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Ursula Siebert - One of the best experts on this subject based on the ideXlab platform.
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health assessment of harbour porpoises phocoena phocoena from baltic area of denmark germany poland and latvia
Environment International, 2020Co-Authors: Ursula Siebert, Harald Benke, Iwona Pawliczka, V Von Vietinghoff, P Wolf, V Pilāts, Tina Kesselring, Kristina Lehnert, Ellen PrengerberninghoffAbstract:Harbour porpoise (phocoena phocoena), the only resident cetacean species of the Baltic Sea is formed of two subpopulations populations, occurring in the western Baltic, Belt Seas and Kattegat and the Baltic Proper, respectively. Harbour porpoises throughout these areas are exposed to a large number of human activities causing direct and indirect effects on individuals, that might also harm this species on a population level. From Latvia, Poland, Germany and Denmark 385 out of 1769 collected dead harbour porpoises were suitable for extensive necropsy. The animals were collected between 1990 and 2015 and were either by-caught or found dead on the coastline. Following necropsies, histopathological, microbiological, virological and parasitological investigations were conducted. Females and males were equally distributed among the 385 animals. Most animals from the different countries were juveniles between 3 months and 3 years old (varying between 46.5 and 100% of 385 animals per country). The respiratory tract had the highest number of morphological lesions, including lungworms in 25 to 58% and pneumonia in 21 to 58% of the investigated animals. Of those with pneumonia 8 to 33% were moderate or severe. The alimentary, hearing, and haematopoietic systems had inflammatory lesions and parasitic infections with limited health impact. 45.5 to 100% of the animals from the different countries were known by-caught individuals, of which 20 to 100% varying between countries had netmarks. Inflammatory lesions, especially in the respiratory tract were found in higher numbers when compared to control populations in areas with less human activities such as arctic waters. The high number of morphological changes in the respiratory tract and of bycatches especially among immature animals before reaching sexual maturity is of serious concern, as well as the low number of adult animals among the material. Data on health status and the causes of death are valuable for management. A next step in this regard will combine data from health and genetic investigations in order to detect differences between the two populations of the Baltic.
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time and tide seasonal diel and tidal rhythms in wadden sea harbour porpoises phocoena phocoena
PLOS ONE, 2019Co-Authors: Beate Zein, Benno Woelfing, Michael Dahne, Tobias Schaffeld, Stefan Ludwig, Jacob Hansen Rye, Johannes Baltzer, Andreas Ruser, Ursula SiebertAbstract:Odontocetes have evolved a rich diversity of prey- and habitat-specific foraging strategies, which allows them to feed opportunistically on locally and temporally abundant prey. While habitat-specific foraging strategies have been documented for some odontocete species, this is less known for the harbour porpoise (phocoena phocoena). We collected multiple years of acoustic data using echolocation click loggers to analyse porpoise occurrence and buzzing behaviour, indicating feeding, in the German Wadden Sea (North Sea). Seasonal, diel and tidal effects were studied using Generalised Estimating Equations (GEE-GAMs). Locally season, time of day and tidal time significantly influenced the probability of porpoise detections and detection of foraging sequences (buzzes). Hunting strategies, and therefore frequency of buzzes, were likely affected by prey distribution and large differences between POD locations indicated that porpoises used highly specific behaviour adapted to tide and time of day to efficiently feed on the available prey. Strong seasonal and spatial variation in diel and tidal effects underline the importance of long-term observations. Studies on porpoise behaviour are often based on short-term observations and might rather reflect a seasonal than a general pattern. The results of this study show clearly that significant changes in porpoise behaviour can be found in short and long-term observations. Here some features are based on short term determinants and others are stable over years and care should be taken about drawing general conclusions based on local patterns. Highly variable spatio-temporal patterns indicate a high flexibility of porpoises in a highly variable environment and address a challenge for complex conservation management plans.
