Introduction
In the Caribbean Sea, orcas (Orcinus orca, also known as killer whales) are present throughout the year, although in low densities such that their occurrence is not predictable (Bolaños-Jiménez et al., Reference Bolaños-Jiménez, Kiszka, Bouveret, Rodríguez-Ferrer, Ramos, Henriquez, Luksenburg, Bernus, Briceño and Sánchez Criollo2023). Despite this, the most recent review indicates 385 records, of which at least 51 (13%) cases have occurred in Venezuelan waters (Bolaños-Jiménez et al., Reference Bolaños-Jiménez, Kiszka, Bouveret, Rodríguez-Ferrer, Ramos, Henriquez, Luksenburg, Bernus, Briceño and Sánchez Criollo2023). That review confirmed seven strandings of the species in the Caribbean Sea in the period May 1851 to January 2023, all of which were single strandings and only one of which occurred on the Venezuelan coastline (Rodríguez et al., Reference Rodríguez, Acosta, Pérez, Urdaneta, Parada, Cabezas, Fuenmayor, Arrieche, Gómez, Bong, Viloria and Duarte1993; Bolaños-Jiménez et al., Reference Bolaños-Jiménez, Mignucci-Giannoni, Blumenthal, Bogomolni, Casas, Henríquez, Iñíguez Bessega, Khan, Landrau-Giovannetti, Rinaldi, Rinaldi, Rodríguez-Ferrer, Sutty, Ward and Luksenburg2014a, Reference Bolaños-Jiménez, Balladares, Barrios-Garrido, Bermúdez-Villapol, De Turris, Espinoza, González-Fernández and Sánchez-Criollo2014b, Reference Bolaños-Jiménez, Kiszka, Bouveret, Rodríguez-Ferrer, Ramos, Henriquez, Luksenburg, Bernus, Briceño and Sánchez Criollo2023, Figure 1). That Venezuelan record was from an adult male approximately 6.5 m in length who live-stranded on 25 January 1979. He stranded on the sand banks near Isla San Carlos at the mouth of Lago de Maracaibo along the coast of the Gulf of Venezuela (Rodríquez et al. Reference Rodríguez, Acosta, Pérez, Urdaneta, Parada, Cabezas, Fuenmayor, Arrieche, Gómez, Bong, Viloria and Duarte1993). That location is approximately 900 km to the west of the mass stranding event (MSE) described herein. The purpose of this report is to document the circumstances of the rescue and release of seven orcas that stranded on the coast of north-eastern Venezuela.
Figure 1. The location of the mass stranding event described herein (blue pin on globe and light-blue circle, right main map) in relation to Venezuela, the equator, the Caribbean Sea and the Atlantic Ocean. Also shown is the location of the only other mass stranding of orca in tropical waters, at the Marquesas Island (pink pin on globe), in the Pacific Ocean. The main map shows the north and north-eastern coast of Venezuela, indicating the single orca stranding site (white circle, left) from 25 January 1979 and sightings of free-swimming orca in central and northern coastal Venezuelan waters (red diamonds). The yellow box indicates the area shown in more detail in Figure 2.
Worldwide, historical records show that orca MSEs are not common. In their worldwide review, covering the period between the late 19th or early 20th centuries and 2007, Brownell et al. (Reference Brownell, Visser, van Helden and Poole2007) documented 22 MSE, with only one in a tropical region (i.e. between 23.5°N to 23.5°S). That orca MSE occurred in the Pacific Ocean at Nuka Hiva (08°48′S, 140°05′W), Marquesas Islands, French Polynesia where three orcas stranded and were rescued on 6 July 2005. Although Barbieri et al. (Reference Barbieri, Raverty, Hanson, Venn-Watson, Ford and Gaydos2013) listed 23 mass strandings of three or more orcas from the northern Pacific, of which only eight overlapped with Brownell et al. (Reference Brownell, Visser, van Helden and Poole2007), and Visser, Cooper and Brownell (unpubl. data) added others from around the world, to bring the total to over 45 events in 11 countries, there were no other MSE in tropical regions.
