Generally, a species is defined as an independent unit that is reproductively isolated from others. However, deviations from this definition are not uncommon. For example, cross-fertilization in pinnipeds has been reported among at least 10 species. Herein, we describe an unexpected hybridization that occurred between female gray seals (Halichoerus grypus) and male spotted seals (Phoca largha) in the presence of adult male gray seals in a mixed-species seal population under human care. To our knowledge, these are the first cases of gray and spotted seal hybrids ever reported. The three hybridized offspring had the appearance of a gray seal body and a spotted seal head. Microsatellite DNA markers were employed as genetic evidence to further support the hybridization events. Our study suggests a natural preference for interspecies hybridization between female gray seals and male spotted seals in human care. Following that, potential causes of cross-species hybridization, including female preference, male competition, and some other factors, are discussed.
{"title":"Hybrids Between Gray Seals (Halichoerus grypus) and Spotted Seals (Phoca largha): A Case of Xeno-Breeding Preference in Pinnipeds","authors":"Dongjiao Liu, Peijun Zhang, Yamian Wang, Zhichuang Lu, Wanxin Deng, Songhai Li","doi":"10.1578/am.49.6.2023.550","DOIUrl":"https://doi.org/10.1578/am.49.6.2023.550","url":null,"abstract":"Generally, a species is defined as an independent unit that is reproductively isolated from others. However, deviations from this definition are not uncommon. For example, cross-fertilization in pinnipeds has been reported among at least 10 species. Herein, we describe an unexpected hybridization that occurred between female gray seals (Halichoerus grypus) and male spotted seals (Phoca largha) in the presence of adult male gray seals in a mixed-species seal population under human care. To our knowledge, these are the first cases of gray and spotted seal hybrids ever reported. The three hybridized offspring had the appearance of a gray seal body and a spotted seal head. Microsatellite DNA markers were employed as genetic evidence to further support the hybridization events. Our study suggests a natural preference for interspecies hybridization between female gray seals and male spotted seals in human care. Following that, potential causes of cross-species hybridization, including female preference, male competition, and some other factors, are discussed.","PeriodicalId":8219,"journal":{"name":"Aquatic Mammals","volume":"4 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-15DOI: 10.1578/am.49.6.2023.495
Rachel Wachtendonk, Mari A. Smultea, Kolby Pedrie
Due to its remoteness, little is known about the occurrence and abundance of cetaceans and sea turtles in the pelagic mid-Atlantic Ocean. Data on cetacean and sea turtle occurrence and distribution were collected by dedicated biological observers to address U.S. monitoring and mitigation requirements associated with a vessel-based academic geophysical survey in international waters in the northwestern and mid-Atlantic Ocean from 14 June through 16 July 2018. A total of 6,949 km (503 h) of visual observations occurred while surveying north from Bermuda and ending in Woods Hole, Massachusetts. A total of 928 cetaceans representing at least 14 species and 15 sea turtles representing three species were observed. The most frequently observed cetacean species was the Atlantic white-sided dolphin (Lagenorhynchus acutus) (340 individuals; 37%) followed by the short-beaked common dolphin (Delphinus delphis) (286 individuals; 31%) and pilot whales (Globicephala spp.) (95 individuals; 10%). These sighting data also included an extralimital sighting of a sperm whale (Physeter macrocephalus) calf at 43.44° N latitude and 36.85° W longitude, and extralimital sightings of Atlantic white-sided dolphins below 38° N latitude. Loggerhead sea turtles (Caretta caretta) were seen most frequently (6 individuals). This study addresses a data gap in documented occurrence and lack of occurrence of cetaceans and sea turtles over a large pelagic area in the northwestern Atlantic Ocean during summer.
