Turbot population in Bulgarian waters is stable but remains small
The turbot population in the Bulgarian Black Sea zone has been stabilising over the last two to three years, with studies reporting biomass of between 900 and 1,000 tonnes, but a trend towards improvement of the population size has not been registered yet, BTA learnt from Assoc. Prof. Elitsa Petrova, Director of the Fishing Resources Institute with the Agriculture Academy in Varna.
The fish stocks remain several-fold lower than those registered in the late 1970s, and the turbot species is ranked as overexploited, she specified. The Fishing Resources Institute has been responsible for the evaluation of the turbot stocks since 2014. Initially, the studies were conducted in the autumn-winter period but now these are carried out twice a year: in spring and autumn.
As a whole, commercial fish species in the Black Sea are limited in number and their stocks have been depleted, Petrova told BTA. The decline in fish populations is a general trend for the World Ocean, and the two main reasons are pollution and overfishing, she specified. In the Black Sea in particular, overcoming the problems depends on the behavior of all coastal countries, the expert went on to say. Joint declaration has been adopted obliging its parties to take measures for the management of commercial fish species. However, the individual countries have yet to synchronize their actions for protecting the sea and marine resources, Petrova added.
The Fishing Resources Institute continues to actively work on identifying the quantities of Black mussel and Rapana species which, according to scientists, are two elements of a single ecosystem with a very fragile balance between them. The latest studies in the Bulgarian Black Sea zone between 20 and 45 metres of depth indicate reduced quantities of these species, as well as diminished size of Rapana individuals since the 2013 studies.
The Rapana species found in the Black Sea are invasive but have already become a commercial resource. Two problems are related to them: they feed on the Black mussel, which is involved in natural sea filtration, and the method used for their fishing affects the bottom biocenoses, Petrova explained.
The latest studies have not detected new invasive species from the Mediterranean or other seas.
Source: BTA, 02/02/2018