Material and Methods
Data and information for this report were collected onsite by two of the authors (Y. N. and M. N.) in coordination with J. A. M. and M. A. B. V., and by means of additional interviews with fishers. We also reviewed the videos and multimedia material made available to the authors by eyewitnesses. Confirmation of species was based on species-specific field identification features such as the post-ocular eye patch and the sexually dimorphic dorsal fin of an adult male (e.g. see details given in Heyning and Dahlheim, Reference Heyning and Dahlheim1988; Dahlheim and Heyning, Reference Dahlheim, Heyning, Ridgway and Harrison1999; Jefferson et al., Reference Jefferson, Webber and Pitman2015).
We determined the ages/sexes of the individuals as follows; an adult sexually mature male had a dorsal fin that was prominent and could attain a height of up to 1.8 m, it had relatively larger pectoral fins, the tips of its tail flukes may curl down/inwards and its overall body was significantly larger than an adult female. Of note is that no other cetacean species has a dorsal fin of such proportions as found on adult male orca (Jefferson et al., Reference Jefferson, Webber and Pitman2015). A sub-adult (adolescent/pubescent) male had a dorsal fin which may have begun to sprout (i.e. a secondary sexual characteristic where the dorsal fin undergoes rapid growth in height during the onset of sexual maturity), the pectoral fins may have begun to grow, its tail flukes may have begun to curl and it may be similar or larger in body size to an adult female. An adult female had a dorsal fin that reached a maximum of ~1 m and she did not show any of the secondary sexual characteristics in the dorsal fin, pectoral fin and tail flukes as seen in an adult or pubescent male. We considered an individual that was ~50–80% smaller in size than an adult female to be a juvenile and an individual that was <50% smaller in size than an adult female to be a calf (i.e. likely to be partially or exclusively nutritionally dependent on its mother). We note that without viewing the genital region to confirm sex, it can be difficult to determine a non-sprouted (pre-pubescent) male from an adult female and in this publication all animals of this size which were not identified as sub-adult male were classified as adult female (see Dahlheim and Heyning, Reference Dahlheim, Heyning, Ridgway and Harrison1999; Jefferson et al., Reference Jefferson, Webber and Pitman2015 for detailed descriptions of species morphology and Olesiuk et al., Reference Olesiuk, Bigg and Ellis1990, Reference Olesiuk, Ellis and Ford2005 for further details regarding sexual maturity in the species).
All cetacean species are protected in Venezuelan waters on the basis of the ‘Ley de Protección a la Fauna Silvestre' (República de Venezuela. 1970) and the ‘Ley de Gestión de la Diversidad Biológica’ (República Bolivariana de Venezuela. 2008). Furthermore, all species are included in Annex II of the Specially Protected Areas and Wildlife (SPAW) Protocol of the International Convention for the Protection and Development of the Marine Environment of the Wider Caribbean Region (Cartagena Convention) that require the parties to ensure total protection and recovery to listed species, including O. orca.
In Venezuela, marine mammal rescues are conducted on an ad hoc basis and are coordinated at a local level by those on site who may have little to no experience with strandings and/or rescues (Bolaños-Jiménez et al., Reference Bolaños-Jiménez, Mignucci-Giannoni, Blumenthal, Bogomolni, Casas, Henríquez, Iñíguez Bessega, Khan, Landrau-Giovannetti, Rinaldi, Rinaldi, Rodríguez-Ferrer, Sutty, Ward and Luksenburg2014a, Reference Bolaños-Jiménez, Balladares, Barrios-Garrido, Bermúdez-Villapol, De Turris, Espinoza, González-Fernández and Sánchez-Criollo2014b; Bolaños-Jiménez, unpubl. data). Typically, all rescued cetaceans are released directly into the ocean without any welfare assessment and follow up is not conducted. Therefore, in order to determine post hoc if the orcas described herein were indeed suitable candidates for the rescue and release that was undertaken, we assessed the status of the animals using interviews with those on site as well as the videos and photos obtained. For body condition, if the outlines of the ribs or spinal processes were not visible, if there was no depression behind the head at the location of the nuchal fat pad [which when concave in shape is colloquially referred to as peanut head] and if their bodies had an overall robust shape (i.e. they were not skinny), then we considered that the individual was in excellent body condition (see Raverty et al., Reference Raverty, St. Leger, Noren, Burek Huntington, Rotstein, Gulland, Ford, Hanson, Lambourn, Huggins, Delaney, Spaven, Rowles, Barre, Cottrell, Ellis, Goldstein, Terio, Duffield, Rice and Gaydos2020 for examples of a range of body conditions in stranded orca). For sunburn/windburn the skin was assessed for sloughing, cracking and blisters (see Sweeney and Ridgway, Reference Sweeney and Ridgway1975) and St. Leger et al. (Reference St. Leger, Raverty, Mena, Terio, Mcaloose and St. Leger2018) for some diagnostics in cetaceans and Bossley and Woolfall (Reference Bossley and Woolfall2014) for case studies. As some stranded cetaceans are assumed to be dehydrated (e.g. see Nollens et al., Reference Nollens, Venn-Watson, Gili, Mcbain, Gulland, Dierauf and Whitman2018), if the individuals' skin was smooth and showed no signs of wrinkling or cracking and pressure from human hands did not result in any depressions on the skin, we considered that the animal did not show external signs of harmful water deprivation. We also assessed the visible portions of each animal's body for injuries and entanglements.
