No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Strandings, bycatches and injuries of aquatic mammals in China, 2000–2006, as reviewed from official documents: A compelling argument for a nationwide strandings programme
... According to historic information (Zhu et al., 2000(Zhu et al., , 2004Wang, 2012), cetacean diversity in China is especially rich with more than 30 of~90 extant species in Chinese territorial waters, but most species are poorly monitored due to lacking field investigations . Wang et al. (2015) have ever reviewed 97 strandings, 66 bycatches, and 30 injuries of 18 cetacean species in China. However, the authors only reported limited records from official documents between 2000 and 2006. ...
... At regional scales, a few CS networks have been established in the Taiwan, Hong Kong, and Hainan (Zhao et al., 2017;Liu et al., 2019;Tsui et al., 2020;. So far, there has no long-term, systematic, and national CS database in Chinese waters, because CSs were not well monitored nationwide (Zhu et al., 2000;Wang et al., 2015). ...
... org/). Typically, the species/taxon was well identified and documented for records from books, literature, and online databases, which were generally ensured by cetacean researchers, veterinaries, and/or fishery administration staff (Parsons, 1998;Wang et al., 2015;Zhao et al., 2017;Liu et al., 2019). For those records from news reports, the identification of species/taxon was manually processed by an experienced inspector, either through photos or videos of the animals involved, according to morphological characteristics of stranded animals (Wang, 2012;Jefferson et al., 2015). ...
Stranding data can provide conservation-valuable information on cetaceans over long time and large space, representing a low-cost but useful approach to monitor these indicator species and their inhabiting environments. Here, we established a national dataset by collating all available records of cetacean strandings (CSs) along >30,000-km coastline of China over seven decades. Between 1950 and 2018, a total of 1763 CSs were recorded across 36 cetacean species from eight families. Importantly, 30.5% of the recorded species are currently recognized as threatened levels on the IUCN Red List. In quantity, Odontocete species accounted for 89.9% of total CSs. In 1763 CSs, 91.8% were events of single individual. Furthermore, 31.9% and 42.4% were events of alive and dead animals, respectively. The number of CSs increased gradually from 1950 to 2018, and more rapidly between 1990 and 2018. CSs occurred in all months, while a seasonal pattern could be observed with 38.5% reports between March and June. The most commonly recorded species were finless porpoises (Neophocaena spp., n = 492) and Indo-Pacific humpback dolphin (Sousa chinensis, n = 291). The highest number of CSs (n = 509) was documented in Hong Kong, while the greatest species richness (n = 28) and the highest stranding density (24.6 CSs per 100-km coastline) were observed in Taiwan. Several CS hotspots were identified in the southern and eastern China, while hotspots differed among taxonomic categories. To conclude, these findings provided a comprehensive understanding of cetacean communities in the coastal waters of China, which are beneficial for improving further research, conservation, and management on cetaceans.
... Bycatch associated with intensive fishing activity in the Yangtze River has been identified as a likely driver of decline for the country's two endemic freshwater cetaceans, the Yangtze finless porpoise Neophocaena asiaeorientalis asiaeorientalis and the Yangtze River dolphin or baiji Lipotes vexillifer (Zhang et al., 2003;Turvey et al., 2007;Zhao et al., 2008;Mei et al., 2012). Over 30 marine mammal species are recorded to inhabit the South China Sea (SCS;Jefferson, Webber & Pitman, 2011), including the waters around Hainan Island, China's southernmost province, which comprises an area of c. 3.3 million km 2. However, data on the population status, threats and mortality associated with artisanal fisheries for these species are currently very limited (Zhou & Wang, 1994;Yang, Zhou & Xu, 1999;Wang et al., 2011;Wang, Li & Van Waerebeek, 2015). According to official statistics, there are over 200,000 registered marine fishers in Hainan, of which 83.0% make a professional living from marine fisheries in the SCS (Yearbook, 2014). ...
... Our fishers' LEK survey around Hainan provides an important new baseline for understanding fishing activities and bycatch in the SCS. Many previous studies have found that bycatch events of marine mammals primarily occur in spring (e.g.Harris & Poiner, 1990;Wang et al., 2015), although this seasonality has not been universally demonstrated. In our survey, bycatch events also reportedly occurred most frequently in spring, matching the seasonal intensity of fishing activities by local fishers (Fig. 4). ...
... Increasing media and public attention is being focused on conservation issues and efforts on marine mammals in China, including reporting of bycatch and stranding reports, and development of databases of these events (Wang et al., 2015; http://tcsn.whale.org.tw/; http://www.cetacean.csdb.cn/). ...
Bycatch mortality is a significant driver of marine mammal population declines. However, there is little information available on patterns or magnitude of bycatch mortality in many heavily fished Asian marine systems such as the South China Sea (SCS). To address this limited knowledge base, we conducted interviews with fishers to gather local ecological knowledge on marine mammal bycatch around Hainan Island, China. Gillnets were the primary fishing gear used in local fisheries, and were also responsible for the majority of reported marine mammal bycatch events in recent decades. Bycatch events were reported from all seasons but were most frequent in spring (38.4%), which might relate to seasonal variation in fishing activities. The spatial pattern of relative bycatch densities for Indo-Pacific humpback dolphins, Indo-Pacific finless porpoises and unidentified small dolphins varied around Hainan and neighbouring waters. A substantial proportion of informants (36.1 and 9.2% respectively) reported that they have eaten or sold marine mammal meat, demonstrating the continued existence of cultural practices of consuming marine mammals on Hainan. Responses of fishers to bycatch events were dependent both on their existing attitudes and perceptions towards marine mammals and on other sociocultural factors. Almost half of informants agreed that marine mammal populations in the SCS have decreased. Declines were thought by informants to have been caused by overfishing, water pollution and vessel collisions, with bycatch responsible for further declines in dolphins.
... Some specific gears (notably hook-based gears comprising longlines with hundreds of unbaited hooks and electrofishing) have been highlighted as possible drivers of Yangtze cetacean decline (Zhou and Wang, 1994;Zhou et al., 1998;Zhang et al., 2003;Turvey et al., 2007;Turvey et al., 2013), and legislation prohibiting electrofishing is widely promoted and enforced in the mainstem and appended lakes (Turvey et al., 2015;Mei et al., 2019). However, investigation of porpoise bycatch has been largely restricted to opportunistic reporting of observed deaths in gear entanglement (Zhou and Wang, 1994;Wang et al., 2000;Wang et al., 2015a;Mei et al., 2019). Analysis of porpoise mortality data obtained through interviews with artisanal fishers by Turvey et al. (2013) suggested that bycatch mortality has decreased over time, and might therefore merely be tracking rather than driving population decline. ...
... However, whereas hook-based gears are often identified as a particularly lethal gear for Yangtze cetaceans (Zhou and Wang, 1994;Zhou et al., 1998;Turvey et al., 2007;Turvey et al., 2013), we found no significant differences in porpoise mortality associated with fixed nets and non-fixed nets, which were both used more widely by respondents. These findings highlight the need for more systematic investigation of porpoise deaths in the Yangtze system, to obtain direct data on deaths by different gears (e.g., through a regional strandings investigation program; Wang et al., 2015a). ...
