Journal of Fisheries
Year:2010 | Volume:63 | Issue:2|Papers Count:7

The present study was done to investigate the relationship of biochemical composition and fillet yield with size of Caspian sea carp (Cyprinus carpio). Obtained results showed that there was inverse regression relationship between moisture content with fish size, but there was a positive regression relationship between fish size with fillet lipid and energy content and fillet yield in wet weight. There was not any relationship between fish size with fillet protein and ash content. Fillet moisture content had an inverse regression relationship with lipid, protein and energy content. The results showed that fish size had a positive regression relationship with lipid content and fillet yield in dry weight. Fillet parameters which had relationship with fish size and moisture content will been measured rapidly for requested purpose without much cost.

To evaluate the ability of Caspian brown trout males (Salmo trutta caspius,) in production of semen with desirable quality, the quality characteristics of semen including: sperm production (semen volume, sperm density and spermatocrit), sperm motility characteristics (percentage and duration of motility) and semen pH were investigated during the sequential strippings in the spawning season. In this regard, the tagged males were stripped four times during the spawning season. According to the data, the values of semen volume, sperm density and spermatocrit showed a significant decrease towards the end of the season (p<0.05). The semen pH, the duration and percentage of sperm were comparatively stable (p>0.05) and only a significant decrease was recorded for these parameters at the end of the season (p<0.05). As well as, significant positive relationships were found for semen volume vs. sperm density (p<0.0001); semen volume vs. spermatocrit (p<0.0001); spermatocrit vs. sperm density (p<0.0001); the pH of semen vs. the duration of motility (p<0.0001).

This study was conducted from February 2007 till July 2007 in which two types of trap B & C with 5 and 7 cm mesh were compared to usual 3.5 – 4 cm mesh size used by artisanal fishermen. Two different dhows and traps were used in 6 sets of 50 each. Bushehr province was selected as study area. As a result, 1755 pieces of fish belonging to 30 species from 14 families were caught. More than 41% catches number belonged to (Carangoides talamporoides) and other species (Argyrops spinifer), (Pomadasys kaakan), (Acanthopagrus latus), (Caranx ignobilis) ,(Epinephelus coioides) and (Lutjanus malabaricus) respectively. Total number of fishes were 90.99% in type A,  95.56% in type B and 93.83% in type C. Total weight of fishes were 90.77 % in type A ,93.15% in type B and 87.19% in type C which all belonged   to only 7 species.  The catch per trap month (CPUE) in A, B and C type traps were estimated to be , 1.8 , 1.0 and 0.6 kg / trap- month respectively , while the highest CPUE belonged to type A in May  (3.9 kg / trap- month). The results from one way ANOVA (LSD) indicated that there is a significant difference between A and B type traps with C in all measured factors (P<0.05) and B type indicated significant difference with A type in weight average and length (P<0.05). Due to high percentage of fish escape from C type traps (7cm mesh size), it isn't advisable to be used in further investigation. Re–enforcing the trap wires in B type traps and increasing the frequency of inspection per month should be investigated.

The aim of present study was to screen Rainbow trout broodstock population of Kelardasht Reproduction and Rearing Center, with emphasis on presence and non-presence of Microsatellite markers associated with resistance to IHN virus. For this purpose, 92 samples of caudal fin tissue from Kelardasht Rainbow trout brood stock population were obtained and genomic DNA of these samples were extracted. Two microsatellite loci include Ssa7NVH, Ssa94NVH were amplified using the polymerase chain reaction (PCR) with their specific primers. This study showed that presence of these microsatellite markers in this brood stock population were 98.49%, 95.46% and the number of polymorphs for those were 4, 11 respectively. According to sex-differentiation, the presence of these microsatellite markers based on Ssa94NVH in male and female were 92.4 & 97.5 and based on Ssa7VNH were 100 & 97.5 respectively.