For a posteriori behavioural and welfare assessments we used the observations of co-authors YN and MN, who were onsite, interviews and videos from the event and we noted if the individuals appeared to be attempting to move, reacted to external stimulus and if they were bright, alert and responsive (BAR). Although assessment of stranded cetaceans, using video, has been conducted before (e.g. Boys et al., Reference Boys, Beausoleil, Pawley, Betty and Stockin2022), such work has not included orcas. Noting that INV has attended multiple cetacean strandings of various species (including more than 10 orca events), we used unpublished data from those strandings as a framework to assess welfare and stress at a behavioural level. For example, we noted if there were any signs of thrashing or sudden adverse reactions to the rescuers or the events of the rescue. We noted if there were vocalisations and their extent (e.g. intermittent or continuous) and we used breathing rates along with the force of exhalation, all as proxies to assess stress.
Results
On 23 August 2023, at approximately 06:30 h, fishers from the fishing towns of Chacopata and Guayacán discovered seven orcas stranded in shallow (~1–2 m deep) waters near the mouth of the Chacopata Lagoon (approx. 10°39′30″N, 63°49′43″W, Figure 2), Parroquia Chacopata, Municipio Cruz Salmerón Acosta, Sucre State, Venezuela. The seafloor in this area is composed entirely of sand and although generally flat, there were 15–30 cm high ridges, typical of tidal sand habitats of this region. The stranding location was protected from large swells from the Caribbean Sea by the Islas de Margarita, Coche and Cubagua (Nueva Esparta State) to the north and north-west, and the headland of Chacopata to the north-east (Figure 2). At the time of the event the sea state varied between Beaufort 0 and 1, with no swell. Low tide was at 00:48 h and high tide was at 10:47 h, i.e. the tide was incoming, with a tidal height variation of 0.10–0.25 m between low and high tide respectively (data sourced from www.tablasdemareas.com). There was a light haze with no cloud cover and the air temperature upon discovery was ~22°C, reaching ~24°C by the time of release at about 9 am, and the sea surface temperature was ~27°C.
Figure 2. Stranding location (blue dot in A, B and C) and locations mentioned in the text; (A) Islas de Margarita, Cubagua, Coche and Archipiélago de los Frailes, north-eastern coast of Venezuela, (B) the Chacopata headland, towns of Chacopata and Guayacán, Laguna de Chacopata and Isla Caribe, (C) Laguna de Guayacán. The blue arrow (C) indicates direction of travel after the rescue. Note the extensive sand banks in the region where the animals stranded.
The fishers reported the event to the authorities of the Socialist Institute for Fisheries and Aquaculture (INSOPESCA) and the Bolivarian National Coast Guard Division (GNB-DVC) of the town of Guayacán. Immediately, authorities and fishers totalling ~40 people began a spontaneous yet coordinated effort to rescue the animals and release them into deeper waters. This effort was managed directly in the water and from vessels anchored and floating nearby. It was based primarily on the expertise and leadership of the fishers.
