Integrating Multiple Pressures at Different Spatial and Temporal Scales: A Concept for Relative Ecological Risk Assessment in the European Marine Environment

ABSTRACT

A Relative Ecological Risk Assessment model is presented with an emphasis on risk calculation and risk characterization. Several types of impacts are incorporated including mortality, competition, and disturbance effects at different spatial scales exemplifying fisheries effects on benthic communities, marine mammals, and birds. Fisheries sectors analyzed are beam trawlers, demersal otter trawlers, gillnet, and sandeel fisheries in the German Exclusive Economic Zone of the North Sea. The basic ecological unit to which the risk score applies is the population/stock level or the distribution range of a community. The risk function comprises an exposure term and the loss function. The loss function is driven by a relative term, that is, the ratio between negative potential, that is, decline or mortality, and positive potential, that is, recovery. Sensitivity analysis is carried out to indicate model precision and its capabilities to distinguish between high and low risk areas and impacts. Limit reference values important for characterization of relative ecological risk are analytically defined. Model parameterization is based on literature review, and calculated examples show that beam trawling appears as a strong risk component to benthic communities, likely to exceed the limit reference value. For marine mammals (i.e., Harbour porpoise) in the German EEZ, by-catch in gillnet fisheries is a relatively strong risk.

Key Words:

• ecological risk assessment
• North Sea
• marine protected area
• Natura2000
• ecosystem approach
• fisheries impact

ACKNOWLEDGMENTS

Thanks go to Stefan Garthe, Ursula Siebert, Helena Herr, Anne Sell, Norbert Rohlf, Jake Rice, and Sören A. Pedersen for sharing data and for many helpful discussions, and two anonymous reviewers for helpful comments.

Notes

*IMPACT II, Table 3.4.2 (Lindeboom and Groot 1998), several tickler chains.

**Taking into account effects of bridles /doors on the seabed thus raising 0.02 to 0.15.

***Trippel et al. 1996

^¶Under certain conditions (smaller trawls, derated engine power), large beamers (TBBL) are entitled to fish in the coastal area of the North Sea. However, no alleviation of the impact factor is considered here for these TBBL fishing operations.

*After Hiddink et al. 2006b; Kaiser et al. 2002.

**Hiddink et al. 2006a.

⁺ = estimated.

*Based on Tab 16 (Rachor and Nehmer 2003).

*Categories defined by Garthe and Hüppop 2004.

**See data for Common eider in Salvig et al. 1994.