{"title":"Cetacean and Sea Turtle Observations in the Remote Mid-Atlantic (NW) Ocean","authors":"Rachel Wachtendonk, Mari A. Smultea, Kolby Pedrie","doi":"10.1578/am.49.6.2023.495","DOIUrl":"https://doi.org/10.1578/am.49.6.2023.495","url":null,"abstract":"Due to its remoteness, little is known about the occurrence and abundance of cetaceans and sea turtles in the pelagic mid-Atlantic Ocean. Data on cetacean and sea turtle occurrence and distribution were collected by dedicated biological observers to address U.S. monitoring and mitigation requirements associated with a vessel-based academic geophysical survey in international waters in the northwestern and mid-Atlantic Ocean from 14 June through 16 July 2018. A total of 6,949 km (503 h) of visual observations occurred while surveying north from Bermuda and ending in Woods Hole, Massachusetts. A total of 928 cetaceans representing at least 14 species and 15 sea turtles representing three species were observed. The most frequently observed cetacean species was the Atlantic white-sided dolphin (Lagenorhynchus acutus) (340 individuals; 37%) followed by the short-beaked common dolphin (Delphinus delphis) (286 individuals; 31%) and pilot whales (Globicephala spp.) (95 individuals; 10%). These sighting data also included an extralimital sighting of a sperm whale (Physeter macrocephalus) calf at 43.44° N latitude and 36.85° W longitude, and extralimital sightings of Atlantic white-sided dolphins below 38° N latitude. Loggerhead sea turtles (Caretta caretta) were seen most frequently (6 individuals). This study addresses a data gap in documented occurrence and lack of occurrence of cetaceans and sea turtles over a large pelagic area in the northwestern Atlantic Ocean during summer.","PeriodicalId":8219,"journal":{"name":"Aquatic Mammals","volume":"3 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-15DOI: 10.1578/am.49.6.2023.569
Rose Borkowski, Allison C. Perna, Nadia J. Gordon, Alvin C. Camus, John M. Gliatto, Connie Merigo, Lauren A. Polimeno
Trauma from stingray spines (caudal barbs) has been intermittently documented as a cause of mild to fatal illness in odontocetes, particularly bottlenose dolphins (Tursiops truncatus), as well as in pinnipeds, sirenians, the loggerhead sea turtle, great white shark, and cobia. Although stingray spines have been noted to cause serious injury to various organ systems, their potential involvement in cetacean reproductive tract pathology has not been previously described. In North America, published descriptions of wild cetacean strandings associated with stingray spines have all involved bottlenose dolphins in the southeastern United States, plus a bottlenose dolphin and a common dolphin (Delphinus delphis) in Mexico. In 2018, uterine rupture was observed in a gravid bottlenose dolphin found deceased in Florida with stingray spine penetration into the abdominal cavity. Gross necropsy and histopathology findings were compatible with the stingray spine being involved with the rupture. To provide fuller insight into the case, a scientific literature review was conducted, and results of an unpublished 1998 necropsy involving a coastal female bottlenose dolphin that stranded in the northeastern state of Massachusetts with stingray spine presence was reviewed. Additionally, a query of the nationwide U.S. marine mammal stranding database was conducted for stingray spine-associated cetacean strandings from 1995 to 2019. Of 61 cetacean strandings revealed in the query to involve stingray spine presence, 59 were bottlenose dolphins from the southeastern U.S. states, plus Puerto Rico and Virginia; a bottlenose dolphin in southern California and a short-finned pilot whale (Globicephala macrorhynchus) were also noted. Query results did not support a bottlenose dolphin sex predilection for stingray spine-associated strandings; most such strandings involved adults. Behavioral, environmental, anthropogenic, and climatic events may influence marine mammal–stingray interactions. Continued vigilance for stingray spine-associated pathologic changes is warranted during marine mammal stranding investigations at diverse geographic sites.
