FEATURE CREATURE
FEATURE CREATURE
INDO-PACIFIC FINLESS PORPOISE (NEOPHOCAENA PHOCAENOIDES ) FEATURE IUCN RED LIST 2017 PHOTOGRAPHY ADA NATOLI – UAE DOLPHIN PROJECT
RED LIST CATEGORY & CRITERIA: VULNERABLE Scientific Name: Neophocaena phocaenoides Synonym(s): Delphinus phocaenoides (G. Cuvier, 1829) Common Name: Indo-Pacific Finless Porpoise TAXONOMIC The recognition of two externally distinct morphological forms of Finless Porpoises as separate biological species, the Indo-Pacific Finless Porpoise (Neophocaena phocaenoides) and the Narrow-ridged Finless Porpoise (N. asiaeorientalis), was accepted only recently when it was demonstrated that the two forms are reproductively isolated (and likely have been separated since the last glacial maximum) even though they occur sympatrically in a fairly large area of eastern Asia (Wang et al. 2008, Jefferson and Wang 2011). [Much of the literature published before ca 2010 refers to all Finless Porpoises (both species) as N. phocaenoides.] Differences in the external morphology of the dorsal aspect of the two species are distinguishable even amongst free-ranging animals (as opposed to only specimens in-hand) (Wang et al. 2010). Intermediates between the two main forms have never been reported even though several hundreds to thousands of carcasses have been examined. The two species also 30
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clearly differ in craniometry (Amano et al. 1992, Jefferson 2002). There is evidence to suggest subpopulation structure within Indo-Pacific Finless Porpoises in some areas (Jefferson 2002,Yang et al. 2008, Chen et al. 2010, Xu et al. 2010, Li et al. 2011, Ju et al. 2012, L. Li et al. 2013, S. Li et al. 2013, Jia et al. 2014, Lin et al. 2014) and this may apply throughout much of the species’ distribution. JUSTIFICATION With some of the largest concentrations of Humans in the world living along the shores of, and harvesting the resources from, the warm coastal waters inhabited by Indo-Pacific Finless Porpoises, the impacts of human activities on this species must be considerable. Partly because of their small size, which limits their strength to break free once entangled, phocoenids are exceptionally vulnerable to incidental mortality in gillnets (e.g., Jefferson and Curry 1994), and incidental mortality in fishing gear has been documented throughout the range of Indo-Pacific Finless Porpoises. Fishing effort with gear documented to catch Finless Porpoises accidentally (including gillnets, trawls, stow nets, and seines) is intense in many areas where the species occurs or occurred. Although not quantified as rigorously as for some N. asiaeorientalis populations, regional
declines (and possible local extirpations) of N. phocaenoides have been reported, presumably due to a combination of fishing pressure, coastal development and industrialisation, pollution, and heavy vessel traffic (Reeves et al. 1997, Collins et al. 2005, Braulik et al. 2010). The data are insufficient to make a rigorous quantitative assessment of population trend for this species in any part of its range, but the scale of threats is large enough over enough of the range to suspect and infer a decline of at least 30% over the last three generations (about 45 years, assuming 15 years/generation as estimated for N. asiaeorientalis by Moore 2015) (A2), over three generations into the future (A3), and over a three-generation period that includes both the past and the future (A4). The factor most responsible for such a decline would be incidental mortality in fisheries (subcriterion d, “exploitation”), but the loss and degradation of habitat (subcriterion c) and pollution (chemical and acoustic; subcriterion e) are likely contributing factors as well. None of the threats has been seriously addressed in any part of the species’ range, even though threat levels are presumably increasing. Therefore, the Indo-Pacific Finless Porpoise qualifies for Vulnerable under Red List criteria
