Presence Of Cetaceans Research Articles

Earliest Records of Holocene Cetaceans in the Black Sea

ABSTRACTThe timing of the Holocene transition of the Black Sea from a brackish lake to a marine sea has long been debated. Here, we report on the earliest records of cetaceans in the Black Sea region as a proxy for the connection with the Mediterranean and the transition from a brackish to marine environment. We base our analysis on cetacean skeletal finds and archival data on cetacean skeletal remains from the Bosphorus, the western, northern and eastern Black Sea, and the Kerch Strait. We find that all three contemporary cetacean species in the Black Sea – the harbour porpoise, bottlenose dolphin and common dolphin – had migrated out of the Mediterranean to the Bosphorus and the Black Sea at least 8000–7000 years ago and reached the northern Black Sea by 5500 years ago at the latest. Our study suggests the establishment of a Mediterranean–Black Sea biogeographical connection for marine vertebrates at least 7000 years ago. The early presence of cetaceans in the Black Sea has implications for understanding its Holocene transition, as well as the evolutionary and ecological history of these species more generally.

The WhaleReport Alert System: Mitigating threats to whales with citizen science

Ship strikes are a pervasive threat to cetaceans globally. Real-time observations of cetaceans reported by citizen scientists unlock an opportunity to develop ship strike mitigation tools. The Ocean Wise Sightings Network (OWSN) is an example of a long-running and expansive citizen science program. The OWSN curates sightings data collected by coastal communities, mariners, and tourists into a database that can be utilized to monitor the 23 cetacean species inhabiting British Columbia and Washington State waters. Recently, the OWSN mobilized real-time sightings data into a mitigation tool, the WhaleReport Alert System (WRAS), which alerts professional mariners to the presence of cetaceans within their vicinity, allowing them to take action (e.g., slow down or divert course), to mitigate the risk of ship strike. The success of the WRAS (550 registered users) can be largely attributed to outreach events conducted in coastal communities which recruit new observers who report sightings to the WhaleReport app. Partnering with mariners to develop the WRAS has resulted in its continued support from and use by marine industry. We highlight the critical role of a sightings network for mitigating threats to cetaceans, emphasize the need to collaborate with marine industry, non-governmental, and government bodies to support endorsement of the tool, and stress the importance of metrics to evaluate success of the WRAS. This approach taken by Ocean Wise has resulted in the delivery of >20,000 WRAS alerts and is a framework which could be integrated into existing sightings networks globally to mitigate the risk of ship strikes on cetaceans.

Frekuensi Pemunculan, Tingkah laku, dan Diversitas Cetacea di Perairan sekitar Labuan Bajo, Flores, Nusa Tenggara Timur


 
 
 
 At least 30 cetaceans live in Indonesia, especially in the eastern waters of Indonesia, consisting of whales and dolphins. Cetaceans play an important role as a key species in determining the health of marine ecosystems. This study aims to determine the frequency of appearance, behavior, and diversity of cetaceans along Labuan Bajo, Flores, and East Nusa Tenggara. The study was conducted in October-November 2021, with four weeks to collect field data and interviews. The data involved a ship carrying a group of observers consisting of four people, with each task assigned to look for the appearance, species, and behavior of cetaceans. In the interview methods, interviews were conducted with fishermen regarding the presence of cetaceans. The data was then processed using the Microsoft Excel program and later plotted using the ArcView program as the outpour of the cetacean distribution. The results showed 19 occurrences of cetaceans, with six occurrences found in the field survey and 13 based on interviews with fishermen. Appearances were found to be evenly distributed in the study area, with a total of 7 species of cetaceans found, namely Stenella longirostris, Stenella attenuata, Tursiops truncates, Pseudorca crassidens, Grampus griseus, Kogia simus, and Physeter macrocephalus. In species composition and abundance, S. longirostris species had the highest value, and the P. crassidens species had the lowest composition value. A value of 1.06 was found in diversity, indicating that the cetaceans in Labuan Bajo were classified as moderate. Some behaviors include aerials, spy hopping, bow-riding, feeding, and avoidance.
 