The cetaceans were confirmed as O. orca based on the species-specific black, white (Figure 3) and grey pigmentation patterns (Figure 4). The presence of an adult male was also confirmation of the species. Of note is that the saddle patches on the individuals were all a ‘typical’ grey colour, i.e. similar to those described for some of the orcas found in the region (Bolaños-Jiménez et al., Reference Bolaños-Jiménez, Mignucci-Giannoni, Blumenthal, Bogomolni, Casas, Henríquez, Iñíguez Bessega, Khan, Landrau-Giovannetti, Rinaldi, Rinaldi, Rodríguez-Ferrer, Sutty, Ward and Luksenburg2014a, Reference Bolaños-Jiménez, Balladares, Barrios-Garrido, Bermúdez-Villapol, De Turris, Espinoza, González-Fernández and Sánchez-Criollo2014b) and not opaque or dark as has been noted for a number of tropical orcas (e.g. see Mäkeläinen et al., Reference Mäkeläinen, Visser, Cooper and Cusson2024) or faint as found on a few individuals from the wider Caribbean Sea (Bolaños-Jiménez et al., Reference Bolaños-Jiménez, Mignucci-Giannoni, Blumenthal, Bogomolni, Casas, Henríquez, Iñíguez Bessega, Khan, Landrau-Giovannetti, Rinaldi, Rinaldi, Rodríguez-Ferrer, Sutty, Ward and Luksenburg2014a, Reference Bolaños-Jiménez, Balladares, Barrios-Garrido, Bermúdez-Villapol, De Turris, Espinoza, González-Fernández and Sánchez-Criollo2014b) or missing altogether (e.g. Visser et al., Reference Visser, Cooper, Cothran, McCormack, Grimm, Mäkeläinen and Cusson2024).
Figure 3. Species-specific pigmentation characteristics included white pigmentation on the mandibles and eye patches, as illustrated on two of the stranded orcas (A, juvenile; B, adult female). The arrow in A indicates where the adult male was stranded in relation to the juvenile, approximately 40 m away. Images from video by Freddy Romero, courtesy Mary Jose González Silva.
Figure 4. Grey saddle patches on three of the orcas (A, juvenile; B, adult female (foreground); C, sub-adult male), with B also showing the tight clustering of the group of three orcas. A fourth orca, an adult female is just out of frame to the right in B (see Figure 6 which shows her position in relation to these three). Note the notch in the trailing edge of the fin of the sub-adult male in C. Images from video by Freddy Romero, courtesy Mary Jose González Silva.
The group of seven orcas was comprised of one adult and two sub-adult males of differing sizes – one with a clearly sprouted fin and one with a fin that was yet to sprout but which had curled tail flukes and which was larger than the females, three females and one juvenile. Both sub-adult males had distinctive notches on the trailing edge of their dorsal fin suitable for individual identification (Figures 4 and 5). A comparison was made with the Caribbean catalogue but no matches were found (Ruano, Reference Ruano Cobian2024). Photographs/video of the event illustrated the distribution of the orcas when they were discovered (Figure 6A), with the females clustered within 1–4 body lengths of each other (Figure 6B) and the smaller of the sub-adult males near this cluster. The adult male was ~40 m from this cluster with the larger sub-adult male a further ~40 m away. The juvenile was originally stranded near the cluster of females but once refloated and, due to its smaller size, it was able to swim around the other orcas for most of the duration of the rescue. The larger of the sub-adult males was originally stranded the furthest from any of the other orca but once refloated he moved near to the cluster of females and restranded (Figure 7). At various times during the rescue the orcas were observed flexing their bodies, lifting their tails (occasionally clearly of the water) and appeared to be attempting to dislodge themselves from the benthos in order to swim. Occasionally, as the tide came in, an individual would make a small amount of progress forward, but then become stranded again due to the uneven seafloor.
Figure 5. A sub-adult male orca with two notches in the trailing edge of his dorsal fin that can be used for individual identification. Although his dorsal fin has not sprouted much, he was classified as a male due to slightly curled tail flukes and a body size that was slightly more robust than the adult female orcas in the group. Image from video by Ysair Narváez.
Figure 6. The positions of the orcas. (A) An illustration (not to scale) of each of the seven orcas at the beginning of the rescue, based on the collective videos and photos available from those on site. The approximate distances in meters are between the extremities of each animal, not necessarily the body part indicated by the arrows. Illustration by INV. (B) Distribution of four orcas, note that the female depicted on the far right in A has moved to the far left in B and the ‘footprints’ from her tail movement can be seen. The grey saddle patch, often used as a diagnostic feature of the species, is visible on her as she swims. The water depth varied due to the sand ridges, as indicated by the water levels on the various people in frame. Photo: David González.
Figure 7. Two of the three females (one nearly completely obscured by the fishermen, centre, but with its tail flukes lifted just above the surface of the water) were refloated concurrently. At this point the larger of the sub-adult males is stranded to the rear of the fishers. Isla Caribe is in the background. Photo: David González.
