Interannual monsoon wind variability as a key driver of East African small pelagic fisheries

Small pelagic fisheries provide food security, livelihood support and economic stability for East African coastal communities—a region of least developed countries. Using remotely- sensed and field observations together with modelling, we address the biophysical drivers of this important resource. We show that annual variations of fisheries yield parallel those of chlorophyll-a (an index of phytoplankton biomass). While enhanced phytoplankton biomass during the Northeast monsoon is triggered by wind-driven upwelling, during the Southeast monsoon, it is driven by two current induced mechanisms: coastal “dynamic uplift” upwelling; and westward advection of nutrients. This biological response to the Southeast monsoon is greater than that to the Northeast monsoon. For years unaffected by strong El-Niño/La-Niña events, the Southeast monsoon wind strength over the south tropical Indian Ocean is the main driver of year-to-year variability. This has important implications for the predictability of fisheries yield, its response to climate change, policy and resource management.

[1]  Yannice Faugère,et al.  DUACS DT2014: the new multi-mission altimeter data set reprocessed over 20years , 2016 .

[2]  W. Adger,et al.  Vulnerability of national economies to the impacts of climate change on fisheries , 2009 .

[3]  C. Lingen,et al.  Feeding Biology and Ecology , 2014 .

[4]  W. L. Lane,et al.  Nine nations, one ocean : a benchmark appraisal of the South Western Indian Ocean Fisheries Project (2008-2012) , 2009 .

[5]  Athanassios C. Tsikliras,et al.  Spawning period of Mediterranean marine fishes , 2010, Reviews in Fish Biology and Fisheries.

[6]  S. Solomon.  The Physical Science Basis : Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change , 2007 .

[7]  R. Murtugudde,et al.  A reduction in marine primary productivity driven by rapid warming over the tropical Indian Ocean , 2016 .

[8]  F. Werner,et al.  Complex small pelagic fish population patterns arising from individual behavioral responses to their environment , 2018 .

[9]  G. Steinert,et al.  Influence of local environmental conditions and bleaching histories on the diversity and distribution of Symbiodinium in reef-building corals in Tanzania , 2016 .

[10]  F. Schott,et al.  Structure and transport of the East African Coastal Current , 1991 .

[11]  M. Srokosz,et al.  Shelf‐Break Upwelling and Productivity Over the North Kenya Banks: The Importance of Large‐Scale Ocean Dynamics , 2020, Journal of Geophysical Research: Oceans.

[12]  Masson-Delmotte,et al.  The Physical Science Basis , 2007 .

[13]  G. M. Wagner,et al.  The Rufiji Estuary: Climate Change, Anthropogenic Pressures, Vulnerability Assessment and Adaptive Management Strategies , 2016 .

[14]  A. Yool,et al.  Could the Madagascar bloom be fertilized by Madagascan iron , 2015 .

[15]  B. Hickey,et al.  Transport of surface waters from the Juan de Fuca eddy region to the Washington coast , 2005 .

[16]  James A. Carton,et al.  Earth's climate : the ocean-atmosphere interaction , 2004 .

[17]  M. van den Berg,et al.  Phytoplankton production and adaptation in the vicinity of Pemba and Zanzibar islands, Tanzania , 2011 .

[18]  P. Ochumba.  Oceanographic Features Along the Kenyan Coast : Implications for Fisheries Management and Development , 1983 .

[19]  Thierry Penduff,et al.  An ERA40-based atmospheric forcing for global ocean circulation models , 2010 .

[20]  K. V. Ramesh,et al.  Indian Ocean‐monsoon coupled interactions and impending monsoon droughts , 2006 .

[21]  Vicente Pérez-Muñuzuri,et al.  Extreme Wave Height Events in NW Spain: A Combined Multi-Sensor and Model Approach , 2017, Remote. Sens..

[22]  J. Fasullo,et al.  Warming of the Eurasian Landmass Is Making the Arabian Sea More Productive , 2005, Science.

[23]  G. Losse.  The Elopoid and Clupeoid fishes of East African Coastal waters , 1968 .

[24]  Y. Loya,et al.  Diversity Partitioning of Stony Corals Across Multiple Spatial Scales Around Zanzibar Island, Tanzania , 2010, PloS one.

[25]  Bruno Blanke,et al.  Kinematics of the Pacific Equatorial Undercurrent: An Eulerian and Lagrangian Approach from GCM Results , 1997 .

[26]  D. Pauly,et al.  Catch reconstructions reveal that global marine fisheries catches are higher than reported and declining , 2016, Nature Communications.

[27]  B. Hickey,et al.  The physical oceanography of upwelling systems and the development of harmful algal blooms. , 2010, Progress in oceanography.

[28]  P. Oke,et al.  Topographically Induced Upwelling off Eastern Australia , 2000 .

[29]  I. Kimirei,et al.  Seasonal and spatial variation of surface current in the Pemba Channel, Tanzania , 2019, PloS one.