{"title":"Notable Stingray Spine-Associated Strandings Involving Two Female Bottlenose Dolphins in Florida and Massachusetts, USA, in the Context of Literature and Database Reviews","authors":"Rose Borkowski, Allison C. Perna, Nadia J. Gordon, Alvin C. Camus, John M. Gliatto, Connie Merigo, Lauren A. Polimeno","doi":"10.1578/am.49.6.2023.569","DOIUrl":"https://doi.org/10.1578/am.49.6.2023.569","url":null,"abstract":"Trauma from stingray spines (caudal barbs) has been intermittently documented as a cause of mild to fatal illness in odontocetes, particularly bottlenose dolphins (Tursiops truncatus), as well as in pinnipeds, sirenians, the loggerhead sea turtle, great white shark, and cobia. Although stingray spines have been noted to cause serious injury to various organ systems, their potential involvement in cetacean reproductive tract pathology has not been previously described. In North America, published descriptions of wild cetacean strandings associated with stingray spines have all involved bottlenose dolphins in the southeastern United States, plus a bottlenose dolphin and a common dolphin (Delphinus delphis) in Mexico. In 2018, uterine rupture was observed in a gravid bottlenose dolphin found deceased in Florida with stingray spine penetration into the abdominal cavity. Gross necropsy and histopathology findings were compatible with the stingray spine being involved with the rupture. To provide fuller insight into the case, a scientific literature review was conducted, and results of an unpublished 1998 necropsy involving a coastal female bottlenose dolphin that stranded in the northeastern state of Massachusetts with stingray spine presence was reviewed. Additionally, a query of the nationwide U.S. marine mammal stranding database was conducted for stingray spine-associated cetacean strandings from 1995 to 2019. Of 61 cetacean strandings revealed in the query to involve stingray spine presence, 59 were bottlenose dolphins from the southeastern U.S. states, plus Puerto Rico and Virginia; a bottlenose dolphin in southern California and a short-finned pilot whale (Globicephala macrorhynchus) were also noted. Query results did not support a bottlenose dolphin sex predilection for stingray spine-associated strandings; most such strandings involved adults. Behavioral, environmental, anthropogenic, and climatic events may influence marine mammal–stingray interactions. Continued vigilance for stingray spine-associated pathologic changes is warranted during marine mammal stranding investigations at diverse geographic sites.","PeriodicalId":8219,"journal":{"name":"Aquatic Mammals","volume":"4 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-15DOI: 10.1578/am.49.6.2023.519
Caroline Tribble, Agnieszka Monczak, Lindsey Transue, Alyssa Marian, Patricia Fair, Brian Balmer, Joseph Ballenger, Hannah Baker, Meghan Weinpress-Galipeau, Alayna Robertson, Allan Strand, Eric W. Montie
The Charleston Harbor in South Carolina (SC)is a major port that experiences high levels of vessel traffic. Historical analyses of coastal bottlenose dolphin (Tursiops truncatus, now Tursiops erebennus) sightings identified multiple core use areas in the harbor that overlap with these anthropogenic activities. Informed by these long-term spatial data, passive acoustic monitoring, visual surveys, and prey sampling were conducted from December 2017 to June 2019 to assess the relationships and multivariate interactions that may influence dolphin vocalization patterns. Vocalizations varied spatially and temporally, peaking in fall and winter months coinciding with decreases in water temperature and daylight hours, following patterns previously reported in other SC estuaries. Dolphin prey and total fish abundance decreased with water temperature, which may indicate that dolphins echolocate and whistle more frequently in the winter months when prey are scarce and sound-producing species are less soniferous. Dolphin sightings and vocalizations were highly correlated. Dolphin occurrence was highest in the areas surrounding the confluence of the Cooper and Wando Rivers, along the shipping channel, where vessel and sound-producing fish detections were greatest. When vessel noise occurred, dolphins increased their vocalizations, which suggests that this population may be modifying its acoustic repertoire in response to increased noise levels. Multivariate interactions indicate strong spatial and seasonal patterns in vocalization rates that may be associated with dolphin and prey abundance as well as noise-induced redundancy.
