Carmen Georgeta Nicolae

Experimental Rearing of the Golden Gray Mullet Liza Aurata (Risso, 1810) in a Recirculating System at the Black Sea

Abstract Recirculating Aquaculture Systems (RAS) used in aquatic research and production are a viable alternative to traditional open-sea mariculture. The rearing of marine living resources in controlled environments is one of NIMRD’s constant concerns. Golden gray mullet Liza aurata (Risso, 1810) is spread in the Mediterranean, Black and Caspian Seas, as well as along the Atlantic coast, and culture in extensive and semi-intensive enclosures has been practiced worldwide for centuries, especially in the Far East and the Mediterranean, reaching a global production of 134,329 tons in 2010. The species’ potential for aquaculture is enhanced by its eurihalyne and eurithermal adaptability, allowing it to grow in a variety of ecosystems. The biological material used for the experiment was represented by golden gray mullet fingerlings fished using the beach seine from the Black Sea. They were monitored for health state, growth rythm (mean length and weight determinations), behavior under RAS conditions, survival rate and overall adaptability. The growth of juveniles after 90 days was 89.2% for total length and 246% for mean biomass. Concerning overall adaptability, after approximately one month, the golden gray mullet individuals fully adapted to rearing in the RAS tanks and handling during measurements. Moreover, the food administered (Skretting Classic K) was easily accepted, active feeding behavior being observed even in the presence of NIMRD’s staff. The fish’s health state was good, with no mortalities caused by infections or parasites. The survival rate upon completion of the two monitoring months was 76.66% (23 of the 30 individuals included in the experiment). The preliminary results obtained showed a good adaptability and a normal growth rate, which makes Liza aurata a potential candidate for aquaculture targeting the national and regional market.

Conservation Status of the Fish Fauna in the Danube Delta Marine Zone

Establishing the necessary measures for the conservation of habitats and species of the Marine Zone of the Danube Delta (ROSCI 0066) is based on the assessment of their current conservation status. Conservation measures instituted aimed at maintaining or restoring the species and habitats for which the site was designated, at an appropriate stage of conservation. The marine protected area ROSCI 0066 (overlapping the Danube Delta – marine zone) is a national protected area within the Natura 2000 European ecological network (Habitats Directive 92/43/EEC, Romanian Government Emergency Ordinance 57/2007, Minister’s of Environment, Water and Forests Order no. 46/2016), and also has the status of Ramsar and UNESCO site. The overall assessment of the conservation status of marine species and habitats derived from Annex E (V) matrix of the EC official reporting format. It was performed for marine fish species of Community interest, whose presence is certain and confirmed by research in the marine protected area’s perimeter. According to the results, Alosa immaculata Bennet, 1835 (Pontic shad) and Alosa tanaica Grimm, 1901 (Black Sea shad) have a favorable conservation status; Huso huso Linnaeus, 1758 (Beluga) and Acipenser stellatus Pallas, 1771 (Starry sturgeon) have an unfavorable conservation status – inadequate U1, while Acipenser gueldenstaedtii Brandt and Ratzeburg 1833 (Danube sturgeon) – unfavorable conservation status – bad U2. Assessing the conservation status of marine fish species contributes to the development of good management measures for biodiversity conservation in the marine protected area (MPA).