Preprint volume - SIBM

Pre-print Volume – Introductory lecture
Topic 1: BIODIVERSITY AND CONSERVATION SCIENCE: CONTRIBUTING TO MANAGEMENT
that a trend towards more intense and widespread pressures is bad when these pressures
overlap with the habitats under investigation. As well as a variety in the criteria uses to
look at trends, there is also the issue that the reference points used to assess state are
very much dependent on when monitoring and long-term time series information
becomes available. For species, trends are measured from the 1940s (plankton), 1960s
(grey seals), 1980s (harbour seals), 1986 (seabirds), 1975/76 (waterbirds), 1980s (fish)
and 1994 (cetaceans). For habitats there is no monitoring data similar to that collected
for the species groups, which means the assessment of status cannot be compared
against a particular decade: baseline conditions are defined, therefore, as “a concept of
former unimpacted conditions”. The benefits of the species chapters is that at least real
long term trends can be shown, based on actual evidence, despite the fact that the lack
of an agreed reference point (baseline) means changes can’t be compared in a
consistent way across the groups (how close or far is the status from a specified target
value). The issue of choosing a “baseline” or reference point to represent the vision
goes beyond what scientists can deduce by analyzing data and trends and also becomes
linked to what is acceptable to policy-makers, stakeholders and the wider public. An
example is to consider the idea that large (and preferably stable or increasing) species
populations are a good thing. Grey seal (Halichoerus grypus) population numbers are
at historically high levels in the UK and recent evidence suggests a “leveling off”,
probably due to density dependent factors. However, the high numbers of grey seals in
the UK, as elsewhere in the world, is actually seen as a problem by groups such as
fishermen who see them as competitors for resources (Pinnegar et al., in press). At
least the high numbers can be attributed to positive developments such as being
protected from human persecution (Duck, 2010 in press). Despite declines in seabird
numbers in many UK regions, there has been a large increase in the number of Fulmars
(Fulmarus glacialis). However, this is thought to be almost entirely due to the fact that
Fulmars feed on discards from fishing boats so that numbers are elevated beyond levels
that naturally occurring food sources can sustain (Mitchell, 2010 in press). There are
many other cases in the marine environment where populations of species thrive due to
anthropogenic causes. The main issue is what point is selected as a baseline/reference
condition along a continuum from completely natural and unimpacted conditions to
conditions occurring as a result of high levels of impact or exploitation. Mee et al.
(2008) point out the value-laden nature of making this type of decision as different
levels of impact are acceptable to different parties with differing values and
expectations. For example, “former natural unimpacted conditions” is used as a
reference point for habitats in CP2 and this type of reference point is implicit, if not
explicit in many nature conservation approaches. The main difficulty with this
approach is that there is very little information on what “unimpacted, natural, historical
conditions” look like (Crowder, 2005). The commercial fish assessment has a
completely different approach accepting high levels of exploitation (impact) as long as
this is sustainable so the baseline is far from “unimpacted”. The issue for commercial
fish stocks is that the agreed baseline is always changing anyway (Pauly, 1995). For
the non-commercial fish communities in CP2 there was much discussion over where
along this continuum the baseline/reference point should be with the result that two
analyses are presented, one using historical relatively unimpacted conditions and one
using a more recent period.
Conclusions - To summarise, there is a major challenge in defining what is meant by
the vision of healthy and biologically diverse seas and CP2 has made an important
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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