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The snoek, Thyrsites atun, is a pelagic fish of the family Gempylidae that inhabits cold waters of the southern hemisphere. It is an important fishing resource species (e.g. Chile, Namibia, New Zealand) linked mainly to the artisanal fisheries, however, its phylogeographic and population aspects are largely unknown. In this study we provide the first detailed analysis of the phylogeographic patterns and demographic processes of the snoek for the southern hemisphere using mitochondrial data of the Cytochrome c Oxidase subunit I gene. Our results indicate two lineages: (i) Australia-New Zealand, and (ii) Chile-South Africa-Namibia. The Australia-New Zealand clade shows partial isolation between populations associated with distinct biogeographic regions, likely driven by the region's oceanography. The divergence between the lineages happened ∼800,000 years ago. On the other hand, analysis of the fish caught in the South-eastern Pacific (Chile) showed that the genetic diversity among localities (hT = 0.657) was lower than within localities (hS = 0.664), which was consistent with the pairwise comparisons results, suggesting the absence of phylogeographic structure. Based on our estimations, population expansion in T. atun would have occurred ∼7.5 ka (after LGM) under the Bayesian skyline plots approximation. We discuss the scope that this study could have in fisheries management of this important species. [ABSTRACT FROM AUTHOR]

Here, we present a gillnet survey of Lake Liambezi a 370 km2 shallow ephemeral floodplain lake situated in north‐eastern Namibia, which is fed irregularly by the upper Zambezi and Kwando Rivers during years of high flooding. The lake dried up in 1985 and, with the exception of sporadic minor annual inundation events, remained dry until 2007. We describe the temporal succession of fish species over an 8 year period from initial inundation 2007 to maturation in 2014. The succession of the fish community did not follow the typical pattern of opportunistic strategists during colonisation, to periodic strategists that are eventually succeeded by equilibrium strategists. Instead, the evolution of the fish community was characterised by three distinct phases. The first phase involved the inundation and colonisation of the lake in 2007, followed by its decline until the floods that filled the lake in 2009. During this phase the lake was colonised by fishes from the adjacent upper Zambezi and Chobe River floodplains. Fish communities predominantly comprised floodplain specialists including the barbs Enteromius paludinosus and Enteromius poechii, the mormyrid Marcusenius altisambesi and catfishes Schilbe intermedius and Clarias gariepinus. The filling of the lake in the March 2009 floods marked the beginning of the second, successional phase. The barbs declined in abundance and the alestid Rhabdalestes maunensis underwent explosive population growth between 2009 and 2010, but populations crashed equally rapidly and were replaced by Brycinus lateralis which, together with S. intermedius went on to dominate the fish community 2011–2014. Larger, slower growing tilapiine cichlids increased steadily in abundance and became the dominant components in a 2700 t y–1 artisanal fishery that developed on the lake. The fish community in the ephemeral Lake Liambezi is clearly influenced by numerous factors including connectivity, lake level fluctuations, competition and the effects of fishing, which may disrupt typical succession processes in floodplain ecosystems. [ABSTRACT FROM AUTHOR]

This paper examines small-scale fish vending in a southern African floodplain from two perspectives: as a link between natural resource use and consumption, and as a livelihood in itself. We used a combination of observation, surveys and semistructured interviews in a market in Katima Mulilo, Namibia, to determine sources of fish, preferences and constraints to vending, average investment and profit, as well different routes into fish vending and perceptions regarding vending. Most vendors come from fishing households, but their stock is often an accumulation of purchases from other fishers. There is little evidence of formal arrangements between fishers and vendors, yet most adapt to the highly variable natural and social environments of the region. Although all vendors ranked selling fish as their most important livelihood activity, a wide range of investment and profit exists among individuals. Our findings indicate that fisheries management proposed for the area must be developed with a careful understanding of how changes in access and use will affect vending livelihoods. [ABSTRACT FROM AUTHOR]