1092 Journal of Environmental Protection and Ecology 15, No 3, 1092–1100 (2014) Environmental management fish stoCk indiCators: aPPliCation of desCriPtor 3 of Msfd in blaCk sea V. ST. RAYKOV Institute of Oceanology, 40 ‘Parvi Mai’ Street, P.O. Box 152, 9000 Varna, Bulgaria E-mail: vio_raykov@abv.bg abstract. A review of the present state and future perspectives of the ishery in the Bulgarian marine part of the Black sea basin is presented. Following the approach suggested by the european union (2008/56/EC) Marine Strategy Framework Directive (MSFD), particular species may be good indica- tors of speciic environmental factors in their local environment. It is advisable to set the indicators for monitoring the healthy state of a marine isheries ecosystem, concerning both pelagic and benthos organisms before making a suggestions and assessments about any given stock. Formal decision rules using these indicators for maintenance of the ishery ecosystem in a productive condition, and for stock recovery, need to be urgently implemented. In the present paper the example with sprat stock in the Black sea was emphasised. It was found that one of the main objectives for effective and sustainable management of the ish stocks is to make regular annual assessment of the parental stock biomass, length and weight growth, age determination, mortality estimation and reproductive potential estimation. Levels of ishing that break normal productivity of the given stock and to far- reaching effects caused by other environmental variations and anthropogenic activities. Keywords: the Black sea, ish stock indicators, sustainable management. AIMS AND BACKGROUND The present paper aims to represent the contemporary status of the sprat population in the Black sea according to the deined Descriptor 3 under MFSD (Ref. 1). Particular species may be good indicators of speciic environmental factors in their local environment 2 . It was found that one of the main objectives for effective and sustainable management of the ish stocks is to make regular annual assess- ment of the parental stock biomass, length and weight growth, age determination, mortality estimation and reproductive potential estimation 3 . The Black sea sprat (Sprattus sprattus L.) is a key species in the Black sea ecosystem 4–8 . Sprat is a marine pelagic schooling species sometimes entering in the estuaries (especially as juveniles) and the Azov sea and tolerating salinities as low as 4‰. In the daytime it keeps to deeper water and in the night moves near the surface. It forms big schools and undertakes seasonal movements between foraging (inshore) and spawning (open sea) areas 5 . adults tend to remain under the seasonal thermocline. penetrating above its only during the spring and autumn homothermia. Juveniles are distributed