EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Interannual monsoon wind variability over the South tropical Indian ocean drives East African small pelagic fisheries

Fatma Jebri1, Zoe Jacobs1, Dionysios Raitsos2,3, Meric Srokosz1, Stuart Painter1, Stephen Kelly1, Mike Roberts1,4, Lucy Scott5, Sarah Taylor1, Matthew Palmer1, Hellen Kizenga6, Yohana Shaghude6, Juliane Wihsgott1, and Ekaterina Popova1
Fatma Jebri et al.
  • 1National Oceanography Centre, Southampton, United Kingdom
  • 2Department of Biology, National and Kapodistrian University of Athens, Athens, Greece
  • 3Plymouth Marine Laboratory, Plymouth, United Kingdom
  • 4Nelson Mandela University, Port Elizabeth, South Africa
  • 5South African Environmental Observation Network, Cape Town, South Africa
  • 6Institute of Marine Sciences, Zanzibar, Tanzania

Small pelagic fisheries play a critical role in food security and economic stability for East African coastal communities ― a region of least developed countries. Using satellite and field observations together with modelling, we show the links between the small pelagic fisheries along the East African coast and the changes in Western Indian Ocean currents due to the interannual variability of the monsoonal wind field. The annual variations in phytoplankton biomass and fisheries yield are strongly associated. During the Northeast monsoon, the enhanced phytoplankton biomass is triggered by local wind-driven upwelling. During the Southeast monsoon, however, the enhanced phytoplankton biomass is due to two current induced mechanisms: coastal “dynamic uplift” upwelling; and westward advection of waters with higher nutrient concentrations. This biological response to the Southeast monsoon is greater than that to the Northeast monsoon. Interannually, an extreme increase (decrease) in chlorophyll concentrations is induced by strengthened (weakened) surface currents, which occur during anomalously “strong” (“weak”) Southeast monsoon years. For years where the effects of El Niño / La Niña are weak, the Southeast monsoon wind strength over the south tropical Indian Ocean is the main driver of year-to-year variability. Such changes have important implications for the predictability of fisheries yield, its response to climate change, policy and resource management.  

How to cite: Jebri, F., Jacobs, Z., Raitsos, D., Srokosz, M., Painter, S., Kelly, S., Roberts, M., Scott, L., Taylor, S., Palmer, M., Kizenga, H., Shaghude, Y., Wihsgott, J., and Popova, E.: Interannual monsoon wind variability over the South tropical Indian ocean drives East African small pelagic fisheries, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2381,, 2020


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