[30]  M. Öhman,et al.  Marine fisheries in Tanzania. , 2002 .

[31]  M. Öhman,et al.  Marine Fisheries in Tanzania , 2002, Ambio.

[32]  Trevor Platt,et al.  Remotely Sensing the Biophysical Drivers of Sardinella aurita Variability in Ivorian Waters , 2018, Remote. Sens..

[33]  B. Child,et al.  Lessons learned : case studies in sustainable use , 2001 .

[34]  D. Pauly,et al.  What catch data can tell us about the status of global fisheries , 2012 .

[35]  Ow,et al.  Oceans and Coasts , 2016, Global Environment Outlook – GEO-6: Healthy Planet, Healthy People.

[36]  T. Platt,et al.  Impact of El Niño Variability on Oceanic Phytoplankton , 2017, Front. Mar. Sci..

[37]  E. Best.  The impending crisis. , 2019, Oral hygiene.

[38]  D. Pauly,et al.  Agreeing with FAO: Comments on SOFIA 2018 , 2019, Marine Policy.

[39]  Sarah F. W. Taylor,et al.  Measurement and implications of marine food security in the Western Indian Ocean: an impending crisis? , 2019, Food Security.

[40]  L. Chauka.  Diversity of the Symbiotic Alga Symbiodinium in Tanzanian Scleractinian Corals , 2012 .

[41]  L. Chauka.  Diversity of symbiotic algae in the genus Symbiodinium in Scleractinian corals of Tanzania , 2012 .

[42]  Shang-Ping Xie,et al.  Indian Ocean circulation and climate variability , 2009 .

[43]  O. Maury,et al.  Indian Ocean Dipole and El Niño/Southern Oscillation impacts on regional chlorophyll anomalies in the Indian Ocean , 2013 .

[44]  D. Pauly,et al.  Bottom-up, global estimates of small-scale marine fisheries catches. , 2006 .

[45]  Reuben.,et al.  The Role of a Stable Ocean in Larval Fish Survival and Subsequent Recruitment , 2004 .

[46]  M. Gómez-Gesteira,et al.  Has upwelling strengthened along worldwide coasts over 1982-2010? , 2015, Scientific Reports.

[47]  Bohua Huang,et al.  The Rossby wave as a key mechanism of Indian Ocean climate variability , 2004 .

[48]  D. Zeller,et al.  An update of the reconstructed marine fisheries catches of Tanzania with taxonomic breakdown , 2015 .

[49]  R. Okoola.  A diagnostic study of the eastern Africa monsoon circulation during the northern hemisphere spring season , 1999 .

[50]  M. Jury,et al.  West Indian Ocean variability and East African fish catch. , 2010, Marine environmental research.

[51]  Dudley B. Chelton,et al.  A Global Climatology of Surface Wind and Wind Stress Fields from Eight Years of QuikSCAT Scatterometer Data , 2008 .

[52]  Shubha Sathyendranath,et al.  An improved optical classification scheme for the Ocean Colour Essential Climate Variable and its applications , 2017 .

[53]  R. Wootton,et al.  Reproductive Biology of Teleost Fishes: Wootton/Reproductive Biology of Teleost Fishes , 2014 .

[54]  F. Schott,et al.  The monsoon circulation of the Indian Ocean , 2001 .

[55]  P. Kasapidis.  Phylogeography and Population Genetics , 2014 .

[56]  George S. Triantafyllou,et al.  Indications of a climate effect on Mediterranean fisheries , 2013, Climatic Change.

[57]  Christoph Heinze,et al.  Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models , 2013 .

[58]  Thomas R. Anderson,et al.  MEDUSA-2.0: an intermediate complexity biogeochemical model of the marine carbon cycle for climate change and ocean acidification studies , 2013 .

[59]  M. Giannoulaki,et al.  Habitat Characterization and Migrations , 2014 .

[60]  K. Wyrtki,et al.  Oceanographic atlas of the International Indian Ocean Expedition , 1971 .

[61]  Yadvinder Malhi,et al.  Seasonality in CO2 and H2O flux at an eastern Amazonian rain forest , 2002 .

[62]  D. Enfield,et al.  Tropical monsoons around Africa: Stability of El Niño–Southern Oscillation associations and links with continental climate , 2002 .

[63]  Bernard Barnier,et al.  The Making of the DRAKKAR FORCING SET DFS5 , 2014 .

[64]  D. Smythe-Wright,et al.  Epipelagic mesozooplankton dynamics around the Mascarene Plateau and Basin, Southwestern Indian Ocean , 2005, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[65]  A model for super El Niños , 2018, Nature Communications.

[66]  A. Yool,et al.  Ecological connectivity between the areas beyond national jurisdiction and coastal waters: Safeguarding interests of coastal communities in developing countries , 2019, Marine Policy.