Mass Stranding Research Articles

Decompressive Pathology in Cetaceans Based on an Experimental Pathological Model.

Decompression sickness (DCS) is a widely known clinical syndrome in human medicine, mainly in divers, related to the formation of intravascular and extravascular gas bubbles. Gas embolism and decompression-like sickness have also been described in wild animals, such as cetaceans. It was hypothesized that adaptations to the marine environment protected them from DCS, but in 2003, decompression-like sickness was described for the first time in beaked whales, challenging this dogma. Since then, several episodes of mass strandings of beaked whales coincidental in time and space with naval maneuvers have been recorded and diagnosed with DCS. The diagnosis of human DCS is based on the presence of clinical symptoms and the detection of gas embolism by ultrasound, but in cetaceans, the diagnosis is limited to forensic investigations. For this reason, it is necessary to resort to experimental animal models to support the pathological diagnosis of DCS in cetaceans. The objective of this study is to validate the pathological results of cetaceans through an experimental rabbit model wherein a complete and detailed histopathological analysis was performed. Gross and histopathological results were very similar in the experimental animal model compared to stranded cetaceans with DCS, with the presence of gas embolism systemically distributed as well as emphysema and hemorrhages as primary lesions in different organs. The experimental data reinforces the pathological findings found in cetaceans with DCS as well as the hypothesis that individuality plays an essential role in DCS, as it has previously been proposed in animal models and human diving medicine.

Directly Reprogrammed Neurons as a Tool to Assess Neurotoxicity of the Contaminant 4-Hydroxy-2',3,5,5'-tetrachlorobiphenyl (4'OH-CB72) in Melon-Headed Whales.

Whales accumulate high levels of environmental pollutants. Exposure to polychlorinated biphenyls (PCBs) and their metabolites (OH-PCBs) could be linked to abnormal behavior, which may lead to mass stranding of marine mammals. Whales may thus suffer from adverse effects such as neuronal dysfunction, yet testing the neurotoxicity of these compounds has never been feasible for these species. This study established neurons chemically reprogrammed from fibroblasts of mass stranded melon-headed whales (Peponocephala electra) and used them for in vitro neurotoxicity assays. Exposure to 4-hydroxy-2',3,5,5'-tetrachlorobiphenyl (4'OH-CB72), a metabolite of PCBs, caused apoptosis in the reprogrammed neurons. Transcriptome analysis of 4'OH-CB72-treated whale neurons showed altered expressions of genes associated with oxidative phosphorylation, chromatin degradation, axonal transport, and neurodegenerative diseases. These results suggest that 4'OH-CB72 exposure may induce neurodegeneration through disrupted apoptotic processes. A comparison of the results with human reprogrammed neurons revealed the specific effects on the whale neurons. Our noninvasive approach using fibroblast-derived neurons is useful for hazard and risk assessments of neurotoxicity in whales.

Why Trillions of Jellyfish Washed Ashore from Canada to California

Although warming oceans may make population booms and mass strandings more common, the species may ultimately be one of the beneficiaries of climate change.

Stejneger's beaked whale strandings in Alaska, 1995–2020

AbstractPresented here is the first comprehensive and updated compilation of history, distribution, and findings of Stejneger's beaked whales (Mesoplodon stejnegeri) in Alaska. Stejneger's beaked whales are a poorly understood, elusive, deep‐diving cetacean species found in the North Pacific Ocean. Since Stejneger's beaked whale strandings data in Alaska through 1994 were last published, 35 additional strandings have been documented. Twenty‐seven animals stranded in the Aleutian Islands, seven stranded in Southcentral Alaska, and one animal stranded on St. Lawrence Island. Twenty‐two carcasses were necropsied, but only four were fresh. Seventeen of the 22 died during mass stranding events and cause of death could not be definitively determined. Barotrauma was suspected in three cases and infectious disease possibly complicated by barotrauma occurred in two cases. We documented an expansion of strandings into the northern Bering Sea, characterized a sex bias, examined stomach contents that included macroplastic, and identified parasites not previously associated with Stejneger's beaked whales. Also included are data on the largest known mass stranding of Stejneger's beaked whales, which occurred on Adak Island in 2018. The history, distribution, and findings presented here are central to further our understanding of this species.