From when they were first discovered until their release, all the stranded orcas were in a recumbent position, i.e., with their blowholes either clear of the water or able to be lifted clear as the animals flexed and/or as the tide changed.
All the individuals were in excellent body condition and none showed any signs of emaciation. When the fishers arrived, they noted that all the orcas were partially covered (at least to the depth of their eyes) by the tidal water. The skin that was exposed was dry and the fishers began to splash water on the animals. Post-hoc review of the photographs and video indicated that, despite exposure to the air, the skin on all individuals was smooth, showing no sloughing, signs of wrinkling or cracking (i.e. no immediate signs of sunburn/windburn and no external signs of dehydration) (e.g. see Figures 3 and 4). The dorsal fin of two males was starting to lean over (Figure 8), likely as a consequence of the stranding as the fin was no longer supported by the water. Similar partial collapse has been documented in stranded male orca before (Visser and Fertl, Reference Visser and Fertl2000; Visser et al., Reference Visser, Cooper, Hardie, Carvalho De Oliveira and Carvalho Mocellin2021). There were no visible injuries or entanglements.
Figure 8. The recently released animals, including the sub-adult male (far left) and two females (right) moved towards, and then stayed near, the stranded adult male (middle, with tallest dorsal fin). Note that the dorsal fin of both males appears to be starting to lean over as they are no longer supported by the water. Image from video by Ysair Narváez.
Despite the fact that the orcas were stranded, their breathing rate and force of exhalation were considered normal under the conditions (i.e. not rapid, nor forced). All the orcas appeared to be BAR during the entire rescue and subsequent to their release. They remained calm and did not exhibit any notable outward signs of stress. At least one individual was documented vocalising, and the calls were intermittent and not strident.
The rescue was conducted with the fishers firstly refloating and releasing the juvenile, followed by the sub-adult male furthest from the cluster and then the females. These refloatings and releases were made using only the manual force of pushing from behind the dorsal fin (Figures 4 and 7). Once floating, the fishers used gentle guiding and the animals were directed into deeper water (Figure 4). As there were multiple people available to assist, this effort was conducted concurrently for up to three animals at any given moment (Figure 7). Once they were moved into deeper water most of the individuals swam towards the still stranded adult male where they stayed together near him (Figure 8). When near the adult male, due to the undulating bottom and ridges which created localised shallower water, some of them re-stranded, but were subsequently re-released or refloated themselves. The juvenile first swam towards the cluster of females and then carried on onwards towards the adult male and interacted with the rescue team by swimming around their legs (Pablo Tormes, pers. com.).
The adult male was in deeper water than the position where the cluster of four orcas first stranded. He was the last animal to be released because of his size and weight and/or logistical constrains. In his case, the fishers, not being familiar with standard operating procedures for moving stranded orcas (e.g. see issues with pectoral fins in Visser et al., Reference Visser, Cooper, Hardie, Carvalho De Oliveira and Carvalho Mocellin2021), moved him by tying a rope around his thorax, anterior to the dorsal fin and made sure that the rope was posterior to his pectoral fins. They used a quick-release knot to ensure that they could remove the rope should he become distressed during the rescue and that they could remove the rope once he was released. One fisher straddled the orca between the dorsal fin and the rope so that the rope could be quickly accessed. The rope was slowly drawn tight from a vessel with a low-power auxiliary engine (Yamaha 15 hp two-stroke), which then began idling towards deeper water drawing the line tighter. Given the depth of the surrounding water (i.e. more than 1.5 m, based on the depth of the water compared to the rescuers, see Figure 9), only a minimal amount of very gentle pulling was required and within just three body lengths the adult male orca was floating. He remained calm and did not show a reaction to the man straddling him to remove the rope. During this period the adult male orca was facing slightly south-westwards and in the general direction of shallower water. Once released he began to swim slowly, increasing speed until he left a wake of water behind himself (Figure 9). Once he had attained some speed he turned northwards, towards the other orcas who were already free-swimming, but milling in the general area. As soon as he approached nearby, the whole group left together while swimming within a few body lengths of each other and heading north (see Figure 2C for direction of travel). The duration of the rescue and release was approximately 2.5 h. Some of the boats which had been involved in the rescue followed the orcas for ~3.5 km until they passed by Isla Caribe as the orcas continued to head towards Isla de Margarita, at approximately 9 am. The animals appeared to be swimming strongly, breathing regularly and headed in a consistent direction (i.e. they were not milling about or uncertain in their actions or behaviours). No re-strandings were documented in the Wider Caribbean Region since the event (i.e. one year and four months later at the time of publishing) and we consider the rescue and release a success.
