Conservation ecology of Irrawaddy dolphins in estuarine waters of Kuching

Cetaceans in the nearshore waters of Sarawak have ecological functions and economic importance to the state. Being the keystone species of the ocean, they are valuable as indicators of the health of the environment as they sit on top of the ocean’s food chain. The presence of marine mammals in an area indicate that the fishing stock of the particular area is still present. In addition to that, the Irrawaddy dolphins also serve as important attraction for the eco-tourism industry within Kuching Bay. However, populations of the Irrawaddy dolphins throughout South East Asia are facing risk of local extinction due to anthropogenic factors such as bycatch in fisheries, habitat loss and degradations, decreased fitness from pollutions or contaminants

Distribution of small cetaceans in the nearshore waters of Sarawak, East Malaysia

Between June 2008 and September 2009, 56 days of small boat surveys were conducted off the coast of Sarawak, Malaysia with the aim of recording cetacean distribution. These surveys, which focused on the Miri, Bintulu-Similajau and Kuching regions, comprised 173 hours of survey effort and covered 2851 km of pre-determined systematic tracks. Surveys were clustered into three sets of seasonal snapshots: June-July, September-October and March-April. A total of 115 cetacean sightings were made, of which 65 were on-effort and used in analyses of cetacean encounter rates in relation to habitat characteristics. Species observed included (in order of frequency) Irrawaddy dolphins (Orcaella brevirostris), fi nless porpoises (Neophocaena phocaenoides), Indo-Pacifi c bottlenose dolphins (Tursiops aduncus) and Indo-Pacifi c humpback dolphins (Sousa chinensis). One hundred and ten of 115 sightings were made in less than 10 m water depth, highlighting the importance of nearshore coastal habitats for these species. Despite an apparent overlap in habitat, Irrawaddy dolphins showed a statistically signifi cant affi liation with areas of shallower depth and closer proximity to shore and river mouths than fi nless porpoises or bottlenose dolphins. This preference for nearshore areas renders the species vulnerable to threats such as fi sheries by-catch and habitat degradation from coastal development. Irrawaddy dolphins were more frequently encountered in Kuching, while the highest encounter rate for fi nless porpoises was in the Bintulu-Similajau region. Depictions of encounter rates in these regions in relation to survey effort in 2 km × 2 km grid-cells give an indication of the preferred habitats of Irrawaddy dolphins, and show that the highest encounter rates in both Kuching and Similajau occurred in areas that are destined for major coastal developments. The information presented here should help researchers and managers design effective future research and conservation strategies

The Important Marine Mammal Area network : a tool for systematic spatial planning in response to the marine mammal habitat conservation crisis

Major support to the IMMA process was provided by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) on the basis of a decision adopted by the German Bundestag, through the Global Ocean Biodiversity Initiative (GOBI). Funding was also provided by the MAVA Foundation and by the French Biodiversity Agency (OFB) in cooperation with IUCN’s Global Marine and Polar Program. The support from the Prince Albert II of Monaco Foundation, OceanCare, NRDC, the Animal Welfare Institute, and the Pacific Life Foundation is also gratefully acknowledged.The Important Marine Mammal Areas (IMMAs) initiative was launched by the Marine Mammal Protected Areas Task Force of the International Union for the Conservation of Nature in 2016, as a response to a conservation crisis in the protection of marine mammals and wider global ocean biodiversity. IMMAs identify discrete portions of habitat that are important for one or more marine mammal species, and that have the potential to be delineated and managed for conservation. They are identified by scientific experts during regional workshops, on the basis of satisfying one or more of eight criteria that capture critical aspects of marine mammal biology, ecology and population structure. Candidate IMMAs undergo independent scientific review prior to being accepted, and then are publicly available via a searchable and downloadable database and a dedicated online e-Atlas. Between 2016 and 2021, eight expert workshops - engaging more than 300 experts - have resulted in the identification of 173 IMMAs located in 90 countries or territories, across a third of the globe. IMMAs identified to date provide important habitats for 58 of the 131 recognized marine mammal species. Around two-thirds of all IMMAs (65%) were identified on the basis of important habitat for a marine mammal species that is threatened on the IUCN Red List. Approximately 61% of IMMA surface areas occur within Exclusive Economic Zone waters, while 39% fall within areas beyond national jurisdiction. The Task Force undertook implementation planning exercises for IMMAs in Palau (Micronesia), the Andaman Islands (India) and the Bazaruto Archipelago and Inhambane Bay (Mozambique), engaging with a range of stakeholders including government and management bodies. IMMAs are increasingly being utilized in environmental impact assessments, marine planning exercises and in international, national and supra-regional conservation, policy and management initiatives, including the Convention on Migratory Species and Convention on Biological Diversity, as well as the design and management of Marine Protected Areas (MPAs) and the extension of MPA networks. The Task Force is working toward completing a global network of IMMAs that will contribute the scientific information needed to fulfill the current collective goal of protecting 30% of the ocean by 2030.Publisher PDFPeer reviewe

Red-list status and extinction risk of the world’s whales, dolphins and porpoises

