Fin Whales Research Articles

Soviet catches of whales in the North Pacific: revised totals

The USSR conducted a global campaign of illegal whaling beginning in 1948. Catch records for Soviet pelagic operations in the Southern Hemisphere (and the northern Indian Ocean) have been largely corrected, but major gaps have remained for the North Pacific. Here, using newly discovered whaling industry reports, corrected figures for Soviet catches in this ocean are provided. During the period 1948–79, a minimum of 190,183 whales were killed by the USSR in the North Pacific (195,783 if one includes an estimate for sperm whales taken in years for which there are no true data); of these, only 169,638 were reported to the IWC, a difference of 20,568 whales (26,168 including the sperm whale estimate). Figures were falsified for 8 of 12 hunted species, with some catches over-reported to camouflage takes of illegal species. Revised catch totals (caught vs. reported) are as follows: blue whale – 1,621 vs. 858; fin whale – 14,167 vs. 15,445; humpback whale – 7,334 vs. 4,680; sperm whale – 153,686 vs. 132,505; sei whale – 7,698 vs. 11,363; North Pacific right whale – 681 vs. 11; bowhead whale – 145 vs. 0; gray whale – 172 vs. 24. Bryde’s, minke, killer and Baird’s beaked whale catches were reported correctly. Of all the hunted species, sperm and North Pacific right whales were the most heavily impacted. Major falsifications for sperm whales involved figures for both total catch and sex ratio.

Widespread passive acoustic monitoring reveals spatio-temporal patterns of blue and fin whale song vocalizations in the Northeast Pacific Ocean

The NOAA-NPS Ocean Noise Reference Station Network (NRS) is a passive acoustic monitoring effort to record the low-frequency (<2 kHz) sound field throughout the U.S. Exclusive Economic Zone. Data collection began in 2014 and spans 12 acoustic recording locations. To date, NRS datasets have been analyzed to understand spatial variation of large-scale sound levels, however, assessment of specific sound sources is an area where these datasets can provide additional insights. To understand seasonal patterns of blue whale,Balaenoptera musculus, and fin whale,B. physalus, sound production in the eastern North Pacific Ocean, this study explored data recorded between 2014 and 2020 from four NRS recording sites. A call index (CI) was used to quantify the intensity of blue whale B calls and fin whale 20 Hz pulses. Diel and seasonal patterns were then determined in the context of their migratory patterns. Most sites shared similar patterns in blue whale CI: persistent acoustic presence for 4–5 months starting by August and ending by February with a CI maximum in October or November. Fin whale patterns included persistent acoustic presence for 5–7 months starting by October and ending before April with a CI maximum between October and December. The diel patterning of blue whale song varied across the sites with the Gulf of Alaska, Olympic Coast, Cordell Bank, and Channel Islands (2014–2015) exhibiting a tendency towards nighttime song detection. However, this diel pattern was not observed at Channel Islands (2018–2020). Fin whale song detection was distributed evenly across day and night at most recording sites and months, however, a tendency toward nighttime song detection was observed in Cordell Bank during fall, and Gulf of Alaska and Olympic Coast during spring. Understanding call and migration patterns for blue and fin whales is essential for conservation efforts. By using passive acoustic monitoring and efficient detection methods, such as CI, it is possible to process large amounts of bioacoustic data and better understand the migratory behaviors of endangered marine species.

Abundance and distribution of marine mammals in nearshore waters off New Jersey, USA

Marine mammal abundance and distribution in New Jersey’s nearshore waters are not well known due to limited dedicated studies. The first yearround systematic surveys were conducted to determine the spatial/temporal distribution and estimate the abundance of marine mammals in this region prior to wind power development. Eight marine mammal species were observed: North Atlantic right whale (Eubalaena glacialis), humpback whale (Megaptera novaeangliae), minke whale (Balaenoptera acutorostrata), fin whale (Balaenoptera physalus), bottlenose dolphin (Tursiops truncatus), common dolphin (Delphinus delphis), harbour porpoise (Phocoena phocoena) and harbour seal (Phoca vitulina). Results indicate clear seasonal patterns in distribution and abundance. The fin whale, humpback whale and bottlenose dolphin were sighted during all seasons. The abundance of large whales in the study area was relatively low while the abundance of dolphin and porpoise species was high and largely seasonal. The bottlenose dolphin was the most abundant species; however, abundance was high only during spring and summer. Common dolphins and harbour porpoises were common in the study area during winter and spring. These baseline data will be used to assess potential environmental impacts of the construction and operation of offshore wind power facilities in this region.