 
 

Exploring and verifying the acoustic presence of southern right whales (Eubalaena australis) off Elephant Island, Antarctica.

Passive acoustic monitoring (PAM) can be used to monitor acoustic presence and behaviour of cetaceans, providing continuous, long-term, and seasonally unbiased data. The efficiency of PAM methods, however, depends on the ability to detect and correctly interpret acoustic signals. The upcall is the most prevalent vocalization of the southern right whale (Eubalaena australis) and is commonly used as a basis for PAM studies on this species. However, previous studies report difficulties to distinguish between southern right whale upcalls and similar humpback whale (Megaptera novaeangliae) vocalizations with certainty. Recently, vocalizations comparable to southern right whale upcalls were detected off Elephant Island, Antarctica. In this study, these vocalizations were structurally analyzed, and call characteristics were compared to (a) confirmed southern right whale vocalizations recorded off Argentina and (b) confirmed humpback whale vocalizations recorded in the Atlantic Sector of the Southern Ocean. Based on call features, detected upcalls off Elephant Island could be successfully attributed to southern right whales. Measurements describing slope and bandwidth were identified as the main differences in call characteristics between species. With the newly gained knowledge from this study, additional data can be analyzed providing further insight into temporal occurrence and migratory behaviour of southern right whales in Antarctic waters.

Current knowledge of the cetacean fauna of the Greek Seas

From 1991-2002 data on the presence and distribution of cetaceans in the Greek Seas have been systematically collated in a database (821 sightings and 715 strandings). Data originated from dedicated surveys, stranding reports, opportunistic sightings and published or unpublished photographic and video documents. Twelve cetacean species have been recorded. Seven of them are permanently present and commonly observed in one or more of the Greek Seas: striped dolphin, common bottlenose dolphin, short-beaked common dolphin, Cuvier’s beaked whale, sperm whale, Risso’s dolphin and fin whale. In addition, the harbour porpoise is present locally in the Thracian and northern Aegean Seas. The humpback whale, false killer whale and common minke whale are occasional Mediterranean species that were sighted or stranded infrequently; the Sowerby’s beaked whale is an accidental species that was found floating dead only once. Five other species (white whale, Blainville’s beaked whale, long-finned pilot whale, killer whale, blue whale) have been erroneously included in the Greek cetacean fauna in the past due to wrong assumptions, false identifications or lack of supporting evidence. The occasional occurrence of pilot and killer whales in the Greek Seas should still be regarded as unconfirmed. The distributional range, stranding numbers and sighting frequencies of sperm whales, Cuvier’s beaked whales and short-beaked common dolphins in the Greek Seas indicate that their local ‘sub-populations’ are among the most important in the entire Mediterranean Sea. Harbour porpoises in the Thracian and northern Aegean Seas are important from a conservation perspective since this species does not inhabit any other part of the Mediterranean Sea.

Acoustic Presence of Cetaceans in the Miaodao Archipelago, China.

Once an important cetacean habitat, the Miaodao Archipelago has been altered by human-induced disturbances over several decades. While cetacean diversity is known to have decreased, no recent data on species diversity around Miaodao are known to exist. Capitalizing on the high vocal activity of cetaceans, three passive acoustic surveys, including towed and stationary types, were undertaken to detect the presence of species-specific vocalizations in May 2021, October 2021, and July 2022, as most cetacean sightings occurred during May and August in recent years. The results revealed that the East Asian finless porpoise is the sole cetacean species that can be reliably observed around the archipelago, as no other species were detected. The acoustic data also revealed potentially clumped distributions of finless porpoises with some seasonal variation. While not acoustically detected during any of the surveys, humpback whales, minke whales, and killer whales have been visually sighted in the region. The lack of acoustic detection of these species suggests that they are likely to be temporary visitors to the region, or at least exhibit strong seasonality in their presence within the region. These new data provide the latest snapshot of cetacean presence around the Miaodao Archipelago that can help inform future research and conservation.

