideal species to be studied with passive acoustic techniques. To increase our limited knowledge of sperm whale occurrence patterns in remote and inaccessible locations of the North Pacific, we analyzed a five-year-long (June 2007–April 2012) acoustic data set recorded at Ocean Station PAPA (OSP; 50°N, 145°W) in the Gulf of Alaska (GOA). Firstly, we assessed the sperm whale detection performance of the Passive Aquatic Listener (PAL), and secondly, we investigated temporal patterns of sperm whale presence at OSP. The PAL proved highly efficient, with above 50% probability of detecting more than two sperm whales, a condition met for over 50% of the recordings. Results indicated that sperm whale clicks were recorded year-round, with a clear seasonal pattern. The number of detections during the summer months was approximately 70% higher compared to winter. An ambient noise analysis showed that differences in detection rates were likely not driven by seasonal changes in ambient noise levels. The average propagation range of sperm whale clicks ranged between 7 and 8 km between summer and winter, with slightly decreased detection distances observed in winter. Seasonal shifts in the intensity of the Alaska Current and the latitudinal oscillations of the North Pacific Transition Zone results in changes in water mixing, transport of nutrients and the concentration of prey such as squid, which likely drives sperm whale distribution.
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year round acoustic presence of sperm whales Physeter Macrocephalus and baseline ambient ocean sound levels in the greek seas
Mediterranean Marine Science, 2019Co-Authors: Nikoletta Diogou, Jeffrey A Nystuen, Evangelos Papathanassiou, Holger Klinck, Alexandros Frantzis, Stelios KatsanevakisAbstract:The sperm whale ( Physeter Macrocephalus ) is the largest odontocete occurring in the Greek Seas. However, monitoring the species’ spatiotemporal distribution patterns is especially difficult during the winter months when unfavorable weather conditions often hinder survey efforts. In the Greek Seas, visual cetacean surveys are typically not conducted between November and March. In a first attempt to collect year-round baseline information on sperm whale occurrence patterns in Greek waters, two Passive Aquatic Listeners (PALs) were deployed for 19 months, at Pylos Station (36.8 N, 21.6ο E) in the Hellenic Trench, and at Athos Station (40.0 N, 24.7ο E) in the North Aegean Trough. Results revealed the year-round presence of sperm whales at Pylos Station with a higher number of detections observed during late spring and throughout the summer. No sperm whale vocalizations were detected at Athos Station. An ambient sound level analysis revealed higher winter and lower summer levels at both sites largely driven by local weather conditions. Results showed that marine life in the Hellenic Trench area was exposed to higher low frequency (< 1 kHz) sound levels (by up to 10 dB re 1 μPa2/Hz). Ambient noise below 1 kHz is frequently dominated by anthropogenic sources including shipping. Ship strikes and noise disturbance constitute major threats for the small, genetically isolated, endangered sperm whale population. The results of this study are useful for sperm whale conservation efforts in the region and may help policymakers in prioritizing mitigation measures, including the establishment of speed limits and rerouting of ship traffic.
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The acoustic presence of sperm whales (Physeter Macrocephalus) at Ocean Station PAPA in the Gulf of Alaska 2007–2012
Journal of the Acoustical Society of America, 2013Co-Authors: Nikoletta Diogou, Holger Klinck, Jeffrey A NystuenAbstract:Sperm whale (Physeter Macrocephalus) populations were severely depleted by commercial whaling worldwide in the 18th through the 20th century. Consequently, in 1970, this species was listed in the United States as an endangered species. To date, accurate information on the abundance and distribution of sperm whales in offshore areas of the North Pacific are scant. Sperm whales regularly produce high intensity sounds for navigation, prey detection, and communication. Thus, this species can be very effectively monitored using passive acoustic techniques especially in remote and inaccessible locations such as the Gulf of Alaska (GOA). In this study, a Passive Aquatic Listener (PAL) was deployed at Ocean Station PAPA (50°N, 145°W) in the GOA between 2007 and 2012 to monitor the seasonal occurrence of sperm whales in the area. Preliminary results indicate that within the 5-year deployment period sperm whales were acoustically present year round and that the number of acoustic sperm whale detections showed a sea...