The impacts of fisheries interactions on cetaceans can be challenging to determine, often requiring multiple complementary investigative approaches. The Yangtze finless porpoise ( Neophocaena asiaeorientalis asiaeorientalis ), one of the few Critically Endangered cetaceans, is endemic to the middle-lower Yangtze drainage, a system impacted by multiple anthropogenic pressures. Bycatch mortality is implicated in regional porpoise decline, but the significance and dynamics of porpoise interactions with fishing activities and other threats remain poorly understood. We conducted boat-based surveys to map seasonal distributions and spatial congruence of porpoises and two potential threats (fishing and sand-mining), and an interview survey of fishing communities to understand temporal patterns and drivers of regional fishing activity, across Poyang Lake and the adjoining Yangtze mainstem. Variation in harmful and non-harmful gear use (non-fixed nets versus static pots and traps) between these landscapes might be an important factor affecting local porpoise status. Within Poyang Lake, spatial correlations between porpoises and threats were relatively weak, seasonal porpoise and threat hotspots were located in different regions, and two protected areas had higher porpoise encounter rates and densities than some unprotected sections. However, porpoise hotspots were mostly in unprotected areas, threats were widely observed across reserves, and more fishing and sand-mining was seasonally observed within reserves than within unprotected areas. Compared to null distributions, porpoises were detected significantly closer to fishing activities in summer and further from sand-mining in winter, indicating possible spatial risks of gear entanglement and disturbance. Reported porpoise bycatch deaths are associated with fixed and non-fixed nets, hook-based gears, and electrofishing. Longitudinal patterns in reported gear use indicate that hook-based fishing has decreased substantially and is generally conducted by older fishers, and significantly fewer respondents now practice fishing as their sole source of income, but electrofishing has increased. This combined research approach indicates a continued potential risk to porpoises from changing fisheries interactions and other threats, highlighting the importance of fishing restrictions and appropriate support for fishing communities impacted by this legislation. A potential “win–win” for both biodiversity and local livelihoods could be achieved through wider use of static pots and traps, which are not associated with bycatch deaths.
... Information for China is anecdotal and limited, e.g., Jefferson and Van Waerebeek (2002) presented photographic evidence of bycaught common dolphins landed at fish markets of Putian, Fujian Province. Wang et al. (2015) presented records of 193 incidents of bycatch, stranding and injuries (mostly fisheries inflicted) of aquatic mammals nationwide in 2000 to 2006, but did not report on subsequent use of carcasses. A short study on the use of Chinese social media and national online news services to monitor cetacean trade in fish markets in China indicated that the sale of cetaceans for food, particularly finless porpoise (Neophocaena spp.), is not uncommon and that some trade occurs far inland (IWC, 2016). ...
... A short study on the use of Chinese social media and national online news services to monitor cetacean trade in fish markets in China indicated that the sale of cetaceans for food, particularly finless porpoise (Neophocaena spp.), is not uncommon and that some trade occurs far inland (IWC, 2016). As elsewhere, the lack of a nationwide reporting scheme and the poorly known status of most populations of aquatic mammals in China, hampers our understanding of the impact of both targeted and incidental takes (Wang et al., 2015). ...
Wild animals are captured or taken opportunistically, and the meat, body parts, and/or eggs are consumed for local subsistence or used for traditional purposes to some extent across most of the world, particularly in the tropics and subtropics. The consumption of aquatic animals is widespread, in some places has been sustained for millennia, and can be an important source of nutrition, income, and cultural identity to communities. Yet, economic opportunities to exploit wildlife at higher levels have led to unsustainable exploitation of some species. In the literature, there has been limited focus on the exploitation of aquatic non-fish animals for food and other purposes. Understanding the scope and potential threat of aquatic wild meat exploitation is an important first step toward appropriate inclusion on the international policy and conservation management agenda. Here, we conduct a review of the literature, and present an overview of the contemporary use of aquatic megafauna (cetaceans, sirenians, chelonians, and crocodylians) in the global tropics and subtropics, for species listed on the Appendices of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). We find that consumption of aquatic megafauna is widespread in coastal regions, although to varying degrees, and that some species are likely to be at risk from overexploitation, particularly riverine megafauna. Finally, we provide recommendations for CMS in the context of the mandate of the Aquatic Wild Meat Working Group.
... Therefore, another reason may be due to increased calves stranding [30]. The peak period of porpoise strandings coincides with the increased incidence of fishing and incidental injury events involving this species in the study area [83], indicating that fishing may also contribute to the seasonality of strandings. Nevertheless, thorough necropsies are required to corroborate the cause of death. ...
The frequency of cetacean strandings is increasing, with multiple causes identified. We examined temporal and spatial trends in stranding numbers along the coastal areas of the East China Sea from 1990 to 2021. Using structural equation models, we analyzed the relationships between strandings and climate, oceanic properties, and human activities. Our findings revealed time-dependent interannual variability in strandings but no linear trend, indicating relative stability in cetacean strandings. Seasonal patterns were observed only in narrow-ridged finless porpoises (Neophocaena asiaeorientalis), with significant spring increases (March to May). Clustering of strandings occurred in central Fujian and northern/southern Taiwan, according to spatial analysis. The impact of variables on cetacean strandings varied across time periods. Storm surges, coastal fishing, and the Pacific decadal oscillation were associated with stranding events from 1990 to 2006. However, from 2006 to 2021, the influence of storm surges weakened, while the climate index only indirectly affected strandings through sea surface temperature and salinity, with an increased intensity in the effects of winter sea surface temperature and salinity. Structural equation models unveiled the cascading effects of environmental changes on strandings. This study reports changing trends in cetacean strandings and identifies relevant variables. Although not exhaustive, understanding the reasons behind strandings enhances our comprehension of cetacean responses to environmental changes, supporting targeted conservation and management efforts.
... Reducing the threat of bycatch is of high priority for the conservation of finless porpoises, and the use of acoustic equipment, such as pingers, has been demonstrated to be effective [43,44] and should be promoted for widespread use. It is also important to establish rescue organizations to aid injured finless porpoises affected by bycatch and stranding events [45]. ...
The baseline data pertaining to the population of the East Asian finless porpoise (Neophocaena asiaeorientalis sunameri) in Chinese waters are significantly deficient. Boat-based visual line transect surveys were conducted from 2018 to 2020 to evaluate the distribution and abundance of the East Asian finless porpoise in the coastal waters (depth < 30 m) of the Yellow Sea, with a specific focus on the Shandong Peninsula. A total of 50 transects covering 2705 km were conducted, encompassing an area of 23,604 km2 between 119°30′ E–123°15′ E and 35°25′ N–38° N. Throughout the surveys, a total of 117 East Asian finless porpoise groups were detected, with over 90% of these groups occurring within 15 km of the coast or adjacent islands. The estimated abundance of the East Asian finless porpoise in the study area was determined to be 3978 individuals (CV = 22.39%, 95%CI = 2561–6177), reflecting a low density of 0.169 individuals/km2 (CV = 22.39%, 95%CI = 0.109–0.262) within the coastal waters of the Yellow Sea in the Shandong Peninsula. The findings highlight the need for conservation measures to address the threats faced by this species, including bycatch, habitat degradation, and pollution. The establishment of marine protected areas and the implementation of bycatch mitigation measures are crucial for the long-term survival of the East Asian finless porpoise population in the study area. By providing valuable data on the distribution and abundance of the East Asian finless porpoise, this study contributes to our understanding of the population dynamics and conservation status of this threatened species in the Yellow Sea of the Shandong Peninsula.
