Iranian Scientific Fisheries Journal
Year:2002 | Volume:11 | Issue:1|Papers Count:15

Mugil cephalus belongs to Mugilidae family and is found in the creeks and coastal waters of the Hormozgan province and mostly are caught by castnet and setnet. Regarding to study this species and determination of the frequency of this species 14 stake-nets were selected in Bandar Abbas, Qeshm and Khamir regions. Sampling were carried out monthly. The weight and frequency perecentage of M. cephalus in proportion to the total edible fishes were estimated 1.33 and 0.19%, respectively. Also, it was found that this species among the other Mugilidae had lower frequency (5%). The length measurment results showed that most of mullets were small and young (immature) with 13-15 cm length. The most aboundance of the species was observed in March.

In this study the effects of LHRHa, a mixture of common carp and sturgeon pituitary extracts (CCP+SPE), Thyroxin hormone (T3) with commonly method used in hatcheries were compared. The experiments were conducted using different doses of hormones with several replicates in order to determine the most effective dose. Total number of brood stocks were 58 females and 22 males. Prior to injecting the fishes, the Germinal Vesicle (GV) situation of all broodstocks were determined. The results showed that broodstocks has been injected with LHRHa were very satisfactory and the percentage of response; fertilization and hatching of them had significantly different. The least effective dose of LHRHa that induced maturation was 250µg/fish for single injection and 350-375µg/fish for double injection. Thus it was determined that under the experimental conditions, 20.0 to 31.2 µg/Kg of body weight of brood stock was the most effective dose. In the case of male broodstocks LHRHa was the most effective hormone and the sperms collected from these broodstocks were better in quality and quantity.

Regarding to measure some hematological factors of Caspian Salmon (Salmo trutta caspius), 55 immature and 21 mature individuals were studied. The main results were:                                                                                immature                                mature- Hemoglobin value (gr/dl)                                  7.20                                        9.87- Hematocrit (%)                                                   34.1                                        39.2- Mean No. of red blood cells (per mm3)          934300                                   1306200- Mean No. of white blood cells (per mm3)       8380                                       6219- Mean No. of platelets (per mm3)                     21180                                      13159As the results showed the number of white blood cells and platelets in immature individuals were more than mature specimen.The obtained results of blood indices were as follow:                                                                                immature                                matur- Mean MCV (FL)                                                385.4                                       302.9- Mean MCH (Pg)                                                82.0                                         75.5- Mean MCHC (%)                                               21.6                                         25.6- Lymphoc)'te (%)                                                96.1                                         69.9- Neutrophil (%)                                                   3.4                                           29.4- Monocyte (%)                                                    0.52                                         1.14Notice: Eusinophil and basophil cells weren't observed.

Some biological aspects of yellowfin and skipjack tuna according to catch data of traditional gillnet fisheries were studied in the north of Oman Sea during 1997-99. Based on Gonadosomatic Index (GSI) results, the spawning period of yellowfin begins in spring and reaches to the peak level in May-June. For skipjack tuna, in addition to the above mentioned spawning period, the other observed period was found in autumn-winter with a peak in January-February. The first length of maturity (LM50%) of yellowfin and skipjack tuna females were estimated 76 and 61 cm, respectively. Observation of stomach contents showed that squid was the major components of diet for yellowfin and fish for skipjack tuna. A comparsion between mean length of different years and landing sites using two-way analysis of variance indicated a significant differences. The length-weight equations showed an allometric growth in yellowfin tuna and isometric growth in skipjack.

There are 3 species of kilka in the Caspian Sea consist of: Clupeonella engrauliformis: C. grimmi and C. cultriventris. These species are ca ugh t by fishing method of funnel net with underwater light in the inshore waters (depths of 40-100m). The maximum recorded catch for three species in the Iranian waters had been 85,000 tons per year during period of 1998-99. In the next years (2000-2001) despite of increasing the catch effort, the amount of catch was deopped drastically. The result of collected commercial catch data showed that there are some changes in kilka catch composition, and also the frequency of common kilka has been increased since 1998. On the other hand, this species was a main part of commercial catch composition during all months. Meanwhile in the previous years, they were observed only during warm seasons (spring and summer). Based on fishermen and personal observations, the transparency of sea water was decreased rapidly during the years of 1999-2000 and at that time there were found a high abundance of Mnemiopsis leidyi in commercial catches. Simultaneously, with an increase in the mass of Mnemiopsis leidyi, the amount of catch and CPUE of kilka have been sharply decreased.

Kargan-rood is one of the most important rivers in the west of Guilan province. Identification of fish species of this river was carried out in 1995-96. Ten stations were selected for sampling and samples were collected monthly by using castnet, beach-seine and hook. The 12 species belong to 5 families were identified in which family of Cyprinidae with 6 species (and 6 different genus) were the most dominant family. The identified species were: Rutilus frisii kutum, Chalcalburnus chalcoides, Capoeta capoeta gracilis, Barbus lacerta, Alburnus bipunctatus eichwaldi, Leuciscus cephalus, Caspiomyzon wagneri, Cobitis caspia eichwaldi, Gobius kessleri, Salmo tmtta caspius, Salmo trutta lario, Syngnathus abaster.

To determine the chromosome numbers of artemia brine-shrimp in Urmiyah lake (Azarbaijan-e- Gharbi province), cytogenetic studies were carried out on artemia cysts. In order to identify the collected samples, each sample of cysts, first incubated in sea water (35 ppt salinity) and then to determine the reproduction mode, the cyst samples were feeded with Dunaliella tertiolecta, for three generations (F3) up to adult. The results showed that there were two types of artemia in terms Chromosome spreads were prepared from freshly hatched nauplius by squashing method. The results of counting 100 metaphases plates from bisexual artemia and 35 metaphases plates of parthenogenetic specimen, it was found that the number of chromosomes in these 2 types of artemia were the same, 2n=42. In these population, very small chromosomes with metacentric, submetacentric, telocentric and acrocentric types were observed. Karyotype formulas of bisexual an parthenogenetic artemia were determined as 2n=30 M / SM+12 A/T and 2n=32 M/ SM+10 A/T, respectively. All studied samples in Interphase stage lacked and chromocenter. Due to very small size of chromosomes, it was difficult to do precise determination of the type of chromosomes and in this regard various C-banding experiments were performed. Also, since chromosomes in artemia lacked any chromocenter, the differentiation of chromosomes based on the types of C-banding was impossible.