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the acoustic presence of sperm whales Physeter Macrocephalus at ocean station papa in the gulf of alaska 2007 2012
Journal of the Acoustical Society of America, 2013Co-Authors: Nikoletta Diogou, Holger Klinck, Jeffrey A NystuenAbstract:Sperm whale (Physeter Macrocephalus) populations were severely depleted by commercial whaling worldwide in the 18th through the 20th century. Consequently, in 1970, this species was listed in the United States as an endangered species. To date, accurate information on the abundance and distribution of sperm whales in offshore areas of the North Pacific are scant. Sperm whales regularly produce high intensity sounds for navigation, prey detection, and communication. Thus, this species can be very effectively monitored using passive acoustic techniques especially in remote and inaccessible locations such as the Gulf of Alaska (GOA). In this study, a Passive Aquatic Listener (PAL) was deployed at Ocean Station PAPA (50°N, 145°W) in the GOA between 2007 and 2012 to monitor the seasonal occurrence of sperm whales in the area. Preliminary results indicate that within the 5-year deployment period sperm whales were acoustically present year round and that the number of acoustic sperm whale detections showed a sea...
Giuseppe Notarbartolo Di Sciara - One of the best experts on this subject based on the ideXlab platform.
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overview of sperm whale Physeter Macrocephalus mortality events in the adriatic sea 1555 2009
Mammal Review, 2011Co-Authors: Giovanni Bearzi, Nino Pierantonio, Marco Affronte, Nicola Maio, Draško Holcer, Giuseppe Notarbartolo Di SciaraAbstract:1In the Mediterranean Sea, the sperm whale Physeter Macrocephalus is one of eight regular cetacean species. Poor knowledge of its ecology and status, together with suspected decline in numbers, make studies of historical and present occurrence especially relevant. Long-term time series of stranding events are the most reliable data to provide a scientific framework for testing hypotheses that seek to explain the mechanisms responsible for cetacean strandings. 2We present a comprehensive overview of cases of sperm whale mortality and human response to such events encompassing five centuries (1555–2009) within a portion of the Mediterranean Sea that offers a wealth of historical information – the Adriatic Sea. 3A total of 36 mortality events were validated, involving 68 animals. Two findings of skeletal materials are also reported. The geographic distribution of strandings within the basin clearly was uneven: 44% of records (n = 16) were clustered along a 280km portion of the western Adriatic coast. A relatively high number of mortality events occurred along gently sloping sandy beaches away from suitable sperm whale habitat. 4Until the first half of the 20th century, live-stranded animals were routinely killed: all but one cases with known human response elicited killing attempts. Starting from the 1980s, killing was replaced by efforts to rescue the animals. 5Mass strandings of sperm whales have occurred since historical times in the Adriatic Sea. Mortality events involving multiple individuals accounted for at least 17% of the total sample (6 of 36 mortality events). At least 29% of live strandings (6 of 21) involved more than one individual. 6This study contributes a long-term dataset based on careful validation of historical information, suitable for hypothesis testing aimed at investigating spatial and temporal correlates of sperm whale strandings – particularly live strandings – as a clue to their causes.