Cetaceans in the Mediterranean Sea: Encounter Rate, Dominant Species, and Diversity Hotspots

We investigated the presence and diversity of cetaceans in the Mediterranean Sea, analysing the data collected by 32 different research units, over a period of 15 years (2004–2018), and shared on the common web-GIS platform named Intercet. We used the encounter rate, the species prevalence, and the Shannon diversity index as parameters for data analysis. The results show that cetacean diversity, in the context of the Mediterranean basin, is generally quite low when compared with the eastern Atlantic, as few species, namely the striped dolphin, the bottlenose dolphin, the fin whale, and the sperm whale, dominate over all the others. However, some areas, such as the Alboran Sea or the north-western Mediterranean Sea, which includes the Pelagos Sanctuary (the Specially Protected Area of Mediterranean Interest located in the northern portion of the western basin), show higher levels of diversity and should be considered hotspots to be preserved. Primary production and seabed profile seem to be the two main drivers influencing the presence and distribution of cetaceans, with the highest levels of diversity observed in areas characterized by high levels of primary production and high bathymetric variability and gradient. This collective work underlines the importance of data sharing to deepen our knowledge on marine fauna at the scale of the whole Mediterranean Sea and encourages greater efforts in the networking process, also to accomplish the requirements of the Marine Strategy Framework Directive, with particular reference to Descriptor 1: biological diversity is maintained.

Diversity, habitat associations and stock structure of odontocete cetaceans in the waters of American Samoa, 2003-06

Little is known about the species composition, distribution, abundance or stock structure of odontocetes in the central and western tropical Pacific Ocean, including those inhabiting the US Exclusive Economic Zone (EEZ) waters of American Samoa. While some information on species presence in this region has been gleaned from anecdotal sightings and whaling and stranding records, odontocete diversity in the waters of American Samoa has never been formally investigated. This lack of information precludes efforts to determine the sustainability of cetacean populations within US EEZ waters. This paper reports on the first dedicated surveys to document the presence and distribution of odontocete cetaceans in the waters of American Samoa. A series of small-boat photo-identification and biopsy surveys for cetaceans were conducted in the nearshore waters of Tutuila during 2003-06. In addition, ship-based visual surveys were conducted in the waters surrounding the Manu‘a Islands, Rose Atoll and Swains Island in summer 2006. A total of 58 groups of odontocete cetaceans were encountered during both small-boat and ship-based surveys: spinner dolphins (Stenella longirostris, n=34), rough-toothed dolphins (Steno bredanensis, n=10), sperm whales (Physeter macrocephalus, n=3), false killer whales (Pseudorca crassidens, n=5), bottlenose dolphins (Tursiops truncatus., n=1), dwarf sperm whales (Kogia sima, n=1), short-finned pilot whales (Globicephala macrorhynchus, n=1), and three groups of unidentified odontocetes. Photographs were analysed for quality and individuals with distinctive markings were selected for entry into a photo-identification catalogue. The resultant catalogue included 46 spinner dolphins, 41 rough-toothed dolphins, 2 bottlenose dolphins, 5 false killer whales, 4 pilot whales, 1 dwarf sperm whale and 4 sperm whales. Thirteen spinner dolphins and 14 rough-toothed dolphins were sighted in multiple years. To investigate stock structure, spinner dolphin genetic data were used to compare mitochondrial control region genetic diversity and allele frequencies between American Samoa and the Hawaiian Islands. American Samoa had a higher genetic diversity, and populations at the two locations were genetically distinct (FST = 0.21). The high diversity at American Samoa indicates that spinner dolphins at this location are not reproductively isolated, but the data do not rule out the possibility that these dolphins may be demographically isolated on ecological timescales.