{"title":"Enhancing Interpretation of Cetacean Acoustic Monitoring: Investigating Factors that Influence Vocalization Patterns of Atlantic Bottlenose Dolphins in an Urbanized Estuary, Charleston Harbor, South Carolina, USA","authors":"Caroline Tribble, Agnieszka Monczak, Lindsey Transue, Alyssa Marian, Patricia Fair, Brian Balmer, Joseph Ballenger, Hannah Baker, Meghan Weinpress-Galipeau, Alayna Robertson, Allan Strand, Eric W. Montie","doi":"10.1578/am.49.6.2023.519","DOIUrl":"https://doi.org/10.1578/am.49.6.2023.519","url":null,"abstract":"The Charleston Harbor in South Carolina (SC)is a major port that experiences high levels of vessel traffic. Historical analyses of coastal bottlenose dolphin (Tursiops truncatus, now Tursiops erebennus) sightings identified multiple core use areas in the harbor that overlap with these anthropogenic activities. Informed by these long-term spatial data, passive acoustic monitoring, visual surveys, and prey sampling were conducted from December 2017 to June 2019 to assess the relationships and multivariate interactions that may influence dolphin vocalization patterns. Vocalizations varied spatially and temporally, peaking in fall and winter months coinciding with decreases in water temperature and daylight hours, following patterns previously reported in other SC estuaries. Dolphin prey and total fish abundance decreased with water temperature, which may indicate that dolphins echolocate and whistle more frequently in the winter months when prey are scarce and sound-producing species are less soniferous. Dolphin sightings and vocalizations were highly correlated. Dolphin occurrence was highest in the areas surrounding the confluence of the Cooper and Wando Rivers, along the shipping channel, where vessel and sound-producing fish detections were greatest. When vessel noise occurred, dolphins increased their vocalizations, which suggests that this population may be modifying its acoustic repertoire in response to increased noise levels. Multivariate interactions indicate strong spatial and seasonal patterns in vocalization rates that may be associated with dolphin and prey abundance as well as noise-induced redundancy.","PeriodicalId":8219,"journal":{"name":"Aquatic Mammals","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The southern river otter (Lontra provocax) and the marine otter (Lontra felina) are endangered species that inhabit Chile. In southern Chile, both species cohabit with the American mink (Neogale vison), an invasive exotic species. The Chilean aquaculture industry has grown exponentially since the late 1980s, with salmon farming taking place from central Chile to the Patagonian fjords and channels. This study assessed co-occurrence between otters, mink, and aquaculture in Patagonia by (1) distributing a survey among workers, fisheries personnel, and aquaculture inspectors concerning observations of otters and mink inside or around aquaculture facilities and outcomes; and (2) a geographical assessment of distribution overlap between known otter territory and salmon farming-registered facilities. We recorded the first anecdotal evidence of interaction, described as co-occurrence, among native otters, American mink, and salmon aquaculture in Patagonia, which varied among seasons and seems to be increasing. We also recorded evidence of difficulty in recognition of the three mustelids among respondents. There is a geographically extended interaction between otters and salmon farms in Chile. The evidence of interaction among alien American mink, native endangered otters, and aquaculture is an early alarm for human–wildlife conflict, and further studies are recommended to ensure native otter conservation.
{"title":"Co-Occurrence Between Salmon Farming, Alien American Mink (Neogale vison), and Endangered Otters in Patagonia","authors":"Gonzalo Medina-Vogel, Carlos Calvo-Mac, Nicole Delgado-Parada, Gabriela Molina-Maldonado, Stephanie Johnson-Padilla, Paulette Berland-Arias","doi":"10.1578/am.49.6.2023.561","DOIUrl":"https://doi.org/10.1578/am.49.6.2023.561","url":null,"abstract":"The southern river otter (Lontra provocax) and the marine otter (Lontra felina) are endangered species that inhabit Chile. In southern Chile, both species cohabit with the American mink (Neogale vison), an invasive exotic species. The Chilean aquaculture industry has grown exponentially since the late 1980s, with salmon farming taking place from central Chile to the Patagonian fjords and channels. This study assessed co-occurrence between otters, mink, and aquaculture in Patagonia by (1) distributing a survey among workers, fisheries personnel, and aquaculture inspectors concerning observations of otters and mink inside or around aquaculture facilities and outcomes; and (2) a geographical assessment of distribution overlap between known otter territory and salmon farming-registered facilities. We recorded the first anecdotal evidence of interaction, described as co-occurrence, among native otters, American mink, and salmon aquaculture in Patagonia, which varied among seasons and seems to be increasing. We also recorded evidence of difficulty in recognition of the three mustelids among respondents. There is a geographically extended interaction between otters and salmon farms in Chile. The evidence of interaction among alien American mink, native endangered otters, and aquaculture is an early alarm for human–wildlife conflict, and further studies are recommended to ensure native otter conservation.","PeriodicalId":8219,"journal":{"name":"Aquatic Mammals","volume":"3 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-15DOI: 10.1578/am.49.6.2023.585