Abundance of fin whales (Balaenoptera physalus) in the north‐western Mediterranean Sea, using photo‐identification and microsatellite genotyping

AbstractThe Mediterranean fin whale population, Balaenoptera physalus, is resident, with almost no exchanges with the Atlantic population. The entire population was estimated at 1300 or 13,300 individuals by a recent project depending on the platform used. This disparity shows the importance of long‐term monitoring with a unique protocol of survey. Capture‐recapture approaches using dorsal photographs and genetic identity collections over a 10 years period were used to estimate the abundance of the north‐western Mediterranean fin whale. We identified 332 individuals using photographs and 470 using genotypes, with a total of 546 individuals identified between 2008 and 2019, when some whales were double‐marked. The inter‐annual percentage of recapture varied between 15% and 17% respectively for genotypes and photographs methods. Using Cormack‐Jolly‐Seber models, the abundance of fin whales in the north‐western Mediterranean is estimated at 1295 individuals (95% CI: 1116–1474) with a survival probability of 0.945 (95% CI: 0.690–0.993) from genotypes. Abundance estimates from combined collections (photographs and genotypes) and corrected photograph estimates were similar to the genetic ones. Future studies might prioritize the genetic approach which is the least biased and with a narrower confidence interval. The genetic abundance estimates show relative stability over time, when compared to 1990 estimates, and should be included in future conservation actions.

Distributed acoustic sensing recordings of low-frequency whale calls and ship noise offshore Central Oregon.

Distributed acoustic sensing (DAS) is a technique that measures strain changes along an optical fiber to distances of ∼100 km with a spatial sensitivity of tens of meters. In November 2021, 4 days of DAS data were collected on two cables of the Ocean Observatories Initiative Regional Cabled Array extending offshore central Oregon. Numerous 20 Hz fin whale calls, northeast Pacific blue whale A and B calls, and ship noises were recorded, highlighting the potential of DAS for monitoring the ocean. The data are publicly available to support studies to understand the sensitivity of submarine DAS for low-frequency acoustic monitoring.

Analysis of environmental, social, and anthropogenic factors as potential drivers of breaching behavior in the Mediterranean fin whale

AbstractBreaching is frequently reported for many large cetacean species, but this behavior is considered very rare in fin whales (Balaenoptera physalus). Fin whales are regularly observed in the Mediterranean Sea, and they perform seasonal concentration/dispersal movements throughout this basin. This study aimed to investigate the influence that environmental parameters, social factors, and anthropogenic disturbance may have on breaching behavior in fin whales to deepen the understanding of these displays. Fin whale sightings were collected between 2012 and 2020 within the Fixed Line Transect Monitoring Network along the ferry route from Italy to Spain, crossing the mid‐latitudes of the western Mediterranean Sea. Breaching events were analyzed with respect to season, chlorophyll concentration, sea state, group size, fin whale frequency, distance between a breaching event and the closest whales, distance from the observation platform, and maritime traffic. During the study, breaching events were recorded 27 times over 721 fin whale sightings (3.74%), with a higher frequency during summer and fall (>4.96%) compared to spring (1.77%); no events were observed during winter. The most significant variables were distance from the observation platform as an inhibitory factor and distance between whales, possibly related to socialization and communication.