... Second, given the relative difficulty of monitoring species and assessing their threats in inaccessible and expansive coastal marine habitats (27), the actual situation for megafauna is likely worse than currently indicated. For example, the indirect impact of bycatch (incidental capture of nontarget species) has increasingly become a major threat to coastal and oceanic species globally (28) yet are usually underestimated and underreported in China (29). Third, multiple threats increase the likelihood of compounded or synergistic stressors affecting a given species. ...
To fulfill sustainable development goals, many countries are expanding efforts to conserve ecologically and societally critical coastal ecosystems. Although megafauna profoundly affect the functioning of ecosystems, they are neglected as a key component in the conservation scheme for coastal ecosystems in many geographic contexts. We reveal a rich diversity of extant megafauna associated with all major types of coastal ecosystems in China, including 218 species of mammals, birds, reptiles, cephalopods, and fish across terrestrial and marine environments. However, 44% of these species are globally threatened, and 78% have not yet been assessed in China for extinction risk. More worrisome, 73% of these megafauna have not been designated as nationally protected species, and <10% of their most important habitats are protected. Filling this wide "megafauna gap" in China and globally would be a leading step as humanity strives to thrive with coastal ecosystems.
... Liu et al. (2017) conducted a large-scale interview among local fishermen in Hainan Island, China, reporting a total number of 150 bycatch events involving more than 600 animals from 2000 to 2013 (Liu et al., 2017). Wang et al. (2015) summarized the bycatch data from 2000 to 2006 and found that a total of 66 bycatches and 30 injuries covering at least 18 Cetacean and Carnivora species were attributed to fishery bycatch. ...
Commercial fishing constitutes an important food source but induces undesirable bycatch on animals worldwide. This study extends bycatch research geographically to the Western Pacific Ocean, filling a knowledge gap regarding bycatch and mitigation measures in the region. Bycatch has caused many lethal consequences to the pantropical spotted dolphins (Stenella attenuata) during their interaction with fisheries in the research area. We provided a self-developed acoustic deterrent system and conducted field experiments, suggesting its effectiveness as a potential useful conservation tool to reduce bycatch. Dolphins departed the area and the number of dolphins in sight declined to zero after the deployment of the system. Additional evidence was reflected in acoustic recordings, showing the number of clicks emitted by dolphins decreased from 1,502 to 136 per minute after the ADS was activated. Meanwhile, click amplitude was reduced by 84%, indicating an increase in the distance between dolphins and the system. These combined results indicate that the system was effective in driving dolphins away to facilitate the conservation of the species by protecting them from potential bycatch.
... Under the increasing impacts of climatic change and human activities, more components of favourable ecosystems such as water temperature regimes, flood pulses and sedimentation processes should be designed based on the needs of aquatic organisms (Sabo et al., 2017;Wang, Li, Duan, Chen, et al., 2014;Yang et al., 2015). Third, the need for appropriate and stringent fisheries policies, to ensure sustainable wild capture and aquaculture practices, must be addressed Ma et al., 2018;Wang, Cheng, et al., 2015;Wang, Li, & Waerebeek, 2015), and ecosystem-based fisheries management in the light of selective fishing policies should be implemented (Goulding et al., 2019;Zhou et al., 2010). The lakes (reservoirs) in the Yangtze River Basin potentially suitable for aquaculture should be scientifically differentiated, and sustainable fisheries should be ensured by encouraging responsible well-managed fishing activities compatible with engaging local communities in generating socioecological benefits. ...
Freshwater capture fisheries are globally essential for food security and aquatic biodiversity conservation. The Yangtze River Basin is the third longest, and one of the most human-influenced drainage basins worldwide. Since the founding of P. R. China in 1949, this large river system has suffered increasing human perturbation and its sustainable development is now severely challenged. Meta-analysis showed that Yangtze River fisheries have experienced an extraordinary process of utilization-overexploitation-protection during the past 70 years, to the extent that other globally important rivers may never have encountered. Its fisheries appear to have collapsed over the past four decades, with yield decreasing to only 25% of an historic peak of 400,000 metric tonnes in the late 1950s. Endemic, migratory and rare fishes have been highly threatened with obvious changes in fish community structure and aquatic biodiversity. Anthropogenic activities, including impoundment of water in dams, discharge of pollutants, and riverine modification for vessel navigation, have caused large decreases in fisheries yields. Projections from surplus production modelling showed potential for improvement under fishing ban scenarios, but without any prospect for full recovery to historical stock status. This study revealed that the change in fisheries resources was dominated by the social-ecological watershed system, and an integrated approach to river basin management is warranted. Better management of freshwater ecosystems to integrate food security with biodiversity conservation is urgently needed throughout the world, and the changes evident in the Yangtze River fish populations can serve as an informative global reference.
Simple Summary
The East Asian finless porpoise is a common whale along Chinese coasts. The coast of the Shandong Peninsula is a substantial habitat for the species. However, there is relatively insufficient knowledge of and protection measures for the species population in this region. Based on public literature, media, and internet social websites, we collected and analyzed over two hundred reports on the stranding and accidental catching of finless porpoises along the coast of the Shandong Peninsula from 2000 to 2018. We found that bycatch and stranding incidents occurred widely across the peninsula throughout all seasons. The extensive use of fishing gear was the principal cause of porpoise mortalities and injuries along Shandong Peninsula. We recommend a comprehensive network consisting of an incident reporting system, fishing gear regulations, and scientific monitoring plans to protect the cetacean species in this region.
Abstract
The Shandong Peninsula is located on the western coast of the Pacific and is adjacent to the Bohai Sea (BS) and the Yellow Sea (YS) to the east. The East Asian finless porpoise Neophocaena asiaeorientalis sunameri, a subspecies of the narrow-ridged finless porpoise N. asiaeorientalis, is the dominant cetacean resident along the Shandong Peninsula. However, there is insufficient monitoring data to determine the status of the cetacean species in this region. Based on the publicly available literature, media, and internet social website, this study investigated the spatial–temporal distribution of porpoise stranding and bycatch along the coast of the Shandong Peninsula. Data on over five hundred porpoises from two hundred reports between 2000 and 2018 were compiled and analyzed. Results showed that the bycatch and stranding of porpoises occurred widely across the peninsula throughout all months and increased rapidly between 2010 and 2017. The incidents were more frequent in the area where the BS and YS converged during the spring and early summer than in other seasons. The mean body length of bycaught porpoises was smaller than that of those found stranded. Fishing activities could be the principal cause of local finless porpoise incidents. However, limited data hindered a quantitative evaluation of the living conditions of finless porpoises in this area. Establishing a comprehensive monitoring system, which includes standardized reporting, rescue operations, and scientific research, is essential to finless porpoise protection along the Shandong Peninsula.
