Sound management of coastal resources is based on science-based decisions. Bottlenose dolphins are found around Puerto Rico; however, limited information exists on the ecology, behavior, sex ratio, distribution patterns, and population structure presenting, challenges in managing the bottlenose dolphin as defined in the Marine Mammal Protection Act of 1972. We sequenced the mitochondrial control region (mtDNA-CR) of 27 live and 11 stranded dolphins from Puerto Rico, five stranded dolphins from Guadeloupe and included sequences from the North Atlantic and the Pacific Ocean. Our genetic data from the new samples indicates the presence of distinct genetic lineages (inshore—represented by coastal individuals) and worldwide-distributed form (represented by both coastal and offshore individuals) in Puerto Rico. DNA divergence between inshore/coastal and offshore haplotypes ranged from 4.34 to 6.58

The killer whale (Orcinus orca) is a cosmopolitan cetacean distributed worldwide. Extensive studies have described its ecology and behavior across multiple polar and temperate regions. On the other hand, there is limited information on the distribution, ecological roles, and abundance of killer whales in tropical and subtropical regions. Herein, we build on previous work to update information on the spatiotemporal distribution, exploitation, and natural history of killer whales in the Caribbean Sea. We also document new records on their interaction with other species and human activities. We collated 385 records from the literature, online biodiversity information systems, the Internet (social networks and video-hosting websites), and citizen science-based initiatives. Records included sightings (87.3%), intentional captures (10.6%), bycatch (0.3%), and strandings (1.8%). Data primarily originated from research projects/activities (57%) and citizen science-based initiatives (43%). Records were distributed in the eastern Caribbean (39.5%), the southern Caribbean (19.7%), the Greater Antilles (19.2%), the Bahamian Region (13.0%), Central America (6.8%), and eastern Florida (1.8%). Killer whales were recorded year-round, but most data were reported between March and August (59.6%). The scarcity of records in Central America could reflect true lower densities in the region, lower observation effort, or a combination of the two. Because of the paucity of data, this study supports the growing importance of citizen-science initiatives to document the occurrence and ecology of this species in the Caribbean. Our dataset also confirms the occasional and widespread occurrence of killer whales throughout the Caribbean Sea. Potential low densities and limited predictability of their occurrence hinder dedicated research on this species.

Climate change and climate variability are affecting marine mammal species and these impacts are projected to continue in the coming decades. Vulnerability assessments provide a framework for evaluating climate impacts over a broad range of species using currently available information. We conducted a trait-based climate vulnerability assessment using expert elicitation for 108 marine mammal stocks and stock groups in the western North Atlantic, Gulf of Mexico, and Caribbean Sea. Our approach combined the exposure (projected change in environmental conditions) and sensitivity (ability to tolerate and adapt to changing conditions) of marine mammal stocks to estimate vulnerability to climate change, and categorize stocks with a vulnerability index. The climate vulnerability score was very high for 44% (n = 47) of these stocks, high for 29% (n = 31), moderate for 20% (n = 22), and low for 7% (n = 8). The majority of stocks (n = 78; 72%) scored very high exposure, whereas 24% (n = 26) scored high, and 4% (n = 4) scored moderate. The sensitivity score was very high for 33% (n = 36) of these stocks, high for 18% (n = 19), moderate for 34% (n = 37), and low for 15% (n = 16). Vulnerability results were summarized for stocks in five taxonomic groups: pinnipeds (n = 4; 25% high, 75% moderate), mysticetes (n = 7; 29% very high, 57% high, 14% moderate), ziphiids (n = 8; 13% very high, 50% high, 38% moderate), delphinids (n = 84; 52% very high, 23% high, 15% moderate, 10% low), and other odontocetes (n = 5; 60% high, 40% moderate). Factors including temperature, ocean pH, and dissolved oxygen were the primary drivers of high climate exposure, with effects mediated through prey and habitat parameters. We quantified sources of uncertainty by bootstrapping vulnerability scores, conducting leave-one-out analyses of individual attributes and individual scorers, and through scoring data quality for each attribute. These results provide information for researchers, managers, and the public on marine mammal responses to climate change to enhance the development of more effective marine mammal management, restoration, and conservation activities that address current and future environmental variation and biological responses due to climate change.

Isurus paucus (Longfin Mako) is a mesopelagic shark inhabiting tropical and subtropical waters. While records of Longfin Makos have been documented for the Western North Atlantic, only a few records exist for the Caribbean. On 3 March 2019, a large shark was found stranded off Barceloneta, Puerto Rico. We thoroughly examined the carcass and identified it as a 333-cm adult female shark with diagnostic characteristics consistent with that of a Longfin Mako. We analyzed collected skin for species identification, which confirmed the identification genetically. Longfin Makos are subjected to extensive fishing, both commercially and recreationally. Thus, they are of conservation concern due to their sparse distribution, low abundance, and external threats. International conservation measures need to be implemented to protect this squalid.

