DATE2019-01-08 12:44:23
AUTHORSAysen YILMAZ (1,2)|Selin KUCUKAVSAR (2)|Hakan ERCAN (1,3)
  1. Middle East Technical University-Earth System Science Program, Ankara, Turkey
  2. Middle East Technical University-Institute of Marine Sciences, Erdemli, Turkey
  3. Middle East Technical University-Department of Economics, Ankara, Turkey
ABSTRACTThe Black Sea is very sensitive and vulnerable to environmental changes, anthropogenic impact, and climate forcing. Hydro-meteorological and biochemical data records showed that robust climatic signature at inter-annual to inter-decadal time scales is evident. Long term (45 years) data available through in situ measurements of lower trophic level ecosystem parameters and satellite data provided by Goddard Earth Sciences Data and Information Services Center-NASA are evaluated, whereas the data on meteorological parameters (e.g. Sea Surface Temperature: SST) and fish stocks are collected from Turkish State Meteorological Service and Ministry of Food, Agriculture and Livestock respectively. One of the main concerns regarding the marine environment is reduced primary productivity and consequently decreased fisheries production due to global warming. The general trends in SST and the Total Catch in the Western Black Sea for the last 45 years (1967-2011) has been presented. The eutrophication period after 1970 (intensified after 1980) caused increase in primary production and the related higher trophic level production including fish production in the Black Sea. The sharp decrease in the fish catch in the late 1980s was due to the invasion of a ctenophore, M. leidyi which reached very high biomass level in late 1980s. This caused devastation in the regular food chain of the entire Black sea and a sharp decline in the total fish catch (especially the anchovy) observed in 1990s and the introduction of B. ovata in 1997, a predator of M. leidyi, helped the ecosystem to recover in the second half of 1990s. The increasing trend in the total fish catch just after irregular cooling period (1992- 1993) was separately and clearly defined within this catastrophic ecosystem change. Total fish catch in the Black Sea has declined intensively after 1995 due to increase in the SST which was proved by Mann-Kendall trend. Potential consequences of SST increase on the bottom up nutrient flux processes were the main cause for the decrease in the primary production and ultimate fish catch. Finally, decrease in the profits of fisheries sector was shown using the present data and appropriate models/projections were performed for the coming 20 years in order to propose sustainable management strategies, economic and policy tools for the Turkish fishery sector.