Raykov V.St.,Bulgarian Academy of Science |
Panayotova M.,Bulgarian Academy of Science |
Radu Gh.,G. Antipa NIMRD |
Maximov V.,G. Antipa NIMRD |
And 2 more authors.
Journal of Environmental Protection and Ecology | Year: 2013
Joint pelagic trawl survey was accomplished in June 2010 in the Romanian and Bulgarian Black Sea area. The analysis was based on the reference species biomass (Sprattus sprattus) at the scale of the whole survey. Furthermore, an analysis of the distribution and abundance of the rest species caught as by-catch is presented for each of the regions. The total surveyed area in the EU waters was 17 198.6 km2 and total estimated biomass was 75 080.2 t in Bulgarian area and 59 643 t in Romanian marine area. The number of identified by-catch species in Bulgarian waters was 15, and 29 species in Romanian waters. The asymptotic length reached 12.77 cm and growth rate could be assessed as relatively high k = 0.45 y-1. The growth of sprat from present research is positive allometric (n = 2.66). Sustainable levels of fishing mortality are those around F = 0.5, which would correspond to the catch level of 12.5 thous.t of sprat in the EU Black Sea waters. The exploitation biomasses and equilibrium levels (maximum sustainable yield (MSYs)) should not be regarded as absolute value for possibly future yields in view of the the methods uncertainties and the share of misreported and illegal catches. In such cases, special approaches has been applied, as use of 2/3 MSY.