Factors associated with the differential distribution of cetaceans linked with deep habitats in the Western Mediterranean Sea

Deep-habitat cetaceans are generally difficult to study, leading to a limited knowledge of their population. This paper assesses the differential distribution patterns of three deep-habitat cetaceans (Sperm whale—Physeter macrocephalus, Risso’s dolphin—Grampus griseus & Cuvier’s beaked whale—Ziphius cavirostris). We used data of 842 opportunistic sightings of cetaceans in the western Mediterranean sea. We inferred environmental and spatio-temporal factors that affect their distribution. Binary logistic regression models were generated to compare the presence of deep-habitat cetaceans with the presence of other cetacean species in the dataset. Then, the favourability function was applied, allowing for comparison between all the models. Sperm whale and Risso’s dolphin presence was differentially favoured by the distance to towns in the eastern part of the western Mediterranean sea. The differential distribution of sperm whale was also influenced by the stability of SST, and that of the Risso’s dolphin by lower mean salinity and higher mean Chlorophyll A concentration. When modelling the three deep-habitat cetaceans (including Cuvier’s beaked whale), the variable distance to towns had a negative influence on the presence of any of them more than it did to other cetaceans, being more favourable far from towns, so this issue should be further investigated.

Using Environmental DNA to Detect Whales and Dolphins in the New York Bight

Determining how cetaceans and other threatened marine animals use coastal habitats is critical to the effective conservation of these species. Environmental DNA (eDNA) is an emerging tool that can potentially be used to detect cetaceans over broad spatial and temporal scales. In particular, eDNA may present a useful complementary method for monitoring their presence during visual surveys in nearshore areas, and for co-detecting prey. In conjunction with ongoing visual surveys, we tested the ability of eDNA metabarcoding to detect the presence and identity of cetaceans in the New York Bight (NYB), and to identify fish species (potential prey) present in the area. In almost all cases in which humpback whales and dolphins were visually observed, DNA from these species was also detected in water samples. To assess eDNA degradation over time, we took samples in the same location 15 and 30 min after a sighting in seven instances, and found that eDNA often, but not always, dropped to low levels after 30 min. Atlantic menhaden were detected in all samples and comprised the majority of fish sequences in most samples, in agreement with observations of large aggregations of this important prey species in the NYB. While additional data are needed to better understand how factors such as behavior and oceanographic conditions contribute to the longevity of eDNA signals, these results add to a growing body of work indicating that eDNA is a promising tool to complement visual and acoustic surveys of marine megafauna.

A pioneering survey of deep-diving and off-shore cetaceans in the northern South China Sea.

A pioneering boat-based survey was conducted in 2019, to gather baseline information regarding the presence, composition, relative abundance, and spatial distribution of deep-diving and off-shore cetaceans in the northern South China Sea (SCS). A total of 27 sightings comprising at least 8 cetacean species were recorded during the 13-day survey, including 5 deep-diving species (i.e. Risso's dolphin [Grampus griseus], short-finned pilot whale [Globicephala macrorhynchus], sperm whale [Physeter macrocephalus], Cuvier's beaked whale [Ziphius cavirostris], and an unidentified beaked whale [either the ginkgo-toothed beaked whale, Mesoplodon ginkgodens, or Deraniyagala's beaked whale, Mesoplodon hotaula]), as well as 3 off-shore dolphins (i.e. pantropical spotted dolphin [Stenella attenuate], striped dolphin [Stenella coeruleoalba], and Fraser's dolphin [Lagenodelphis hosei]). With the exception of pantropical spotted dolphins, all other species were sighted and recorded at sea in the northern SCS for the first time. The pantropical spotted dolphin was the most frequently sighted species, comprising 30% of the total sightings. Deep-diving cetaceans were mainly sighted in the northern Xisha Archipelago, whereas off-shore dolphins were distributed across the survey area. The pantropical spotted dolphin was observed in aggregations of more than 100 individuals and nearly all encountered species included calves; these findings suggested that the survey area functions as an important feeding and calving ground for various cetacean species. This pioneering survey provides fundamental information regarding cetacean fauna in the northern SCS and highlights the need to strengthen research and conservation efforts concerning these species.

