Philosophiae Doctor - PhD / In this thesis, I examine household strategies in response to water level fluctuations of Lake Chilwa. I also analyse the frequency and patterns of migration of fishers, conflicts due to migration of fishers and comanagement. The following are the key results:First, the seasonal and periodic lake level changes affect livelihoods of the households. As a coping strategy, the households depend on fishing in pools of water located in influent rivers and hunt birds for income and food while others migrate to find work as casual labourers. When the lake rises during the rain season, inundated areas become suitable for production of maize and rice. However, when the floods recede in the dry season, farming of winter maize and vegetables is common.Second, migration of fishers is common around Lake Chilwa. The pattern of migration varies according to the season and gear type. The northern marshes and floodplain where fishers land the highest catches composed mainly of Barbus paludinosus, attract more fishers operating different fishing gear types. Conflicts emerge due to the Nkacha seine operations,which require removal of aquatic vegetation. The local fishers believe that the aquatic vegetation is a source of food for fish. The conflicts are in various forms including access to fishing grounds, authority to grant access to fishing areas and fish price competition between the local fishers and migrants.Third, the household strategies towards recovery of the fishery after recessions are inherent within the households’ traditional system.However, the introduction of co-management does not recognise key actors that include fishers and river-based fishing households that participated in the formulation of conservation strategies for remnant fish stocks in lagoon and rivers during the 1995 recession. Co-management is characterised by limited participation of the fishers especially those operating seines, district assemblies and non-governmental organisations. Similarly, there is low transparency especially with respect to how the key stakeholders, Department of Fisheries and traditional leaders, take decisions. In stark contrast, accountability among Beach Village Sub- Committees is growing; hence more fishing households now perceive these as representing the interests of Department of Fisheries.Based on the above results, a diversified occupational change involving fishing, farming and trading is necessary. The co-management arrangement should be adaptive with consideration of the traditional customs and values of the participating households. Since these households are dependent on the availability of fisheries, it is thus imperative to promote maximum resource exploitation in between recessions and encourage a complete stop to fishing during recessions.September 2009

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In this study, the factors influencing zooplankton community structure in Turkish shallow lakes were elucidated with four main approaches: (i) space-for-time substitution for shallow lakes using snap-shot sampling in 31 lakes along a latitudinal gradient / (ii) in-situ mesocosm experiments in eleven lakes along a latitudinal gradient using three sets of artificial plants systems / (iii)&lsquo / Habitat Choice&rsquo / laboratory experiments mimicking a &lsquo / shallow littoral&rsquo / zone with plants and a &lsquo / deeper pelagic&rsquo / zone with sediments testing the response of Daphnia magna to predation cues / and (iv) long-term monitoring data (1997-2011) from two interconnected lakes. Snap-shot and long-term monitoring showed that eutrophication has a strong influence on the zooplankton community via increased fish predation, nutrient loading and salinization. Here too the zooplankton community shifted towards a smaller sized profile, especially in lakes located at lower latitudes. Moreover, The laboratory and in-situ mesocosm experiments revealed that under predation risk Daphnia preferred to hide near sediment instead of using submerged plants as a refuge. Accordingly, in-situ mesocosm experiments revealed a predation pressure induced size structure shift towards small-medium sized zooplankton and calanoid copepods. The long-term monitored lakes experienced (i) drought-induced water level drop, leading to increased salinity and eutrophication, and consequent anoxic conditions and fish kill / as well as (ii) biomanipulation in the downstream. Both conditions resulted in major reduction in the top-down control of fish and ultimate predomination by large sized Daphnia spp. Nevertheless, the excessive exploitation of lakes and ongoing warming entail Turkish shallow lakes to become more eutrophic, making this study indicative for the Mediterranean region.