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Overview of sperm whale Physeter Macrocephalus mortality events in the Adriatic Sea, 1555–2009
Mammal Review, 2011Co-Authors: Giovanni Bearzi, Nino Pierantonio, Marco Affronte, Nicola Maio, Draško Holcer, Giuseppe Notarbartolo Di SciaraAbstract:1In the Mediterranean Sea, the sperm whale Physeter Macrocephalus is one of eight regular cetacean species. Poor knowledge of its ecology and status, together with suspected decline in numbers, make studies of historical and present occurrence especially relevant. Long-term time series of stranding events are the most reliable data to provide a scientific framework for testing hypotheses that seek to explain the mechanisms responsible for cetacean strandings. 2We present a comprehensive overview of cases of sperm whale mortality and human response to such events encompassing five centuries (1555–2009) within a portion of the Mediterranean Sea that offers a wealth of historical information – the Adriatic Sea. 3A total of 36 mortality events were validated, involving 68 animals. Two findings of skeletal materials are also reported. The geographic distribution of strandings within the basin clearly was uneven: 44% of records (n = 16) were clustered along a 280km portion of the western Adriatic coast. A relatively high number of mortality events occurred along gently sloping sandy beaches away from suitable sperm whale habitat. 4Until the first half of the 20th century, live-stranded animals were routinely killed: all but one cases with known human response elicited killing attempts. Starting from the 1980s, killing was replaced by efforts to rescue the animals. 5Mass strandings of sperm whales have occurred since historical times in the Adriatic Sea. Mortality events involving multiple individuals accounted for at least 17% of the total sample (6 of 36 mortality events). At least 29% of live strandings (6 of 21) involved more than one individual. 6This study contributes a long-term dataset based on careful validation of historical information, suitable for hypothesis testing aimed at investigating spatial and temporal correlates of sperm whale strandings – particularly live strandings – as a clue to their causes.
Willy Dabin - One of the best experts on this subject based on the ideXlab platform.
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Beached bachelors: An extensive study on the largest recorded sperm whale Physeter Macrocephalus mortality event in the North Sea
PLOS ONE, 2018Co-Authors: Lonneke L Ijsseldijk, Abbo Van Neer, Judith M. A. Van Den Brand, Marco W.g. Van De Bildt, Rob Deaville, Lineke Begeman, Andrew Brownlow, Richard Czeck, Willy Dabin, Mariel Ten DoeschateAbstract:Between the 8th January and the 25th February 2016, the largest sperm whale Physeter Macrocephalus mortality event ever recorded in the North Sea occurred with 30 sperm whales stranding in five countries within six weeks. All sperm whales were immature males. Groups were stratified by size, with the smaller animals stranding in the Netherlands, and the largest in England. The majority (n = 27) of the stranded animals were necropsied and/or sampled, allowing for an international and comprehensive investigation into this mortality event. The animals were in fair to good nutritional condition and, aside from the pathologies caused by stranding, did not exhibit significant evidence of disease or trauma. Infectious agents were found, including various parasite species, several bacterial and fungal pathogens and a novel alphaherpesvirus. In nine of the sperm whales a variety of marine litter was found. However, none of these findings were considered to have been the primary cause of the stranding event. Potential anthropogenic and environmental factors that may have caused the sperm whales to enter the North Sea were assessed. Once sperm whales enter the North Sea and head south, the water becomes progressively shallower (
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beached bachelors an extensive study on the largest recorded sperm whale Physeter Macrocephalus mortality event in the north sea
PLOS ONE, 2018Co-Authors: Lonneke L Ijsseldijk, Abbo Van Neer, Rob Deaville, Lineke Begeman, Judith M A Van Den Brand, Andrew Brownlow, Richard Czeck, Marco W G Van De Bildt, Willy DabinAbstract:Between the 8th January and the 25th February 2016, the largest sperm whale Physeter Macrocephalus mortality event ever recorded in the North Sea occurred with 30 sperm whales stranding in five countries within six weeks. All sperm whales were immature males. Groups were stratified by size, with the smaller animals stranding in the Netherlands, and the largest in England. The majority (n = 27) of the stranded animals were necropsied and/or sampled, allowing for an international and comprehensive investigation into this mortality event. The animals were in fair to good nutritional condition and, aside from the pathologies caused by stranding, did not exhibit significant evidence of disease or trauma. Infectious agents were found, including various parasite species, several bacterial and fungal pathogens and a novel alphaherpesvirus. In nine of the sperm whales a variety of marine litter was found. However, none of these findings were considered to have been the primary cause of the stranding event. Potential anthropogenic and environmental factors that may have caused the sperm whales to enter the North Sea were assessed. Once sperm whales enter the North Sea and head south, the water becomes progressively shallower (<40 m), making this region a global hotspot for sperm whale strandings. We conclude that the reasons for sperm whales to enter the southern North Sea are the result of complex interactions of extrinsic environmental factors. As such, these large mortality events seldom have a single ultimate cause and it is only through multidisciplinary, collaborative approaches that potentially multifactorial large-scale stranding events can be effectively investigated.