Janet M. Lanyon, Helen L. Sneath, Kirsten M. Golding, Claire Madden
The dugong (Dugong dugon) is a fully marine mammal that grazes in nearshore seagrass meadows and whose health is vulnerable to human coastal activities. This study establishes urine baseline ranges for apparently healthy dugongs that can be used as health biomarkers. Voluntary urine samples (uncontaminated by seawater) were collected from 71 wild-caught dugongs in Moreton Bay, Australia, that were held out of water during an annual health assessment from 2008 to 2022. Urine was analysed for qualitative characteristics (colour, turbidity, odour), biochemistry through reactive urinalysis test strips, urine specific gravity (USG) by refractometer, electrolytes by flame photometry, sediment by microscopy, and bacterial culture. Urine of dugongs was typically pale yellow, clear to slightly cloudy, and mildly odorous. Urine was usually slightly alkaline (mean pH 8), and USG was low (mean 1.018). Urinalysis from dipstick indicated consistently negative readings for the presence of glucose, urobilinogen, bilirubin, ketones, and nitrites. Urinary protein was detected in 85% of sampled dugongs. Haemolysed red blood cells were recorded in > 85% of urine samples; microscopy indicated light haematuria (intact red blood cells) in 16% of samples. Seven percent of dugongs had detectable levels of leukocytes suggesting the possibility of mild urinary tract infection. Urinary sediment containing epithelial cells, keratinaceous debris, calcium carbonate crystalluria, and rare struvite crystals were typical. Light to moderate levels of bacteria were present in urine samples, with variable mixed growths, including Halomonas aquamarina, Pseudomonas stutzeri, Photobacterium damselae, Psychrobacter spp., and Staphylococcus aureus. Spermatozoa were present in the urine of 32% of the sexually mature males. Physical characteristics and chemistry of dugong urine showed some similarities to those of manatees and other herbivores. These baseline urinalysis data for healthy wild dugongs in a single population are valuable benchmarks against which dugongs of variable health status (including compromised dugongs) and from other localities may be compared.
{"title":"Baseline Urinalysis of the Fully Marine, Herbivorous Dugong (Dugong dugon)","authors":"Janet M. Lanyon, Helen L. Sneath, Kirsten M. Golding, Claire Madden","doi":"10.1578/am.49.6.2023.585","DOIUrl":"https://doi.org/10.1578/am.49.6.2023.585","url":null,"abstract":"The dugong (Dugong dugon) is a fully marine mammal that grazes in nearshore seagrass meadows and whose health is vulnerable to human coastal activities. This study establishes urine baseline ranges for apparently healthy dugongs that can be used as health biomarkers. Voluntary urine samples (uncontaminated by seawater) were collected from 71 wild-caught dugongs in Moreton Bay, Australia, that were held out of water during an annual health assessment from 2008 to 2022. Urine was analysed for qualitative characteristics (colour, turbidity, odour), biochemistry through reactive urinalysis test strips, urine specific gravity (USG) by refractometer, electrolytes by flame photometry, sediment by microscopy, and bacterial culture. Urine of dugongs was typically pale yellow, clear to slightly cloudy, and mildly odorous. Urine was usually slightly alkaline (mean pH 8), and USG was low (mean 1.018). Urinalysis from dipstick indicated consistently negative readings for the presence of glucose, urobilinogen, bilirubin, ketones, and nitrites. Urinary protein was detected in 85% of sampled dugongs. Haemolysed red blood cells were recorded in > 85% of urine samples; microscopy indicated light haematuria (intact red blood cells) in 16% of samples. Seven percent of dugongs had detectable levels of leukocytes suggesting the possibility of mild urinary tract infection. Urinary sediment containing epithelial cells, keratinaceous debris, calcium carbonate crystalluria, and rare struvite crystals were typical. Light to moderate levels of bacteria were present in urine samples, with variable mixed growths, including Halomonas aquamarina, Pseudomonas stutzeri, Photobacterium damselae, Psychrobacter spp., and Staphylococcus aureus. Spermatozoa were present in the urine of 32% of the sexually mature males. Physical characteristics and chemistry of dugong urine showed some similarities to those of manatees and other herbivores. These baseline urinalysis data for healthy wild dugongs in a single population are valuable benchmarks against which dugongs of variable health status (including compromised dugongs) and from other localities may be compared.","PeriodicalId":8219,"journal":{"name":"Aquatic Mammals","volume":"4 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-15DOI: 10.1578/am.49.6.2023.508
Jonas O. Elnes, André Moan, Kjell T. Nilssen, L. Asbjørn Vøllestad, Arne Bjørge
