EXECUTIVE SUMMARY
Marine mammals strand for various reasons. The recorded Philippine marine mammal stranding events from 2005 to 2016 was analyzed for patterns on (1) species composition of stranded marine mammals, (2) spatial and temporal variation of stranding events, and (3) proportions of alive and dead specimens, to mention a few. A total of 713 stranding events have been recorded comprised mainly of single stranders (n=638), mass stranding events (n=31), out of habitat (n=15) and Unusual Mortality Events (n=29). The UMEs occurred in Region I only. The annual frequency of recorded stranding events ranged from 24 (2005) to 111 (2015), with an average of 59 events per year. Most of the strandings occurred in Luzon (60%) while Visayas and Mindanao had equal share (20% each). Strandings have been recorded in all regions with coastline and in 64 coastal provinces.
The top five regions on a national level which have had the highest number of recorded stranding events (i.e. stranding hotspots) were: Regions I (n= 158), V (n=92), VII (n=68), III (n=53) and II (n=48). The regions with the least number of recorded stranding events were: NCR (n=3), ARMM (n=6), 13 (n=11). In the Visayas, Region VI (n=47) was also an area of concern, apart from Region VII. Similarly, in Mindanao Regions XII (n=44), XI (n=42), and IX (n=25) were hotspots. Region IX was considered as a hotspot primarily because it has the highest proportion of live stranders on record (84%, 21 of 25). Overall, 60% (n=430) of all recorded stranding events involved live animals.
In terms of seasonality, strandings were relatively more frequent during the Northeast monsoon (NE) in most provinces than the Southwest monsoon or Inter-monsoon. The bulk of the recorded strandings (76%) came from the top 20 provinces of the 64 represented. The top six provinces in terms of frequency of recorded strandings were Pangasinan (n= 63), Ilocos Norte (n= 52), Cagayan (n= 40), Sarangani (n= 37), Sorsogon (n=30), and Zambales (n=29).
A total of 29 species (28 cetaceans plus the dugong) of marine mammals have been recorded throughout the Philippines, mostly confirmed through stranding records. Of the 29 species, 27 have stranding records, with Regions III and V both having the highest number of marine mammal species recorded (n=17); followed by Regions I and II (n=16), and 3 (n=15). The most frequent species that stranded was the spinner dolphin (Stenella longirostris, n=115), followed by the Fraser’s dolphin (Lagenodelphis hosei, n=67), Risso’s dolphin (Grampus griseus, n=52), melon-headed whale (Peponocephala electra, n=45), Pantropical spotted dolphin (Stenella attenuate, n=37), dwarf sperm whale (Kogia sima, n=36), and the dugong (Dugong dugon, n=36). Another notable result was that the spinner dolphins was the most common stranded species and had been recorded to have stranded in 15 out of 16 regions. This implies that the spinner dolphin is most likely the most abundant and widely distributed marine mammal species in the Philippines. On the other hand, only 23 (3%) records of baleen whale strandings were documented.
Majority of the stranding events involved adults (n=501, 70%). The ratio of stranded females to males was almost even (0.92). Furthermore, a total of 1561 individuals were recorded to have been involved in all (n=713) stranding events from 2005 to 2016: out of habitat = 745, single = 651, mass = 134, and UME = 31. All the out of habitat animals, except three (3), eventually made it back to open seas. Out of the single stranders, 395 (61%) stranded alive. Of these, 329 were released immediately or after a few hours of supportive care, including 5 baleen whales (i.e. adults to sub-adults). Sixty-six individuals were rehabilitated: 48 died (72%), 11 released (17%), 4 (6%) long-term care, and 3 euthanized (4%).
The response to strandings has remarkably improved through time. This was mainly attributed to the significant increase in numbers of PMMSN Chapter chapters and trained volunteers nationwide. The PMMSN now have at least 12 collaborating BFAR Regional Offices, 11 with MOAs and 1 currently being worked out. In 2010, 5 years after the establishment of PMMSN, there were 1736 trained volunteers. To date, there are 3690 trained volunteers, including at least 75 veterinarians who underwent a special training on medical management for stranded marine mammals. The existence of active PMMSN Chapters in several regions through the initiatives of BFAR Regional Directors, and local chief executives of provinces and cities/municipalities has enabled better response than before. Further, BFAR Regional Offices in regions I, II, II, IVA, V, VII, VIII, XI, and XIII have either already organized or are planning to organize provincial chapters of PMMSN through their Provincial Fisheries Offices to further enhance their capacity to respond to strandings. Regions IX, X and XII are currently setting up their respective Chapters.
However, there are still many challenges. For instance, the coordination between the individual(s) who initially discover stranded marine mammals and trained local personnel (responders) needs to improve. Most often the discovering parties do not know who to call. This is unfortunate because, to date, there are many trained locals, especially in strategic (hotspot) areas, who are knowledgeable about stranding first response protocols. Supposedly, the assistance of the pertinent personnel from BFAR Regional Office (e.g. veterinarian) and/or PMMSN, would be required or immediately pursued only if there was no local individual(s) trained or after the animal has been given first aid and stabilized. Another challenge is finding accessible pond or enclosures for possible use as holding pens for rehabilitation of stranded animals in remote areas.
Another noteworthy finding was the significant number of live animals rescued and released back into their habitats. For the last 12 years, at least 329 individuals were released after providing supportive care. That was equivalent to 27 animals per year. Furthermore, the success rate of rehabilitation has increased from 12% in 2010 to 23%, to date. The 11 animals successfully rehabilitated was equivalent to almost 1 animal released per year. Furthermore, four dolphins, mostly victims of dynamite blasts, and therefore are acoustically challenged, and with almost nil chances of survival if released, are now under human care with their conspecifics. The PMMSN has also observed increasing cases of stranders (dead or dying) with compacted GIT by marine debris. A systematic collection of information regarding these sorts of cases and the like is now in place. These would not have been possible if there was no organized national stranding network (i.e. the PMMSN) that looked after their welfare as well as systematically collected data. Ultimately, the engagement of empowered communities (e.g. PMMSN Chapters), especially mandated agencies (i.e. BFAR, LGUs) and their respective leaders, made the difference for the Philippine marine mammal strandings.
