Ship Strikes Research Articles

Cost-effectiveness of measures to reduce ship strikes: A case study on protecting the Mediterranean fin whale

Collisions between ships and whales can pose a significant threat to the survival of some whale populations. The lack of robust and holistic assessments of the consequences of mitigation solutions often leads to poor compliance from the shipping industry. To overcome this, several papers support a regulatory approach to the management of whale-ship collisions through the International Maritime Organization (IMO), the UN agency responsible for maritime affairs. According to the IMO risk assessment approach, in order to compare the costs of implementing mitigation solutions and their benefits, there is a need for a well-defined risk evaluation criterion. To define such a criterion for whales, we have used an ecological-economic framework based on existence values and conservation objectives. As an illustration, we have applied our framework to the Mediterranean fin whale (Balaenoptera physalus) population and determined the cost of averting a whale fatality as a proxy for the societal benefits. More precisely, we have estimated the ‘Cost of averting a Mediterranean fin whale fatality’ of 562,462 (in 2017 US dollars); this corresponds to 637,790 USD when converted to 2021 US dollars. The societal benefits of solutions that reduce the risk to whales could therefore be weighed against the costs of shipping companies to implement such measures. This could lead to assessments that are more transparent and the introduction of mandatory measures to reduce ship strikes.

Endangered Blue Whale Survival in the North Atlantic: Lagging Scientific and Governance Responses, Charting Future Courses

Abstract Populations of blue whales were heavily depleted across the globe by industrial whaling and are still considered globally endangered today. In the Northwest Atlantic, an estimated 400–600 individuals remain, but these numbers are highly uncertain. Ship strikes, fishing gear entanglement, and marine debris are thought to be leading causes of contemporary human-caused mortality in blue whales, with anthropogenic noise possibly causing sublethal stress and injury. Climate change is recognised as an emerging and intensifying threat that is likely to affect food supply and could limit the capacity of the population to recover. Both Canada and the United States have protected blue whales through their domestic legislation. This article reviews law and policy responses in the two countries, as well as bilateral, regional and international frameworks that address anthropogenic threats to blue whales. Future scientific directions, as well as recommendations for improvements to domestic legislation and multilevel cooperation are outlined.

Computing ship strikes and near miss events of fin whales along the main ferry routes in the Pelagos Sanctuary and adjacent west area, in summer

AbstractThe Mediterranean Sea is a high‐density maritime traffic area, particularly in the Pelagos Sanctuary. Ship strikes pose a substantial threat to fin whales (Balaenoptera physalus) according to reports from the IUCN, the IWC, the ACCOBAMS and the EU Habitats Directive.Near miss events (NMEs) were collected, as a proxy indicator of ship strikes for fin whales, along the main ferry routes crossing the Pelagos Sanctuary and adjacent western waters during ‘summertime’ (April to October). The ‘Fixed Line Transect Med Network’ carries out systematic surveys from ferries and collects data according to the ‘linear transect’ method. From 2008 to 2019, 13 different ferry routes were surveyed with 238,499 km monitored.Of the 2,775 fin whales encountered, 43 individuals were involved in NMEs (1.55% of the sightings). NMEs occur over the great majority of the routes monitored with enough effort and were correlated with the density index of fin whales.High‐risk areas for NMEs were identified in the central and deeper parts of the north‐western Mediterranean Sea and in some sections of the northern Tyrrhenian Sea.Of all NMEs, the majority of whales (63.4%) surfaced in front of the vessel (<50 m), leaving no time for the crew to manoeuvre the vessel. The others were travelling (26.8%) or resting (9.7%) without any noticeable reaction at the vessel.The speed of the ferries seems to play a role in the occurrence of the NME, as this parameter is significantly different (t‐test,P = 0.002) for NMEs compared to all fin whale sightings, whereas month and hour of day were not.Quantifying NMEs based on real‐time observation with observers on board, could be used as a feasible and efficient way to limit collisions, raising awareness by the crew, and testing or evaluating other potential tools that can help mitigate this threat.

