Fisheries play a significant role in the livelihoods of the world population, while the dependence on fisheries is acute in developing countries. Fisheries are consequently a critical element for meeting the sustainable development (SDG) and FAO goals to reduce poverty, hunger and improve health and well-being. However, 90% of global marine fish stocks are fully or over-exploited. The amount of biologically unsustainable stocks increased from 10% in 1975 to 33% in 2015. Freshwater ecosystems are the most endangered ecosystems and freshwater fish stocks are worldwide in a state of crisis. The continuous fish stock decline indicates that the world is still far from achieving SDG 14 (Life Below Water), FAO’s Blue Growth Initiative goal and SDG 15 (Life on Land, including freshwater systems). Failure to effectively manage world fish stocks can have disastrous effects on biodiversity and the livelihoods and socio-economic conditions of millions of people. Therefore, management strategies that successfully conserve the stocks and provide optimal sustainable yields are urgently needed. However, successful management is only possible when the necessary data are obtained and decision-makers are well informed. The main problem for the management of fisheries, particularly in developing countries, is the lack of information on the past and current status of the fish stocks. Sound data collection and validation methods are, therefore, important. Stock assessment models, which support sustainable fisheries, require life history traits as input parameters. In order to provide accurate estimates of these life history traits, standardized methods for otolith preparation and validation of the rate of growth zone deposition are essential. This review aims to assist researchers and fisheries managers, working on marine and freshwater fish species, in understanding concepts and processes related to stock assessment and population dynamics. Although most examples and case studies originate from developing countries in the African continent, the review remains of great value to many other countries.

Lake Tana has a remarkable fish diversity, including 17 endemic Labeobarbus species, of which nine spawn in the inflowing rivers. Three of the migratory species are threatened, namely the endangered Labeobarbus macrophtalmus and the vulnerable L. acutirostris and L. platydorsus. In July–November 2016 during the wet season netting upstream and downstream of large weirs in two rivers and in two undammed rivers showed that weirs had a severe negative effect on migratory Labeobarbus, including the three threatened species. Of eight Labeobarbus species caught below the Gelda River weir, only L. intermedius was recorded above the weir, and in the Shini River, five Labeobarbus species were caught below the weir, but none above it. Labeobarbus diversity below the Gelda River weir (H’ = 1.4) was significantly different to that above the weir (H’ = 0), whereas in the two rivers without any weirs, Labeobarbus diversity downstream (H’ = 1.39 and 1.55) was not significantly different from that upstream (H’ = 1.52 and ...

The effects of land-use change on ecosystem services in Kurt Bahir wetland were investigated during 2013 to 2014 using LANDSAT satellite images from 1973, 1986, 2002 and 2013 to identify and map ch...

Freshwater fish biodiversity faces immense pressures, especially in tropical developing regions where it provides critical protein and income. Effective conservation strategies require knowledge of species at scales matching their distribution and life history. Lake Tana and its inflowing rivers contain the most diverse flock of cyprinid ( Labeobarbus ) fishes globally, most of which are endemic to this ecosystem and of heightened extinction concern. We collated Labeobarbus abundance datasets from this aquatic biodiversity hotspot from 1992 to 2020 to allow spatial prioritization of future conservation actions. Percentage abundance data were compared across multiple spatial scales, between endemism and IUCN Red List categories and by proximity to weirs. The overall species contribution of endemics to assemblages was half that of those presumed nonendemics and far less for IUCN data deficient, vulnerable or endangered species than those of Least Concern status. Assemblages varied significantly between geomorphic habitats, between catchments and in relation to weirs, driven foremost by habitat‐generalists and lake‐specialists. Multiple habitats in various catchments require protection to conserve river‐dependent species, especially those at a higher extinction risk. Species designated as vulnerable or endangered were particularly associated with specific river mouths and main river channels. For freshwater fishes in which spawning aggregation and migration appear to be obligatory life‐history traits, details such as these at the scale of their distribution are essential for determining where best to implement conservation measures. Future barrier construction and fishing closures should account for patterns in Labeobarbus species segregation to minimize disruption of migratory spawning events and avoid species losses. Statement of Significance: We collated 17 Labeobarbus abundance datasets from Ethiopia’s Lake Tana and its inflowing rivers and a 28‐year period. This allowed the first assessment at a whole‐of‐drainage scale of how these high‐endemicity assemblages were distributed and where best to implement conservation measures. Relative abundance of endemic species was half that of those presumed non‐endemic, and Vulnerable and Endangered species were highly segregated within and between rivers. However, sites upstream of weirs were dominated by a single habitat‐generalist species. Locating weirs and fishing closures must consider species’ uneven distributions to avoid species losses and reduced assemblage diversity. These findings contribute to a stronger understanding of this Africa‐wide genus, and provide a template for managing tropical lake fishes for improved conservation outcomes.

The migratory and endemic Labeobarbus platydorsus and Labeobarbus tsanensis are threatened by extinction. This study is the first to use otolith microstructural analyses to infer life history traits of these species to assist in future conservation. We examined whole asterisci otoliths from 750 L. tsanensis and 542 L. platydorsus collected monthly between May 2016 and April 2017. The size of the L. tsanensis and L. platydorsus individuals collected was in the range 123–363- and 115–630-mm fork length respectively. For both species, 4- and 5-year-old individuals were dominant, whereas specimens older than 6 years were rarely recorded. The maximum ages recorded for L. tsanensis and L. platydorsus were 11 and 17 years respectively. Of the different growth models evaluated, the logistic growth model yielded the best fit to age-at-length data. For both species, growth parameters differed significantly between males and females, and sexual maturation proceeded faster in males than in females. Natural mortality estimates based on longevity were higher than the estimates based on growth parameters. For both species, females were predominant over males and the length–weight relationships were curvilinear. The estimated life history traits are important input parameters in further stock assessment evaluation of the species and should allow fisheries managers to optimise future conservation strategies.