Psetta maxima (Linnaeus, 1758)
Rhombus maeoticus Pallas: Chichkoff, 1912: 38; Stojanov et al., 1963: 194; Drensky, 1951: 150; Bothus maeoticus Pallas: Drensky, 1923: 107.
Conservation status: in Bulgaria: Endangered EN [A1b,d; B1b (v),c (iv)].
General distribution. It is found along the Black Sea coast, mainly in the shelf zone, where it forms local schools. It partially enters the southern parts of the Sea of Azov and the Bosphorus, and it enters occasionally the Mediterranean and the Adriatic Seas.
Distribution and abundance in Bulgaria. In the past, an abundant species along the Bulgarian Black Sea coast, representing a substantial share of the Bulgarian commercial sea catches [1, 2]. In recent years, the stocks of the species in the Black Sea drastically decreased: from 5 000 tonnes in 1970 to 500 tonnes in 1992 . Therefore, in the period 1990-1994, the fishing of turbot in front of the Bulgarian coast was prohibited, which partly contributed to the restoration if its stocks. During the 2002-2005 period, however, the annual catch of turbot again decreased about 10-fold .
Habitats. A marine, bottom-dwelling fish. It inhabits sandy bottoms, mainly in the coastal area, at comparatively small depths.
Biology. The turbot reaches sexual maturity at the age of 3-5 years. Spawning occurs at water temperature of 8-16 °C, in the period from the middle of April to the middle of June; for spawning the turbot approaches the coast to depths of 10–30 m. The fecundity of females reaches 5-6 millions of eggs at average. The turbot is a predator, feeding on fish (mainly whiting and horse mackerel), crustaceans and mollusks [2, 5, 6, 7].
Similar species. The scaldback (Arnoglossus kessleri). The turbot differs by the rhomboid shape of the body, scattered with bony tubercles. By the same feature, it can be differentiated from the brill(Scophthalmus rhombus), which also lacks bony tubercles.
Negative factors. The main threats to the species are poaching and overfishing, including that of sexually immature individuals, as well as water pollution.
Conservation measures taken. In the period 1990–1994, a ban on the catch of the species in front of the Bulgarian coast was imposed.
Conservation measures needed. Introduction of a ban on the fishing of turbot during the spawning period. Control of observing the minimum landing size regulations for the species. Protection of the Black Sea waters against pollution.
References. 1. Drensky, 1951; 2. Stojanov et al., 1963; 3. Zivkov et al., 2005; 4. Ministry of Agriculture and Forestry, 2002-2005; 5. Karapetkova, Zivkov, 1995; 6. Svetovidov, 1964; 7. Bulgurkov, 1968.
Authors: Yanaki Sivkov, Teodora Trichkova