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The Ecosystem Approach to Fisheries (EAF) requires the investigation of the biology of the species, the structure of the fish communities, processes and carrying capacity in the ecosystem and the interrelationships between compartments of the system.
A key requirement for understanding the status and development of a fish stock and its response to environmental changes is in the early life stages of the species. Eggs and larvae are the most vulnerable stages related to abiotic impacts or predators. Physiological constraints impact distribution and survival of the young stages and have a direct influence on year class strengths. Estuaries along tropical coasts play an important role as nursery areas for many species relevant to coastal fisheries.
Small scale fisheries are of outstanding importance for the protein supply of local populations along tropical coasts. However, in most cases the catches of the artisanal fishermen are poorly or not registered and do not appear in any official statistics. The biology and distribution of many species that are exploited are poorly studied or unknown, and stocks may be depleted before we even have the chance to learn their role in the ecosystem. This development leads to a decrease in biodiversity and may influence the stability of the coastal ecosystems.
The overall goal of the research of this working group is to investigate the impact of a variable and changing environment on fish communities, the growth and condition of fishes in coastal waters and their exploitability through fisheries:
Dynamics of estuarine tropical fish communities
The role of estuaries for the recruitment of coastal fish stocks is documented manifold. Estuaries are visited by different life stages of fishes for feeding, shelter, or spawning, respectively. Abundance and seasonality as well as growth and early life history patterns of coastal fishes is thus a central part of the working group’s activities. The analysis of otolith microstructure provides information on daily-based growth and allows the understanding of individual life histories of fish and thus a more detailed understanding of species-specific habitat use and related ecological processes.
We strive for an understanding of the conditions and challenges coastal fishes are faced to under changing climate conditions. A comparative approach is used to understand the impact of temperature, salinity and other factors by using the steep gradients in these parameters normally occurring in estuaries. A good example for such a system is the inverse estuary Sine Saloum in Senegal, where salinity is increasing upstream.