BSEP116B Biodiversity in the Baltic Sea - Helcom

6 HUMAN PRESSURES ON BIODIVERSITY
A human population of approximately 85 million
people lives in the catchment or drainage area of
the Baltic Sea. A great number of different types
of human activities taking place in the catchment
area, coastal zone, and open sea exert pressures
on Baltic Sea biodiversity.
Some pressures act on a local scale, while others
act at basin-wide scales. For example, dredging
may have a local and short-term impact, while
eutrophication affects vast areas and is long
lasting. Similarly, certain pressures act at the level
of species, while others have an impact at the
greater landscape level of biodiversity (Figure
6.1). Many of the pressures also cause synergistic
effects, whereby the negative impact of one pressure
is exacerbated by another.
This chapter addresses the magnitude and impact
of different pressures originating from various
economic sectors. It mainly covers human activities
that are directly associated with the Baltic Sea
and that exert multiple pressures on biodiversity,
namely, fisheries, maritime traffic, technical installations,
and recreational activities. In addition, the
chapter provides an overview of the magnitude
and known impact of eutrophication, hazardous
substances, alien species, noise, and hunting. Projected
changes in climate caused by anthropogenic
factors are also presented as a case of anticipated
future pressure.
Pressures addressed in this chapter include the
predominant pressures and impacts on Baltic Sea
biodiversity. They also largely cover the pressures
and impacts listed in Annex III, Table 2 of the EU
Marine Strategy Framework Directive (MSFD).
6.1 Fisheries
Fisheries have been an important source of livelihood
for people of the Baltic countries for centuries.
There is archaeological evidence suggesting
that fishing was conducted along the Baltic
coasts already since before the Middle Ages (e.g.,
Makowiecki & van Neer 1996). However, the
magnitude of landings and fishing effort is mostly
documented for the 20th century, while information
on the stock status of the eastern Baltic cod
population dates back to the 1920s (Eero 2008)
and for herring and sprat only to the 1970s (ICES
2008b).
There is increasing evidence that fisheries have a
substantial impact on the biodiversity and function
of the entire Baltic ecosystem. This extends
from key abiotic parameters to the upper trophic
levels of the food web. The biodiversity segment of
the Baltic Sea Action Plan (BSAP) includes a large
number of actions targeted to fisheries; in fact,
the number of measures related to fisheries in the
biodiversity segment is larger than that related to
any other human activity. Moreover, the BSAP specifically
includes a recommendation to implement
the ecosystem approach to fisheries management
in the Baltic Sea.
Fishing and Fisheries
Constructions Eutrophication
Physical Environment
Communities
Species
(Genes)
and
and
Hazardous substances
Biotopes
Water quality
Climate Change
6.1.1 Description of fisheries
Cod (Gadus morhua callarias), herring (Clupea
harengus membras), sprat (Sprattus sprattus) and
salmon (Salmo salar) are the most important internationally
assessed and managed fish stocks in
the Baltic Sea. Most other fish species are mainly
of local importance and are therefore managed
nationally and/or locally. The assessment and
management units of the internationally assessed
species are provided in Figure 6.1.1.
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Hunting
Alien Species
Maritime Traffic
Oil Spills
Figure 6.1. Human pressures in the Baltic Sea region act on
different levels and scales of biodiversity.
Pelagic trawls dominate in the herring and sprat
fishery. Usually the catch consists of a mixture of
these two species, while their proportion in the
catch varies by area and season. Herring is also
caught by trapnets/pound-nets and gillnets in
coastal areas as well as with bottom trawls. In