Influence of anthropogenic activities on marine mammal strandings in the estuary and northwestern Gulf of St. Lawrence, Quebec, Canada, 1994–2008

Stranding records have long been used to monitor marine mammal mortalities and to help identify threats to populations. In coastal areas, marinemammals face numerous anthropogenic threats such as marine traffic and commercial fishing. The objective of this study was to investigate marinemammal stranding records from the St. Lawrence Estuary (SLE) and the northwestern Gulf of St. Lawrence (NWGSL), Quebec, Canada from 1994to 2008 for evidence of anthropogenic trauma caused by entanglement in fishing gear, ship collisions and gunshots. Of 1,590 marine mammalstranding records, 12% (n = 192) had evidence of anthropogenic trauma, most incidents being reported during summer when activities such asmarine traffic, most commercial fishing and recreational boating, occurred and a greater number of species were present in the area. These incidentswere classified into five categories (Incidental catch, Ship collision, Severe injury, Gunshot, Other). There were 1,245 mortalities and observationson carcasses suggested that anthropogenic trauma led to the death of 11% (141/1,245) of marine mammals: 14% (87/627) of cetaceans and 9%(54/618) of seals. Mortality of seals due to anthropogenic trauma was low, involving mainly Gunshot for grey (26% or 8/31) and harbour seals(26% or 8/31). Over the study period, marine mammal incidents with evidence of anthropogenic trauma increased significantly, driven by an increasein Incidental catch for two mysticete species, the common minke whale, 42% (39/92) and humpback whale, 13% (12/92) and Other for harbourporpoise 67% (16/24). Ship collision was the most common anthropogenic trauma for fin whales (22% or 8/36) and SLE beluga5 (22% or 8/36).Severe injury was reported for 22% (2/9) of small cetaceans and 78% (7/9) of seals. Evidence from some harbour porpoise stranding records(categorised as Other) suggests illegal hunting, incidental catch, predation or scavenging by grey seals in a marine protected area. The observedincrease in Incidental catch of common minke and humpback whales may be due to: (1) a shift in distribution of these two species into the SLE andNWGSL, possibly related to changes in the ecosystem; (2) changes in fishery practices; and (3) an increase in detection of marine mammal strandings.Anthropogenic trauma affecting marine mammals was documented including some species at risk, such as the harbour porpoise, the St. LawrenceEstuary beluga population, blue and North Atlantic right whales, in the St. Lawrence ecosystem including in a marine protected area. This studydemonstrates the usefulness of stranding records in helping to monitor human-caused mortality in marine mammal populations.

The molecular evolution of genes previously associated with large sizes reveals possible pathways to cetacean gigantism

Cetaceans are a group of aquatic mammals with the largest body sizes among living animals, including giant representatives such as blue and fin whales. To understand the genetic bases of gigantism in cetaceans, we performed molecular evolutionary analyses on five genes (GHSR, IGF2, IGFBP2, IGFBP7, and EGF) from the growth hormone/insulin-like growth factor axis, and four genes (ZFAT, EGF, LCORL, and PLAG1) previously described as related to the size of species evolutionarily close to cetaceans, such as pigs, cows, and sheep. Our dataset comprised 19 species of cetaceans, seven of which are classified as giants because they exceed 10 m in length. Our results revealed signs of positive selection in genes from the growth hormone/insulin-like growth factor axis and also in those related to body increase in cetacean-related species. In addition, pseudogenization of the EGF gene was detected in the lineage of toothless cetaceans, Mysticeti. Our results suggest the action of positive selection on gigantism in genes that act both in body augmentation and in mitigating its consequences, such as cancer suppression when involved in processes such as division, migration, and cell development control.

Synchronous Swimming and Diving Behaviour in a Group of Fin Whales (Balaenoptera physalus)

Synchronous Swimming and Diving Behaviour in a Group of Fin Whales (Balaenoptera physalus)

Cetacean diversity of the eastern South Atlantic Ocean and Vema Seamount detected during a visual and passive acoustic survey, 2019