Wetlands are among the most productive ecosystems in the world. Zooplanktons are important organisms in wetlands because they are nutritious food for the fish larvae. The nutritional value of zooplankton varies based on species composition, community structure and physicochemical parameters of water in different seasons. This study aimed to measure amino acids composition of freshwater zooplankton in Hanna wetland over four seasons. The sampling was carried out by vertical haul using a plankton net (140 μm, diameter of 25 cm) in the mid-season from summer 1386 till spring 1387. The dominant crustacean zooplanktons in Hanna wetland were Cladocera (3 species of Daphnia genus and each one species from genus Moina, Ceriodaphnia, Bosmina) and Copepoda (including the genus Microcyclops, Acanthocyclops, Allocyclops, Macrocyclops, Metacyclops and Cyclops). Results showed that the average total essential amino acids (EAA) were 28.7 %, 31.0 %, 31.6 % and 34.5 % of total amino acid, while total non-essential amino acids (NEAA) were 71.3%, 69.0 %, 68.4 % and 67.0 % of total amino acid in spring, summer, fall and winter, respectively. Among EAA, arginine 8.9%, 10.7%, 4.1%, and 5.5 %: threonine 6.4%, 4.9%, 6.2%, 7.0 %: thyrosine 4.6%, 4.7%, 4.1%, 3.3 % and methionine 2.4%, 2.2%, 1.6%, 4.1 % of total amino acid respectively in spring, summer, fall and winter were in the highest average levels during study period. Correspondingly, glutamic acid 21.4%, 18.9%, 18.3%, 18.7 %: alanine 16.9%, 15.6%, 14.8%, 12.8 % and aspartic acid 12.3%, 13.0%, 12.1%, 11.3 % were the highest compared to other NEAA in zooplankton samples. The results of this study illustrated that the amino acid composition of the zooplanktons collected from Hanna wetland vary in different seasons.

The use of live food in larviculture is of great concern in modern aquaculture. Live food not only provides the essential nutritional elements for fish larvae, but also increases their digestive enzymes activity. In addition, the role of live food in increasing the growth and survival rates of the larvae by enhancement of digestion efficiency of concentrated feeds has been proven. In this study the effects of five different feeding rations, concentrated feed (treatment 1), decapsulated Artemia urmiana cysts (treatment 2), Artemia nauplii (treatment 3), mixture of concentrated feed and decapsulated Artemia cysts (treatment 4) and mixture of concentrated feed and Artemia nauplii (treatment 5), on the growth, survival rates, feed conversion ratio (FCR) and fatty acids and protein profiles of Rainbow trout larvae were investigated. Each treatment was done in triplicates. Results showed significant differences in the growth rate of the larvae of different treatments (P < 0.05). The larvae fed with Artemia nauplii had the highest growth rate and FCR = 0.82. This was significantly different from the other feeing treatments. While, the larvae which fed with concentrated feed had the lowest growth rate and highest FCR (FCR = 1.04) compared to the other treatments. The maximum survival rate (90.6% and 92.6%) was observed in the larvae of treatments 3 and 5, and these were significantly different from those of the remaining treatments.

In this study the effects of diet nucleotide on serum cortisol and glucose levels before and after of acute stresses including: water volume reduction, 6 h O2 deficit, handling and exposure to air for 2 mins were investigated on giant sturgeon juveniles at the end of 62 days cultivation period. The juveniles were fed by 5 nucleotide levels: 0, 0.15, 0.25, 0.35 and 0.50 percent in diet. Each trial was done in 3 replicates containing 30 juveniles with the average weight of 12.57 ± 0.5 gr., for a 62 days cultivation period. According to the results, the cortisol levels showed no significant difference at the beginning of the experiment, whereas after acute stress cortisol levels were significantly higher in trials. The lowest response was observed in trial with 0.35% nucleotide and the highest was in control with no added nucleotide in diet. The glucose levels were no significantly differe neither before nor after acute stress. The survival rate after stress experiment was %100 for trials. It can be concluded that %0.15 and %0.35 nucleotide added to giant sturgeon diet has a positive effect on stress tolerance in these fishes.