Arctic Marine Data Collection Using Oceanic Gliders: Providing Ecological Context to Cetacean Vocalizations

To achieve effective management and understanding of risks associated with increasing anthropogenic pressures in the ocean, it is essential to successfully and efficiently collect data with high spatio–temporal resolution and coverage. Autonomous Underwater Vehicles (AUVs) are an example of technological advances with potential to provide improved information on ocean processes. We demonstrate the capabilities of a low-power AUV buoyancy glider for performing long endurance biological and environmental data acquisition in Northern Norway. We deployed a passive acoustic sensor system onboard a SeagliderTM to investigate presence and distribution of cetaceans while concurrently using additional onboard sensors for recording environmental features (temperature, salinity, pressure, dissolved oxygen, and chlorophyll). The hydrophone recorded over 108.6 hours of acoustic data during the spring months of March and April across the continental shelf break and detected both baleen and odontocete species. We observed a change in cetacean detections throughout the survey period, with humpback whale calls dominating the soundscape in the first weeks of deployment, coinciding with the migration towards their breeding grounds. From mid-April, sperm whales and delphinids were the predominant species, which coincided with increasing chlorophyll fluorescence values associated with the spring phytoplankton blooms. Finally, we report daily variations in background noise associated with fishing activities and traffic in the nearby East Atlantic shipping route. Our results show that gliders provide excellent platforms for collecting information about ecosystems with minimal disturbance to animals, allowing systematic observations of our ocean biodiversity and ecosystem dynamics in response to natural variations and industrial activities.

Palaeoenvironmental interpretation of the Pliocene fan-delta system of the Vera Basin (SE Spain): Fossil assemblages, ichnology and taphonomy

The marine fossil assemblages of the Pliocene of south Spain constitute the record of the marine fauna that colonised the western part of the Mediterranean after the Messinian Salinity Crisis. This work focuses on the analysis of lithofacies and fossil assemblages including trace fossils, invertebrates, and vertebrates with special attention to taphonomic features, for interpreting palaeoenvironmental conditions in the Vera Basin (SE Spain). The sedimentary sequences of the northern region of the Vera Basin display diverse stratigraphical, sedimentological, and palaeontological features that correspond to the evolution of a fan-delta in a narrow basin. The Vera Basin was characterised by shallow-marine shelf conditions during the early-mid Pliocene (Cuevas Formation). The basin emergence with the development of Gilbert-type fan deltas (Vera Member), and a protected, partially-enclosed marine embayment (Almanzora Member) occurred during the mid-late Pliocene due to regional uplift and movements of the Palomares strike-slip Fault along the eastern basin margin. The progradation of the central fan-delta lobes and the interaction with marginal fan-delta resulted in the partitioning of the basin that formed a small sub-basin with restricted stagnant conditions that favoured a Konservat Fossil-Lagerstätte. The high input of siliciclasts due to the uplift context of the margins of the basin favoured a high sedimentation rate and the fast burial of vertebrate remains. Fossil marine mammals occurs from shallow shelf deposits (Cuevas Formation) to bottomset (Cuevas Formation-Vera Member transition) and lower part of the clinoforms in the foreset (Vera Member). Cetacean remains are usually recorded not only in the relatively deep-water silty marls and sandy marls of the outer shelf and distal facies of the fan-delta (Espiritu Santo Formation), but also in the shallower coarse sands and conglomerates (Cuevas Formation and Espiritu Santo Formation). Sirenian remains, in contrast, are only recorded in coarse sand facies (Cuevas Formation and Espiritu Santo Formation) associated to charcoal wood fragments deposited in shallow waters near the shoreline. This narrow and relatively protected basin is interpreted as an area of reproduction and nursery of juveniles on the basis of the presence of cetaceans.

Influence of depredating cetaceans on albatross attraction and attendance patterns at fishing boats

