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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. [ABSTRACT FROM AUTHOR]

The article reports that Barbara Taylor has been researching marine mammals, and led the marine mammal genetics program at the Southwest Fisheries Science Center in La Jolla, California. It mentions that the group identifies Units to Conserve using genetic data and has promoted developing guidelines and standards to facilitate naming new taxa of cetaceans using primarily genetic data.

In cases of severe wildlife population decline, a key question is whether recovery efforts will be impeded by genetic factors, such as inbreeding depression. Decades of excess mortality from gillnet fishing have driven Mexico’s vaquita porpoise (Phocoena sinus) to ~10 remaining individuals. We analyzed whole-genome sequences from 20 vaquitas and integrated genomic and demographic information into stochastic, individual-based simulations to quantify the species’ recovery potential. Our analysis suggests that the vaquita’s historical rarity has resulted in a low burden of segregating deleterious variation, reducing the risk of inbreeding depression. Similarly, genome-informed simulations suggest that the vaquita can recover if bycatch mortality is immediately halted. This study provides hope for vaquitas and other naturally rare endangered species and highlights the utility of genomics in predicting extinction risk. [ABSTRACT FROM AUTHOR]

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 (∼150km), 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. [Copyright &y& Elsevier]

Under the U.S. Endangered Species Act (ESA), a species can be listed if it is at risk “in all or a significant portion of its range,” but the ESA provides no guidance on how to interpret this key phrase. We propose a simple test to determine whether the areas of a species' range in which it is currently at risk amount to a significant portion: If the species were to become extirpated from these areas, at that point would the entire species be at risk? If so, then these areas represent a significant portion of the species' range. By establishing the species itself as the point of reference for determining significance, this test directs attention to biological risk factors and avoids difficulties inherent in subjective evaluations of importance to humans. For broadly distributed species this framework could provide ESA protection due to cumulative risks before the entire species met the criteria to be considered threatened or endangered. This framework also allows a somewhat broader concept of range to include major components of diversity necessary for long-term persistence. The concept of a historical template (i.e., conditions under which the species was known to be viable) is important in providing a fixed reference point for evaluating viability. Empirical examples illustrate how these concepts have been applied in recent ESA listing determinations. Most ESA-listed units of Pacific salmon (Oncorhynchus spp.) can be divided into multiple strata that differ in terms of ecology, geology, or life-history traits of the component populations. The goal of ESA recovery planning is to restore viable populations in enough strata that the listed unit as a whole is no longer threatened or endangered in all or a significant portion of its range. In a recent review of Pacific herring (Clupea pallasii ) in Puget Sound, current status (some populations increasing and others declining) was evaluated in the context of the historical template, and it was concluded that current patterns of distribution and abundance do not depart substantially from what would be expected at any point in time under natural conditions in a large metapopulation. The Canadian lynx (Lynx canadensis ) is ESA listed in the contiguous United States, where it occurs in four geographic areas. Populations in one region, the Northern Rockies/Cascades, have always been the most important for long-term persistence of the species in the United States. Because the other regions never contained more than limited amounts of good-quality lynx habitat, those areas are not considered to represent a significant portion of the species' range. [ABSTRACT FROM AUTHOR]

The authors reports that the vaquita (Gulf of California porpoise, Phocoena sinus), is in imminent danger of extinction by the use of gillnet fishing in El Golfo de Santa Clara and San Felipe, Mexico as of December 2007. They call for the use of economic incentives to the fishing communities as a way of halting the use of such nets, and the incidental death of the porpoises caused by their use. Using computer models, they found that the vaquita has two years before they reach a population level of no return.