Protecting right whales from ship strikes

Protecting right whales from ship strikes

Western Gull Foraging Behavior as an Ecosystem State Indicator in Coastal California

With accelerating climate variability and change, novel approaches are needed to warn managers of changing ecosystem state and to identify appropriate management actions. One strategy is using indicator species—like seabirds as ecosystem sentinels—to monitor changes in marine environments. Here, we explore the utility of western gulls (Larus occidentalis) breeding on Southeast Farallon Island as a proxy of ecosystem state in coastal California by investigating the interannual variability in gull foraging behavior from 2013 to 2019 in relation to upwelling conditions, prey abundances, and overlap with humpback whales (Megaptera novaeangliae) as gulls frequently feed in association with whales. Western gulls have a flexible diet and forage on land and at-sea. We combined gull GPS tracking data during the incubation phase, ecosystem survey data on multiple predator and prey species, and derived oceanographic upwelling products. When foraging at sea, gulls overlapped with cool upwelled waters. During 2015–2017, 25% more gull foraging trips visited land than in other years, where land trips were on average ∼8 h longer and 40% further than sea trips, which coincided with high compression of coastally upwelled waters (habitat compression) in 2015–2016. Gull foraging behavior was related to local prey abundances, where more foraging occurred near shore or on land when prey abundances were low. However, visual surveys indicated that ∼70% of humpback whale observations co-occurred with gulls, and the year with the most foraging on land (2017) corresponded to regionally low relative whale abundances, suggesting gull movement patterns could be an indicator of whale presence. Further, both whales and gulls forage near-shore under high upwelling habitat compression and low krill abundance. Hence, the deployment of year-round tags on gulls with the capability of near real-time data accessibility could provide important fine-scale metrics for conservation and management of the threatened yet recovering eastern Pacific humpback whale population between infrequent and coarse surveys. Entanglement in fishing gear and ship strikes are major inhibitors to whale recovery and have increased concomitantly with human use of ocean resources. Moreover, as climate variability and change increase, novel indicators should be explored and implemented to inform marine spatial planning and protect species across multiple scales from new risks.

Morphology and Histology of the Mysticete’s Prostate and Its Implications in Male Fertility

The global whale population has dramatically declined in the past centuries due to anthropogenic abuse, whereas, climate change, ship strikes, entanglements, pollution, and water debris are currently making an enormous impact on the recovery of all whales on the planet.
 The prostate is recognized as the only male accessory gland in odontocete cetaceans, and prostatic pathologies have been recently described as very common in these animals. But nothing is reported about the male accessory gland in any species of mysticete. Here, we describe the topography and histology of the prostate of two baleen whales: a fin whale (Balaenoptera physalus) and a Bryde’s whale (Balaenoptera edeni) and conclude that in the mysticetes, the prostate displays the same general morphologic and histologic characteristics as in odontocetes.
 The prostatic gland of the mysticete may be a target for many pathogens that wants to spread by a sexual transition to other animals and the offspring which may have great impact on reproductive capability for the individuals.

Vessel Strikes of Large Whales in the Eastern Tropical Pacific: A Case Study of Regional Underreporting