Abstract Cetaceans in the eastern South Atlantic Ocean are poorly studied. We present results from a 2 week ship-based survey from Cape Town to Vema Seamount (980 km to the west) during October–November 2019, including visual and towed-hydrophone observations from the vessel, and 10 days of acoustic monitoring on the seamount. Fifty-two hours of visual surveys resulted in 39 encounters of whale groups including seven of humpback, six of fin and one sei whale, as well as four unidentified baleen whales, 18 unidentified balaenopterid whales and four unidentified odontocetes. Two humpback whales at the seamount were engaged in possible feeding behaviour. A large aggregation of mostly fin whales was observed near the continental shelf edge (22 encounters over a 70 × 50 km2 area, six fin, one sei whale, 15 not confirmed to species), an historic whaling ground for both fin and sei whales. Towed-hydrophone data (78.7 h) detected five groups of sperm whales, 45 of delphinids, one beaked whale and no Kogiids. Acoustic data from the seamount detected calls from several baleen whale species including humpback whale non-song calls, Antarctic minke ‘bioduck’ calls, sei whale down-sweep calls and a likely Bryde's whale call. Two call types could not be assigned to species, including the most detected – a simple frequency-modulated call with peak power around 130 Hz. This study contributes to an improved understanding of cetacean occurrence in the eastern South Atlantic Ocean and highlights the need for more research to improve identification of cetacean vocalizations in the region.

Alkenone Uk’37 index differs between thermally separated populations of fin whales and krill

Although habitat temperature is an important determinant of species distributions, its measurement is difficult in mobile marine organisms. Chemical tracers such as alkenones constitute an alternative tool for gauging marine habitat temperature, something particularly relevant in the current scenario of global warming. The unsaturation index of alkenones, the Uk’37 index, can be used to estimate sea surface temperature (SST) in living organisms. Here, we analyse alkenone concentrations in a predator species, the fin whale, and its prey, the northern krill, both sampled in 2 areas with different SSTs: SW Iceland and NW Spain. In NW Spain (but not in SW Iceland), alkenone concentrations were higher in krill than in fin whale blubber, suggesting that they may biodilute along the trophic transfer. Consistently with local SST, the Uk’37 index was lower in the Icelandic samples of both fin whales and krill than in those from NW Spain, confirming the ability of this index to distinguish populations that are thermally separated. Whales are migratory animals; thus, the alkenones present in their blubber are a mix of those ingested locally and in recently visited regions. Consistently, the Uk’37 index showed a higher correlation with the local SST in krill than in fin whales. Alkenone turnover rates should be considered when using this proxy to assess the thermal range of the feeding habitat of a species. We conclude that the Uk’37 index is a potentially efficient tool to study the behaviour of whales, thus providing an alternative perspective to other chemical tracers.

An Inventory of Some Relatively Large Marine Mammals, Reptiles, and Fishes Sighted, Caught, By-Caught, or Stranded in the Mediterranean Coast of the Gaza Strip-Palestine

The Mediterranean Sea is home to an interesting biodiversity. The current cumulative and descriptive study aims to enumerate some relatively large marine mammals, reptiles, and fishes that have been spotted, caught, by-caught, or stranded on the coast of the Gaza Strip, Palestine, which extends about 42 km along the Mediterranean Sea. This 20-year study from 2003 to 2022 relied much on frequent field visits, meetings, and discussions with stakeholders, following local media sites and social media pages, and photography. The study recorded at least 26 giants or relatively large marine organisms on the Mediterranean coast of the Gaza Strip, Palestine. Certainly, the coming years may bring other marine organisms of relatively large sizes. Marine mammals included three species of cetaceans with the Fin Whale (Balaenoptera physalus) being the largest mammal and even the largest animal ever recorded in this study. Marine reptiles included three species of sea turtles, the largest of which is the Leatherback Sea Turtle (Dermochelys coriacea), which is in fact the world’s largest sea turtle. The bony fishes were represented by ten species, the largest of which was the Ocean Sunfish (Mola mola), which is the largest bony fish in the world. The cartilaginous fishes included ten species with the largest specimens encountered were the Shortfin Shark (Isurus oxyrinchus), Bluntnose Sixgill Shark (Hexanchus griseus), Scalloped Hammerhead Shark (Sphyrna lewini), and Giant Devil Ray (Mobula mobular). Seabirds were not included in the study. The Alexandria Pompano (Alectis alexandrinus) and the Silver-Cheeked Toadfish (Lagocephalus sceleratus), which are bony fishes, appear to be the relatively smallest marine organisms recorded here. In conclusion, the role of the various parties must be coordinated to ensure the sustainability of human activities and their compatibility with the task of conserving local marine biota, including the gigantic or relatively large ones.

