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Discussion
Workshop participants wished to emphasise the importance of looking beyond the categories alone when
interpreting the proposed listings. The reason(s) for listing, i.e. the criterion or criteria used, must be considered
in all cases. For example, as highlighted in the table above, the two dolphin populations (subspecies) in the
Black Sea were assessed as Endangered primarily on the basis of past declines caused in large part by heavy
exploitation (criteria A1d and A2cde). Specifically, the massive documented legal removals by deliberate
exploitation in the USSR, Romania and Bulgaria until 1966 and in Turkey until 1983 caused precipitous declines
in those populations within the last three generations, i.e. during the last 60 years. With the closure of the cetacean
fisheries in the Black Sea countries, it was assumed that the principal cause of the reductions (or at least one of
the principal causes in the case of the bottlenose dolphin) had ceased. In fact, some recovery may have taken
place, although there is no clear evidence of trend for either Bottlenose Dolphins or Common Dolphins in the
Black Sea. In contrast, the Black Sea Harbour Porpoise subspecies was assessed as Endangered not only
because of the decline in numbers caused by legal hunting until 1983 and illegal hunting until 1991 (criterion
A1d), but also because of an inferred continuing decline caused by a suite of threat factors that show no sign
of moderating and may well be worsening (e.g. incidental mortality in fisheries, habitat degradation and prey
depletion: criterion A4cde).
A major difference of similar kind should be noted for the Mediterranean, where the subpopulations of Bottlenose
Dolphins and Striped Dolphins were both assessed as Vulnerable even though the latter is much more abundant
(possibly by an order of magnitude) than the former. Bottlenose Dolphins exist in the Mediterranean region as
a collection of subpopulations, the size and range of which vary considerably in different areas. This made it
difficult for the workshop to agree on a proposed listing for the region as a whole. Trend data were available for
only a few areas, in one of which (the northern Adriatic Sea) a decline in abundance and area of occupancy was
evident. In other areas such as the Alborán Sea, surveys over the past 15 years have found no signs of a decline.
It was nevertheless recognised by all participants that, as the most coastal species in the region, the Bottlenose
Dolphin is likely to have been affected in numerous ways by human activities, including culling campaigns to
exterminate or greatly reduce its numbers in some areas. Incidental mortality in fishing gear, prey depletion as a
result of overfishing or habitat degradation, disturbance from ship traffic, and health effects caused by pollution
are all suspected of having had at least local effects on Bottlenose Dolphins. Therefore, a decline of at least 30%
in the Mediterranean as a whole over the last 60 years (3 generations) was suspected, based on concerns about
degradation, loss and fragmentation of habitat as well as the removals due to deliberate killing (now largely
stopped) and incidental mortality in fisheries (ongoing). In the case of Striped Dolphins, suspected substantial
recent and ongoing mortality in pelagic driftnets (thousands of animals per year), together with the residual
effects of a large-scale die-off from an epizootic in the early 1990s, provided the main basis for the proposed
listing as Vulnerable. Although disease would, in some circumstances, be properly regarded as a factor in the
population’s natural mortality and thus not directly relevant to the decline criteria, there was reason in the case of
Mediterranean Striped Dolphins to suspect that exposure to high levels of organochlorine chemicals had played
a role in making the animals exceptionally susceptible to the morbillivirus infection that killed them.
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