With a significant number of marine mammals stranded in the Philippines over the past years, it is within the scope of local government units (LGUs) to address this pressing concern, scientists from the University of the Philippines-Diliman College of Science (UPD-CS) indicated in a recent study that encompasses data from nearly the past two decades.
Dr. Lemnuel Aragones, Alessandra Nicole Morado, and Honey Leen Laggui of the Institute of Environmental Science and Meteorology (IESM), along with Dr. Marie Christine Obusan of the Institute of Biology (IB), Dr. Jonah Bondoc of the Natural Sciences Research Institute (NSRI), and Dr. Leo Suarez of Ocean Adventure and Ewen Lawler of University of Canberra, assessed the changes in marine mammal strandings in the Philippines over space and time, as well as the types of species that got stranded in Philippine territory from 2005 to 2022.
Role of LGUs
A stranding occurs when a marine mammal is found on seashores or in shallow waters and cannot return to deeper waters on its own. The researchers mapped the stranding hotspots in the Philippines, representing areas where stranding frequencies are relatively high, and designed the hotspots to identify designated LGUs to inform them about the implications of the strandings for marine mammal conservation and management. With the help of the hotspots, concerned LGUs can also be proactive in addressing marine mammal strandings. A total of 35 LGU hotspots for strandings were identified in this study. The majority of these stranding hotspots were located in Luzon (24 hotspots), particularly in Regions 1 and 2.
“Strandings can be of natural causes, but when marine mammals with good body condition (become stranded), we have to worry because it could imply that they are in trouble. It is possible that their habitat is compromised in various ways—most likely from human activities such as pollution and overexploitation of our key marine resources,” explained Aragones, who also serves as the president of the Philippine Marine Mammal Stranding Network (PMMSN).
A rare ginkgo-toothed beaked whale (Mesoplodon ginkgodens) is stranded in Subic Bay. Annual stranding frequencies in the Philippines increased from 29 in 2005 to 2007 to 106 in 2020 to 2022 (Photo by PMMSN)
While natural causes such as tropical monsoons and oceanographic factors can affect marine mammal strandings, the study emphasized that fisheries production and fisheries interaction are major contributors to the stranding frequencies of these mammals. This can occur through fishing equipment that increases the chances of entanglement, or various illegal fishing activities, such as dynamite fishing.
“We recommend that LGUs and concerned regional offices establish their own stranding response team and rehabilitation tank and eradicate illegal fishing activities in their area by providing appropriate crew and patrol boats,” the researchers stated in their study. They also emphasized the importance of information, education, and communication (IEC) campaigns regarding marine mammals and regulating fishers and their fishing gear. By institutionalizing these programs, LGUs and concerned regional offices will help sustain their implementation.
Their study also revealed that the species most frequently stranded in Philippine waters were spinner dolphins (Stenella longirostris) with 218 strandings, dugongs (Dugong dugon) with 104, Risso’s dolphins (Grampus griseus) with 100, Fraser’s dolphins (Lagenodelphis hosei) with 95, and melon-headed whales (Peponocephala electra) with 89. By establishing a “species stranding status,” an index of the impacts of stranding on these already vulnerable and endangered species, this study has introduced an important additional key factor in assessing species conservation status by concerned agencies.
More research from stranded marine mammals
Knowing the species—particularly identifying their genetics and genomics—is important for ensuring the proper management of stranded marine mammals. This is the focus of the new ongoing studies by Aragones and his colleagues.
“We should determine the main causes of strandings. Since we suspect that dynamite blasts can cause strandings, we want to understand the acoustics of marine mammals,” elaborated Aragones. “We also like to examine the impact of fisheries on our marine mammals, to identify what types of fishing gears can entangle them, and the bycatch rates as well.”
Their findings underscore the importance of continuing and advancing monitoring efforts for marine mammal strandings, given the inevitable impact of human activities such as increasing population, illegal fishing, pollution, and climate change. The evidence-based results provided by this study can guide hotspot LGUs and concerned regional offices in managing and conserving Philippine marine resources, including marine mammals. (Eunice Jean C. Patron/ UPD-CS Science Communications)