To understand the scope and scale of the loss of biodiversity, tools are required that can be applied in a standardized manner to all species globally, spanning realms from land to the open ocean. We used data from the International Union for the Conservation of Nature Red List to provide a synthesis of the conservation status and extinction risk of cetaceans. One in 4 cetacean species (26% of 92 species) was threatened with extinction (i.e., critically endangered, endangered, or vulnerable) and 11% were near threatened. Ten percent of cetacean species were data deficient, and we predicted that 2–3 of these species may also be threatened. The proportion of threatened cetaceans has increased: 15% in 1991, 19% in 2008, and 26% in 2021. The assessed conservation status of 20% of species has worsened from 2008 to 2021, and only 3 moved into categories of lesser threat. Cetacean species with small geographic ranges were more likely to be listed as threatened than those with large ranges, and those that occur in freshwater (100% of species) and coastal (60% of species) habitats were under the greatest threat. Analysis of odontocete species distributions revealed a global hotspot of threatened small cetaceans in Southeast Asia, in an area encompassing the Coral Triangle and extending through nearshore waters of the Bay of Bengal, northern Australia, and Papua New Guinea and into the coastal waters of China. Improved management of fisheries to limit overfishing and reduce bycatch is urgently needed to avoid extinctions or further declines, especially in coastal areas of Asia, Africa, and South America.Publisher PDFPeer reviewe

Utilizing interview-based data to measure interactions of artisanal fishing communities and cetacean populations in Kuching Bay, Sarawak, East Malaysia

Kuching Bay is a significant area for artisanal fishing activities as well as an Important Marine Mammal Area (IMMA) for coastal cetaceans. A total of 286 fishers from eight fishing communities were interviewed between 2011 and 2019 to determine the nature and extent of cetacean-fishery interactions in the area. The main types of fishing gears recorded were gillnets, trammel nets, trawl nets, longlines, handlines and crab traps, with the use of gears varying by season and target species. Depredation, net damage, and entanglements in fishing gear were the most frequently reported negative interactions with cetaceans. Thirty-six percent of fishers reported having experienced a cetacean entanglement in their fishing gear at least once. More than half (58.1%) of the respondents who experienced bycatch were able to disentangle and release the animals alive. The more conservative calculated bycatch rate of 0.36 cetaceans per fisher over a fishing career indicates that a minimum estimated average of 19 cetaceans are involved in bycatch annually in Kuching Bay, with as many as nine of these incidents likely resulting in mortality. However, a less conservative method yields a bycatch rate of 0.57 per fisher, and estimated an average of 30 bycaught cetaceans per year. Irrawaddy dolphins (Orcaella brevirostris) were reported to be at the highest risk (72.9% of reported incidents), with an estimated minimum of seven individuals caught and killed per year. Despite the negative interactions, 77.2% of respondents reported a generally positive attitude toward cetaceans based on their value for tourism and as indicators of fish presence and a healthy ecosystem. Mutualistic relationships between fishers and cetaceans were documented, with 53% of respondents reporting that they feed discarded fish to cetaceans. The results of this study can be used to guide effective mitigation measures, which should focus on training fishers in safe handling and release of entangled cetaceans, and, more importantly, methods to prevent interactions with gillnets

Commentary on Coram et al. (2021) on the use of Facebook to understand marine mammal stranding issues in Southeast Asia

We reviewed Coram et al. (Biodivers Conserv 30:2341–2359, 2021, https://doi.org/10.1007/s10531-021-02196-6), a paper that highlights the use of social media data to understand marine litter and marine mammals in Southeast Asia. While we commend its intent, we find that the methodology used and conclusions drawn portray an incomplete and inaccurate perception of how strandings, stranding response, and analysis of stranding data have been conducted in the region. By focusing on investigative results revealed by a very limited search of one social media platform (Facebook), using only English keywords, and insuffcient ground-truthing, Coram et al. (2021) have, unintentionally, given the perception that Southeast Asian scientists have not conducted even the bare minimum of investigation required to better understand the issue of marine litter and its impact on marine mammals. In this commentary we provide a more accurate account of strandings research in Asia and include recommendations to improve future studies using social media to assess conservation issues

Records of Postmortem Attentive Behavior on an Irrawaddy Dolphin (Orcaella brevirostris) Calf and Implications for Conservation in Kuching Bay, Sarawak, East Malaysia

Postmortem Attentive Behaviors (PABs), also known as epimeletic behaviors, have been observed in terrestrial mammalian species, such as primates, giraffes, and elephants (Nakamichi etal., 1996; Douglas-Hamilton etal., 2006; Li etal., 2012; Strauss & Muller, 2013), as well as in aquatic mammals (Reggente etal., 2016; Bearzi & Reggente, 2017; Bearzi etal., 2017). In cetaceans, epimeletic behavior is described as one or more adults attending to an injured, distressed, dying, or deceased animal by keeping it afloat if sinking, pushing it down if buoyant, performing “resuscitation” attempts, and/or carrying it on the dorsum, head, rostrum, or in the mouth (Reggente etal., 2016; Bearzi & Reggente, 2017). Most records of cetacean PAB involved Indo-Pacific humpback dolphins (Sousa chinensis), common bottlenose dolphins (Tursiops truncatus), and Indo-Pacific bottlenose dolphins (Tursiops aduncus) (e.g., Porter, 2002; Kuczaj etal., 2015; Bearzi etal., 2017, 2018; Cheng etal., 2018; Reggente etal., 2018; Pedrazzi etal., 2022). Until now, only one case of this behavior has been documented in Irrawaddy dolphins (Orcaella brevirostris) from Balikpapan Bay, Indonesia (Kreb etal., 2020). Herein, we describe a rare event of PAB towards an Irrawaddy dolphin calf in Kuching Bay, Sarawak, East Malaysia, and its implications for conservation