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diet composition and food consumption rate of harbor porpoises phocoena phocoena in the western baltic sea
Marine Mammal Science, 2017Co-Authors: Ursula Siebert, Anita Gilles, Heidi Andreasen, Stine Dalmann Ross, Niels Gerner Andersen, Katrin RonnenbergAbstract:Stomach content composition and prey-specific consumption rates of juvenile and adult harbor porpoises (phocoena phocoena) were estimated from a data set including 339 stomachs collected over a 32 yr period (1980–2011) in the western Baltic Sea. The stomach contents were mainly hard parts of fish prey and in particular otoliths. The bias originating from differential residence time of otoliths in the stomachs was addressed by use of a recently developed approach. Atlantic cod and herring were the main prey of adults, constituting on average 70% of the diet mass. Juvenile porpoises also frequently consumed gobies. Here, the mass contribution by gobies was on average 25%, which was as much as cod. Other species such as whiting, sprat, eelpout, and sandeels were of minor importance for both juveniles and adults. The diet composition differed between years, quarters, and porpoise acquisition method. Yearly consumption rates for porpoises in the western Baltic Sea were obtained in three scenarios on the daily energy requirements of a porpoise in combination with an estimate including the 95% CLs of the porpoise population size. Cod of age groups 1 and 2 and intermediate-sized herring suffered the highest predation from porpoises.
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high density areas for harbor porpoises phocoena phocoena identified by satellite tracking
Marine Mammal Science, 2011Co-Authors: Signe Sveegaard, Jonas Teilmann, Jakob Tougaard, Rune Dietz, Kim N Mouritsen, Genevieve Desportes, Ursula SiebertAbstract:The population status of harbor porpoises has been of concern for several years, and the establishment of Marine Protected Areas (MPAs) has been suggested as a method to protect the harbor porpoise (phocoena phocoena, Linneaus 1758) and other small cetaceans. In order to designate MPAs, high-density areas for the species must be identified. Spatial distribution of small cetaceans is usually assessed from ship or aerial surveys. As a potentially more accurate alternative, this study examined the movements and area preferences of 64 harbor porpoises, satellite tagged between 1997 and 2007, in order to determine the distribution in the North Sea, the western Baltic, and the waters in between. Results show that harbor porpoises are not evenly distributed, but congregate in nine high-density areas within the study area. Several of these areas are subject to significant seasonal variation. The study found no differences in the home range size of males and females, but immature harbor porpoises have larger home ranges than mature porpoises. The use of satellite telemetry for identifying areas of high harbor porpoise density can be of key importance when designating MPAs.
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mitochondrial control region and microsatellite analyses on harbour porpoise phocoena phocoena unravel population differentiation in the baltic sea and adjacent waters
Conservation Genetics, 2010Co-Authors: Annika Wiemann, Ursula Siebert, Per Berggren, Jonas Teilmann, Harald Benke, Iwona Pawliczka, Liselotte Wesley Andersen, Christina Lockyer, Krzysztof Skora, Anna RoosAbstract:The population status of the harbour porpoise (phocoena phocoena) in the Baltic area has been a continuous matter of debate. Here we present the by far most comprehensive genetic population structure assessment to date for this region, both with regard to geographic coverage and sample size: 497 porpoise samples from North Sea, Skagerrak, Kattegat, Belt Sea, and Inner Baltic Sea were sequenced at the mitochondrial Control Region and 305 of these specimens were typed at 15 polymorphic microsatellite loci. Samples were stratified according to sample type (stranding vs. by-caught), sex, and season (breeding vs. non-breeding season). Our data provide ample evidence for a population split between the Skagerrak and the Belt Sea, with a transition zone in the Kattegat area. Among other measures, this was particularly visible in significant frequency shifts of the most abundant mitochondrial haplotypes. A particular haplotype almost absent in the North Sea was the most abundant in Belt Sea and Inner Baltic Sea. Microsatellites yielded a similar pattern (i.e., turnover in occurrence of clusters identified by STRUCTURE). Moreover, a highly significant association between microsatellite assignment and unlinked mitochondrial haplotypes further indicates a split between North Sea and Baltic porpoises. For the Inner Baltic Sea, we consistently recovered a small, but significant separation from the Belt Sea population. Despite recent arguments that separation should exceed a predefined threshold before populations shall be managed separately, we argue in favour of precautionary acknowledging the Inner Baltic porpoises as a separate management unit, which should receive particular attention, as it is threatened by various factors, in particular local fishery measures.
