MEPS 293:201-212 (2005)  -  doi:10.3354/meps293201

ABSTRACT: Fat content (as % of total body wet wt) of the sprat Sprattus sprattus phalericus in the Black Sea was determined annually during the peak feeding period (i.e. summer) between 1960 and 2001. Interannual variations of this characteristic were quite high (from 8.0 to 16.0%). Sprat fat content can be used as an indicator of food supply (or recent feeding history). In the Black Sea, different periods could be distinguished with respect to food supply of this species: Period I (1960 to 1964) with stable sprat fat content values of 11.2 to 13.7%; Period II (1965 to 1972) with decreased values of 8.5 to 10.3%; Period III (1974 to 1982) with higher values of 11.4 to 15.7%; Period IV (1983 to 1990) when there were the highest interannual fluctuations and a decrease to 9.9 to 10.7%; Period V (1991 to 1997) again with high fat content values of 12.2 to 14.7%; Period VI (1998 to 2001) with stabilized fat content values of 12.0 to 12.3%. These periods are closely related to the general situation in the Black Sea ecosystem caused by climatic changes, increased trophic competition, eutrophication and pollution. Relationships between interannual fluctuations in sprat fat content, on the one hand, and sprat biomass and phytoplankton concentration, on the other, are revealed. The features of the interannual dynamics of the Black Sea sprat fat content are similar to those (biomass and catches) of small pelagic fishes in the Mediterranean and in some other parts of the World Ocean.

KEY WORDS: Sprat · Sprattus sprattus phalericus · Black Sea · Fat content · Food supply · Interannual periods · Stock biomass · Phytoplankton · Mesozooplankton