River cetaceans are particularly vulnerable to anthropogenic impacts due to their constrained ranges in freshwater systems of China, South Asia, and South America. We undertook an exhaustive review of 280 peer-reviewed papers and grey literature reports (1998−2020) to examine the current status of knowledge regarding these cetaceans and their conservation. We aimed to better understand the scale of threats they face, and to identify and propose priority future efforts to better conserve these species. We found that the species have been studied with varying frequency and that most of the research on threats has focused on habitat degradation and fragmentation (43%, mainly driven by dams and extractive activities such as sand mining and deforestation), and fishery interactions (39%, in the form of bycatch and direct take). These threats occur across all
species, but more information is needed, primarily on quantifying the population impacts as a basis for designing mitigation measures. Other threats identified include pollution, vessel collisions, traditional use, and poorly managed tourism. Emerging methods such as environmental DNA and unmanned aerial vehicles are described for studying these species. Promising conservation interventions include cetacean-specific protected areas, natural ex situ protection, community-led conservation, and education programmes. However, transnational political will is required for a step change towards broad-scale protection in freshwater environments. In addition, we propose in creasing capacity building, developing management plans, working closely with fishing communities, enhancing public awareness, expanding regional collaborations, and diversifying funding.
Systematic records of cetacean strandings provide valuable baseline data on conservation actions, yet an effective scheme of nationwide stranding records is still lacking in Chinese waters. Non‐traditional data sources such as media offer a cost‐effective alternative to supplement the baseline gaps.
Media reports on cetacean strandings from 2007 to 2019 in Chinese waters were collected and verified through online searching. In a total of 1,298 stranding events, 1,576 individuals were identified, including at least seven species of Mysticeti and 22 species of Odontoceti.
The stranding events were not evenly distributed along the coastline of Chinese waters. Taiwan had the highest number of events, followed by Guangdong, Hong Kong and Fujian. Cetacean strandings occurred in all months, but most frequently in spring from March to May.
The increasing annual number might be due to rising stranding events or reflect an increase in social awareness, which demonstrated the potential value of the citizen science programme.
Standardized media reports with more comprehensive, accurate and detailed information were recommended, conducive to establishing a nationwide stranding record network in Chinese waters. The combination of data from different regions on a large scale can help inform the effective conservation of cetaceans.
Conservation management requires evidence, but robust data on key parameters such as threats are often unavailable. Conservation-relevant insights might be available within datasets collected for other reasons, making it important to determine the information content of available data for threatened species and identify remaining data-gaps before investing time and resources in novel data collection. The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) has declined severely across the middle-lower Yangtze, but multiple threats exist in this system and the relative impact of different anthropogenic activities is unclear, preventing identification of appropriate mitigation strategies. Several datasets containing information on porpoises or potential threats are available from past boat-based and fishing community surveys, which might provide novel insights into causes of porpoise mortality and decline. We employed multiple analytical approaches to investigate spatial relationships between live and dead porpoises and different threats, reproductive trends over time, and sustainable offtake levels, to assess whether evidence-based conservation is feasible under current data availability. Our combined analyses provide new evidence that mortality is spatially associated with increased cargo traffic; observed mortality levels (probably a substantial underestimate of true levels) are unsustainable; and population recruitment is decreasing, although multiple factors could be responsible (pollutants, declining fish stocks, anthropogenic noise, reduced genetic diversity). Available data show little correlation between patterns of mortality and fishing activity even when analyzed across multiple spatial scales; however, interview data can be affected by multiple biases that potentially complicate attempts to reconstruct levels of bycatch, and new data are required to understand dynamics and sustainability of porpoise-fisheries interactions. This critical assessment of existing data thus suggests that in situ porpoise conservation management must target multiple co-occurring threats. Even limited available datasets can provide new insights for understanding declines, and we demonstrate the importance of an integrative approach for investigating complex conservation problems and maximizing evidence in conservation planning for poorly known taxa.
Little effort has been made to conserve the East Asian finless porpoise, which is hindered by a lack of robust baseline data on their population status and threats. We conducted a local ecological knowledge survey around south Bohai Sea to collect information about the spatio-temporal distribution, population trends, and threats to East Asian finless porpoises. Based on the local ecological knowledge of 186 fishermen, April and September were the two months when porpoises were most frequently sighted, while February, November and December were when sightings were rare. Western coastal of Laizhou Bay and southern regions around Yellow River Estuary were identified as hotspots for sightings. More than half of the fishermen reported an overall decline in population through increasing water pollution, lower food resources and sustained fishery bycatch. These results provide insights into the distribution pattern and seasonal trends of the East Asian finless porpoises living in south Bohai Sea, thereby providing useful information for local authorities tasked with protecting this endangered cetacean.
Marine mammals in Indonesia mainly consisting of whales and dolphins belonging to the Cetacean and duyung or dugong of the order Sirenia. These rare animals are protected by law. However, the frequency of marine mammal occurrences stranded in Indonesia is now getting higher, as in East Java. Based on data from whale stranding of Indonesia, at least 12 marine mammal stranded incident occurred only in East Java in 2003-2017. Some events are also reported by BKSDA East Java and BPSPL Denpasar. Knowledge and readiness of coastal communities is needed in the handling of fast and precise in accordance with the guidelines handling. Fast and proper handling of alive stranded animals can reduce the risk of death so that the animals' hope for life and can be restored to their habitats is higher. Whereas in dead stranded animals, rapid and good handling can reduce the risk of disease from stranded animal carcasses.
The South China Sea (SCS) is known to support diverse cetacean species, yet their stranding information has not been well documented. To fill this knowledge gap, available records on cetacean stranding around Hainan Island in the SCS from 1978 to 2016 were collected and overviewed. In total, 112 records were obtained. Among them, 19 records involved 19 baleen whales (5 mysticeti species) and 93 records involved 134 toothed whales (12 odontoceti species). More stranding events occurred in the waters along the east coast than in the waters along the west coast, which was especially true for toothed whales stranding events. This may reflect the distribution patterns of cetaceans around Hainan Island. The spatial distribution of stranding events might be driven by different oceanographic features between the east and west offshore waters of the Hainan Island. The number of stranding events increased gradually from 1978 to 2000 and more rapidly from 2000 to 2016, which is likely due to both increasing public attentions and increasing anthropogenic activities within the SCS in recent decades. Stranding events were recorded throughout the year but peaked in spring (p = 0.016). In sum, cetacean stranding events occurred rather frequently around Hainan Island. The establishment of a regional stranding network in the SCS is conducive for further research, conservation and management of cetaceans in this region. More scientific data about the survival status of cetaceans and threats to them in the SCS are also needed.