Vessel strike is recognized as a major modern threat to the recovery of large whale populations globally, but the issue is notoriously difficult to assess. Vessel strikes by large ships frequently go unnoticed, and those involving smaller vessels are rarely reported. Interpreting global patterns of vessel strikes is further hindered by underlying reporting biases caused by differences in countries’ research efforts, legislation, reporting structures and enforcement. This leaves global strike data “patchy” and typically scarce outside of developed countries, where resources are more limited. To explore this we investigated vessel strikes with large whales in the Eastern Tropical Pacific (ETP), a coastal region of ten developing countries where heavy shipping and high cetacean densities overlap. Although this is characteristic of vessel strike “hotspots” worldwide, only 11 ETP strike reports from just four countries (∼2% of total reports) existed in the International Whaling Commission’s Global Ship Strike Database (2010). This contrasts greatly with abundant reports from the neighboring state of California (United States), and the greater United States/Canadian west coast, making it a compelling case study for investigating underreporting. By reviewing online media databases and articles, peer review publications and requesting information from government agencies, scientists, and tourism companies, we compiled a regional ETP vessel strike database. We found over three times as many strike reports (n= 40), from twice as many countries (n= 8), identifying the geographic extent and severity of the threat, although likely still underestimating the true number of strikes. Reports were found from 1905 until 2017, showing that strikes are a regional, historic, and present threat to large whales. The humpback whale (Megaptera novaeangliae) was the most commonly hit species, and whale-watch industries involving small vessels in areas of high whale densities were recognized as a conservation and management concern. Industrial fishing fleets and shipping were suggested to be underrepresented sectors in the database, and are likely high-risk vessels for strikes with whales. We demonstrate the implications of known vessel strike reporting biases and conclude a more rapid assessment of global vessel strikes would substantially benefit from prioritized research efforts in developing regions, with known vessel strike “hotspot” characteristics, but few strike reports.

Ocean Regime Shift is Driving Collapse of the North Atlantic Right Whale Population

Ocean warming linked to anthropogenic climate change is impacting the ecology of marine species around the world. In 2010, the Gulf of Maine and Scotian Shelf regions of the Northwest Atlantic underwent an unprecedented regime shift. Forced by climate-driven changes in the Gulf Stream, warm slope waters entered the region and created a less favorable foraging environment for the endangered North Atlantic right whale population. By mid-decade, right whales had shifted their late spring/summer foraging grounds from the Gulf of Maine and the western Scotian Shelf to the Gulf of St. Lawrence. The population also began exhibiting unusually high mortality in 2017. Here, we report that climate-driven changes in ocean circulation have altered the foraging environment and habitat use of right whales, reducing the population’s calving rate and exposing it to greater mortality risks from ship strikes and fishing gear entanglement. The case of the North Atlantic right whale provides a cautionary tale for the management of protected species in a changing ocean.

Modeling Whale Deaths From Vessel Strikes to Reduce the Risk of Fatality to Endangered Whales

Vessel strikes have been documented around the world and frequently figure as a top human cause of large whale mortality. The shipping lanes in the Santa Barbara Channel, California and nearby waters have some of the highest predicted whale mortality from vessel strikes in the United States waters of the eastern Pacific. Beginning in 2007, National Oceanographic and Atmospheric Administration requested voluntary vessel speed reductions (VSRs) for vessels greater than 300 GT traveling in the Santa Barbara Channel shipping routes to decrease whale mortality from ship strikes. We employed a ship strike model using whale density data and automatic identification system (AIS) vessel data to estimate mortality under several management scenarios. To assess the effect of the VSR on strike mortality, we bootstrapped speeds from vessels greater than 19 m long that transited when no VSR was in place. Finally, we calculated the predicted mortality for hypothetical cooperation scenarios by artificially adding speed caps post-hoc to real vessel transits. For 2012–2018, we estimated that in our study area on average during summer/fall (June–November) 8.9 blue, 4.6 humpback, and 9.7 fin whales were killed from ship strikes each year (13–26% greater than previously estimated). We evaluated winter/spring (January–April) humpback mortality for the first time, resulting in an estimate of 5.7 deaths on average per year. Poor cooperation with the VSR led to low (5% maximum) to no reductions in the estimated number of strike mortalities. Evaluating potential scenarios showed that if 95% cooperation occurred in the lanes, whale deaths there would decrease by 22–26%. Adding VSRs with similar cooperation levels at the northern end of the Santa Barbara Channel and south of Channel Islands National Marine Sanctuary could decrease estimated strike mortalities in those areas by 30%. If VSRs were added and cooperation reached 95% there and in the lanes, we estimate a 21–29% decrease in vessel strike mortalities could be attained relative to estimated mortality in the entire study area. To decrease the vessel strike related whale mortalities in this region, we recommend expanding the VSR areas and increasing cooperation voluntarily, or considering mandatory speed limits if desired cooperation levels cannot otherwise be met.