Thierry Jauniaux - One of the best experts on this subject based on the ideXlab platform.
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Multi-approach analysis to assess diet of harbour porpoises phocoena phocoena in the southern North Sea
Marine Ecology Progress Series, 2017Co-Authors: Céline Mahfouz, Thierry Jauniaux, Thibaut Bouveroux, Françoise Henry, Gaby Khalaf, Tarik Méziane, Carine Abi Ghanem, Jérôme Spitz, Rachid AmaraAbstract:Over the past decade, the distribution of harbour porpoises phocoena phocoena has undergone a southward shift in the North Sea, which has led to an increase in the number of stranded porpoises in its southern part. Since the changes in distribution and relative abundance of porpoises may be linked to the changes in prey availability, the aim of the present work was to investigate whether any changes in the feeding habits of harbour porpoises along the North Sea occurred in the past decade. The diet of harbour porpoises stranded along the southern North Sea (northern France and Belgian coast) was assessed through 3 complementary methods: stomach content analysis, stable isotopes (carbon and nitrogen) analysis determined from muscle samples, and fatty acids analysis determined from blubber samples. Fatty acid patterns and stable isotope values from 52 porpoises were compared to 14 potential prey species collected from the southern North Sea. Our results showed that the diet of porpoises along the southern North Sea comprises fish species that are among the most abundant and widely distributed in the area, except for the sardine Sardina pilchardus that appeared to be a new potential prey. Moreover, our results suggested that the decline in sandeel (Ammodytidae) in the northern parts of the North Sea along with the re-invasion of the southern North Sea by sardine species might affect the distribution of harbour porpoises.
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bite injuries of grey seals halichoerus grypus on harbour porpoises phocoena phocoena
PLOS ONE, 2014Co-Authors: Thierry Jauniaux, J Haelters, Mutienmarie Garigliany, Pauline Loos, Jeanluc Bourgain, Thibaut Bouveroux, Freddy Coignoul, Jacky Karpouzopoulos, Sylvain Pezeril, Daniel DesmechtAbstract:Bite-like skin lesions on harbour porpoises (phocoena phocoena) have been suspected to be caused by grey seals (Halichoerus grypus), and a few field observations have been reported. Bite-like skin lesions observed on stranded animals were characterized by two main components: large flaps of loose or missing skin and blubber with frayed edges and puncture lesions. Definitive demonstration of predation by a grey seal was not reported so far in those stranded animals. In this study, five stranded porpoises with bite-like skin lesions were swabbed for genetic investigations. In addition, the head of a recently dead grey seal was used to mimic bite-like skin injuries on a porpoise carcass. Subsequently, the artificial skin injuries were swabbed, along with the gum of the seal used for inflicting them (positive controls). Total DNA was extracted from the swabs and was used to retrieve a fragment of mitochondrial DNA by PCR. Primers were designed to amplify a specific stretch of mitochondrial DNA known to differ between grey seals and porpoises. The amplicon targeted was successfully amplified from the positive control and from two of the stranded porpoises, and grey seal-specific mitochondrial DNA was retrieved from all those samples. We conclude that (1) it is possible to detect grey seal DNA from dead porpoises even after several days in seawater and (2) bite-like skin lesions found on dead porpoises definitively result from grey seals attacks. The attacks are most likely linked with predation although, in a number of cases, scavenging and aggressive behaviour cannot be excluded.
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Harbour porpoises (phocoena phocoena) stranded along the southern North Sea: An assessment through metallic contamination.
