Zeller-BIOL3305-Lec-29-Nyingi-Kenya Freshwater PDF

Freshwater Fisheries Dr. Wanja Nyingi Sea Around Us – Indian Ocean UWA  Kenya freshwater Lower to middle income country... emerging economy Rapidly growing population >55 million Food and nutritional security concerns… m...

Freshwater Fisheries Dr. Wanja Nyingi Sea Around Us – Indian Ocean UWA  Kenya freshwater Lower to middle income country... emerging economy Rapidly growing population >55 million Food and nutritional security concerns… malnutrition & micronutrient deficiencies Unique coastal country… >90% of fisheries catches are freshwater Dominated by Lake Victoria, 2nd largest lake in the world Kenya owns 6% of the lake Schubert et al. (2022) Marine and Freshwater Research 73:57-70 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater fisheries Historically, dominated by extremely high diversity (>350 spp.) of endemic cichlids Very popular aquaria species Supported an ancient, sustainable fishery In 1954… Schubert et al. (2022) Marine and Freshwater Research 73:57-70 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater fisheries Historically, dominated by extremely high diversity (>350 spp.) of endemic cichlids Very popular aquaria species Supported an ancient, sustainable fishery In 1954… Deliberate introduction of the Nile perch (Lates niloticus) and Nile tilapia (Oreochromis niloticus) Voracious predator, thought to provide a bigger fish for fishers to catch Schubert et al. (2022) Marine and Freshwater Research 73:57-70 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater fisheries Introduced populations remained small until late 1970s, then exploded Decimated native fish populations Until late 1970s, 80% of fish biomass was native cichlids, 20% were introduced spp. By late 1980s, >80% of fish biomass was Nile perch Over ½ of all endemic cichlids spp. thought extinct Schubert et al. (2022) Marine and Freshwater Research 73:57-70 28/40 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater fisheries Change in target spp. caused other related problems Traditionally, the much smaller native cichlids were preserved by drying in the sun But the only way they could preserve the much bigger Nile perch was to fry them for rapid consumption, or preserve them via smoke Ever more forest land was cleared for the needed firewood, and this additional deforestation increased the harmful runoff into the lake while devastating the surrounding forest ecosystems Schubert et al. (2022) Marine and Freshwater Research 73:57-70 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater fisheries Multi-million dollar Nile perch export fishery developed in the 1980s Marketing to Europe, USA, and more recently to China In addition, much native cichlid catches were increasingly reduced to fishmeal for animal feed Much catch and employment… but little for local population to eat Redirecting protein and nutrients away from local populations, which more recently replaced in local markets with cheap aquaculture raised tilapia imported from China Serious data concerns, not only related to Lake Victoria, but also because other freshwater bodies not necessarily comprehensively monitored Schubert et al. (2022) Marine and Freshwater Research 73:57-70 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p. Silver cyprinid is an important fish for Lake Victoria fishermen. It is caught using light attraction during moonless nights  Kenya freshwater catch reconstruction team Aidan Schubert, MSc UWA Dr Wanja Nyingi, Nat. Dr Paul Tuda, Leibnitz Dr Christopher Aura, Museum, Kenya Centre, Germany KMFRI, Kenya Dr Kevin Obiero, KMFRI, Pro Julius Manyala, Odinga Prof Ian Cox, University of Matthew Ansell, UWA Kenya Univ., Kenya Hull, UK Schubert et al. (2022) Marine and Freshwater Research 73:57-70 30/40 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater catches By waterbody Divided into 16 major waterbodies to group into 3 categories: - Lake Victoria - Lakes, dams and Tana River Delta (n = 9) - Rivers (n = 6) Schubert et al. (2022) Marine and Freshwater Research 73:57-70 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater catches Reconstructed 32% higher than reported data Lake Victoria: 92% Lakes, dams and TRD: 7% Rivers: 1% 2008-2016 FAO > KeFS….. Miss-reporting of aquaculture production as capture data by FAO Schubert et al. (2022) Marine and Freshwater Research 73:57-70 32/40 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater catches Lakes, dams and TRD Lake Turkana dominates, but… Mid-1970s driven by large fisheries infrastructure investment Latter pattern driven by sporadic flooding events that drive Lake Turkana ecology Schubert et al. (2022) Marine and Freshwater Research 73:57-70 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater catches Artisanal 80%, driven by commercial Lake Victoria fishery Subsistence 20% 91% of artisanal deemed report 71% of total unreported catches were subsistence Schubert et al. (2022) Marine and Freshwater Research 73:57-70 34/40 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater catches 26 taxa in total… but many at genus or higher level Nile perch 73%, declining since 2000 Silver cyprinid 29%, increased strongly since 2000 (fishmeal) Nile tilapia 8% Schubert et al. (2022) Marine and Freshwater Research 73:57-70 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Kenya freshwater catches Outcome for catch data: Clear point that freshwater systems suffer from same data challenge Kenya an exception (~30% only), as best data in Africa Rest of world likely far worse data situation (Sorensen & Palomares 2021) Developing countries miss ~80+% Developed countries miss ~20% Outcome for Aidan Schubert: Excellent thesis & paper Quickly landed a new job in Canada - International Year of the Salmon Coordinator at North Pacific Anadromous Fish Commission Sorensen & Palomares (2021) Sustainability 13(15):8420 Schubert et al. (2022) Marine and Freshwater Research 73:57-70 36/40 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p.  Impacts of Introduced species: Invasive Alien Species Introduction of Nile tilapia led to extinction of two endemic species by competitive replacement Nile tilapia (Oreochromis niloticus) Victoria tilapia (Oreochromis variabilis) Singida tilapia (Oreochromis esculentus) Schubert et al. (2022) Marine and Freshwater Research 73:57-70 Schubert (2020) Rebuilding Kenya's freshwater fisheries catch datasets: 1950-2017. MSc thesis, UWA, 50 p. The Rise of Trout on Mt. Kenya (1930-1990s) Rainbow and Brown Trout Mountain Catfish  The Fall of Trout (2008-2018)! Climate Change and Pollution: Warmer water thus reduced oxygen in water, and pollution from farms (chemicals and nutrients) increasing fish pests and diseases  Indicator of ecosystem health: Trout has turned from the villain (pest) to a victim of climate change and pollution and an important indicator species Ecosystem health: water quality and macroinvertebrates Gilbert Kosgei MSc Flood-dependent ecosystems Floods are the engine of the Delta Nov May Floodplain Mangrove Kenya Wetlands Biodiversity Research Consortium Impacts of dams on the Tana River Delta Before dams After dams Mangroves along the delta and coast are important fish breeding sites Several are now degraded due to: Inadequate freshwater flows Climate change causing sea water rise and intrusion of sea water into the rivers/delta  Impacts of seawater intrusion on fisheries and livelihoods 09/2019 26 Purity Njeri Msc Tana River Delta - Ramsar Site since 2012 Interionational Treaty on Wetlands of International Importance Freshwater Hub of Sea Around Us - Indian Ocean Ichthyology Freshwater Fisheries Aquatic Ecology International Research Experiences for Students Sharing knowledge: Wetlands management – Ramsar Sites Freshwater Hub of Sea Around Us - Indian Ocean