Holger Klinck - One of the best experts on this subject based on the ideXlab platform.
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sperm whale Physeter Macrocephalus acoustic ecology at ocean station papa in the gulf of alaska part 1 detectability and seasonality
Deep Sea Research Part I: Oceanographic Research Papers, 2019Co-Authors: Nikoletta Diogou, Daniel M Palacios, Sharon L Nieukirk, Jeffrey A Nystuen, Evangelos Papathanassiou, Stelios Katsanevakis, Holger KlinckAbstract:Abstract Sperm whales Physeter Macrocephalus produce loud, stereotypical click sequences and are an ideal species to be studied with passive acoustic techniques. To increase our limited knowledge of sperm whale occurrence patterns in remote and inaccessible locations of the North Pacific, we analyzed a five-year-long (June 2007–April 2012) acoustic data set recorded at Ocean Station PAPA (OSP; 50°N, 145°W) in the Gulf of Alaska (GOA). Firstly, we assessed the sperm whale detection performance of the Passive Aquatic Listener (PAL), and secondly, we investigated temporal patterns of sperm whale presence at OSP. The PAL proved highly efficient, with above 50% probability of detecting more than two sperm whales, a condition met for over 50% of the recordings. Results indicated that sperm whale clicks were recorded year-round, with a clear seasonal pattern. The number of detections during the summer months was approximately 70% higher compared to winter. An ambient noise analysis showed that differences in detection rates were likely not driven by seasonal changes in ambient noise levels. The average propagation range of sperm whale clicks ranged between 7 and 8 km between summer and winter, with slightly decreased detection distances observed in winter. Seasonal shifts in the intensity of the Alaska Current and the latitudinal oscillations of the North Pacific Transition Zone results in changes in water mixing, transport of nutrients and the concentration of prey such as squid, which likely drives sperm whale distribution.
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Sperm whale (Physeter Macrocephalus) acoustic ecology at Ocean Station PAPA in the Gulf of Alaska – Part 1: Detectability and seasonality
Deep Sea Research Part I: Oceanographic Research Papers, 2019Co-Authors: Nikoletta Diogou, Daniel M Palacios, Sharon L Nieukirk, Jeffrey A Nystuen, Evangelos Papathanassiou, Stelios Katsanevakis, Holger KlinckAbstract:Abstract Sperm whales Physeter Macrocephalus produce loud, stereotypical click sequences and are an ideal species to be studied with passive acoustic techniques. To increase our limited knowledge of sperm whale occurrence patterns in remote and inaccessible locations of the North Pacific, we analyzed a five-year-long (June 2007–April 2012) acoustic data set recorded at Ocean Station PAPA (OSP; 50°N, 145°W) in the Gulf of Alaska (GOA). Firstly, we assessed the sperm whale detection performance of the Passive Aquatic Listener (PAL), and secondly, we investigated temporal patterns of sperm whale presence at OSP. The PAL proved highly efficient, with above 50% probability of detecting more than two sperm whales, a condition met for over 50% of the recordings. Results indicated that sperm whale clicks were recorded year-round, with a clear seasonal pattern. The number of detections during the summer months was approximately 70% higher compared to winter. An ambient noise analysis showed that differences in detection rates were likely not driven by seasonal changes in ambient noise levels. The average propagation range of sperm whale clicks ranged between 7 and 8 km between summer and winter, with slightly decreased detection distances observed in winter. Seasonal shifts in the intensity of the Alaska Current and the latitudinal oscillations of the North Pacific Transition Zone results in changes in water mixing, transport of nutrients and the concentration of prey such as squid, which likely drives sperm whale distribution.
