130925-studie-wildlife-comeback-in-europe

% change
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150
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50
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populations. Although the overall size of the
European population of Harbour seal is twice
that of 1960 by the end of the time series in 2005,
abundance at this point is decreasing. The trend
for Harbour seal is based on 20 populations from
Denmark, Germany, the Netherlands, Sweden and
the United Kingdom, which represent an average
of 47,000 individuals or 58% of the total European
population of 2008, and cover 33% of the countries
of occurrence.
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1960s 1970s 1980s 1990s 2000–05 1960–2005
Drivers of recovery
Figure 2.
Change in Harbour
seal population
abundance by
decade and overall
change between
1960 and 2005. Please
note that due to the
way change was
calculated, decadal
change does not sum
to overall change.
Table 3.
Major reasons for
positive change in the
status of the Harbour
seal in Europe.
Rank Reason for change Description
1 Species management –
Reduced hunting pressure
(1599) and 1955 in the English Channel, North Sea
and northern Russian coast is likely an artefact of
incomplete distributional information in historic
times. It seems plausible that seals were, in fact,
only documented in areas that were of interest to
humans [19] . In addition, the 1955 map may suffer
from lack of detail, giving rise to over- or underestimations
of change to the present day. According
to the information in Figures 1a and b, the species
lost territory in the Baltic Sea while it expanded
around the United Kingdom and the Russian coast.
This represents a recovery from range decreases
prior to the middle of the 20 th century, leaving the
species to occupy an area that is 6% larger than in
historical times.
The increasing trend in distribution is in line
with the change in population size, as European
Harbour seals doubled in abundance over the
45-year study period between 1960 and 2005
(Figure 2). Declines occurred in the 1960s and
2000s, the latter coinciding with the second
outbreak of PDV [12] . However, the trend in Figure 2
also suggests increases in the 1970s and 1980s,
which are unexpected due to the PDV outbreak
in 1988. It is therefore possible that the expected
declines are masked by increases in unaffected
Following a reduction in hunting pressure, the
Harbour seal recovered from 3,000 individuals in
1974 to more than 15,000 in 2003 in the Wadden
Sea [13] .
2 Legislation Increased European-wide and country-level legal
protection of the species and its haul-out sites
from the late 1970s helped recovery throughout its
range [15, 16] .
The Kalmarsund population recovered from 50 in
the 1970s [34] to 630 in 2007 [40] due to protection.
Hunting is now prohibited in all countries except
Norway and Iceland [2] .
3 Land/water protection &
management
4 Other – Collaborative
management
Habitat protection also contributed to the recovery
of the Harbour seal in the Wadden Sea [13] .
Some countries are collaborating on management
plans, e.g. the Netherlands, Germany and Denmark
in the Wadden Sea [30–33] .
As discussed above, disease has had a profound
impact on the abundance trend of the Harbour
seal in Europe. Along with exploitation, disease
emerged as one of the predicting factors of
population decline from our analysis, while habitat
degradation and unknown threats were generally
associated with positive trends. In addition, the
presence of management intervention, specifically
the cessation of hunting, was beneficial, although
change was also positive for those populations
which received no attention. As expected, non-utilised
populations increased, while those with
unknown utilisation status declined.
The importance of the factors identified in our
data set is also confirmed by the literature (Table 3).
Increased legal protection was implemented from
the late 1970s both in individual countries at a
European scale [15, 16] , and this undoubtedly helped
the Harbour seal recover in number and range. For
example, protection was key in the recovery of the
Kalmarsund population in the Baltic from a mere
50 individuals in the 1970s [34] to 630 in 2007 [40] . In
the Wadden Sea, the species increased from 3,000
individuals in 1974 to more than 15,000 in 2003 due
to a reduction in hunting pressure and increased
habitat protection [13] , made possible by collaborative
management between the Netherlands,
Germany and Denmark [30–33] . At present, hunting
is prohibited in all countries except Norway and
Iceland [2] . Other, non-governmental conservation
measures include the rescue and rehabilitation of
seal pups [43] , and while these efforts were unable to
save infected seals during the two epidemics, they
may have made some contribution to population
recovery. However, there is some debate as to
whether this intervention is beneficial for the
species in the long-term, as it side-steps natural
selection by keeping alive individuals that may
otherwise perish, and also increases the risk of
infection if healthy seals are brought to a centre
where the disease is present.
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