Strandings provide insight into social group structure of Atlantic white‐sided dolphins

AbstractAtlantic white‐sided dolphins (Lagenorhynchus acutus) are highly social odontocetes with a poorly understood tendency to mass strand. With limited capacity to study social ecology in the open ocean, mass strandings provide an opportunity to improve our understanding of group structure. Our study of 32 mass stranding events that occurred on Cape Cod, Massachusetts, between 1999 and 2009 identifies aspects of social ecology that vary across the year. A greater number of mass stranding events occurred outside of the breeding season and there was evidence of age‐structuring during the breeding season. We find generally low average intragroup pairwise relatedness assessed across eight microsatellite loci in a subset of 16 mass stranding events. Mass stranded groups do not show higher than expected relatedness when compared to a baseline estimate derived from single‐stranded individuals. Overall, our integration of genetic estimates of relatedness with data on sex and maturity‐class from stranded specimens suggests that Atlantic white‐sided dolphins fall near the more fluid end of the continuum from short‐term, highly fluid social associations to long‐term, stable groups represented among the odontocetes. Despite their tendency to mass strand, stable, kin‐based associations are not a defining feature of social group structure in this species.

Cetacean exploitation in Roman and medieval London: Reconstructing whaling activities by applying zooarchaeological, historical, and biomolecular analysis

Cetacean (whale, dolphin, and porpoise) remains are occasionally encountered at Roman and medieval sites in London and are regularly the topic of medieval historical sources. These sources are often concerned with whale strandings and the subsequent claims on the carcass by the king, queen, or other members of the nobility or clergy with jurisdiction over the coastline that the whale stranded upon. The meat stripped from the carcasses was regularly transported to London and cetaceans have therefore been ascribed as a “high-status food source”. Besides, strandings, several historical sources also suggest that active whaling was undertaken, and that meat was sold at several London markets. Based on these historical sources it however remains unclear to what extent active whaling was undertaken, and which species were exploited.Zooarchaeological studies address whales and their role in Roman and medieval society more directly through the study of animal bones. This study combines historical sources and the identification of zooarchaeological cetacean remains from the London sites of Bermondsey Abbey, Westminster Abbey (cellarium), Winchester Palace, Vintry, St Peter’s Hill, and Trig Lane through Zooarchaeology by Mass Spectrometry (ZooMS) and morphological analysis. The historical and zooarchaeological evidence from London indicates that cetacean meat was indeed associated with a high-status diet, in particular the ecclesiastical diet, though some form of commercialization of cetacean meat also took place. On occasion, whale bone was used for the creation of bone artefacts or tools, primarily during the Middle Saxon period. Additionally, it is suggested that active whaling might occasionally have been undertaken, potentially already from the Middle Saxon period onwards. However, the majority of the remains were probably acquired through opportunistic scavenging of stranded individuals.

Persistence, bioaccumulation and vertical transfer of pollutants in long-finned pilot whales stranded in Chilean Patagonia

Long-finned pilot whales (LFPW) are cetaceans with strong social groups often involved in mass strandings worldwide. However, these beachings occur for reasons that are not fully understood. In 2016, 124 LFPW were stranded on the Chilean Patagonian islands, offering a unique opportunity to obtain crucial information on the ecology, biology, and genetics of this population. In addition, we examined whether persistent organic pollutants (POPs) and trace elements (TEs) were responsible for this mass mortality. Stable isotopes (δ13C & δ15N) and genetic analyses were used to reconstruct the trophic ecology, social structure, and kinship of LFPW and compared to POPs and TEs levels found in LFPW. Mitochondrial DNA analyses on 71 individuals identified four maternal lineages within the stranded LFPW. Of these animals, 32 individuals were analyzed for a suite of POPs, TEs, and lipid content in blubber. The highest levels were found for ΣDDXs (6 isomers) (542.46 ± 433.46 ng/g, lw) and for total Hg (2.79 ± 1.91 mg/kg, dw). However, concentrations found in these LFPW were lower than toxicity thresholds and those reported for LFPW stranded in other regions. Evidence was found of ΣDDX, Σ7PCBs, and Cd bioaccumulation and maternal transfer of POPs in mother/offspring groups. Nevertheless, no clear relationship between contaminant concentrations and LFPW mortality was established. Further research is still needed to assess LFPW populations including conservations status and exposure to chemicals in remote areas such as Patagonia.