Locating ship strike risk hotspots for fin whale (Balaenoptera physalus) and sperm whale (Physeter macrocephalus) along main shipping lanes in the North-Western Mediterranean Sea

The Pelagos Sanctuary is the only pelagic marine protected area in the Mediterranean Sea, instituted for the conservation of cetaceans. Considering the number and size of commercial and touristic ports located along its coasts, this protected area is highly impacted by human activities, and especially marine traffic. Fin whales and sperm whales are regularly sighted in the Pelagos Sanctuary, and ship strikes with large vessels are one of the main threats affecting these two species. Mapping hotspots of distribution along main shipping lanes could be an effective conservation tool, as they directly allow locating high risk areas. In this work, we used data collected during summer from 2009 to 2019, along main marine traffic corridors in the central region of Pelagos Sanctuary. Ship strike hotspots have been identified, considering the persistence of distribution hotspots over the 11 years period. Hotspots occurrence has then been predicted over the entire Pelagos Sanctuary area applying Generalized Additive Models, allowing for ship strike risk assessment over the marine protected area. Our results highlighted the recurrence of important areas for both species along shipping lanes characterized by high vessel traffic, identifying regions where to address conservation measures.

Patterns of cortisol and corticosterone concentrations in humpback whale (Megaptera novaeangliae) baleen are associated with different causes of death.

Baleen whales are subject to a myriad of natural and anthropogenic stressors, but understanding how these stressors affect physiology is difficult. Measurement of adrenal glucocorticoid (GC) hormones involved in the vertebrate stress response (cortisol and corticosterone) in baleen could help fill this data gap. Baleen analysis is a powerful tool, allowing for a retrospective re-creation of multiple years of GC hormone concentrations at approximately a monthly resolution. We hypothesized that whales that died from acute causes (e.g. ship strike) would have lower levels of baleen GCs than whales that died from extended illness or injury (e.g. long-term entanglement in fishing gear). To test this hypothesis, we extracted hormones from baleen plates of four humpback whales (Megaptera novaeangliae) with well-documented deaths including multiple and chronic entanglements (n = 1, female), ship strike (n = 2, male and female) and chronic illness with nutritional stress (n = 1, male). Over ~3 years of baleen growth and during multiple entanglements, the entangled whale had average corticosterone levels of 80–187% higher than the other three whales but cortisol levels were similar to two of the other three whales. The nutritionally stressed and chronically ill whale showed a slow increase in both cortisol and corticosterone spanning ~3 years, followed by a sharp decline in both hormones before death, possibly indicative of adrenal failure in this moribund individual. This whale’s correlation between cortisol and corticosterone was significant but there were no correlations in the other three whales. Our results show that cortisol and corticosterone concentrations vary according to the type and duration of illness or injury. Single-point GC concentrations should be interpreted with caution as low values can occur in whales experiencing pronounced stress and individual baselines can be highly variable. Baleen analysis is a promising tissue type for retrospective analyses of physiological responses to various stressors affecting baleen whales.

Diel differences in blue whale (Balaenoptera musculus) dive behavior increase nighttime risk of ship strikes in northern Chilean Patagonia.