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 605:49-59 (2018) - DOI: https://doi.org/10.3354/meps12757 Influence of depredating cetaceans on albatross attraction and attendance patterns at fishing boats Julien Collet1,*, Gaétan Richard1,2, Anais Janc1, Christophe Guinet1, Henri Weimerskirch1 1Centre d’Etudes Biologiques de Chizé UMR 7273 CNRS - Université de la Rochelle, 79360 Villiers en Bois, France 2Lab-STICC UMR 6285, ENSTA Bretagne, 2 rue François Verny, 29806 Brest Cedex 9, France *Corresponding author: pro@colletj.fr ABSTRACT: Human fisheries inadvertently attract and provide food for a range of wild organisms worldwide with important ecological consequences. Some animals directly feed on human catch (‘depredators’, e.g. killer whales), causing economical losses and calling for wildlife management. However the impact of depredation (and its potential management) on the behaviour of the other scavengers attracted to vessels (e.g. seabirds) is unknown. We examined how the fine-scale behavioural response of wandering albatrosses to a toothfish longline fleet was influenced by the presence of depredating killer and/or sperm whales. We hypothesized that the presence of depredating whales might facilitate detection of and/or access to food at fishing vessels for surface-feeding albatrosses. We used seabird GPS tracking together with a vessel monitoring system (GPS vessel tracking) coupled with systematic onboard records of depredator numbers during 3 fishing seasons. We found that when albatrosses ‘encountered’ vessels (n = 254), they had the same probability to start attending vessels whether or not cetaceans were present. However, once attracted, they attended the vessel longer when depredators were present. We conclude that birds are attracted to vessels independently of the presence of cetaceans, but that depredating whales probably facilitate access to food for surface-feeding birds such as the wandering albatross. Scavenging behaviour of seabirds does not appear to be strongly dependent on the presence of depredating cetaceans and is likely minimally affected by changes in cetacean behaviour. This type of data is rare and we discuss how these results for wandering albatrosses could be generalized for other seabird species. KEY WORDS: Fisheries interactions · Seabird foraging · Depredation · Longliners · Trophic interactions · GPS tracking · Sub-Antarctic · Toothed whales Full text in pdf format Supplementary material PreviousNextCite this article as: Collet J, Richard G, Janc A, Guinet C, Weimerskirch H (2018) Influence of depredating cetaceans on albatross attraction and attendance patterns at fishing boats. Mar Ecol Prog Ser 605:49-59. https://doi.org/10.3354/meps12757 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 605. Online publication date: October 26, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

Seasonal patterns of floating macro-litter across the Western Mediterranean Sea: a potential threat for cetacean species

Marine litter is a major form of pollution in the Mediterranean, but despite legislative requirements, additional information is still needed to evaluate basin-scale amounts, trends, and potential threats for the biota, especially for Habitats Directive listed species, such as cetaceans. Through repeated sampling of floating macro-litter along a fixed transect between Spain and Italy, this study provided detailed data within four marine sectors of the Western Mediterranean Sea, characterized by seasonal variability in oceanographic/ecological conditions and anthropogenic pressure. Moreover, we identified the areas of major overlap between high density of plastic and cetacean sightings. Litter was composed of plastic for more than 65%, with more diverse compositions occurring in the Balearic and Sardinian Sea compared to the semi-enclosed Bonifacio and Tyrrhenian sectors. The average amount of macro-litter ranged between 1.9 and 2.8 items km−2 and reached the highest values in spring/summer in all basins, suggesting a relationship with the increasing of touristic and maritime activities, both in coastal and offshore waters. The Balearic and Bonifacio sectors showed higher amounts and larger accumulation areas for plastic, likely due to a combination of multiple sources and oceanographic processes influencing the distributional patterns. Cetacean sightings were recorded in all sectors with fin whale (Balaenoptera physalus) and striped dolphin (Stenella coeruleoalba) as the most frequent species. The presence of cetaceans in areas with high densities of plastic emerged mostly during spring/summer in the Balearic and Bonifacio sectors, but other specific areas of potential exposure were identified, indicating the need for a dynamic definition of this threat.

Cetaceans using the marine protected area of "Parque Estadual Marinho da Laje de Santos", Southeastern Brazil

Abstract The aim of this study was to evaluate the presence of cetaceans in the waters surrounding the Marine Protected Area (MPA) known as “Parque Estadual Marinho da Laje de Santos (PEMLS)”, placed in coastal waters at the southeastern coast of Brazil. Boat-based surveys were conducted once a month from June 2013 to June 2015. A specific transect was followed to cover the area of the quoted MPA, as well as its borders. A total of 24 boat-surveys rendered 18 sightings of cetacean groups of the following species: Atlantic spotted dolphin (Stenella frontalis) (12), rough-toothed dolphin (Steno bredanensis) (2), common dolphin (Delphinus delphis) (1), Bryde’s whale (Balaenoptera edeni) (2) and common minke whale (Balaenoptera acutorostrata) (1). Sightings of S. frontalis, the commonest sighted species, was positively correlated with water depth (Mantel test; r = 0.8072; p < 0.05). Photoidentified individuals moved back and forth to inner and outer areas of the MPA, remaining in the area throughout the 2-year survey. “Paisley” cutaneous marks of unknown origin were reported in two common dolphins for the first time in local waters. As the PEMLS has been used as an important spot for SCUBA divers, it is recommended that cetacean sightings could still be gathered in a future partnership, as well as using the acoustics tool to detect their presence when researchers are not in the field.