The main biological factors responsible for the variability of pollutant concentrations in cetaceans are reviewed. Diet is significant because many pollutants are concentrated through food webs. This explains most interspecific differences in pollutant levels and it may also contribute to variation among populations of the same species or even among different components of the same population when diet is subject to age-related or sex-related variations. The effect of body size is complex. Excretion rate and activity of detoxifying enzymes decrease as body weight increases, processes which would lead to higher pollutant concentrations in large animals. In contrast, a high metabolic rate, which is inversely correlated to body size, is associated with high pollutant concentrations. These opposing effects usually result in higher residue levels in smaller individuals. Body composition affects the contribution of each body compartment to the overall pollutant load. Therefore, the body load of lipophilic pollutants will strongly depend on the relative mass of blubber, a variable that shows a threefold variation among cetacean species or, in seasonal feeders, among individuals. Nutritive condition also affects the dynamics of lipophilic pollutants. Lipid mobilisation results in an increase in residue levels, but this variation is not as large as a purely concentrative model would suggest because of enhancement of detoxification processes following a rise in tissue pollutant concentrations. Disease affects pollutant levels in different ways: impoverishing nutritive condition; altering normal physiological functions; and depressing reproduction therefore reducing reproductive transfer in females. The combined result of these processes is usually an increase in pollutant levels in diseased individuals. The concentration of lipophilic pollutants normally increases with age in males because input exceeds the ability of the organism to excrete pollutants. Variable proportions of the pollutant load are transferred to offspring during gestation and lactation, for which reason tissue concentrations in females decrease or stabilise, thus producing lower residue levels than in males. However, because not all compounds are transferred at the same rate, their relative abundance varies with age and sex.Intensity of reproductive transfer is also associated with the reproductive traits of the species, particularly the length of lactation. With the exception of zinc, concentrations of heavy metals increase with age in both sexes but, by contrast with lipophilic pollutants, concentrations in females are similar or higher than in males. The significance of these factors of variation should be taken into account when designing sampling methodology, comparing sample groups, or evaluating toxicological impact.
Fishery-cetacean interactions, including those with longline gear, give rise to economic, ecological and social concerns. This paper reviews problems resulting from cetacean-longline interactions, considers potential strategies to reduce interactions and identifies research priorities and approaches. Depredation by cetaceans (removal and damage of hooked fish and bait from fishing gear) and damage and loss of fishing gear create economic problems; however, the magnitude of this problem is poorly understood. There is also insufficient information to determine whether there are population-level effects resulting from injury and mortality of cetaceans (from incidental entanglement and hooking and from deliberate actions to discourage depredation). Fishery-cetacean interactions may also: change cetacean foraging behaviour and distribution; increase fishing effort to make up for fish taken from gear by cetaceans; and create errors in fish stock assessments that do not account for cetacean depredation. Negative public perceptions of longline fishing can result from news of incidental and deliberate injury and mortality of cetaceans associated with longlining. Information on how to reduce cetacean interactions with longline gear is also limited, as is the understanding of the mechanisms responsible for them. Strategies already employed in some fleets include refraining from setting or cutting sets short when problematic species of cetaceans are observed and fleet coordination of daily fishing times and positions. Many fishermen perceive depredation as an inevitable part of fishing. This paper discusses a number of other possible cetacean avoidance strategies that warrant consideration, including: (1) fleet communication to enable vessels to avoid temporally and spatially unpredictable and sporadic hotspots of aggregations of cetaceans; (2) underwater acoustic masking devices to conceal the sound of the vessel, gear, and setting and hauling activities; (3) quieter vessels to reduce cetaceans’ ability to target longline vessels; (4) encasement of caught fish to reduce cetacean access to or interest in the catch; (5) use of bait or gear with an unpleasant smell or taste to reduce the attractiveness of gear, bait and catch to cetaceans; (6) use of pre-recorded fishing vessel sounds played from stations throughout a fleet’s fishing grounds to distract cetaceans from actual fishing vessels; (7) use of acoustic devices to mask returning cetacean echolocation signals; and (8) use of tethered sonobuoys to track cetaceans and enable fleet avoidance. Vessels with relatively low cetacean interaction rates should be examined for design and operational differences from vessels with high interaction rates, possibly allowing identification of effective avoidance methods. There is a need for experimentation in individual longline fisheries over several seasons to assess fisheryspecific efficacy and commercial viability of cetacean avoidance strategies. This is necessary as different cetacean species likely respond differently to an avoidance method and cetaceans may habituate to an avoidance strategy, especially in fisheries interacting with resident cetaceans.
Published records of cetaceans stranded on the Irish coast during the period 1901-95 are reviewed. In this review the number of stranding events has been used in the analysis and includes both live strandings and those animals washed up dead. There were 529 records involving 21 species. The Harbour Porpoise (27%) was the most frequently reported species, followed by Common Dolphins (16%) and Pilot Whales (15%). Minke Whales (8%) were the most frequently reported mysticete. The number of reported strandings has increased since the 1960s which is thought to be mainly due to increased observer effort. Cetaceans have stranded on all Irish coasts but mainly along the south coast and along the western seaboard but with no apparent overall seasonal trend. There was a peak in the strandings of Common Dolphins during 1991-92 when 27% (28 records) of all strandings were reported and of White-sided Dolphins when 60% (28 records) were reported, both of which were attributed to possible interactions with fisheries. The number of Striped Dolphins stranded on the Irish coast has increased steadily since the 1980s and may reflect increasing water temperatures. These stranding records are considered inadequate to determine the status of most species of cetaceans in Irish waters but are sufficient to identify unusual stranding events such as high mortalities due to fisheries interactions or epizootics. More observer coverage is required before the stranding data are adequate for monitoring the status of most species but a stranding scheme is considered the most effective and efficient method of long-term monitoring of cetaceans in Irish waters.
Organochlorine (OC) contaminant concentrations in tissues and lipid profiles in blubber are summarised for 101 gray whales ( Eschrichtius robustus) from the eastern North Pacific stock. Samples were obtained from presumably healthy gray whales during a 1994 subsistence hunt in the Russian Arctic ( n= 17) and also from biopsy sampling of live animals from the Washington coast ( n= 38). In addition, tissues were collected from two groups of animals (1988-1991, n= 22; and 1999, n= 24) that stranded along the west coast of the USA. These whales represent a diverse group of animals with respect to lipid stores, age, gender, health and reproductive status. Informat ion about these biological factors is necessary before contaminant concentration data can be properly interpreted. Differences in blubber lipid levels and profiles were examined among these groups of whales. Significantly higher lipid levels were found in the blubber of subsistence animals that were sampled following summer feeding in the Bering and Chukchi Seas, compared to lipid levels in the biopsied and strande d animals. Lipid class profiles from blubber of presumably healthy gray whales (i.e. from subsistence and biopsy sampling) contained prima rily triglycerides and were very different from those of stranded animals that showed lipid decomposition (increased proportions of free fatty acids, cholesterol and phospholipids). Furthermore, lipid class profiles were found to be a means of estimating the quality of a blubber sample from stranded cetaceans. An examination of how biological factors (e.g. gender, reproductive status, age) contribute to interpreting the differences found in contaminant concentrations among the gray whales was also undertaken. Although not statistically signi ficant, higher (OC) concentrations were found in males compared to females, thus suggesting the tendency of the mother to shift her con taminant burden to her calf during gestation and lactation. Results also indicated that there was no significant increase in concentrati ons of contaminants in the blubber with increase in length (surrogate for age). Higher concentrations of OC contaminants were found in stranded juvenile gray whales, compared to juvenile subsistence whales, and were thought to result from retention of OCs in blubber of t he stranded animals as lipid stores are mobilised for energy and total lipid levels decrease, rather than from a difference in diet or feed ing areas. OC concentrations in various tissues (blubber, liver, kidney, muscle, brain) were similar on a lipid weight basis, except for brai n, which had lower lipid-adjusted OCs because the blood-brain barrier limits contaminant transfer.
