@book{,

title = {Sousa plumbea},

author = {Braulik, G.,Findlay, K,Cerchio, S,Baldwin, R,Perrin, W.},

year  = {2017},

date = {2017-01-01},

journal = {The IUCN Red List of Threatened Species},

number = {49},

publisher = {e.T82031633A82031644. Downloaded on 10 December 2017.},

abstract = {Endangered: Justification:

In the places where studies have occurred, Indian Ocean Humpback Dolphin subpopulations were found to be small: always fewer than 500 and generally fewer than 100 individuals in discrete, or semi-isolated areas. Humpback dolphins have one of the most specific habitat preferences and restricted distributions of any marine megafauna, and both of these characteristics are well known to reduce the resilience of species to environmental change and anthropogenic threats and to increase their extinction risk (Davidson et al. 2011, Dulvy et al. 2014, Purvis et al. 2000). Indian Ocean Humpback Dolphins are concentrated in coastal waters within 2 km of shore and they are often sighted only a few hundred meters from land. This distribution places them in exactly the same location as the majority of small-scale fishing effort prevalent throughout their range in the same nearshore habitat. As a result, humpback dolphins encounter large numbers of coastal gillnets and are at high risk of entanglement. High and clearly unsustainable mortality rates have been reported from several areas and frequent encounters with fishing gear can be inferred from the high degree of scarring and injury—for example, 41% of individuals in Pemba, Tanzania bore gear-related scars (Braulik unpub. data). Although information on population size, threats and mortality is available only for portions of the species range, there are strong reasons to suspect and infer that the threats will be similar or possibly even more intense elsewhere.



The deaths of only 4.2 individuals per year from a population of 100 would result in a 50% decline (Moore 2015). The available evidence on the studied subpopulations in South Africa and all indications from elsewhere in the range suggest that mortality rates are consistently at or above the rate that would result in a 50% decline in 75 years (three generations). The species’ preferred habitat and small populations overlap in both space and time with several ubiquitous and pervasive threats that are increasing in severity, leaving no refuges for these dolphins. The threats are serious enough in a large enough proportion of the total species range that a range-wide decline of at least 50% over three generations spanning both the past and the future (about 75 years, from 1960 (the start of intensive mono-filament gillnetting in this region) to 2035) is suspected and inferred and the causes of the decline (bycatch and hunting [both considered here to constitute ‘exploitation’], decline in habitat quality and possibly pollution) have not ceased. Therefore, the Indian Ocean Humpback Dolphin qualifies for Endangered A4cd.



The factor primarily responsible for the decline is incidental mortality in small-scale coastal fisheries, but the loss, degradation and pollution of habitat in numerous coastal areas is a contributing and increasing factor. The threats have not been mitigated anywhere in the species’ range, even though threat levels are increasing virtually everywhere. All evidence suggests that threats and declines will continue and are likely to increase in the future and worldwide there are almost no examples where cetacean bycatch in small-scale artisanal fisheries has been successfully addressed. Alternative methods for small-scale fisheries to replace gillnets are not generally available. Therefore, the species also qualifies for Endangered 3cd as a decline of over 50% can be projected to occur over the next three generations (75 years from 2016 to 2091). It also qualifies for Endangered A2cd as a decline of over 50% is suspected over the last 75 years beginning with the expansion of the use of gillnets in global marine fisheries from around the end of the Second World War up to the present day.},

keywords = {Arabian Sea, Bycatch, conservation status, humpback dolphin, Indian Ocean, Indo-Pacific humpback dolphin, Sousa plumbea, Threat assessment},

pubstate = {published},

tppubtype = {book}

}

@book{,

title = {Sousa chinensis},

author = {Jefferson, T.,Smith, B.D.,Braulik, G.,Perrin, W.},

year  = {2017},

date = {2017-01-01},

journal = {The IUCN Red List of Threatened Species},

number = {126},

publisher = {e.T82031633A82031644. Downloaded on 10 December 2017.},

abstract = {Vulnerable: Justification:

The only available population trend estimate for S. chinensis is an estimated 2.46% annual decline in the size of the subpopulation in HK/PRE (Huang et al. 2012), where there are a number of marine parks and reserves in place for dolphin protection, and where the Hong Kong authorities have put more effort into impact assessment and management than in any other part of the species’ range (see Jefferson et al. 2009). The situation elsewhere appears to be more dire, with fisheries bycatch being a nearly-universal threat. Population reductions of at least 3.7% per annum (see below for information that human-caused mortality rates of 3.7% would lead to a 30% decline in abundance over three generations) can therefore be inferred over most of the species’ range, due to known incidental mortality from intensive fishing effort using entangling gears, and ongoing habitat loss and degradation due to coastal development. Vessel collisions and environmental contamination appear to be factors as well, in at least some parts of the range. The above inference is supported in several areas by direct and/or indirect evidence, including documentation of bycatch, the intensive use of gillnets and other fishing gears known to entangle small cetaceans, interviews with fishermen who use entangling gears, and the abandonment of areas of previous occupancy (see Xu et al. 2015). 



The Indo-Pacific Humpback Dolphin therefore qualifies for Vulnerable A3cd+4cd, based on an inferred population size reduction, where subcriterion c is interpreted as quality of habitat, and subcriterion d (actual or potential levels of exploitation) includes fisheries bycatch. We can infer a population reduction of greater than or equal to 30% over three generations (75 years), from approximately 1960 in the past to 2035 in the future. This takes into account that the main causes of the suspected/inferred decline in population size, bycatch and habitat destruction/degradation, have not ceased and are not well understood throughout most of the species’ range. Other than in Hong Kong (and to a lesser extent Taiwan), there have been virtually no conservation actions taken to address these threats, and available evidence suggests that they will continue and may even escalate in the future. The assessment of S. chinensis as Vulnerable based on criterion A3cd+4cd applies, regardless of whether or not the Bangladesh/eastern India animals are included, because it is based on population trends, rather than absolute numbers or a declining range.},

keywords = {Arabian Sea, Bycatch, conservation status, humpback dolphin, Indian Ocean, Indo-Pacific humpback dolphin, Sousa plumbea, Threat assessment},

pubstate = {published},

tppubtype = {book}

}