Environmental Research, 2014Co-Authors: Céline Mahfouz, Thierry Jauniaux, Thibaut Bouveroux, Sylvain Pezeril, Françoise Henry, Lucie Courcot, Willy Dabin, Gaby Khalaf, Rachid AmaraAbstract:Throughout the last few years, the southern North Sea has witnessed an increase in the number of stranded marine mammals, particularly the harbour porpoise (phocoena phocoena). This species is subject to several potential threats such as exposure to contaminants, changes in food supply, marine traffic and fishery by-catch. The aims of this study were to investigate potential associations between contaminants and health status and to analyze spatial and temporal trends of metal concentrations in harbour porpoises. Selected trace elements (As, Cd, Cr, Cu, Hg, Mn, Se, V and Zn) were measured in kidneys and livers of 105 harbour porpoises stranded along the southern North Sea (French and Belgian coasts from 2006 to 2013) and 27 stranded along the Bay of Biscay (French coast from 2009 to 2012). Porpoises that died from infectious disease displayed significant higher hepatic concentrations of Cd, Hg, Se and Zn compared to healthy porpoises that died from physical trauma. Adult porpoises displayed significant higher concentrations of Cd, Cr, Hg, Se and V in livers compared to juveniles. No spatial or temporal trends in metal concentrations were detected in our study. The results of the present study suggested that chemical contamination may represent one of many threats encountered by harbour porpoises, but it cannot explain alone the increase in the number of stranded individuals.
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the stranding anomaly as population indicator the case of harbour porpoise phocoena phocoena in north western europe
PLOS ONE, 2013Co-Authors: Helene Peltier, J Haelters, Thierry Jauniaux, Kees C J Camphuysen, Willy Dabin, Hans J Baagoe, Richard Czeck, Pierre Daniel, Rob DeavilleAbstract:Ecological indicators for monitoring strategies are expected to combine three major characteristics: ecological significance, statistical credibility, and cost-effectiveness. Strategies based on stranding networks rank highly in cost-effectiveness, but their ecological significance and statistical credibility are disputed. Our present goal is to improve the value of stranding data as population indicator as part of monitoring strategies by constructing the spatial and temporal null hypothesis for strandings. The null hypothesis is defined as: small cetacean distribution and mortality are uniform in space and constant in time. We used a drift model to map stranding probabilities and predict stranding patterns of cetacean carcasses under H0 across the North Sea, the Channel and the Bay of Biscay, for the period 1990-2009. As the most common cetacean occurring in this area, we chose the harbour porpoise phocoena phocoena for our modelling. The difference between these strandings expected under H0 and observed strandings is defined as the stranding anomaly. It constituted the stranding data series corrected for drift conditions. Seasonal decomposition of stranding anomaly suggested that drift conditions did not explain observed seasonal variations of porpoise strandings. Long-term stranding anomalies increased first in the southern North Sea, the Channel and Bay of Biscay coasts, and finally the eastern North Sea. The hypothesis of changes in porpoise distribution was consistent with local visual surveys, mostly SCANS surveys (1994 and 2005). This new indicator could be applied to cetacean populations across the world and more widely to marine megafauna.
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the grey seal halichoerus grypus as a predator of harbour porpoises phocoena phocoena
Aquatic Mammals, 2012Co-Authors: J Haelters, Francis Kerckhof, Thierry Jauniaux, S DegraerAbstract:In September 2011, two harbour porpoises (phocoena phocoena) presenting extensive traumatic lesions washed ashore in Belgium. Similar lesions, with large parts of skin and blubber missing, had not been recorded before on harbour porpoises in Belgium but were recently observed in a number of cases in neighbouring countries. We compared the lesions with the mouth and teeth structure of possible predators. The circumstances of the strandings, the observations during the necropsies, and the results of seal skull investigations pointed towards seals, presumably grey seals (Halichoerus grypus), as the prime suspects for having caused the death of both harbour porpoises. Although purely aggressive behaviour cannot be completely excluded, predation is considered most likely as part of the skin and blubber tissue of the harbour porpoises was missing. The grey seal is an opportunistic predator, feeding on a variety of fish and cephalopods, and occasionally even on crustaceans and seabirds, but predation on harbour porpoises, or any other marine mammal, had to our knowledge never been described. This finding might shed a new light on the cause of death of some of the other mutilated harbour porpoises recently stranded on southern North Sea beaches, and it presents a case of a change in the feeding strategy of a top predator.
Rachid Amara - One of the best experts on this subject based on the ideXlab platform.