This study analyses published records of beaked whale strandings from the coasts of the UK and the Republic of Ireland between 1800 and 2002. Strandings of northern bottlenose whales ( Hyperoodon ampullatus) were lowest in April and highest in September. The number of strandings between months differed significantly from an even spread over all months of the year, with more strandings between July and October. Most strandings in late summer and autumn occurred on North Sea coasts and their stomach contents included the squid Gonatus fabricii, which is found only in more northern waters. This suggests that these whales may be migrating southward at this time of year. Most strandings of Sowerby's beaked whales ( Mesoplodon bidens) also occurred in late summer and autumn, although this was not significant. Strandings of Cuvier's beaked whales (Ziphius cavirostris) occurred almost exclusively on the Atlantic coasts of the UK and in Ireland. There were significantly more Cuvier's beaked whale strandings than expected in January and February and in June and July. A Cuvier's beaked whale which stranded in northern Scotland in February contained similar prey to two whales stranded in north-western Spa in at the same time of year, suggesting this animal could have been feeding in more southern waters prior to stranding. Seasonal patterns of strandings of northern bottlenose and Cuvier's beaked whales were significantly different with more of the former stranding in August to October and more of the latter from November to July. This is consistent with a hypothesis of temporal segregation between the two species to reduce potential competition for prey.
Sperm whale (Physeter macrocephalus) is one of the common cetacean species inhabiting the western Mediterranean Sea. The aim of this study was to describe the dive cycle of sperm whales in this region and gain insight into their foraging activity. Dedicated summer field seasons were conducted from 2001-2003. Visual and acoustic measures were undertaken and their relationships analyzed. The measures included surface/dive periods, blow rate, distance traveled, timing of clicks & creak activity, and inter-pulse interval measurements of sperm whale clicks. The whales exhibited dive cycle parameters consistent with those measured in other parts of the world: approximately 45 min dive duration, 9 min surface period (i.e., inter-dive interval), with 5 blows/min, and 1.3 nmi horizontal displacement between dives. An average of 25 creaks per dive were registered. Whale body size appeared to be significantly related with both the number of creaks per dive and the dive time at which the first creak occurred, suggesting that larger whales may increase their prey intake and use deeper water layers than smaller whales. The timing of the first creak and the last click of the dive (around 6 min after fluke-up, and just before the surfacing, respectively) suggest a foraging depth of between 500 and 800 m, based on known descent and ascent rates.
Information on small cetacean mortality in Peruvian fisheries is reviewed for 1990-1993 period, after the national ban on cetacean exploitation. The ban was found not to be enforced or at best only partially so. Principal species affected included Lagenorhynchus obscurus, Delphinus capensis, Phocoena spinipinnis and Tursiops truncatus. -from Authors
The Northwest Region (NWR) Marine Mammal Stranding Network was created in the early 1980s to provide a consistent framework in which to collect and compile data about marine mammal strandings in Oregon and Washington. The NWR includes the nearshore water s and 4,243km (2,632 n.miles) of coastline. For the years 1930-2002, there were 904 stranding events, representing 951 individual animals and 23 species: 4 species of balaenopterids, 1 eschrichtiid, 2 physeterids, 4 ziphiids, 10 delphinids and 2 phocoenids. Gender was determined for 343 males and 266 females. Only one mass stranding was recorded (sperm whales: 1979). A few species comprised th e majority (71%) of stranding events in the NWR: harbour porpoise (34%), gray whales (23%), Dall's porpoise (12%) and Pacific white-sided dolphins (4%). There was a steep increase (511%) in the number of stranding reports beginning in the 1980s with over 86% of all records occurring during the last two decades (1980s and 1990s). The general trend of increased reported strandings during the last two decades corresponds to the formation of a formal stranding network and a heightened interest and dedication by the public and governmen t agencies in reporting and documenting strandings. For all events combined, the primary stranding peak was April-July. Since stranding re coveries depend heavily on reports from the general public, most stranding records were in summer when more people are present along the coastline. Individual species or species groups showed varying levels of conformity to this overall seasonal trend. The value a nd limitations of the use of strandings data in a management context are discussed.
A bstract
Although collisions with motorized ships are a recognized source of whale mortality, little has been done to compile information on the frequency of their occurrence or contributing factors. We searched historical records and computerized stranding databases for evidence of ship strikes involving great whales ( i. e. , baleen whales and the sperm whale). Historical records suggest that ship strikes fatal to whales first occurred late in the 1800s as ships began to reach speeds of 13‐15 kn, remained infrequent until about 1950, and then increased during the 1950s‐1970s as the number and speed of ships increased. Of 11 species known to be hit by ships, fin whales ( Balaenoptera physalus ) are struck most frequently; right whales ( Eubalaena glacialis and E. australis ), humpback whales ( Megaptera novaeangliae ), sperm whales ( Physeter catodon ), and gray whales ( Escbricbtius robustus ) are hit commonly. In some areas, one‐third of all fin whale and right whale strandings appear to involve ship strikes. To assess contributing factors, we compiled descriptions of 58 collisions. They indicate that all sizes and types of vessels can hit whales; most lethal or severe injuries are caused by ships 80 m or longer; whales usually are not seen beforehand or are seen too late to be avoided; and most lethal or severe injuries involve ships travelling 14 kn or faster. Ship strikes can significantly affect small populations of whales, such as northern right whales in the western North Atlantic. In areas where special caution is needed to avoid such events, measures to reduce the vessel speed below 14 kn may be beneficial.
Interactions between marine mammals and fishing gear is an issue of global concern. Entanglements in the western North Atlantic are a major source of injury and mortality for endangered large whales. In this study, entanglements of 31 right whales (Eubalaena glacialis) and 30 humpback whales (Megaptera novaeangliae) were analyzed to determine the types and parts of gear involved. When gear was identified, 89% (n=32) of the entanglements were attributed to pot and gillnet gear; however, a wide range of specific gear types were implicated. Despite gear recovery, gear type was not identified in 20% (n=9) of the cases. Although pot gear was recovered from both species equally, gillnet gear was less frequently retrieved from right whales (n=2) than humpback whales (n=11). When gear part was identified, 81% (n=21) involved entanglements in buoy line and/or groundline. For right whales, the most common point of gear attachment was the mouth (77.4%); for humpback whales, the tail (53%) and the mouth (43%) were common attachment sites. Four right and three humpback whales in this sample were known to have died subsequent to entanglement. However, when identified, the gear types and parts involved in lethal cases were not substantially different from entanglements with non-lethal outcomes. In conclusion, large whales can become entangled in a wide variety of fishing gear types and parts. Additional insight will depend on continued efforts to document entanglements and recover associated gear.