The northern Chilean Patagonia region is a key feeding ground and a nursing habitat in the southern hemisphere for blue whales (Balaenoptera musculus). From 2014 to 2019, during 6 separate research cruises, the dive behavior of 28 individual blue whales was investigated using bio‐logging tags (DTAGs), generating ≈190 h of data. Whales dove to significantly greater depths during the day compared to nighttime (day: 32.6 ± 18.7 m; night: 6.2 ± 2.7 m; P < 0.01). During the night, most time was spent close to the surface (86% ± 9.4%; P < 0.01) and at depths of less than 12 m. From 2016 to 2019, active acoustics (scientific echosounders) were used to record prey (euphausiids) density and distribution simultaneously with whale diving data. Tagged whales appeared to perform dives relative to the vertical migration of prey during the day. The association between diurnal prey migration and shallow nighttime dive behavior suggests that blue whales are at increased risk of ship collisions during periods of darkness since the estimated maximum ship draft of vessels operating in the region is also ≈12 m. In recent decades, northern Chilean Patagonia has seen a large increase in marine traffic due to a boom in salmon aquaculture and the passenger ship industry. Vessel strike risks for large whales are likely underestimated in this region. Results reported in this study may be valuable for policy and mitigation decisions regarding conservation of the endangered blue whale.

Co-occurrence of gray whales and vessel traffic in the North Pacific Ocean

All species of large whales are susceptible to vessel strikes, but the true scale and geographical extent of such strikes is not known. This paper provides a qualitative assessment of the range-wide risks posed to gray whalesEschrichtius robustusby vessels, by comparing patterns of whale distribution with the density of vessel traffic seasonally throughout the North Pacific in 2019. Areas of very high vessel density were evident year-round near many coastlines, along inter-continental trade routes, and at hubs of commercial shipping near port entrances. Gray whales were exposed to vessel strikes throughout their range and in their feeding, southbound migration, wintering, and northbound migration periods. Areas of apparently high risk were in the Russian Far East (Kamchatka peninsula and Okhotsk Sea), Bering Sea (including the Aleutian Islands), Gulf of Alaska, and along the entire west coast of North America. Risk appeared greatest during south- and northbound migration when much of the gray whale population is moving through waters near shore. Tanker, container, and bulk-carrier ships represent considerable risk to whales in the North Pacific Ocean, but the large geographical extent of commercial fishing activities suggests that fisheries are also a substantial source of risk. Vessel-strike risk maps indicate the relative extent of exposure of gray (and other) whales to underwater vessel noise. The number of gray whales killed by ship strikes each year may be in the tens, or perhaps the low hundreds. Additional analyses, including quantitative assessments, are warranted to further clarify the risk of vessel strikes to gray whales.

Gray Whale (Eschrichtius robustus) Health and Disease: Review and Future Directions

The eastern North Pacific gray whale (Eschrichtius robustus) population is considered “recovered” since the days of commercial whaling, with a population of over 25,000 animals. However, gray whale habitat is changing rapidly due to urbanization of the migratory coastal corridor, increases in shipping, and climate change altering water conditions and prey distribution. Increased single strandings and intermittent large-scale mortality events have occurred over the past twenty years, raising questions about how gray whale health is affected by whale population size (density dependence), climate change and coastal development. To understand the impacts of these factors on health and the role of health changes in whale population dynamics, increased understanding of the pathogenesis and epidemiology of diseases in gray whales is needed. To date, most information on gray whale health and disease are in single case reports, in sections of larger papers on whale ecology, or in technical memoranda and conference proceedings. Here we review existing data on gray whale health and disease to provide a synthesis of available information and a baseline for future studies, and suggest priorities for future study of gray whale health. The latter include nutritional studies to distinguish annual physiological fasting from starvation leading to mortality, identification of endemic and novel viruses through increased use of molecular techniques, quantifying parasitic infections to explore interactions amongst prey shifts and parasite infection and body condition, as well as enhancing necropsy efforts to identify stochastic causes of mortality such as ship strikes, entanglements and predation. Integration of health and disease studies on individual animals with population monitoring and models of whale/prey dynamics will require interdisciplinary approaches to understand the role of health changes in population dynamics of this coastal whale.