Incidental capture of non-target species by fisheries, also referred to as bycatch, is a major concern for the management of marine megafauna species. In Norway, it has been estimated that 555 harbor seals (Phoca vitulina) get entangled and drown in gillnets every year. The majority of these bycatch events occur in large-mesh gillnet fisheries targeting cod (Gadus morhua) and monkfish (Lophius piscatorius). Young-of-the-year individuals represent the largest proportion of bycaught harbor seals. To increase our understanding of harbor seal bycatch events along the Norwegian coast, times and areas of potential bycatch risk were identified. Seasonal variation in the at-sea distribution of harbor seals was simulated based on movement from their molting site to predicted at-sea locations. Relative age-specific bycatch abundances were used to weigh the different seasons (times of the year) based on harbor seal age. The overlap in the distribution of harbor seals and the documented distribution of fishing effort was then used to estimate the relative bycatch risks between harbor seals and fisheries in defined Statistical Sea Locations (SSLs) in each of the four seasons. The method used here provides a general framework for understanding temporal and spatial interaction between harbor seals and coastal gillnet fisheries. The times and areas of high interaction risk that were identified can be used in management practices to increase our understanding of bycatch events, and to ultimately reduce unwanted bycatch of harbor seals in coastal fisheries along the Norwegian coast.
{"title":"Temporal and Spatial Distribution of Harbor Seal (Phoca vitulina) Risk of Entanglement in Gillnets Along the Norwegian Coast","authors":"Jonas O. Elnes, André Moan, Kjell T. Nilssen, L. Asbjørn Vøllestad, Arne Bjørge","doi":"10.1578/am.49.6.2023.508","DOIUrl":"https://doi.org/10.1578/am.49.6.2023.508","url":null,"abstract":"Incidental capture of non-target species by fisheries, also referred to as bycatch, is a major concern for the management of marine megafauna species. In Norway, it has been estimated that 555 harbor seals (Phoca vitulina) get entangled and drown in gillnets every year. The majority of these bycatch events occur in large-mesh gillnet fisheries targeting cod (Gadus morhua) and monkfish (Lophius piscatorius). Young-of-the-year individuals represent the largest proportion of bycaught harbor seals. To increase our understanding of harbor seal bycatch events along the Norwegian coast, times and areas of potential bycatch risk were identified. Seasonal variation in the at-sea distribution of harbor seals was simulated based on movement from their molting site to predicted at-sea locations. Relative age-specific bycatch abundances were used to weigh the different seasons (times of the year) based on harbor seal age. The overlap in the distribution of harbor seals and the documented distribution of fishing effort was then used to estimate the relative bycatch risks between harbor seals and fisheries in defined Statistical Sea Locations (SSLs) in each of the four seasons. The method used here provides a general framework for understanding temporal and spatial interaction between harbor seals and coastal gillnet fisheries. The times and areas of high interaction risk that were identified can be used in management practices to increase our understanding of bycatch events, and to ultimately reduce unwanted bycatch of harbor seals in coastal fisheries along the Norwegian coast.","PeriodicalId":8219,"journal":{"name":"Aquatic Mammals","volume":"4 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.1578/am.49.5.2023.422
Ronald A. Kastelein, Lean Helder-Hoek, Laura Van Acoleyen, Linde N. Defillet, Léonie A. E. Huijser, John M. Terhune
Unmasked behavioral audiograms of two California sea lions (Zalophus californianus), an adult female (F01) and a subadult male (M02), were recorded using narrow-band frequency-modulated hearing test signals. Signals had a duration of 1 s and center frequencies ranging from 0.031 to 80 kHz. Hearing thresholds were measured by varying test signal amplitude according to the up-down staircase method. The resulting underwater audiograms (50% detection thresholds) of the two sea lions were similar and showed the typical mammalian U-shape. Maximum hearing sensitivity (58 and 57 dB re 1 mPa) occurred at 11.3 kHz for F01 and at 8 kHz for M02, respectively. The range of best hearing (defined as < 10 dB from the maximum sensitivity) was from 1 to 16 kHz (four octaves). The detection thresholds for hearing test signal frequencies 0.031, 0.040, and 0.050 kHz were lower than expected, possibly caused by a shift in perceptional modality from auditory to vibrotactile, or due to the difficulty in measuring accurate SPLs of such low frequencies in a pool. Measurements of particle motion deemed detection of these very low frequencies via the vibrissae unlikely. The present study extends the frequency range for which the hearing of California sea lions has been tested. Based on the two audiograms of the present study and audiograms reported by Reichmuth et al. (2013) and Cunningham & Reichmuth (2016), a revised generic audiogram for California sea lions is proposed.