First records of Cuvier\u2019s beaked whale (Ziphius cavirostris, G. Cuvier 1823) strandings along the Tunisian coast

The Cuvier’s beaked whale (Ziphius cavirostris) is the only member of the Ziphiidae family with a regular occurrence in the Mediterranean Sea. Much of the knowledge of this species in the Mediterranean has come from stranding data. This note reports the first records of strandings of Cuvier’s beaked whales along the Tunisian coast. The two strandings described are about two specimens, likely adult animals. The first specimens was 530 cm long and beached at El Hicha (Gulf of Gabès, south Tunisia) on March 5th, 2019. The second specimens was 630 cm long and it was reported in Ras Angla (Bizerte, north Tunisia) on June 6th, 2019. Since this species faces multiple threats in the Mediterranean basin, this contribution is intended to extend previous knowledge of this species in the region and to push towards major efforts to be undertaken to fill the knowledge gaps regarding occurrence of Cuvier’s beaked whale along northern Tunisia.

Long-term patterns of mass stranding of the colonial cnidarian Velella velella: influence of environmental forcing

Velella velella is a pleustonic cnidarian noted worldwide for mass stranding of the colonial phase. Utilizing a 20 yr dataset (2000-2019; 23265 surveys) collected by the COASST citizen science program, we examined the spatio-temporal occurrence of mass strandings of V. velella along the Pacific Northwest coast from Washington to northern California, USA. V. velella mass strandings were documented in 14 years, with expansive events in 2003-2006 and 2014-2019. Events predominantly occurred in spring and were synchronous (April) among years, concurrent with shifts to prevailing onshore winds. Autumn mass stranding events occurred infrequently, with no consistent phenology (2005: November; 2014: August). In stranding years, reports of V. velella were mostly synchronous throughout the surveyed area, and events consistently spanned >400 km of coastline, with highest reporting rates in the vicinity of the Columbia River plume, collectively suggesting extensive V. velella blooms throughout the northern California Current system in some years. Annual metrics of spring V. velella reporting rate (proportion of beaches; January-June) were modeled as a function of indices representing sea surface temperature anomaly (SSTa), easterly (onshore) wind speed, and regional upwelling. The best models (based on Akaike’s information criterion corrected for small sample size) indicated that SSTa averaged over the preceding winter (December-February) was positively correlated with spring reporting rate, suggesting that mass strandings of V. velella may be more prevalent in warmer years. As planetary warming continues, and V. velella strandings are easily recorded by citizen science programs globally, we suggest that stranding prevalence may be one relatively easy measure providing evidence for epipelagic ecosystem response.

Occurrence of sperm whale (Physeter macrocephalus) in the Russian Arctic

We report two sperm whale (Physeter macrocephalus) strandings observed in the south-east corner of the Barents Sea (i.e., Pechora Sea) in 2018, unusually far from the species’ hitherto known distribution. While compiling a comprehensive overview of the occurrence of sperm whale sightings and strandings in the Russian Arctic, we learnt about one further stranding in the Pechora Sea, observed in 2017. All other records were from sites considerably closer to the species’ usual distribution. Reports from the eastern Russian Arctic suggest that sperm whales rarely, if ever, entered the Arctic from the Pacific Ocean. Although observed occurrences in the Russian Barents Sea have been few and sporadic, the occurrence of sperm whales in its south-eastern section appears to be a recent phenomenon, which is possibly related to declining sea-ice cover.

First Genetic Record of a Strap-Toothed Beaked Whale (Mesoplodon layardii) Stranding in Chile

Vicerrectoria de Investigacion y Desarrollo of the Universidad de Concepcion 219.153.026-P

Geomagnetic Storms Probably Don’t Cause Mass Cetacean Strandings

Solar-induced geomagnetic activity and mass strandings of whales and dolphins on shorelines both show seasonal patterns, but the beachings likely result from multiple environmental factors.

Occurrence of southern right whales (Eubalaena australis) along southeastern Brazil

This paper reports on the occurrence of southern right whales (Eubalaena australis) in southeastern Brazilian waters (18°S-25°S), withevidence of their use of the region as an important calving area. Only in recent years have right whale sightings and strandings been reportedregularly within the surveyed area. Of 71 distinct sightings reported since 1936, 39 (54.9%) were mother-calf pairs observed close to theshore. Most of these sightings (91.5%) were reported from early July to late October. Eight confirmed strandings of this species wereobserved within the surveyed area, six of which were between July and October. Stranded calves represented 62.5% of these records. Twocalves showed evidence of incidental capture. The increasing number of sightings, and recent reports of stranded calves and one adultfemale could be indicative of an increase in cetacean research efforts in the region. However, it also suggests use of the southeasternBrazilian coast as an important right whale calving area.