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Multi-approach analysis to assess diet of harbour porpoises phocoena phocoena in the southern North Sea
Marine Ecology Progress Series, 2017Co-Authors: Céline Mahfouz, Thierry Jauniaux, Thibaut Bouveroux, Françoise Henry, Gaby Khalaf, Tarik Méziane, Carine Abi Ghanem, Jérôme Spitz, Rachid AmaraAbstract:Over the past decade, the distribution of harbour porpoises phocoena phocoena has undergone a southward shift in the North Sea, which has led to an increase in the number of stranded porpoises in its southern part. Since the changes in distribution and relative abundance of porpoises may be linked to the changes in prey availability, the aim of the present work was to investigate whether any changes in the feeding habits of harbour porpoises along the North Sea occurred in the past decade. The diet of harbour porpoises stranded along the southern North Sea (northern France and Belgian coast) was assessed through 3 complementary methods: stomach content analysis, stable isotopes (carbon and nitrogen) analysis determined from muscle samples, and fatty acids analysis determined from blubber samples. Fatty acid patterns and stable isotope values from 52 porpoises were compared to 14 potential prey species collected from the southern North Sea. Our results showed that the diet of porpoises along the southern North Sea comprises fish species that are among the most abundant and widely distributed in the area, except for the sardine Sardina pilchardus that appeared to be a new potential prey. Moreover, our results suggested that the decline in sandeel (Ammodytidae) in the northern parts of the North Sea along with the re-invasion of the southern North Sea by sardine species might affect the distribution of harbour porpoises.
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Harbour porpoises (phocoena phocoena) stranded along the southern North Sea: An assessment through metallic contamination.
Environmental Research, 2014Co-Authors: Céline Mahfouz, Thierry Jauniaux, Thibaut Bouveroux, Sylvain Pezeril, Françoise Henry, Lucie Courcot, Willy Dabin, Gaby Khalaf, Rachid AmaraAbstract:Throughout the last few years, the southern North Sea has witnessed an increase in the number of stranded marine mammals, particularly the harbour porpoise (phocoena phocoena). This species is subject to several potential threats such as exposure to contaminants, changes in food supply, marine traffic and fishery by-catch. The aims of this study were to investigate potential associations between contaminants and health status and to analyze spatial and temporal trends of metal concentrations in harbour porpoises. Selected trace elements (As, Cd, Cr, Cu, Hg, Mn, Se, V and Zn) were measured in kidneys and livers of 105 harbour porpoises stranded along the southern North Sea (French and Belgian coasts from 2006 to 2013) and 27 stranded along the Bay of Biscay (French coast from 2009 to 2012). Porpoises that died from infectious disease displayed significant higher hepatic concentrations of Cd, Hg, Se and Zn compared to healthy porpoises that died from physical trauma. Adult porpoises displayed significant higher concentrations of Cd, Cr, Hg, Se and V in livers compared to juveniles. No spatial or temporal trends in metal concentrations were detected in our study. The results of the present study suggested that chemical contamination may represent one of many threats encountered by harbour porpoises, but it cannot explain alone the increase in the number of stranded individuals.
Andrew J Bohonak - One of the best experts on this subject based on the ideXlab platform.
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morphological and genetic differentiation of the black sea harbour porpoise phocoena phocoena
Marine Ecology Progress Series, 2007Co-Authors: Karine A Viaudmartinez, Pavel Goldin, Milmer Martinez Vergara, Vincent Ridoux, Ayaka Amaha Ozturk, Bayram Ozturk, Patricia E Rosel, Alexandros Frantzis, Anastasia Komnenou, Andrew J BohonakAbstract:The ecological and conservation status of the geographically isolated Black Sea harbour porpoise is currently unknown. Although it has been suggested that Black Sea harbour porpoises are distinct from other populations, the implementation of specific conservation plans has been hindered by the absence of a genetic and morphological study with large sample sizes. We sought to test the hypothesis that Black Sea porpoises differ from those in the Atlantic Ocean using cranial morphology and mitochondrial DNA variation. A total of 177 adult skulls from the Atlantic coast of France, Dan- ish North Sea including Skagerrak and Inner Danish Waters, Greenland and the Black Sea were scored for 22 morphological variables. A portion of the mitochondrial control region was sequenced for 146 ind. from the eastern north Atlantic, the northern Aegean Sea, the Sea of Marmara and the Black Sea. Within the Black Sea, we found relatively low levels of genetic diversity, and no statisti- cally significant differentiation. However, the Black Sea population shares no haplotypes with the eastern Atlantic populations, suggesting that they have been separated for thousands of years. Black Sea porpoises also show significant morphological differences from other populations, with smaller body and skull size, wider and longer rostrum, smaller orbital length, smaller internal nares and condylar widths and larger occipital ridge. Our results demonstrate that harbour porpoises from the Black Sea, Sea of Marmara and the northern Aegean Sea (eastern region): (1) are genetically differ- entiated; (2) have been reproductively isolated for a considerable period of time; and (3) are likely to be on an independent evolutionary pathway. We recommend that harbour porpoises from the eastern region be recognized as the subspecies phocoena phocoena relicta.
