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Responsible aquaculture, the farming of aquatic organisms, is a sustainable strategic sector for land and coastal communities. It significantly contributes to food security and enhancement of economic development; it provides employment opportunities and often contributes to the ecological services provided by the environment. According to the Food and Agriculture Organization of the United Nations (FAO), the contribution of aquaculture to the global food security is widely demonstrated by an astounding industry growth of 7.5% per year since 1970. In 2018, aquaculture reached the all-time highest production of 114.5 million tonnes in live weight with a total farm gate sale value of USD 263.6 billion. This makes aquaculture a key player within the Blue Growth concept and a strong contributor to some of its key Sustainable Development Goals (SDG). This is particularly true in geographical areas where dependence of local economies on fishery products is high, and yet access to sustainable landings is hampered by ecological barriers. One such area is represented by the Black Sea basin. Whilst the Black Sea annual capture fishery production has varied considerably since 1990 and its current landings are significant, growing attention is currently given to boost aquaculture development along the Black Sea bordering countries, with marine aquaculture being considered as an important contributor to the total fisheries production. Nonetheless, aquaculture development in this region is not homogenous and its development has, so far, been limited by environmental, economic, social, and more generally governance issues. This paper, for the first time, attempts to provide a comprehensive fresh outlook of the aquaculture sector in the Black Sea, stressing the importance of regional cooperation as an essential pillar to support the sustainable development of the industry. The paper addresses aquaculture in the Black Sea from different perspectives: it outlines the key characteristics of the Black Sea environment; it discusses the most common farmed aquatic species and the potential for new ones; it frames the national approaches to aquaculture development, sharing information about success stories, while shedding light on the main challenges and priorities ahead. This collective endeavour will represent a helpful contribution to Black Sea riparian countries to answer the many questions they have, and expectations they hold from the aquaculture sector.

The results of reproduction were tested in females of the African catfish (Clarias gariepinus Burchell 1822) after stimulation of ovulation with carp pituitary (4 mg/kg body weight) or with Lecirelin (15 μg/kg) and metoclopramide (10 mg/kg). After administering the synthetic substance eggs were obtained from all females while in the group treated with pituitary homogenate 7 out of 8 hypophysed females spawned. The applied spawning agent did not significantly influence the weight of eggs expressed in grams, but in the case of females treated with carp pituitary homogenate a significantly higher weight of eggs expressed as the percentage of body weight of fish was recorded. The applied stimulators of ovulation did not affect any trait reflecting the quality of eggs. Females used as an experimental material belonged to two categories in respect of body weight: lighter females with average body weight of 2.63 ± 0.36 kg and heavier females with average body weight of 3.91 ± 0.48 kg. It was proved that the weight of eggs expressed either in grams or as a percentage of a female’s weight was significantly related to the body weight of a female (P ≤ 0.01 and P ≤ 0.05, respectively), as well as the percentage of fertilised eggs and the percentage of living embryos after 28 hours of incubation (P ≤ 0.05 and P ≤ 0.05, respectively). The interaction between the stimulator of ovulation and the female body weight was significant only for traits reflecting the weight of obtained eggs (P ≤ 0.05 and P ≤ 0.01).