Ship-strike forecast and mitigation for whales in Gitga’at First Nation territory

As marine traffic increases globally, ship strikes have emerged as a primary threat to many baleen whale populations. Here we predict ship-strike rates for fin whalesBalaenoptera physalusand humpback whalesMegaptera novaeangliaein the central territorial waters of the Gitga’at First Nation (British Columbia, Canada), which face increases in existing marine traffic as well as new liquified natural gas (LNG) shipping in the next decade. To do so, we utilized Automatic Identification System (AIS) databases, line-transect surveys, shore-based monitoring, whale-borne tags, aerial drone-based focal follows, and iterative simulations. We predict that by 2030, whale encounters will triple for most vessel types, but the change is most extreme for large ships (length >180 m) in prime whale habitat, in which co-occurrences will increase 30-fold. Ship-strike mortalities are projected to increase in the next decade by 2.3× for fin whales and 3.9× for humpback whales, to 2 and 18 deaths yr-1, respectively. These unsustainable losses will likely deplete both species in the coastal region of BC. Models indicate that the largest single source of mortality risk in 2030 will be from the LNG Canada project. Of the mitigation options we evaluated, a 10 knot speed ceiling for all large ships is potentially effective, but the best measure for guaranteed mitigation would be seasonal restrictions on LNG traffic. While certain data gaps remain, particularly with respect to humpback whales, our predictions indicate that shipping trends within Gitga’at waters will impact whale populations at regional levels. We provide our analysis in the R package ‘shipstrike’.

Identifying seasonal distribution patterns of fin whales across the Scotia Sea and the Antarctic Peninsula region using a novel approach combining habitat suitability models and ensemble learning methods

Following their near extirpation by industrial whaling of the 20thcentury, the population status of Southern Hemisphere fin whales (SHFW) remains unknown. Systematic surveys estimating fin whale abundance in the Southern Ocean are not yet available. Records of fin whale sightings have been collected by a variety of organisations over the past few decades, incorporating both opportunistic data and dedicated survey data. Together, these isolated data sets represent a potentially valuable source of information on the seasonality, distribution and abundance of SHFW. We compiled records across 40 years from the Antarctic Peninsula and Scotia Sea from multiple sources and used a novel approach combining ensemble learning and a maximum entropy model to estimate abundance and distribution of SHFW in this region. Our results show a seasonal distribution pattern with pronounced centres of distribution from January-March along the West Antarctic Peninsula. Our new approach allowed us to estimate abundance of SHFW for discrete areas from a mixed data set of mainly opportunistic presence only data.

Exploring marine mammal presence across seven US national marine sanctuaries

The United States of America’s Office of National Marine Sanctuaries (ONMS) hosts 15 National Marine Sanctuaries (NMS) and two Monuments in its waters. Charismatic marine megafauna, such as fin whales (Balaenoptera physalus), humpback whales (Megaptera novaeangliae), and various delphinid species frequent these areas, but little is known about their occupancy. As part of a national effort to better understand the soundscapes of NMS, 22 near-continuous passive acoustic bottom mounted recorders and one bottom-mounted cable hydrophone were analyzed within seven NMS (Stellwagen Bank, Gray’s Reef, Florida Keys, Olympic Coast, Monterey Bay, Channel Islands, and Hawaiian Islands Humpback Whale sanctuaries). The daily acoustic presence of humpback and fin whales across 2 years (November 2018–October 2020) and hourly presence of delphinids over 1 year (June 2019–May 2020) were analyzed. Humpback whales showed variability in their acoustic presence across NMS, but in general were mostly present January through May and September through December, and more scarce or fully absent June through August. Consecutive days of humpback whale vocalizations were greatest at sites HI01 and HI05 in the Hawaiian Islands Humpback Whale NMS and fewest at the Channel Islands NMS. Fin whales exhibited a similar seasonal pattern across the West Coast NMS and Stellwagen Bank NMS. Monterey Bay NMS had the greatest number of median consecutive presence of fin whales with fewest at Stellwagen Bank NMS. Delphinid acoustic presence varied throughout and within NMS, with sites at the Channel Islands and Hawaiʻi NMS showing the highest occupancy. All NMS showed distinct monthly delphinid acoustic presence with differences in detected hours between dayversusnight. Sixteen sites had medians of delphinid presence between one and three consecutive days, while three sites had 5 days or more of consecutive presence, and one site had no consecutive delphinid presence, showing clear variation in how long they occupied different NMS. Marine mammals utilized all NMS and showed a wide range of occupancy, emphasizing the importance of understanding species use across different NMS as biological areas for migration, breeding and foraging.