Collisions with vessels are a well-documented conservation problem for some populations of large whales (LW) in the Northern Hemisphere. Less attention has been given to incidents in the Southern Hemisphere or to small cetaceans (SC) worldwide, therefore an experimental database was compiled (N=256; 119 LW, 137 SC) to allow a rapid assessment. Confirmed collision records were identified for 25 species (7 LW, 18 SC) and unconfirmed but probable records for 10 other species (2 LW, 8 SC). Among LW, ship-caused mortality and traumatic injuries seem to affect primarily southern right (56 reported cases), humpback (15) and Bryde's whales (13), but also sperm (8), blue (5), sei (4) and fin whales (2) are involved, and probably Antarctic minke and dwarf minke whales. Southern right whale populations off South Africa and off eastern South America (Brazil, Uruguay and Argentina) suffer significant mortality. Incidence and potential population impact vary widely among the 26 small cetacean species for which collision records exist. Vessel strikes in at least two populations each of the Indo-Pacific humpback dolphin (Xiamen and Hong Kong/Pearl River, possibly western Taiwan), Irrawaddy dolphin (Mahakam River, Chilika Lagoon, possibly Laos) and finless porpoise (Yangtze River, Hong Kong) may directly compromise long-term survival. Annual vessel-caused mortality (min. 2.9% of population) for Irrawaddy dolphins in the Mahakam River may not be sustainable. The quasi-extinction of the baiji warns for a potential similar fate for the Yangtze River finless porpoise and Ganges river dolphin. Two calves of the endangered Hector's dolphin are known killed by boats. All highly impacted species have a neritic, estuarine or fluviatile habitat, areas where vessel traffic is concentrated. Species that may receive a moderate impact from collisions but which may be sustainable at species level (because many strikes are non-lethal), include common bottlenose dolphins, killer whales, short-finned pilot whales and pygmy sperm whales. Almost 2% of common bottlenose dolphins in the Gulf of Guayaquil showed propeller-inflicted injuries and scars. Propeller guards should be made compulsory for all boat-based cetacean tourism, as habituation to boat traffic seems a contributing factor in accidents. Low impact occurs in 15 small cetacean species with only few reported vessel strikes. However, vast underreporting is thought to be the norm and there is a need for a global, standardised database. RESUMEN: Las colisiones con barcos constituyen un problema de conservación bien documentado en el caso de ballenas grandes (BG) en el hemisferio norte. Menos atención se le ha brindado a los incidentes en el hemisferio sur y a los cetáceos menores (CM) alrededor del mundo. A fin de realizar una evaluación rápida de este problema se ha compilado una base de datos preliminar (N=256; 119 BG, 137 CM), la cual incluye registros confirmados de colisión para 25 especies (7 BG, 18 CM) y registros no confirmados pero probables para otras 10 (2 BG, 8 CM). Entre BG, la mortalidad causada por barcos e injurias traumáticas parecen afectar principalmente a las ballenas francas australes (56 casos reportados), ballenas jorobadas (15) y ballenas de Bryde (13), pero también se vieron involucrados cachalotes (8), ballenas azules (5), sei (4), de aleta (2), y probablemente ballenas minke antárticas y minke enanas. Ballenas francas australes costa afuera de Sudáfrica y de Sudamérica (Brasil, Uruguay y Argentina) sufren mortalidades significativas. La incidencia y el potencial impacto para las poblaciones varían ampliamente entre las 26 especies de cetáceos menores para las que existen registros de colisiones. En al menos dos poblaciones del delfín jorobado del Indo-Pacífico (río Mahakam, laguna Chilika, posiblemente Laos) y del delfín liso (río Yangtze, Hong Kong), las colisiones con barcos pueden directamente comprometer su sobrevivencia a largo plazo. La mortalidad anual causada por barcos para delfines del Rio Irrawaddy en el río Mahakam (min. 2.9% de la población) puede no ser sostenible. La cuasi extinción del baiji es una advertencia de un potencial destino similar para el delfín liso del río Yangtze y para el delfín del río Ganges. Se conoce de dos crías del amenazado delfín de Hector muertos por botes. Todas las especies altamente afectadas tienen un hábitat nerítico, estuarino o fluvial, áreas donde el tráfico marítimo se concentra. Especies que pueden recibir un moderado impacto por colisiones con barcos pero que pueden ser sostenibles a nivel de especies (pues muchas colisiones no son fatales) incluen a los delfines nariz de botella comunes, orcas, ballenas piloto de aleta corta y cachalotes pigmeos. Casi 2% de la población de delfines nariz de botella del golfo de Guayaquil mostraron heridas y cicatrices causadas por hélices. Se debería obligar el uso de dispositivos cubre hélice para todas las embarcaciones que realizan turismo de observación de cetáceos, pues la habituación al tráfico marítimo parece ser un factor que contribuye a los incidentes. Bajo impacto ocurre en 15 especies de cetáceos menores con solo unos pocos casos reportados de colisiones. Se estima que solo una fracción de las colisiones con cetáceos es reportada. Adicionalmente, se requiere una base de datos global estandarizada.
Although there has been extensive research on bottlenose dolphins (genus Tursiops), much controversy over the classification within this genus still exists. Even though many morphological variants occur, the prevailing view is for a single species, Tursiops truncatus (Montagu, 1821). To evaluate this view, two sympatric forms of bottlenose dolphins inhabiting Chinese waters were examined using multivariate statistical analyses of osteological data for two meristic and 18 cranial morphometric characters from 71 specimens. Cluster and principal components analyses revealed clear osteological separation of the two forms. Furthermore, the distributions of the total number of vertebrae and several proportions of cranial characters were non-overlapping between the two forms. These results provided strong evidence that the two sympatric forms of Tursiops in Chinese waters are isolated reproductively and do not support the current view of a monotypic genus. Classification functions of a discriminant analysis and a key of several characters were developed to help researchers identify unassigned specimens. Provisional names (T. truncatus and T. aduncus) were suggested, but a formal taxonomic revision of this genus is still required. However, regardless of the nomenclature, immediate amendments to all present wildlife conservation legislation are strongly urged.
We examined 107 harbor porpoise (Phocoena phocoena) carcasses recovered from beaches in Maryland, Virginia, and North Carolina between 1994 and 1996 for evidence of entanglement in fishing gear. Stranded porpoises ranged in length from 102 to 128 cm, indicating that only juvenile porpoises are present in the nearshore waters of the Mid-Atlantic during winter. Of the 40 porpoises for which we could establish cause of death, 25 displayed definitive evidence of entanglement in fishing gear. Evidence of entanglement consisted primarily of line marks from nets; in four cases we were able to determine specifically that porpoises had become entangled in monofilament nets. These mortalities demonstrate the need for a directed observer program for coastal gillnet fisheries in the Mid-Atlantic.
UK records are based on legislation which requires the reporting of a range of incidents involving cetaceans; thus not all events in the records are strandings as commonly defined. Observer effort has a profound influence on the records, as does the different legal basis for reporting in Scotland. The great advantages of the UK records are that they have been collected using the same basic system throughout and that so much information has been preserved about each event, whether or not the recorders considered such details important enough to publish. Systematic strandings recordings could provide much of the information required today for conservation and management as well as for wider studies of cetaceans. The major limitation is that so far no attention has been given to the relationship between the population sample which arrives on the beach and the rest of the population at sea. -from Author
This study summarizes 660 events involving captured, live-stranded and dead cetaceans in
South Australia between 1881 and 2000. Emphasis is placed on records (n = 361) during
1985-2000 when an active necropsy programme was underway. Average number of events per
year was 30.4 and the most common species were the short-beaked common dolphin
(Delphinus delphis) and Indo-Pacific bottlenose dolphin (Tursiops aduncus). Records were
assigned to nine categories of circumstance/cause of death. Summarizing the total database,
60% were unknown circumstance, 22% not obviously anthropogenic, 13% unintentional
human-related and 5% intentional human-related. In the data set of records for 1985-2000,
50% were unknown, 25% were not obviously anthropogenic, 20% were unintentional humanrelated
and 5% were intentional killings. Non-anthropogenic circumstances included neonatal
deaths, live strandings, significant diseases, shark attacks and choking. Cornynebacterium
ulcerans is recorded for the first time in a cetacean. Unintentional circumstances included
entanglement in fishing and aquaculture equipment (17% of necropsied carcasses from
1985-2000) and boat strikes. Intentional human-related circumstances were captures for live
display and illegal killing. Five percent of the necropsied carcasses during 1985-2000 were
attributed to shootings or stabbings/spearings. There is need for a formal reporting procedure
for marine mammal deaths and human interaction involving injury and for steps to be taken to
reduce human impacts.