Stranding events of southern right whales, Eubalaena australis, in southern Brazil

Although international protection has been granted since 1935, southern right whales have only recently shown signs of recovery, possiblydue to anthropogenic factors. Off Brazil, illegal hunting of right whales occurred until 1973. This paper reports on surveys conducted alongthe southern Brazilian coast and the information recovered on right whale strandings for this area from 1977-1995. In the first 10 years ofthis period only four cases were registered. However, in contrast, 20 cases were counted during the last nine years. These results arediscussed in relation to marine traffic and the fisheries in the area that produce risks of collision and entanglement. Further, the possibilityof storm surges being a preponderant factor in the mortalities in this area is presented. These yearly rates are compared with neighbouringareas that are also inhabited by the right whales. Both possibilities fit the hypothesis that the right whales using the Brazilian coast forbreeding may finally be showing signs of recovery.

Exploring data from an individual stranding of a Cuvier's beaked whale in the Gulf of Taranto (Northern Ionian Sea, Central-eastern Mediterranean Sea)

Cetacean stranding events are an important source of information and biological samples, providing data on species occurrence, distribution and population dynamics as well as on mortality rate induced by human activities or natural causes. This is even truer for species such as Z. cavirostris, whose elusive behavior has made its field observation difficult in many Mediterranean areas. Although the occurrence of single or serial strandings of this species and the rise in survey effort have increased the knowledge on its presence, there are still gaps in some Mediterranean areas, especially in the Gulf of Taranto (North-western Ionian Sea, Italy), where a critical habitat suitable for different cetacean species has been identified. Despite no sightings of Z. cavirostris having been recorded so far, ACCOBAMS designates the Gulf of Taranto as an Area of Special Concern for Beaked Whales (ASC-BW) on the basis of atypical mass strandings of 12 individuals which occurred in the Ionian Sea in 2011. Moreover, the conservation status of the Z. cavirostris has recently passed from Data Deficient to Vulnerable, according the IUCN criteria adopted for the Mediterranean Sea, thus showing the urgent need for basic information on its bio-ecological features, suitable habitat and threats at local or wider scale. This study is the first attempt at application in the Mediterranean Sea of a Lagrangian prediction model simulating the carcass drift trajectories to investigate the at-site sea origin of an individual of Z. cavirostris stranded in the Gulf of Taranto. Moreover, a necropsy was carried out to detect the possible cause of death and the results of bacteriological, biomolecular and toxicological analysis are provided. Finally, a collection of osteological data as well as the process of turning and displaying the skeleton in a museum are detailed, highlighting the importance of these exhibits from a scientific and educational point of view.

Stable isotope assessment of a mass stranding of short-beaked common dolphins (Delphinus delphis delphis) reveals their provenance: Integrating knowledge of a little-known odontocete in the Gulf of California

The short-beaked common dolphin (Delphinus delphis delphis) (SBCD) is an odontocete inhabiting the Gulf of California (GC), Mexico; distributed widely in temperate to tropical waters, it is sometimes observed close to shore or in shallower areas. On 13 February 2018, a mass stranding of 54 SBCDs occurred in La Paz Bay in the southern GC; 21 individuals died, but the rest were released. Skin samples were removed from dead individuals for stable isotope analysis in order to infer their probable geographical provenance. Their mean ± S.D. were 17.0 ± 0.3‰ (δ15N) and -18.3 ± 0.2 (δ13C), with no significant differences between sexes or length. These isotope ratios do not correspond to the GC. Their low δ13C and δ15N values reflect offshore foraging grounds not under the 15N-enriching effects of the intense denitrification in the GC. Rather, these values were within the range of other piscivorous odontocetes that have been sampled in the GC and classified as outsiders (Pacific Ocean). Mean total length of these stranded SBCDs was similar to that reported for SBCDs off the Pacific coast of Baja California and southern California, but widely smaller than that reported for both eastern tropical Pacific SBCDs and long-beaked common dolphins (Delphinus delphis bairdii) in the northern and southern GC. These differences in isotopic niche and size between SBCDs stranded in La Paz Bay and long-beaked common dolphins from other regions of the GC highlight the need to be able to distinguish between the common dolphins (Delphinus) that inhabit the GC from those that visit the GC from off the Pacific coast of Baja California. Our findings confirm the ecological importance of the southern GC, where resident and visitor marine mammals congregate, leading to events like mass strandings that provide a unique source of information useful for research and conservation.