Biologically Important Areas II for cetaceans within U.S. and adjacent waters – Aleutian Islands and Bering Sea Region

We delineated and scored Biologically Important Areas (BIAs) for cetaceans in the Aleutian Islands and Bering Sea region. BIAs represent areas and times in which cetaceans are known to concentrate for activities related to reproduction, feeding, and migration, and also the known ranges of small and resident populations. This effort, the second led by the National Oceanic and Atmospheric Administration (NOAA), uses structured elicitation principles to build upon the first version of NOAA’s BIAs (BIA I) for cetaceans. Supporting evidence for BIA II came from aerial-, land-, and vessel-based surveys; satellite-tagging data; passive acoustic monitoring; Indigenous knowledge; photo-identification data; whaling data, including stomach and fecal contents; prey studies; and genetics. In addition to narratives, maps, and metadata tables, the BIA II products incorporate a scoring and labeling system, which will improve their utility and interpretability. BIAs are compilations of the best available science and have no inherent regulatory authority. They have been used by NOAA, other federal agencies, and the public to support planning and marine mammal impact assessments, and to inform the development of conservation measures for cetaceans. In the Aleutian Islands and Bering Sea region, a total of 19 BIAs were identified, delineated, and scored for seven species, including bowhead, North Pacific right, gray, humpback, fin, and sperm whales, and belugas. These include one hierarchical BIA for belugas that consists of one localized “child” BIA within an overarching “parent” BIA. There were 15 feeding, 3 migratory, and 1 small and resident population BIAs; no reproductive BIAs were identified. In some instances, information existed about a species’ use of a particular area and time, but the information was insufficient to confidently delineate the candidate BIA; in those cases, the candidate BIA was added to a watch list. A total of 22 watch list areas were identified and delineated for 10 species, including all species mentioned above and minke whales, harbor porpoises, and Dall’s porpoises. There were 15 feeding, 4 migratory, 2 reproductive, and 1 small and resident population watch list areas. Some BIAs and watch list areas were transboundary between the Aleutian Islands and Bering Sea region and the Arctic region.

A Robust Method to Automatically Detect Fin Whale Acoustic Presence in Large and Diverse Passive Acoustic Datasets

The growing availability of long-term and large-scale passive acoustic recordings open the possibility of monitoring the vocal activity of elusive oceanic species, such as fin whales (Balaenoptera physalus), in order to acquire knowledge on their distribution, behavior, population structure and abundance. Fin whales produce low-frequency and high-intensity pulses, both as single vocalizations and as song sequences (only males) which can be detected over large distances. Numerous distant fin whales producing these pulses generate a so-called chorus, by spectrally and temporally overlapping single vocalizations. Both fin whale pulses and fin whale chorus provide a distinct source of information on fin whales present at different distances to the recording location. The manual review of vast amounts of passive acoustic data for the presence of single vocalizations and chorus by human experts is, however, time-consuming, often suffers from low reproducibility and in its entirety, it is practically impossible. In this publication, we present and compare robust algorithms for the automatic detection of fin whale choruses and pulses which yield good performance results (i.e., false positive rates < 3% and true positive rates > 76%) when applied to real-world passive acoustic datasets characterized by vast amounts of data, with only a small proportion of the data containing the target sounds, and diverse soundscapes from the Southern Ocean.

A regime shift in the Southeast Greenland marine ecosystem.

