A metacommunity perspective on source–sink dynamics and management: the Baltic Sea as a case study

Area of Science:

• Marine ecology
• Fisheries science
• Metacommunity dynamics

Background:

• Metapopulation processes' influence on fish stock dynamics remains unresolved, particularly for mobile species like Atlantic cod (Gadus morhua) and herring (Clupea harengus).
• The Baltic Sea's heterogeneous environment shapes the distribution of key fish species (cod, herring, sprat), yet they are managed as single units.
• Traditional management ignores spatial variations in species interactions and environmental impacts.

Purpose of the Study:

• To investigate source-sink dynamics in Baltic Sea fish stocks using a metacommunity perspective.
• To analyze area-specific differences in species interactions and the impact of fishing and climate.
• To provide insights for sustainable fisheries management.

Main Methods:

• Utilized a spatially disaggregated statistical food web model.
• Fitted the model to area-specific time series of abiotic and biotic variables.
• Employed state-space methods for robust analysis.

Main Results:

• Identified significant net fluxes between areas, indicating source-sink dynamics.
• Revealed area-specific variations in density dependence, competition, and predator-prey interactions.
• Quantified the distinct impacts of fishing and climate on survival and recruitment across regions.
• Simulations showed reduced fishing in cod source areas increased sink habitats but decreased prey due to predation.

Conclusions:

• Baltic Sea fish stocks exhibit metacommunity structuring with significant source-sink dynamics.
• Area-specific management considering local interactions and pressures is essential.
• The model serves as a tool for implementing ecosystem-based fisheries management.