Figure 9. Aspects of the release of the adult male. (A) The depth of the water as the tide is coming in is indicated by the water level in relation to the fishers who (other than one who is perched on the back of the orca) are standing on the sea floor. Yet despite the water depth, the adult male orca was not yet floating freely. The height of his dorsal fin is apparent when next to the fishers. (B) The rope was placed around his thorax, in front of the dorsal fin and posterior to the pectoral fins. One of the fishers straddled the orca whilst it was being towed to ensure that the rope could be quickly released. The extremities of this male orca are indicated, where the rostrum was just below the water surface and the arch of his left tail fluke is just above the surface. One of the fishers is holding up the dorsal fin as the tension on the line begins and the animal starts to rotate towards the boat. (C) Once the adult male was floating the rope was removed and he then immediately began swimming. Note the strong exhalation visible as a blow in this image. The calm demeanour of the orca was apparently a deliberate action on his behalf as once he was free-floating he moved with vigour and speed, enough to create a wake behind him. Images from video by Ysair Narváez.
An additional note of ecological interest was a suckerfish videotaped on the juvenile (see Annex 1). On the basis of the following characteristics (terminology of Mojekwu and Anumudu, Reference Mojekwu and Anumudu2015): (1) colour grey dark, (2) body robust, (3) body depth contained 4.7 times in standard length (SL) and (4) head disk very long (more than 40% of SL) and reaching beyond the pectoral fins, the sucker fish was identified as a probable whalesucker, Remora australis (Echeneidae, Annex 1). Based on the biometric characteristics visible in the video and screen shots (see Annex 1), the SL of the suckerfish was estimated 46–55 cm. This is the third reported case of a whalesucker on a cetacean species in Venezuelan waters. The first was documented in November 1979 (Notarbartolo di Sciara and Watkins, Reference Notarbartolo di Sciara and Watkins1980) and was ~40 cm long, and was attached on a free-swimming spinner dolphin (Stenella longirostris) ~85 km to the west of the orca mass stranding, whilst the second was documented in April 2009 and was a 185 mm SL specimen found on a live-stranded Atlantic spotted dolphin (Stenella frontalis) on Playa Catica, Bahía de Cata, central Venezuela ~430 km to the west of the orca mass stranding (Bolaños-Jiménez et al., Reference Bolaños-Jiménez, Lasso-Alcalá, Lasso and Willink2011).
Discussion
Historically, more than 45 orca MSE have been documented worldwide, the vast majority of them in temperate regions (Visser, Cooper and Brownell, unpubl. data). The present case represents only the second orca MSE in a tropical location, and the first in the Central-Western Atlantic and Caribbean Sea. In this event, the favourable sea-state and weather conditions, the incoming tide, the recumbent nature of the individuals (i.e. they were not susceptible to drowning which would have been the case if they were positioned on their side during a rising tide, Visser unpublished data), location of the stranding near the populated centres of Chacopata and Guayacán, the quick response of the fishers and the timely notification to the local authorities who likewise responded quickly, were all contributing factors for the completion of the rescue and successful release of the animals.
In this case, the observational skills, general natural history knowledge of the fishers and their hands-on time during the rescue as well observations as post-rescue all contributed to the assessment of the animals. We recognise that such assessments are limited due to the non-formal nature of the data collected. Furthermore, we acknowledge that the animals were only partially visible for assessment due to the surrounding water depth. But, even with those restrictions we believe we could determine if the animals were broadly exhibiting vigour or if they were in a frail or moribund state.
Although the use of the rope was successful in this instance, we do not recommend this technique be used for any cetacean species due to the potential damage that a rope could inflict should it cut into the flesh of the thorax or slip forward into the surrounding tissue of the pectoral fin/scapular joint. At that point the rope may become embedded in the axilla region and not be removable (resulting in an entanglement). The placement of a rope in this region and pulling on it could also result in dislocation, or in extreme cases disarticulation, of the pectoral fin. Alternative methods for moving cetaceans are outlined in various stranding/rescue protocols (e.g. see www.whale-rescue.org).
