The chemical and biochemical composition of caviar in 22 specimens of wild caught and of 2 farmed animals were measured. The results include grain size, protein and fat content, fatty acid composition of triglycerides and phospholipids, as well as the concentrations of relevant heavy metals and chlorinated hydrocarbons. The average protein content varied between 26.2 and 31.1% (wet weight) and fat from 10.9 to 19.4% (wet weight) with lowest values for caviar from farmed sturgeon. The triglycerides and phospholipids contained more n-3 fatty acids, especially eicosapentaenoic and docosahexaenoic acid than n-6 fatty acids. The copper and zinc concentrations varied between 1.20 and 1.69 and 10.3 and 12.4 mg/kg (wet weight), respectively. These values reflect the elevated requirement of sturgeons for these components. Lead content varied between 0.06 and 0.15 mg/kg (wet weight). The cadmium concentrations were less than 5 micrograms/kg (wet weight) leading to the conclusion that no accumulation took place in the eggs. The concentrations of sigma DDT and sigma PCB were extremely high in caviar from Huso huso compared to the samples of the other species thus reflecting the different food habits leading to increased bio-accumulation.

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The fatty acid compositions of both lipid classes, triglycerides (TG) and phospholipids (PL), of caviar from 34 specimens of wild caught and 12 farmed specimens were measured. The investigated caviar samples of wild caught sturgeon comprised Huso huso, Acipenser gueldenstaedti, Acipenser stellatus and Polyodon spathula of different origins and those of farmed sturgeon from Acipenser baeri, A. stellatus, and P. spathula. Oleic acid (18 : 1 n–9) was the dominant fatty acid in TG of all caviar samples. In comparison with the TG, the PL have an elevated content of polyunsaturated fatty acids such as arachidonic (20 : 4 n–6), eicosapentaenoic (20 : 5–3) and docosahexaenoic acid (22 : 6 n–3). In the TG were observed some differences in the fatty acid composition between the caviar samples of the various species, especially in 18 : 1 n–9 and 20.5–3 but not in the PL. The proportion of n–3 to n–6 polyunsaturated fatty acids (PUFAs) was independent from the fish species and origins and did not reveal significant differences. The amount of n–3 PUFAs was in average three times higher compared to n–6 PUFAs. However, the fatty acid composition of the caviar depends on the origin of the sample, probably caused by differences in the food web. The caviar of farmed sturgeon contained a significant higher amount of linoleic acid (18 : 2 n–6) and a lower amount of arachidonic acid, when compared with caviar from wild sturgeon. An explanation could be that sturgeon are not able to convert 18:2 n–6 into 20 : 4 n–6.

A Ab bs st tr ra ac ct t. . The main purpose of this paper is to actualize last data on Danube shad (Alosa pontica Eichwald, 1838) migration process in Danube River. This species was widely studied last time in Danube River, but there are still some biological and ecological aspects to be revealed. Study of periodical changes in the total amount of capture and spawners structure could bring more and relevant information on presumed cyclic decrease and increase of stocks and also about the main causes of their interesting population dynamics. We try to examine some other aspects related to the spawning biology as well as to the biometry of different age-classes and also to link these issues to the last changes in environment conditions.

This paper aims to show the importance of knowing the health status of fish populations in their natural environment and its influence on fish stocks at the Romanian coast. To assess the interrelationship between fish health status and the state of stocks, the following fish species: turbot, sprat, anchovies and horse mackerel were analysed from the pathological point of view. Pathological analyses performed between 2015 and 2017 revealed the presence of infections caused by bacteria of the genus Aeromonas and Vibrio and parasitic diseases Trichodinosis, Botriocephalosis and Nematodosis. The presence of these diseases in natural fish populations may represent a real danger to the state of existing stocks, but also to their evolution.