Mortality and serious injury of northern right whales (Eubalaena glacialis) in the western North Atlantic Ocean

Northern right whales in the western North Atlantic number about 300 animals and have shown little sign of recovery in recent decades.Mortality and serious injury due to human activities, particularly commercial fishing and shipping, are thought to be significant factorslimiting their recovery. From 1970-1999, 45 right whale deaths were reliably documented. Sixteen of these fatalities (35.5%) were due toship collisions, and three (6.7%) were due to entanglement in fishing gear. The remainder were neonates (13; 28.9%) and ‘unknown cause’mortalities (13; 28.9%). Criteria for defining serious injuries and mortalities from entanglement or ship strikes were developed and includeany animal carrying fishing gear, cuts from entanglement or ship strike deeper than 8cm, swelling or necrosis, evidence of poor health fromsuch interactions, and, in carcasses, evidence of haematoma, haemorrhaging or broken bones. A total of 56 animals fitting the definedcriteria were documented from 1970-1999: 31 (55.4%) from entanglement and 25 (44.6%) from ship strikes. Nineteen were fatal (16 shipstrikes, 3 entanglements), 10 were possibly fatal (2 ship strikes, 8 entanglements) and 27 were non-fatal (7 ship strikes, 20 entanglements).The breakdown of potentially serious injuries by age and sex reveals no difference in levels between sexes but shows a 3.3:1 higher levelof interaction in juveniles and calves versus adults. The data show that ship strikes are more immediately lethal, but entanglements can resultin long term deterioration of an animal and may be responsible for higher levels of mortality than previously thought. Considering that someanimals become entangled, drown and never return to the surface, even these levels may be underestimated. Between 1986 and 1999, 84animals were presumed dead based on a lack of resightings for six years. There were 32 confirmed deaths during this time period suggestingthat at least as many unreported deaths occurred as carcasses were reported. Definitive actions need to be taken to reduce the level andseverity of anthropogenic injuries and deaths. Actions could include continued disentanglement efforts, gear modifications, seasonalclosures for fisheries, mandatory ship reporting, ships’ routing measures and speed restrictions for commercial shipping.

Mortalities of right whales and related anthropogenic factors in South African waters, 1963-1998

Between 1963 and 1998, 55 mortalities of southern right whales and a further three ‘possible right whale’ mortalities were recorded on theSouth African coastline. Of the known right whale mortalities, 31 could be classified as ‘calves of the year’, 8 as juveniles and 14 as adults.Relatively few (6.5-16.1%) of the calf mortalities could be attributed to anthropogenic factors, compared to juveniles (25-50%) and adults(35.7-57.1%). Apparent causes of death included ship strikes (4 definite, 7 possible) and entanglement (4 definite, 1 possible), with oneharpooning incident. Five non-fatal ship strikes and 16 instances of non-fatal entanglement were also recorded. Whilst the gear mostcommonly involved in non-fatal entanglement was crayfish trap lines, three of the four entanglement fatalities involved longline gear. Theincidence of scars attributable to previous entanglement remained constant amongst mature females from 1979-1997, at 3-4%. Recordedmortalities increased over the period 1963-1997 at a rate no different from that of population growth over the same period. The current levelof anthropogenic mortality does not seem to be affecting population recovery.

Assessing the lethality of ship strikes on whales using simple biophysical models

AbstractStudies of ship strikes on whales often focus on large vessels (&gt;20 m), with attention to their speeds and the resulting risk of lethality. Smaller coastal vessels also co‐occur with whales, resulting in collisions that merit study. To cast light on injuries caused by vessels of all sizes, we used knowledge of right whale anatomy and Newtonian mechanics to construct simple models that predict the mechanical stresses experienced by whales during collisions. By comparing our predictions with published models and with data from ship strikes on various whale species, we developed a model for lethal injury as a function of several vessel and whale properties, finding that collisions that create stresses in excess of 0.241 MPa were likely to cause lethal injuries to large whales. Furthermore, this model has revealed that (1) vessels of all sizes can yield stresses higher than this critical level, and (2) large vessels produce stresses much larger than this even when travelling at reduced speeds (i.e., 10 knots). The model is fast enough to power an interactive GUI‐based tool (in R) and flexible enough to simulate strikes by vessels of different masses and speeds upon whales of different species, sizes, and physical conditions.

