JOURNAL OF MARINE SCIENCES AND TECHNOLOGY
Year:2002 | Volume:1 | Issue:2|Papers Count:9

Some biological characteristics in common kilka, Clupeonella delicatula, including its sex ratio, the relation between fork length, weight and age, the relation of fecundity, fork length and weight, the ovary weight, the age and peak time of spawning were investigated.For this purpose, over 800 common kilka were sampled in Babolsar commercial fishing region from April to August 2000. The results indicated that common kilk a had 6 different age class with a sex ratio of 1:2 (male- female); its spawning peak in the region was found to be APR-MAY. The average fecundity was 28239.82.

Seal is the sole aquatic mammal representative in the Caspian Sea. Its population has drastically reduced in recent years due to various reasons such as entrapment, disease (canine distemper virus) and contamination. In addition to various agricultural chemicals and insecticides, PAHs due to its high toxicity and bioaccumulations in the fat tissues of aquatic organisms, particularly seal, could be blamed for the impact on reduction of the Caspian seal population.Based on n-hexane extraction (using GC-MS) and analysis of extracts From fat tissue, the presence of naphthalene, antheracene, and phenanthrene at a range of 3.2 - 22.8 mg/g were traced out.

Three native and six exotic fish species inhabiting the Zarivar Lake (west of Iran- Kordestan province) were examined from parasitological point of view. Totally 14 parasites species comprising 3 protozoa, 6 monogenea, 3 crustacea, 1 digenea, and 1 cestoda) were identified to genus and species level.Among them, an Ancyrocephalus species found on the gills of Mastacembelus mastacembelus seems to be a new species and its description will appear in near future. In addition, presence of Diplostomum spathaceum metacercaria in the eyes of Mastacembelus mastacembelus as a new host was recorded for the first time.

The effect of dietary L-carnitine supplementation at levels of 400, 800, and 1200 mg/kg diet on the growth and body composition of rainbow trout was investigated. Four groups of trout tries of 1 g average weight and total biomass of 100 g were fed for 48 days. The fish were fed 3.7 to 6 percent of body weight per day on the basis of water temperature and biomass; their weight was about 7 g at the end of the feeding period.There was no significant difference in the growth, FCR and SGR at the different levels of dietary L-carnitine (P>0.05). No significant difference was also found in total body protein - fat ratio at any of the L-carnitine levels (p>0.05).

The occurrence of a parasitic nematod (Schulmanella petruschewskii, Schulman, 1948) in the liver of an Iranian barble (Barbus koswigi) inhabiting the Dez River of Khoozestan province is reported for the first time.Among several fish species sampled, only the barble (Barbus koswigi) was found to host this parasitic nematod. The main lesion was found to be infiltration of mononuclear leukocytes and connective tissues surroundingthe parasite.

A marine gram positive bacterium was isolated from soft coral "Sinularia erecta" in the Larak Island in the Persian Gulf and was examind for its ability to produce cytotoxic metabolits by using Brine Shrimp Bioassay Test with LC50=0.5 mg/ml.Based on morphological and biochemical chara cteristics, the bacterium was found to belong to Actinomycete group and Streptomyces genus.

Based on monthly data of synoptic maps on the earth surface and level of 500 hp, precipitation on the southern part of the Caspian Sea along Iran during the six cold months of the past 19 years (from 1971 to 1989) was analyzed.The results indicated that intensive precipitation on the northern region of Iran at 500hp level was associated with the ridge extending over the western part of Black Sea, eastern to central part of Europe and eastern Mediterranean Sea, while the deep trough located in eastern reach of the Black Sea. This trough extends from latitude 70°N to south-south west along longitude 40°-50°E.

In fishing season 2000, golden mullet (Liza aurata) were caught along the Mazandaran coast of the Caspian Sea, and the identification of their fatty acids composition was done using Gas- Liquid Chromatography after extraction of the lipid tissue and methylation of esters.Average fat composition was 9.25%, of which unsaturated and saturated fatty acids constituted 72% and 27.95%, respectively. The percentage of unsaturated fatty acids with one double bond and several double bonds was 43.8 and 28.2, respectively. Fatty acids of omega-3 series constituted 18.7% of the total fatty acids, while its ratio to omega-6 series (1.97) was significant. As the amount of golden mullet catch is more than other bonyfishes in the southern Caspian Sea, and according to its fatty acids composition, its food and fisheries values was described and compared with other bony fishes.