Given that the event generated local interest including news articles and comments from the Venezuela Presidential Office (e.g. https://archive.is/UewpM), and that the northern coastal region of Venezuela is populated and is regularly frequented by fishers, residents and sightseers, the lack of reported strandings in the region for more than a year afterwards should be indicative that none of the orcas re-stranded. That, coupled with the overall robust status of the animals and their strong swimming behaviour post refloating, adds weight to our opinion that the rescue and release were a success. Re-sighting of photo identifiable individuals would help confirm the success of this rescue. One might be tempted to speculate as to the possible cause(s) of the MSE described herein, however without any further details it would be imprudent to do so. But no matter the cause, the rescue (without the requirement of holding any of the animals in any facility for rehabilitation), resulted in the entire group surviving and being successfully released. These orcas are part of a little-known population, which is likely comprised of only a small number of individuals (Bolaños-Jiménez et al., Reference Bolaños-Jiménez, Kiszka, Bouveret, Rodríguez-Ferrer, Ramos, Henriquez, Luksenburg, Bernus, Briceño and Sánchez Criollo2023). During the 19th century, orcas were occasionally taken by foreigner whalers in Venezuelan waters since at least 1894 (Reeves and Mitchell, Reference Reeves and Mitchell1988) and whaling for the species continues in St. Vincent and the Grenadines in the eastern Caribbean to this day (Kiszka et al., Reference Kiszka, Caputo, Méndez-Fernandez and Fielding2021). In this case, the animals were not slaughtered but rather considerable work was put into their rescue. The local fishers, community and authorities are to be commended for their efforts to save these orcas who are part of the high marine environment biodiversity of the region and an iconic species in Venezuela.
Supplementary Material
The supplementary material for this article can be found at https://doi.org/10.1017/S0025315425000207.
Data
All the videos and photographs used for this work will be available without undue reservation from the corresponding authors.
Acknowledgements
Alfredo González, Paulo Gómez, Donnis Rojas, Pablo Tormes, and their crew sent notice of the stranding to the authorities of INSOPESCA and Bolivarian National Guard and participated in the release efforts. David González provided colour photographs. Mary José González Silva provided information and contacts with the fishers. Mauricio Soler provided information about the tide heights. Silvia Ruano compared the orca pictures with the Caribbean Catalogue, hosted by the Caribbean-Wide Orca Project. We are most grateful to all the fishers and Government officers who used their knowledge and expertise to rescue and release the animals back to the sea. All these activities counted on coordination with and support of the Coast Guard Division of the Bolivarian National Guard, GNB-DVC-53, PVC Guayacán, SM2 Arcia Patiño Angelo and S1 Pastrán Calzadilla Argenis, of the Bolivarian National Guard. Professor Emeritus Ivan Sazima kindly identified the whalesucker. We thank Leonel Rodríguez and Argenis Gómez, from the Fishers’ Council Las Piedras, Juangriego, Municipio Marcano, Isla de Margarita, for providing original videos and information on the orca sighting off Archipiélago de los Frailes. Dilcia Morales, Rina Solórzano and Jesús Salazar sent notice and provided additional information about the Archipiélago de los Frailes encounter. This manuscript was greatly improved by the comments of four anonymous reviewers.
Author contributions
J. B.-J.: Conceived the study, reviewed videos and photographs, interviewed witnesses, wrote and reviewed the manuscript, compiled and designed figures. I. N. V.: Reviewed videos and photographs, wrote and reviewed the manuscript, provided original data, compiled and designed figures. Y. N.: Collected data and information onsite, reviewed videos and photographs, interviewed witnesses, reviewed the manuscript. M. N.: Collected data and information onsite, reviewed videos and photographs, interviewed witnesses, reviewed the manuscript. J. A. M.: Coordinated the stranding response, reviewed videos and photographs, interviewed witnesses, reviewed the manuscript. M. A. B.-V.: Helped coordinate the stranding response, reviewed videos and photographs, interviewed witnesses, reviewed the manuscript.
Financial support
This project had no dedicated funding. Ingrid N. Visser thanks her Patreon supporters for their financial assistance during the preparation of this publication and she extends a special thanks to the Avatar Alliance Foundation and OceanX for their philanthropic support of her work and that of the Orca Research Trust, through the Global Orca Charity. Participation of Jaime Bolaños-Jiménez in the CWOP initiative is possible thanks to a grant by the Animal Welfare Institute (AWI).
Competing interest
None.
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