Metabolic strategy in pelagic squid of genus Sthenoteuthis (Ommastrephidae) as the basis of high abundance and productivity. An overview of the Soviet investigations

The long-term investigations of nektonic squid Sthenoteuthis pteropus and Sthenoteuthis oualaniensis (between 1978 and 1990) have revealed some special features in a metabolism of these animals. These are: (1) rate of energy expenditure is very high (coefficient V in equation Q = aW(k) is from 3.1 to 4.7 at 26degrees to 30degreesC (more than that of other fast swimming animals); (2) hepatopancreatic index is about 4% wet body weight, twice that of actively swimming fishes; (3) protein is the main substrate for energy metabolism; (4) the polyenoic fatty acid 22:6w3 in phospholipids of squid muscle is 42.6 to 45.7% of fatty acids (more than in the most active marine animals); (5) the large proportion of anaerobic metabolism of nitrogenous substances in energy metabolism enables the squid to inhabit zones of very low oxygen concentration

Significance of Physiological and Biochemical Approaches for Black Sea Fishery Investigations

Physiological and biochemical methods are important tools for solving certain fishery problems, such as observed trends of fish distribution and migrations; estimation of productivity of commercial species; indicators and monitoring of stock condition and separating populations. In the review, major results of related long-term studies are presented

Application Of Esterase Polymorphism to Specıyf Population Genetic Structure of Engraulis Encrasicolus ( Pisces Engraulidae) in the Black and Azov Seas

Genetic structure of anchovy populations was studied using genetic-biochemical markers. Anchovy samples collected between 1980 and 2006 from different Black Sea regions (off the Bulgarian, Turkish, Ukraine, and Georgian coasts) as well as from the Sea of Azov were analyzed. Three methods of electrophoresis were applied: starch gel electrophoresis, vertical polyacrylamide electrophoresis, and isoelectric focusing on thin polyacrylamide ampholine gel plates. On the base of long-term monitoring of allelic frequencies of the polymorphic non-specified esterases loci (EST-1* and EST-2*), wintering migration of Azov anchovy may have alternative routs along the western Black Sea coasts. Typical Azov anchovy winter together with the Black Sea anchovy form the mixed populations along the Ukrainian, Georgian, and Turkish Black Sea coasts. Azov anchovy was also registered along Bulgarian coast during the second part of May and July. The results allow supposing the north-western Black Sea as complementary spawning areas of Azov anchovy

Nutritional condition of female Calanus euxinus from cyclonic and anticyclonic regions of the Black Sea

The content and composition of lipids in Calanus euxinus females were studied in cyclonic and anticyclonic regions in the southern Black Sea during the period of persistent density stratification (September 1996). The lipid content of C, euxinus from cyclonic regions was greater than of individuals from anticyclonic regions (average 101.9 and 58.8 mu g ind.(-1), respectively). Total Lipid content (mainly wax esters, 70 to 72%, and triacylglycerols, 8 to 13%) of female C. euxinus was correlated with chlorophyll a (chl a) (mean integrated concentration) (r = 0.92, p < 0.005). The high correlation with chi a was shown also for wax ester content. used as a long-term index of food supply (r = 0.89, p < 0.05). The correlation between triacylglycerol content (a short-term index) and chi a was not significant (r = 0.66, p < 0.2). In cyclonic regions the mean integrated chi a concentration (0.38 mg m(-3)) (as an indicator of phytoplankton food biomass) was 1.7-fold higher than in anticyclonic areas. The same trend occurred for mean integrated concentrations of nitrate and phosphate (0.996 and 0.299 mu M in cyclonic and 0.438 and 0.061 mu M in anticyclonic regions. respectively) in the chi a containing layer. Thus, conditions for total primary productivity in cyclonic regions were more favorable than in anticyclonic ones. This was consistent with lipid levels in female C, euxinus

Present Condition of Small Pelagic Fishes in the Black Sea

Recent data on the fat content and abundance of sprat and anchovies are considered here along with data related to sea temperatures and phytoplankton biomass. Findings showed that signicant changes in fish conditions were strongly related to environmental factors

Fat content in Black Sea sprat as an indicator of fish food supply and ecosystem condition

Fat content (as % of total body wet wt) of the sprat Sprattus sprattus phalericus in the Black Sea was determined annually during the peak feeding period (i.e. summer) between 1960 and 2001. Interannual variations of this characteristic were quite high (from 8.0 to 16.0%). Sprat fat content can be used as an indicator of food supply (or recent feeding history). In the Black Sea, different periods could be distinguished with respect to food supply of this species: Period I (1960 to 1964) with stable sprat fat content values of 11.2 to 13.7 %; Period II (1965 to 1972) with decreased values of 8.5 to 10.3 %; Period III (1974 to 1982) with higher values of 11.4 to 15.7 %; Period IV (1983 to 1990) when there were the highest interannual fluctuations and a decrease to 9.9 to 10.7 %; Period V (1991 to 1997) again with high fat content values of 12.2 to 14.7 %; Period VI (1998 to 2001) with stabilized fat content values of 12.0 to 12.3 %. These periods are closely related to the general situation in the Black Sea ecosystem caused by climatic changes, increased trophic competition, eutrophication and pollution. Relationships between interannual fluctuations in sprat fat content, on the one hand, and sprat biomass and phytoplankton concentration, on the other, are revealed. The features of the interannual dynamics of the Black Sea sprat fat content are similar to those (biomass and catches) of small pelagic fishes in the Mediterranean and in some other parts of the World Ocean