Standardized sightings of the common bottlenose dolphin (Tursiops truncatus) from the south and west coasts of Puerto Rico were quantitatively analyzed to determine the spatio-temporal distribution patterns of sighting location, group size, composition and behavior in relation to key features such as distance from shore, depth and habitat type. Dolphin inhabit primarily the nearshore zone within 5 km of the coast, but they are also associated with edge and slope habitats of the platform and bank/islands off the west coast. Dolphins were rare both over the central portion of the western platform, characterized as a broad area of sand, as well as in deep waters outside the shelf edge zone. Although dolphins were sighted in various habitat types, the most predominant were sea grass beds (44%), sand (25%), and reef (22%). Only 17% of the sightings were in deeper waters, such as the shelf edge and mid platform, which were dominated by hard bottom. Multiple, multivariate correlations based on distance (DISTLM) showed that the only statistically significant predictor for dolphin relative abundances was Habitat Evenness (AIC = 250.89; R-2 = 0.12; p = 0.003). On the other hand, for behavior data, DistLM showed that the only significant predictor was average rugosity (AICc = 551.21, R-2 = 0.09, p = 0.02), where social behavior was more common in high rugosity areas, while traveling predominated in low rugosity areas. Given the predominately inshore distribution of bottlenose dolphins, their low abundance, and multiyear residency we believe the area off the west coast of Puerto Rico should be designated as a Critical Habitat.

Opportunistic encounters by experts and the public (i.e. fishermen, tourists) can be great assets to understanding cetacean distribution, especially in areas where surveys are limited. Sightings of Puerto Rican pelagic cetaceans have been reported in the past, with known seasonality in some species. Within this report, we document sightings for eight species, report new monthly distributions for three of these species, as well as the presence of rough-toothed dolphins close to the coast, and the first underwater sighting of a minke whale (Balaenoptera acutorostrata) off San Juan, Puerto Rico. Unfortunately, the lack of long-term studies due to limited funding and resources has been an obstacle in determining species diversity and overall health of cetacean populations. However, this note provides evidence that collaboration between marine biologists and citizen-based science is possible and desired, and serves as a valuable resource to protect and conserve native, pelagic, and transient cetacean species around Puerto Rican waters.

A new record of Megachasma pelagios is here reported for the tropical western North Atlantic Ocean from Puerto Rico.

The abundance of the common bottlenose dolphin, Tursiops truncatus (Montagu, 1821), was investigated by mark-recapture methods using photographic surveys on the south and west coasts of Puerto Rico from 2013 to 2015.The number of individuals having distinctive marks was 62, representing 46.5% of dolphins observed.Additionally, two dorsal fins were matched with photos taken during a study in 2000, making this the first report of long-term resightings in Puerto Rico.The abundance estimate for the south and west coast of Puerto Rico was of 127 dolphins.This represents a statistically significant, 60% decrease from the reported estimate back in 2001.It is unclear whether this decline is due to emigration, mortality, or a combination of the two.Management should prioritize further studies on the health of this population and the potential factors contributing to the decline, such as overfishing or excessive boat traffic.

Despite years of collecting anecdotal and scientific information of cetaceans around Puerto Rico, the false killer whale (Pseudorca crassidens), was never reported. Here, we report the first stranding and sighting event to take place in Puerto Rico in January, and March 2013, respectively. Both events took place along the south coast of Puerto Rico. During the sighting, cooperative prey sharing tactics were observed when two animals appeared to attack a common dolphinfish (Coryphaena hippurus).

Killer whales Orcinus orca are found in all oceans of the world, but most of our knowledge on the species comes from studies conducted at higher latitudes. Studies on killer whales in the Caribbean have been scarce. We compiled 176 records of killer whales from the Caribbean, including 95 previously unreported records and 81 records recovered from the literature, consisting of 27 capture or kill records, 4 stranding records and 145 sighting records. Our results indicate that killer whales are widespread in the Caribbean Sea and can be found year-round in the region. Mean group size was 3.7 animals. A diversity of prey items was recorded, including sea turtles and marine mammals and possibly fish. We cannot exclude ecotype or morphotype-specific dietary specialization in the Caribbean population. A preliminary morphological analysis of 10 characters in 52 individuals from 21 different groups suggests that Caribbean killer whales do not represent any of the four Antarctic and subantarctic types, type 1 from the northwest Atlantic, or ‘resident’ and ‘transient’ killer whales from the northwest Pacific. Some Caribbean killer whales share a combination of characters typical of type 2 in the North Atlantic, whereas others share those typical of ‘offshore’ killer whales in the northwest Pacific. The significance of this is unclear. Comparison of Caribbean killer whales to previously described morphotypes and ecotypes is hampered by the lack of detailed, quantitative data on variation within other types, as well as by the lack of comparisons of genetic diversity. Our study adds to the growing knowledge of the diversity of killer whales worldwide but underscores that additional research is warranted in the tropics.