JOURNAL OF MARINE SCIENCES AND TECHNOLOGY
Year:2004 | Volume:3 | Issue:1|Papers Count:9

The effect of local conservation measure on the whiskered tern populations in two perennial ponds of Zarrinkola and Marzoonabad of Mazandaran province was investigated during May-Sep. 2003. There was one breeder group of whiskered tern (Chlidonias hybridus) (930 pairs) in Zarrinkola pond. In Marzoonabad pond, however, due to local conservation and security measures as well as unoccupied spatial niches, two breeder groups (1390 pairs) were observed. Clutch size was 1-4 eggs in Zarrinkola and the second breeder group in Marzoonabad ponds, whereas, in the first breeder group was 1-5 eggs.Breeding success in Zarrinkola, first and second breeder groups of Marzoonabad was %57.08, %82.96 and %75.87, respectively. Significant difference (p<0.05) in mortality rate among the reproductive phenology stages was observed. The highest mortality was found before the incubation, due to intensive rainfall. No significant difference in breeding success among Zarrinkola and the Marzoonabad breeding groups were found. This indicated that local conservative activities had affected the regional security but it did not play the sole role in breeding success.

Wind data recorded every 3 hours at Babolsar synoptic station in southern part of the Caspian Sea and also wave information measured by Neka buoy was used to investigate the wave climate in this region. For this purpose, monthly and seasonally wind roses of the region were drawn. The results reveal that most of the time the weather is calm. Besides, the dominant direction of the wind is northerly. Further, with the help of software provided in visual basic environment, the wind duration in different conditions was calculated. The results confirm that duration of winds of higher intensity is shorter.Then, Pierson-Moskowitz and JONSW AP spectral models together with the SMB method were used for wave hind casting from wind data. Based on the results, sea state is calm in most of conditions. Wave height often is less than 0.5m. The fully developed condition is rarely observed in the region. Comparing the predicted results with the actual values (Neka buoy information) revealed that the 5MB method has the least error. Error analysis also indicates that the Pierson-Moskowitz model, which is rather suitable for fully developed conditions, results in errors of more than one hundred percent. Because of using raw wind data, the JONSW AP model also results in more errors in comparison with the 5MB method. Finally, the SMB method is suggested as the most suitable wind wave predicting method in the Babolsar region.

Quality characteristics of golden mullet (Liza aurata) kept in ice was evaluated by monitoring changes in lipid and sensory parameters over a 20-days period. According to results, samples showed significant changes in peroxide value (PV), free fatty acid (FFA), thiobarbitoric acid (TBA), heme iron (HI) and sensory evaluation. For samples stored in ice FFA, PV, TBA increased while HI decreased. Sensory evaluation indicated excellent-to-good attributes at d7 and good-to-acceptable at d10. Based on this assessment, 10 day is determined to be the shelf life of golden mullet stored in ice.

Some aspects of reproductive biology of yellowfin Seabream, Acanthopagrus latus, in coastal waters of Bushehr was investigated from Mar-Apr 1997 to Mar-Apr 1998 (1 year). Sampling was conducted monthly and a total of 182 samples were examined to determine sex, sex ratio, gonad weight, gonadal maturation index, fecundity, and also length weight relationship. According to result, average sex ratio (male to female) was 1:1. Spawning peak was found to occur in Jan-Feb. The average absolute fecundity was 1842700, and was found to have correlation with length-weight relationship.

Total protein, lipid and ash contents in amphipod, Pontogammarus maeoticus, of southern coast of the Caspian Sea was measured from July to October. The average amount of total protein in dried gammarid was 42.43% (43.46% in July, 40.55% in August and 43.20% in October); lipid was about 4.14 % (4.39% in August and 3.88% in October) and ash was about 30.49% (34.08% in August and 26.89% in October). The percentage of total protein increased a little from west to east and in all the stations; it decreased after reproduction and then increased again in October, but the amount of lipid and ash decreased in October in comparison with August.

This experiment was conducted to increase the resistance of rainbow trout larva to environmental stress by feeding freshwater and brackish water gammarid powder as supplementary diet in two different levels (10% and 25%) for 60 days. Larvae which had absorbed 2/3 of their yolksac collected from rearing tanks and fed with 5 diet treatments including 100% artificial diet (control group), 10% freshwater gammarus powder and 90% artificial feed, 25% freshwater gammarus powder and 75% artificial feed, 10% brackish water gammarus powder and 90% artificial feed, 25% brackish water gammarus powder and 75% artificial feed. The groups fed with both levels of freshwater and brackish water gammarid powder showed higher survival than the controlled group. Best results obtained from fourth group which 10% of brackish water gammarus powder was replaced in their diet. Survival rate in low pH (3.8) and high temperature (24c°) stress in fourth group was significantly (P≤0.05), more than control group. Despite higher survival in the fourth group for high pH (11.8) stress, the difference was not significant from the control group (P≥0.05). Based on the results, it can be suggested that using of 10% brackishwatwer gammarus powder is suitable for production of high quality and healthy larvae.

The effect of three activating solutions (Activator No 1, 2 and water) on the sperm motility duration and fertilization rate of rainbow trout was investigated. Different activators had significant differences on duration of sperm motility. Activator 2 had the highest motility/time (91.08±2sec) in comparison with others; water showed the lowest (26.01±0.24sec) motility time. Use of activator 2 resulted to the highest fertilization rate (86.85±1.45) as well as significant difference in comparison with water (82.45±1.58). In this regard, no significant differences were found between activator 2 and water in comparison with activator 1.

Some reproduction characteristics of Liza klunzingeri were studied during Apr. 2003 to Feb. 2004 in Khouzestan waters of the Persian Gulf. A total of 836 samples were monthly collected from 2 landings of Bahrekan and Hendijan; 727 specimens were studied from point of sex determination and 60 specimens were studied from the fecundity point of view.This species was found to have more abundance in autumn (esp. Oct-Nov). The samples composed of 89 (12.2%) male, 467 (64.2%) female and 171 (23.6%) immature; the sex ratio was found (M)I:5(F).The advanced stages of maturity (4th & 5th) were found in October onward. The highest Gonadosomatic Index was in December and the lowest was in June. The maximum absolute and relative fecundities were 183045 and 2232, respectively; the minimum absolute and relative fecundities were 44700 and 582, respectively.