The concentrations of chlorinated hydrocarbons (CHs) such as polychlorinated biphenyls (PCBs), 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethanes (DDTs), 1,1-dichloro-2,2-bis(p- chlorophenyl) ethenes (DDEs), and chlordanes, and essential (e.g., zinc, selenium, copper) and toxic (e.g., mercury, lead) elements were measured in tissues and stomach contents from 22 gray whales (Eschrichtius robustus) stranded between 1988 and 1991. The stranding sites ranged from the relatively pristine areas of Kodiak Island, Alaska, to more urbanized areas in Puget Sound, Washington, and San Francisco Bay, California, with the majority of the sites on the Washington outer coast and in Puget Sound. Similar to concentrations in tissues, no significant differences were observed in concentrations of elements in stomach contents between whales stranded in Puget Sound and whales stranded at the more pristine sites. The lack of data from apparently healthy gray whales limits the assessment of whether the levels of anthropogenic contaminants found in tissues may have deleterious effects on the health of gray whales.
Cetaceans display numerous anatomic and physiologic adaptations to life in a dense, three-dimensional medium. Their bodies
have changed radically from those of their terrestrial ancestors, yet their behaviors and types of social organization are
broadly similar to those of animals on land. An exploration of cetacean ways helps in understanding how habitat influences
habits. For example, it is now recognized that in some important ways, cetacean residents of the open ocean resemble some
of their mammalian relatives on the savanna. As air breathers that are inseparably tied to the surface, cetaceans are highly
trackable; they may thus help in the monitoring of habitat degradation and other long-term ecologic change.
Although there has been extensive research on bottlenose dolphins (genus Tursiops), much controversy over the classification within this genus still exists. Even though many morphological variants occur, the prevailing view is for a single species, Tursiops
truncatus (Montagu, 1821). To evaluate this view, two sympatric forms of bottlenose dolphins inhabiting Chinese waters were examined using multivariate statistical analyses of osteological data for two meristic and 18 cranial morphometric characters from 71 specimens. Cluster and principal components analyses revealed clear osteological separation of the two forms. Furthermore, the distributions of the total number of vertebrae and several proportions of cranial characters were non-overlapping between the two forms. These results provided strong evidence that the two sympatric forms of Tursiops in Chinese waters are isolated reproductively and do not support the current view of a monotypic genus. Classification functions of a discriminant analysis and a key of several characters were developed to help researchers identify unassigned specimens. Provisional names (T.
truncatus and T.
aduncus) were suggested, but a formal taxonomic revision of this genus is still required. However, regardless of the nomenclature, immediate amendments to all present wildlife conservation legislation are strongly urged.
Published records of cetaceans stranded on the Irish coast during the period 1901–95 are reviewed. In this review the number of stranding events has been used in the analysis and includes both live strandings and those animals washed up dead. There were 529 records involving 21 species. The Harbour Porpoise (27%) was the most frequently reported species, followed by Common Dolphins (16%) and Pilot Whales (15%). Minke Whales (8%) were the most frequently reported mysticete. The number of reported strandings has increased since the 1960s which is thought to be mainly due to increased observer effort. Cetaceans have stranded on all Irish coasts but mainly along the south coast and along the western seaboard but with no apparent overall seasonal trend. There was a peak in the strandings of Common Dolphins during 1991–92 when 27% (28 records) of all strandings were reported and of White-sided Dolphins when 60% (28 records) were reported, both of which were attributed to possible interactions with fisheries. The number of Striped Dolphins stranded on the Irish coast has increased steadily since the 1980s and may reflect increasing water temperatures.
These stranding records are considered inadequate to determine the status of most species of cetaceans in Irish waters but are sufficient to identify unusual stranding events such as high mortalities due to fisheries interactions or epizootics. More observer coverage is required before the stranding data are adequate for monitoring the status of most species but a stranding scheme is considered the most effective and efficient method of long-term monitoring of cetaceans in Irish waters.
Baiji were sighted 17 times during three recent simultaneous multi‐vessel surveys in the Yangtze River, China (November 4–10, 1997; December 4–9, 1998; October 31–November 5, 1999). There were 11 sightings in 1997 (consisting of 17 animals), five in 1998 (seven animals), and two in 1999 (four animals). It was concluded that 13 individuals could be considered as a minimum number of the baiji currently in the Yangtze River.
An annual rate of population decrease was roughly estimated as 10%. From the body sizes observed, the proportions of old, adult and immature individuals were approximately estimated at 57, 26, and 17% respectively.
Baiji showed a significant attraction to confluences and sand bars with large eddies. The present distribution range of the baiji is less than 1400 km in length in the Yangtze main river. Distances between the two nearest groups of baiji appear to be increasing.
Two typical sightings are described, in which surfacing and movements of baiji were recorded. Baiji were often found swimming together with finless porpoise. In the surveys they occurred in the same group in 63% of occurrences. Interactions between baiji and finless porpoise are described and discussed.
Human activities are the main threats to the baiji. Illegal electrical fishing accounted for 40% of known mortalities during the 1990s. Engineering explosions for maintaining navigation channels have become another main cause of baiji deaths. The last hope of saving the species may be to translocate the remaining baiji into a semi‐captive reserve, known as the ‘Baiji Semi‐natural Reserve’.
Copyright © 2003 John Wiley & Sons, Ltd.
The Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is endemic to the middle and lower reaches of the Yangtze River, China. It is the only freshwater population of porpoises in the world and is currently listed as Endangered by IUCN. In November and December 2006 we used two boats and line transect methods to survey the entire current range of the population, except for two lakes (Poyang and Dongting). Sighting results were similar for both boats, so we pooled all data and analyzed them using two line transect models and a strip transect model. All models produced similar estimates of abundance (1111, 1225 and 1000). We then added independent estimates of the number of porpoises from the two lakes for a total estimate of approximately 1800 porpoises. Our findings indicate that the population continues to decline and that its distribution is becoming more fragmented. Our current estimate in the main river is slightly less than half the estimate from surveys between 1984 and 1991 (which was probably an underestimate). We also found an apparent gap in the distribution of porpoises between Yueyang and Shishou (∼150 km), where sightings had previously been common. Continued threats to Yangtze finless porpoises include bycatch in unregulated and unselective fishing, habitat degradation through dredging, pollution and noise, vessel strikes and water development. Immediate protective measures are urgently needed to ensure the persistence of finless porpoises in the Yangtze River. The survey design and analytical methods developed in this study might be appropriate for surveys of cetaceans in other river systems.