Seasonal characterisation of maritime traffic and the relationship with cetacean presence in the Western Mediterranean Sea

Seasonal maritime traffic was investigated in relation to cetaceans, through direct observations (July 2013–June 2015) along three fixed transects in Western Mediterranean. Visually obtained vessel abundance was compared with Automatic Identification System data to explore if the two methods provided different results. Traffic intensity and composition were characterised by seasons and vessel categories. Finally, cetacean presence was investigated in relation to traffic by measuring the difference of vessel abundance in the presence and absence of animal sightings. Results showed that visual sampling was consistent with AIS data, providing more information on small-medium vessels. Traffic was more intense and diverse in Spring/Summer, and the highest vessel abundance and seasonal variations in composition emerged for inshore subareas. The difference of traffic in the presence and absence of cetaceans was higher in most offshore subareas in Spring/Summer, verified for B. physalus and S. coeruleoalba; in inshore waters, mostly occupied by T. truncatus, no significant differences emerged.

Detection rates of wild harbour porpoises and bottlenose dolphins using static acoustic click loggers vary with depth

Acoustic echolocation click loggers are widely used to study the presence and behaviour of coastal cetaceans. Various studies have examined their performance and how animal behaviour may affect click detection. This study examined the effect of logger depth in the water column on click detection rates for harbour porpoises (Phocoena phocoena) and bottlenose dolphins (Tursiops truncatus) at a coastal nearshore site. There were significantly more harbour porpoise clicks logged at the click loggers moored in the water column, closer to the surface, compared with those near the seabed. No such difference was recorded for bottlenose dolphins. The results were consistent throughout the study period and across sites, apart from a site closest to a possible feeding site, indicating that cetacean behaviour is among the possible factors explaining these findings. The study emphasizes the need for prior understanding of the target species and its habitat use, and stresses the importance of pilot studies to achieve reliable and meaningful data from static acoustic monitoring programs.

Seasonal presence of cetaceans and ambient noise levels in polar waters of the North Atlantic

In 2009 two calibrated acoustic recorders were deployed in polar waters of the North Atlantic to study the seasonal occurrence of blue, fin, and sperm whales and to assess current ambient noise levels. Sounds from these cetaceans were recorded at both locations in most months of the year. During the summer months, seismic airguns associated with oil and gas exploration were audible for weeks at a time and dominated low frequency noise levels. Noise levels might further increase in the future as the receding sea ice enables extended human use of the area.

Detecting and identifying cetaceans species from their acoustic emissions.

In the past decade, the use of autonomous remote passive acoustic recorders to detect the presence of cetaceans has grown enormously throughout the world. Since these devices digitize acoustic signals at sampling rates in the tens of kHz, a single device can quickly accumulate many Gbytes of data in a short time. Therefore, automatic detection and recognition algorithms must be developed to handle the large amount of data. There is no general signal method processing method that can be applied to all species of cetacean. The algorithm by the name of ROCCA (real-time odontocete call classification algorithm) developed by Dr. Julie Oswald is probably the most general one that has been applied to the whistles of dolphins. The program, extensible bio acoustics tool (XBAT) developed by Harold Figueroa, is probably the most general tool for use with baleen whales. However, investigators also tend to develop their own algorithms to suit their requirements. The problems and difficulties in developing automatic detection and recognition algorithms will be the focus of this presentation. General principles associated with the geography, biology, and the characteristics of sound emissions in relation to the development of algorithms will be discussed along with examples of different approaches.