采用窄带调频听力测试信号，记录了两只加利福尼亚海狮(Zalophus californianus)，一只成年雌性(F01)和一只亚成年雄性(M02)的行为听力图。信号的持续时间为1秒，中心频率范围为0.031至80khz。根据上下阶梯法，通过改变测试信号幅度来测量听力阈值。由此得到的两只海狮的水下听力图(50%检测阈值)相似，并显示出典型的哺乳动物u形。F01和M02在11.3 kHz和8 kHz时的最大听觉灵敏度分别为58和57 dB / 1 mPa。最佳听力范围(定义为<从最大灵敏度10分贝)从1到16千赫(四个八度)。听力测试信号频率0.031、0.040和0.050 kHz的检测阈值低于预期，可能是由于感知方式从听觉转变为振动触觉，或者是由于在池中难以准确测量如此低频率的SPLs。对粒子运动的测量认为不可能通过触须检测到这些极低频率。目前的研究扩大了加州海狮听力测试的频率范围。基于本研究的两个听力图和Reichmuth et al.(2013)和Cunningham &Reichmuth(2016)提出了一种修订后的加州海狮通用听力图。
{"title":"Underwater Sound Detection Thresholds (0.031-80 kHz) of Two California Sea Lions (Zalophus californianus) and a Revised Generic Audiogram for the Species","authors":"Ronald A. Kastelein, Lean Helder-Hoek, Laura Van Acoleyen, Linde N. Defillet, Léonie A. E. Huijser, John M. Terhune","doi":"10.1578/am.49.5.2023.422","DOIUrl":"https://doi.org/10.1578/am.49.5.2023.422","url":null,"abstract":"Unmasked behavioral audiograms of two California sea lions (Zalophus californianus), an adult female (F01) and a subadult male (M02), were recorded using narrow-band frequency-modulated hearing test signals. Signals had a duration of 1 s and center frequencies ranging from 0.031 to 80 kHz. Hearing thresholds were measured by varying test signal amplitude according to the up-down staircase method. The resulting underwater audiograms (50% detection thresholds) of the two sea lions were similar and showed the typical mammalian U-shape. Maximum hearing sensitivity (58 and 57 dB re 1 mPa) occurred at 11.3 kHz for F01 and at 8 kHz for M02, respectively. The range of best hearing (defined as < 10 dB from the maximum sensitivity) was from 1 to 16 kHz (four octaves). The detection thresholds for hearing test signal frequencies 0.031, 0.040, and 0.050 kHz were lower than expected, possibly caused by a shift in perceptional modality from auditory to vibrotactile, or due to the difficulty in measuring accurate SPLs of such low frequencies in a pool. Measurements of particle motion deemed detection of these very low frequencies via the vibrissae unlikely. The present study extends the frequency range for which the hearing of California sea lions has been tested. Based on the two audiograms of the present study and audiograms reported by Reichmuth et al. (2013) and Cunningham & Reichmuth (2016), a revised generic audiogram for California sea lions is proposed.","PeriodicalId":8219,"journal":{"name":"Aquatic Mammals","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135352793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.1578/am.49.5.2023.475
Jong-U Kim, Younggeun Oh, Youmin Kim, Jeong-Hoon Kim
{"title":"Rare Observation of a Living Southern Elephant Seal (Mirounga leonina) at Terra Nova Bay, Victoria Land Coast, Ross Sea, Antarctica","authors":"Jong-U Kim, Younggeun Oh, Youmin Kim, Jeong-Hoon Kim","doi":"10.1578/am.49.5.2023.475","DOIUrl":"https://doi.org/10.1578/am.49.5.2023.475","url":null,"abstract":"","PeriodicalId":8219,"journal":{"name":"Aquatic Mammals","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135353426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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