Abstract
The biomass of jellyfish off Namibia is currently thought to exceed that of finfish there, and this has implications for our understanding of ecosystem functioning in the region. Our knowledge about even the basic biology of jellyfish is scant. Here we examine seasonality of jellyfish off Namibia using information provided by the Namibian Ministry of Fisheries and Marine Resources from the commercial fisheries sector. The data span the period from the mid 1990s until 2006 and include information from both the demersal and pelagic sectors. The data cannot be considered quantitative and we are restricted to presenting information on seasonal changes in the percentage of trawls containing jellyfish; subdivided by depth and latitude. Jellyfish represent just one (the pelagic) lifehistory phase of the organisms and their release by the benthic life-history phase is often cued by sudden changes in temperature. Given that upwelling ecosystems are characterized by often sudden changes in temperature throughout the year, we hypothesize that jellyfish will be present all year around off Namibia. We also present some preliminary information on the possible associations between finfish and jellyfish.