Estimating effectiveness of speed reduction measures for decreasing whale-strike mortality in a high-risk region

Recent estimates of blue (Balaenoptera musculus) and humpback (Megaptera novaeangliae) whale ship-strike deaths on the US west coast are above the Potential Biological Removal limit determined by the National Marine Fisheries Service. Beginning in 2015, the National Oceanographic and Atmospheric Administration requested voluntary Vessel Speed Reductions (VSR) in the designated shipping routes off San Francisco, California, USA, in order to decrease whale mortality from ship strikes. We applied a ship strike model based on whale density and Automatic Identification System (AIS) vessel data. We bootstrapped speeds from vessels that transited when no VSR was in place to assess the effect of the VSR on strike mortality rates. Finally, we calculated the expected mortality for hypothetical compliance scenarios by programmatically imposing speed caps. Average predicted mortality for the region was 2.7 blue whales and 7.0 humpback whales in a 4 month period. Compared to years prior to the VSR (2012-2014), vessel speeds during the VSR were slower. This lowered blue whale deaths within the shipping lanes by 11-13% and humpback whale deaths by 9-10% in 2016-2017. If 95% of mariners adhered to recommended 10 knot (kn) limits in the shipping lanes alone, we predicted twice as many blue whale and 3 times as many humpback whale deaths would be avoided relative to current adherence. Adding a 10 kn speed limit (with 95% cooperation) at the ends of each of the lanes would result in about 5- and 4-fold reductions in blue whale and humpback whale mortality, respectively, relative to current practices. Our approach can evaluate ship strikes and mitigation measures for whale populations around the globe.

Lipids of lung and lung fat emboli of the toothed whales (Odontoceti)

Lipids are biomolecules present in all living organisms that, apart from their physiological functions, can be involved in different pathologies. One of these pathologies is fat embolism, which has been described histologically in the lung of cetaceans in association with ship strikes and with gas and fat embolic syndrome. To assess pathological lung lipid composition, previous knowledge of healthy lung tissue lipid composition is essential; however, these studies are extremely scarce in cetaceans. In the present study we aimed first, to characterize the lipids ordinarily present in the lung tissue of seven cetacean species; and second, to better understand the etiopathogenesis of fat embolism by comparing the lipid composition of lungs positive for fat emboli, and those negative for emboli in Physeter macrocephalus and Ziphius cavirostris (two species in which fat emboli have been described). Results showed that lipid content and lipid classes did not differ among species or diving profiles. In contrast, fatty acid composition was significantly different between species, with C16:0 and C18:1ω9 explaining most of the differences. This baseline knowledge of healthy lung tissue lipid composition will be extremely useful in future studies assessing lung pathologies involving lipids. Concerning fat embolism, non-significant differences could be established between lipid content, lipid classes, and fatty acid composition. However, an unidentified peak was only found in the chromatogram for the two struck whales and merits further investigation.

Habitat suitability of Rhincodon typus in three localities of the Gulf of California: Environmental drivers of seasonal aggregations.

The whale shark is an endangered species that usually feeds in coastal areas of highly productive seas such as the Gulf of California, Mexico. This study aims to describe the effect of sea surface temperature, chlorophyll a, bathymetry and slope on the habitat suitability of whale sharks in three important aggregation sites of the Gulf of California. A total of 2396 records of occurrence of whale sharks were obtained from international databases and scientific literature between 1996 and 2018. These records were used for the creation of a species distribution model using MaxEnt for each of the three aggregation sites. The concentration of chlorophyll a explained 71% of the habitat suitability, followed by bathymetry and slope with a combined 17%, and sea surface temperature constituting 10% of the model. Habitat suitability was related to areas where nontargeted fisheries may impact whale sharks through bycatch, entanglement and ship strikes. The implications for the conservation of whale sharks should be considered for management decisions in terms of marine protected areas, fishing refugees or bans, and other regulations regarding fisheries activities.