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year round acoustic presence of sperm whales Physeter Macrocephalus and baseline ambient ocean sound levels in the greek seas
Mediterranean Marine Science, 2019Co-Authors: Nikoletta Diogou, Jeffrey A Nystuen, Evangelos Papathanassiou, Holger Klinck, Alexandros Frantzis, Stelios KatsanevakisAbstract:The sperm whale ( Physeter Macrocephalus ) is the largest odontocete occurring in the Greek Seas. However, monitoring the species’ spatiotemporal distribution patterns is especially difficult during the winter months when unfavorable weather conditions often hinder survey efforts. In the Greek Seas, visual cetacean surveys are typically not conducted between November and March. In a first attempt to collect year-round baseline information on sperm whale occurrence patterns in Greek waters, two Passive Aquatic Listeners (PALs) were deployed for 19 months, at Pylos Station (36.8 N, 21.6ο E) in the Hellenic Trench, and at Athos Station (40.0 N, 24.7ο E) in the North Aegean Trough. Results revealed the year-round presence of sperm whales at Pylos Station with a higher number of detections observed during late spring and throughout the summer. No sperm whale vocalizations were detected at Athos Station. An ambient sound level analysis revealed higher winter and lower summer levels at both sites largely driven by local weather conditions. Results showed that marine life in the Hellenic Trench area was exposed to higher low frequency (< 1 kHz) sound levels (by up to 10 dB re 1 μPa2/Hz). Ambient noise below 1 kHz is frequently dominated by anthropogenic sources including shipping. Ship strikes and noise disturbance constitute major threats for the small, genetically isolated, endangered sperm whale population. The results of this study are useful for sperm whale conservation efforts in the region and may help policymakers in prioritizing mitigation measures, including the establishment of speed limits and rerouting of ship traffic.
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The acoustic presence of sperm whales (Physeter Macrocephalus) at Ocean Station PAPA in the Gulf of Alaska 2007–2012
Journal of the Acoustical Society of America, 2013Co-Authors: Nikoletta Diogou, Holger Klinck, Jeffrey A NystuenAbstract:Sperm whale (Physeter Macrocephalus) populations were severely depleted by commercial whaling worldwide in the 18th through the 20th century. Consequently, in 1970, this species was listed in the United States as an endangered species. To date, accurate information on the abundance and distribution of sperm whales in offshore areas of the North Pacific are scant. Sperm whales regularly produce high intensity sounds for navigation, prey detection, and communication. Thus, this species can be very effectively monitored using passive acoustic techniques especially in remote and inaccessible locations such as the Gulf of Alaska (GOA). In this study, a Passive Aquatic Listener (PAL) was deployed at Ocean Station PAPA (50°N, 145°W) in the GOA between 2007 and 2012 to monitor the seasonal occurrence of sperm whales in the area. Preliminary results indicate that within the 5-year deployment period sperm whales were acoustically present year round and that the number of acoustic sperm whale detections showed a sea...
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the acoustic presence of sperm whales Physeter Macrocephalus at ocean station papa in the gulf of alaska 2007 2012
Journal of the Acoustical Society of America, 2013Co-Authors: Nikoletta Diogou, Holger Klinck, Jeffrey A NystuenAbstract:Sperm whale (Physeter Macrocephalus) populations were severely depleted by commercial whaling worldwide in the 18th through the 20th century. Consequently, in 1970, this species was listed in the United States as an endangered species. To date, accurate information on the abundance and distribution of sperm whales in offshore areas of the North Pacific are scant. Sperm whales regularly produce high intensity sounds for navigation, prey detection, and communication. Thus, this species can be very effectively monitored using passive acoustic techniques especially in remote and inaccessible locations such as the Gulf of Alaska (GOA). In this study, a Passive Aquatic Listener (PAL) was deployed at Ocean Station PAPA (50°N, 145°W) in the GOA between 2007 and 2012 to monitor the seasonal occurrence of sperm whales in the area. Preliminary results indicate that within the 5-year deployment period sperm whales were acoustically present year round and that the number of acoustic sperm whale detections showed a sea...