Jonas Teilmann - One of the best experts on this subject based on the ideXlab platform.
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Click communication in wild harbour porpoises (phocoena phocoena).
Scientific reports, 2018Co-Authors: P. M. Sørensen, Danuta Maria Wisniewska, Frants H. Jensen, Mark P. Johnson, Jonas Teilmann, Peter T MadsenAbstract:Social delphinids employ a vocal repertoire of clicks for echolocation and whistles for communication. Conversely, the less social and acoustically cryptic harbour porpoises (phocoena phocoena) only produce narrow-band high-frequency (NBHF) clicks with properties that appear poorly suited for communication. Nevertheless, these small odontocetes likely mediate social interactions, such as mate choice and mother-calf contact, with sound. Here, we deployed six tags (DTAG3) on wild porpoises in Danish waters for a total of 96 hours to investigate if the patterns and use of stereotyped NBHF click trains are consistent with a communication function. We show that wild porpoises produce frequent (up to 27 $$\bullet $$ min−1), high-repetition rate click series with repetition rates and output levels different from those of foraging buzzes. These sounds are produced in bouts and frequently co-occur with emission of similar sounds by nearby conspecifics, audible on the tags for >10% of the time. These results suggest that social interactions are more important to this species than their limited social encounters at the surface may indicate and that these interactions are mediated by at least two broad categories of calls composed of short, high-repetition rate click trains that may encode information via the repetition rate of their stereotyped NBHF clicks.
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comparing distribution of harbour porpoises phocoena phocoena derived from satellite telemetry and passive acoustic monitoring
PLOS ONE, 2016Co-Authors: Lonnie Mikkelsen, Jakob Tougaard, Signe Sveegaard, Rune Dietz, Frank F Riget, Line A Kyhn, Julia Carlstrom, Ida Carlen, Jens C Koblitz, Jonas TeilmannAbstract:Cetacean monitoring is essential in determining the status of a population. Different monitoring methods should reflect the real trends in abundance and patterns in distribution, and results should therefore ideally be independent of the selected method. Here, we compare two independent methods of describing harbour porpoise (phocoena phocoena) relative distribution pattern in the western Baltic Sea. Satellite locations from 13 tagged harbour porpoises were used to build a Maximum Entropy (MaxEnt) model of suitable habitats. The data set was subsampled to one location every second day, which were sufficient to make reliable models over the summer (Jun-Aug) and autumn (Sep-Nov) seasons. The modelled results were compared to harbour porpoise acoustic activity obtained from 36 static acoustic monitoring stations (C-PODs) covering the same area. The C-POD data was expressed as the percentage of porpoise positive days/hours (the number of days/hours per day with porpoise detections) by season. The MaxEnt model and C-POD data showed a significant linear relationship with a strong decline in porpoise occurrence from west to east. This study shows that two very different methods provide comparable information on relative distribution patterns of harbour porpoises even in a low density area.