Two major oceanographic changes have recently propagated through several trophic levels in coastal areas of Southeast Greenland (SEG). Firstly, the amount of drift-ice exported from the Fram Strait and transported with the East Greenland Current (EGC) has decreased significantly over the past two decades, and a main tipping element (summer sea ice) has virtually disappeared since 2003 leading to a regime shift in oceanographic and ecological conditions in the region. The following 20-year period with low or no coastal sea ice is unique in the 200-year history of ice observations in the region, and the regime shift is also obvious in the volume of ice export through the Fram Strait after 2013. In the same period, the temperature of the EGC south of 73.5N has increased significantly (>2°C) since 1980. Secondly, the warm Irminger Current, which advects warm, saline Atlantic Water into the region, has become warmer since 1990. The lack of pack ice in summer together with a warming ocean generated cascading effects on the ecosystem in SEG that are manifested in a changed fish fauna with an influx of boreal species in the south and the subarctic capelin further north. At higher trophic levels there has been an increase in the abundance of several boreal cetaceans (humpback, fin, killer, and pilot whales and dolphins) that are either new to this area or occur in historically large numbers. It is estimated that the new cetacean species in SEG are responsible for an annual predation level of 700,000 tons of fish. In addition, predation on krill species is estimated at >1,500,000 tons mainly consumed by fin whales. Simultaneously, there has been a reduction in the abundance and catches of narwhals and walruses in SEG and it is suggested that these species have been impacted by the habitat changes.

Fin Whale (Balaenoptera physalus) Mortality along the Italian Coast between 1624 and 2021.

The Mediterranean Sea hosts a population of fin whale (Balaenoptera physalus), the only species of Mysticete regularly occurring in the basin. Observed and inferred mortality suggests that the population is likely declining. Accordingly, understanding the causes of mortality and assessing the health status is pivotal to the survival of this endangered population. While such studies are inherently difficult for a highly roaming species with a pelagic distribution, mortality events provide the opportunity to investigate biological and epidemiological traits linked to these events, and evaluate the footprint of human activity, especially when long-term data series exist. We present a comprehensive spatial-temporal overview of fin whale mortality events along the Italian coast encompassing four centuries (1624-2021). Time series analysis was used to highlight structural changes in the evolution of mortality through time, while spatial-temporal patterns in the distribution of mortality events were assessed through emerging hot spot analysis methods. Recent mortality events (1964-2021) were further explored to evaluate, where possible, the primary causes of mortality and to identify anthropogenic threats of conservation concerns. This long-term survey offers the basis for an understanding of the health status of this B. physalus population and provides much-needed information for developing an effective management and conservation plan for the species in the region.

Acoustic and visual cetacean surveys reveal year-round spatial and temporal distributions for multiple species in northern British Columbia, Canada

Cetaceans spend most of their time below the surface of the sea, highlighting the importance of passive acoustic monitoring as a tool to facilitate understanding and mapping their year-round spatial and temporal distributions. To increase our limited knowledge of cetacean acoustic detection patterns for the east and west coasts of Gwaii Haanas, a remote protected area on Haida Gwaii, BC, Canada, acoustic datasets recorded off SG̱ang Gwaay (Sep 2009–May 2011), Gowgaia Slope (Jul 2017–Jul 2019), and Ramsay Island (Aug 2018–Aug 2019) were analyzed. Comparing overlapping periods of visual surveys and acoustic monitoring confirmed presence of 12 cetacean species/species groups within the study region. Seasonal patterns were identified for blue, fin, humpback, grey and sperm whale acoustic signals. Killer whale and delphinid acoustic signals occurred year-round on both coasts of Haida Gwaii and showed strong diel variation. Cuvier’s, Baird’s, beaked whale and porpoise clicks, were identified in high-frequency recordings on the west coast. Correlations between environmental factors, chlorophyll-a and sea surface temperature, and cetacean acoustic occurrence off Gwaii Haanas were also examined. This study is the first to acoustically monitor Gwaii Haanas waters for an extended continuous period and therefore serves as a baseline from which to monitor future changes.