Insights on the origin and drift trajectories of Portuguese man of war (Physalia physalis) over the Celtic Sea shelf area

Many marine animals are difficult to study because they are widely dispersed across oceans and are not captured by traditional sampling methodologies such as fishery surveys. A case in point is the Portuguese man of war (Physalia physalis) (Linnæus, 1758), which despite being pleustonic and remarkably conspicuous, is one of the least studied and understood gelatinous zooplankton species, especially in terms of its ecology. During August to October 2016, the Irish coastline experienced the largest mass stranding of P. physalis in over 150 years. At the same time, P. physalis were recorded offshore in the Porcupine Seabight. Here we used these stranded and offshore observations of P. physalis to inform a Lagrangian particle-tracking model forced by wind to 1) hindcast the backwards drift of this species for three months to determine their likely origin and provide some insights on likely pathways to Irish shores and, 2) forecast the drift of this species towards the Irish coastline. Hindcasting stranded P. physalis from the Irish coastline suggested that they most likely originated from an extensive source area located over the European basin but ultimately from the North Atlantic Current. Our forecast model indicated that particles released from the Porcupine Seabight stranded on Irish shores, in fact, stranding patterns were 82% similar to actual strandings. Both models combined suggested that the Porcupine Seabight was an important source area, but that many P. physalis likely originated from further south and took a more tortuous trajectory towards Ireland determined by wind. This study also highlights the value of collecting routine beach strandings data and opportunistic offshore visual observations to inform future coastal and shelf modelling studies.

Statistical Analysis of the Possible Association Between Geomagnetic Storms and Cetacean Mass Strandings

AbstractCetacean mass strandings are one of the long‐standing mysteries in marine biology and many explanations have been proposed for the often‐fatal animal behavior. Geomagnetic activity that is driven by solar phenomena such as coronal mass ejections is one of the proposed explanations. In this study, we investigate if there is statistical evidence for a possible connection between mass strandings and geomagnetic storms. Fresh (live or recently deceased animals) mass stranding records from Cape Cod, USA, the United Kingdom, and New Zealand, together with global geomagnetic indices and local geomagnetic observations, are utilized in this investigation. While seasonal statistical association is found between cetacean mass strandings and geomagnetic field variations, the connection is likely a byproduct of the seasonality found in both types of data. No statistical associations are found in 30‐day or shorter time scales that are believed to be relevant for possible animal response to changes in geomagnetic conditions. If geomagnetic activity plays any role in fresh mass strandings analyzed in this investigation, the connection has to be very subtle and likely coupled with a complex combination of multiple environmental factors.

“Mostri Marini”: Constantine S. Rafinesque's names for three of Antonino Mongitore's Sicilian whales

In 1815, the naturalist Constantine Samuel Rafinesque (1783–1840) previewed three new species of cetaceans – Delphinus dalippus, Physeter urganantus and Oxypterus mongitori – that he intended to describe from Sicily based on illustrations in Antonino Mongitore's published work Della Sicilia ricercata nelle cose più memorabili (1742–1743). Although formal descriptions of the three species were never published, Rafinesque's reference to Mongitore's illustrations made the names available by “indication”. The names, nonetheless, fell into obscurity, most likely a result of contemporary taxonomists' lack of access to Mongitore's work. Rafinesque's names remain relevant to the history of cetacean taxonomy, although they are no longer applicable. Moreover, the animals associated with these names add to the historical record of whale strandings in the Mediterranean. For these reasons, we studied the illustrations Rafinesque indicated for his cetaceans and reviewed Mongitore's accompanying text, which together provide sufficient distinctive characters that two of the three animals can be confidently identified with modern species, namely the sperm whale, Physeter catodon Linnaeus, 1758 , and the false killer whale, Pseudorca crassidens (Owen, 1846). Had Rafinesque's name D. dalippus been recognized for what it was, it would have had priority over P. crassidens as the earliest scientific name for the false killer whale.

Morphometric regressions for the endangered Knysna seahorse, Hippocampus capensis, in the Swartvlei Estuary from mass stranding events

No abstract available.