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high density areas for harbor porpoises phocoena phocoena identified by satellite tracking
Marine Mammal Science, 2011Co-Authors: Signe Sveegaard, Jonas Teilmann, Jakob Tougaard, Rune Dietz, Kim N Mouritsen, Genevieve Desportes, Ursula SiebertAbstract:The population status of harbor porpoises has been of concern for several years, and the establishment of Marine Protected Areas (MPAs) has been suggested as a method to protect the harbor porpoise (phocoena phocoena, Linneaus 1758) and other small cetaceans. In order to designate MPAs, high-density areas for the species must be identified. Spatial distribution of small cetaceans is usually assessed from ship or aerial surveys. As a potentially more accurate alternative, this study examined the movements and area preferences of 64 harbor porpoises, satellite tagged between 1997 and 2007, in order to determine the distribution in the North Sea, the western Baltic, and the waters in between. Results show that harbor porpoises are not evenly distributed, but congregate in nine high-density areas within the study area. Several of these areas are subject to significant seasonal variation. The study found no differences in the home range size of males and females, but immature harbor porpoises have larger home ranges than mature porpoises. The use of satellite telemetry for identifying areas of high harbor porpoise density can be of key importance when designating MPAs.
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mitochondrial control region and microsatellite analyses on harbour porpoise phocoena phocoena unravel population differentiation in the baltic sea and adjacent waters
Conservation Genetics, 2010Co-Authors: Annika Wiemann, Ursula Siebert, Per Berggren, Jonas Teilmann, Harald Benke, Iwona Pawliczka, Liselotte Wesley Andersen, Christina Lockyer, Krzysztof Skora, Anna RoosAbstract:The population status of the harbour porpoise (phocoena phocoena) in the Baltic area has been a continuous matter of debate. Here we present the by far most comprehensive genetic population structure assessment to date for this region, both with regard to geographic coverage and sample size: 497 porpoise samples from North Sea, Skagerrak, Kattegat, Belt Sea, and Inner Baltic Sea were sequenced at the mitochondrial Control Region and 305 of these specimens were typed at 15 polymorphic microsatellite loci. Samples were stratified according to sample type (stranding vs. by-caught), sex, and season (breeding vs. non-breeding season). Our data provide ample evidence for a population split between the Skagerrak and the Belt Sea, with a transition zone in the Kattegat area. Among other measures, this was particularly visible in significant frequency shifts of the most abundant mitochondrial haplotypes. A particular haplotype almost absent in the North Sea was the most abundant in Belt Sea and Inner Baltic Sea. Microsatellites yielded a similar pattern (i.e., turnover in occurrence of clusters identified by STRUCTURE). Moreover, a highly significant association between microsatellite assignment and unlinked mitochondrial haplotypes further indicates a split between North Sea and Baltic porpoises. For the Inner Baltic Sea, we consistently recovered a small, but significant separation from the Belt Sea population. Despite recent arguments that separation should exceed a predefined threshold before populations shall be managed separately, we argue in favour of precautionary acknowledging the Inner Baltic porpoises as a separate management unit, which should receive particular attention, as it is threatened by various factors, in particular local fishery measures.
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stress level in wild harbour porpoises phocoena phocoena during satellite tagging measured by respiration heart rate and cortisol
Journal of the Marine Biological Association of the United Kingdom, 2009Co-Authors: I G Eskesen, Jonas Teilmann, Rune Dietz, Genevieve Desportes, Frank F Riget, B M Geertsen, Finn Larsen, Ursula SiebertAbstract:During satellite tagging of harbour porpoises ( phocoena phocoena ), heart rate, respiration rate and cortisol value were measured to evaluate stress effects during handling and tagging. Respiration rates were obtained using video recordings, heart rates were recorded and serum cortisol levels were analysed from blood samples. Differences in heart rates, respiration rates and cortisol levels before and during the tagging events were investigated. An overall significant decrease of 31.5% in respiration rate was found during the tagging event period, while mature porpoises respired significantly more often than immature individuals. Though significant differences in heart rates were found for some individuals, no general significant change for all animals was detected. We found no correlation between cortisol concentration and either heart rate or respiration rate, nor did we find any relationships between cortisol and month of year, sex and body length. As high individual variations occurred in response to tagging of harbour porpoises, it is not possible to give general advice based on the factors investigated, on how to reduce stress during handling. However, pouring water over the animal and lowering it into the water seem to stabilize a stressed animal. Therefore, general precaution and individual judgement based on experience is essential when handling wild harbour porpoises.