مجله علوم شیلاتی ایران (انگلیسی)
سال:1390 | دوره:11 | شماره:1 |تعداد مقالات:24

Estimates of age, growth parameters, length-weight relationship and length and age at first maturity of the otolithes ruber are required for fishery management. We used counting annuli on the section of sagittal otoliths to age O.ruber from the Northwest Persian Gulf in south of Iran. Estimated ages ranged from 0 to 6 years, and maximum frequency of fishes was observed in age-group 1. The values of growth parameters L¥, k and to were calculated by von Bertalanffy model and the results were 67.57 (cm), 0.27 (year-1) and -0.43 respectively. Parameters b and an in length-weight relationship were calculated 3.19 and 0.005 respectively. Length and age at first maturity were estimated 28 cm and 1.55 year.

The length-weight relationship, age, growth parameters, sex ratio, mortality and exploitation rate of Salmo trutta fario were determined in Lar dam. The sex ratio (male: female) was 1: 1.84 which differed significantly from the expected 1: 1. The length-weight regression was W=0.028L2.706 (females) and W=0.0341L2624 (males) indicating a negative allometric growth for both sexes. Growth parameters were estimated as L¥=45.0 cm, K=0.27 yr-1, t0=-0.23 yr. The instantaneous coefficients of natural, total and fishing mortality were estimated as 0.40 yr-1, 0.75 yr-1 and 0.35 yr-1. The results showed that S. trutta fario is moderately a rapidly-growing species in Lar dam. The exploitation rate was 0.47. Therefore, the population appeared to be in good condition in 2004.

This study aimed to design a bycatch reduction device (BRD) for shrimp beam trawl, which is manufactured by flexible materials to reduce bycatch for the gear in the South Sea of Korea. The model test was carried out to understand the shape of the gear in the water and to measure the variation of flow speed due to the BRD in a circulating water channel. Catches were compared between a shrimp beam trawl without BRD (control gear) and others with BRD (treatment gears) in the field. BRDs were two different types in this study. In the case of BRD (a), a square-shaped grid net and a funnel-shaped net were installed in the front part of the cod end to help fish sorting and expelling through the outlet at the bottom. BRD (b) has one more outlet which is added at the upper part of the BRD (a). On the model test, water speed was reduced a little in the gear by installing the BRD. At the results of comparing with a control gear, the bycatch (%) of fish excluding shrimp was reduced between 17 and 68% using BRD (a) and 5 and 66% for BRD (b) respectively. By the signed test of significant level 0.05, the quantity of shrimp catches for BRD (a) was not different in comparison to the control gear but it decreased for the gear installing BRD (b).

The acute toxicity and effects of diazinon on some haematological parameters of kutum (Rutilus frisii kutum, Kamensky, 1901) weighing 613.33±157.06 g were studied under static water quality conditions at 15 oC±2 oC. These experiments were carried out based on the standard TRC, 1984 method over 4 days, and controlled for the effective water physicochemical factors having pH rangesof 7-8.2, total hardness 300 mgl-1 (caco3), dissolved oxygen 7 mgl-1. The results showed that the 96h LC50 value of diazinon was 0.4 mgl-1 and that the maximum allowable concentration (MAC) value of this toxin was 0.04 mgl-1. The second stage of experiments consisted of four treatments: LC0: 0 as blank, treatment A with a concentration of LC1: 0.107 mgl-1, treatment B with a concentration of LC5: 0.157 mgl-1, treatment C with a concentration of MAC value: 0.04 mgl-1. Male brood stocks of R. frisii were treated with these concentrations for 45 days. The results showed that long-term exposure to diazinon causes a decrease in the erythrocyte count (RBC), haemoglobin (Hb), haematocrit (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), leucocyte count (WBC), lymphocyte, testosterone, iron (Fe), sodium (Na), lactate dehydrogenase (LDH) and cholinesterase (CHeS) (P<0.05). Diazinon also causes an increase in prolymphocyte, aspartate aminotransferase (AST), cholesterol, alkaline phosphatase (ALP) and adrenaline (P<0.05). There are no significant effects on monocyte, eosinophil, magnesium (Mg), chloride (Cl), glucose (BS), urea (BUN), uric acid (U.A), triglyceride (TG), calcium (Ca), albumin (Alb), total protein (TP), cortisol, noradrenaline and high density lipoprotein (HDL) levels in R. frisii male brood stocks (P>0.05). The results showed that long-term exposure to low concentrations of diazinon causes changes in some haematological and biochemical parameters of R. frisii male brood stocks.

To determine the best live food and to reevaluate the optimal weaning period for beluga fish (Huso huso) larvae, seven experimental diets: Daphina (DP), Chironomids (CH), Gammarid (G), Daphina+formulated diet (DPFD), Chironomids+formulated diet (CHFD), Gammarid+formulated diet (GFD) and formulated diet (FD) in triplicate groups were fed to 4662 sixteen-days-old larvae which were captured from the stock tank and randomly distributed into 21 tanks. The microdiets contained 48-50% crude protein, 12-13% crude fat, 9-11% moisture and 8.5-9.5% ash. After 25 days feeding trial, weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) of fish fed CHFD were significantly higher than those of fish fed the other diets (P<0.05). Frequent cannibalism and higher mortality in larvae fed G, GFD and FD diets were observed. These results may show the importance of live food followed by formulated diets in a gradual application pattern, as early as on the fourth to fifth day after hatching.

Baseline ecological studies of Pondicherry mangroves are important for monitoring, management and conservation of mangrove ecosystems. A brachyuran crab faunal assemblage at four stations of Pondicherry mangroves is described and monthly samplings were made during September 2008 - August 2009. Totally 22 species of brachyuran crabs belonging to 12 genera and 5 families were recorded; crabs belonging to the family Portunidae and Ocipodidae are most dominant group represented by total of 16 species. Six species considered are as a commercially important and out of which, on three species Scylla serrata, Thalamitta crenata and Portunus sanguinolentus are catch large quantities from stations 1 and 2. Portunus pelagicus, P. sanguinolentus and T. crenata were totally absent in stations 3 and 4. Population densities of brachyuran fauna ranged from 29 -71 ind. m2, the diversity ranged from 0.96 -2.18 bit. ind -1, the richness varied from 0.42 -0.74, and the evenness varied from 0.41 -.072. Maximum diversity values were recorded during post monsoon. The crab community recorded was analyzed by univariate and multivariate statistical techniques. Crab community structure was correlated with vegetation structure, and environmental factors were positively correlated with surface water pH, salinity, tree dominance, tree diversity and tidal inundation and negatively correlated with sulphide, organic matter, senescent leaves and decaying leaves, suggesting that the mangrove vegetation is important to the crab fauna as a habitat and food supply.

In this study changes in fatty acids profile during frozen storage at -18oC of Cobia (Rachycentron canadum), caught from the Persian Gulf (Bandar Abbas) were studied. Changes in saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), EPA+DHA/C16, n-3 PUFA/n-6 PUFA (n-3/n-6) and polyunsaturated fatty acids /saturated fatty acids (PUFA/SFA) were investigated during a six- month storage at -18oC. Eighteen fatty acids were found in Cobia, with higher percentage of saturated fatty acids (46.07%), monounsaturated fatty acids (33.72%) and polyunsaturated fatty acids (15.44%). The MUFAs and PUFAs reduced from 33.72 to 26.26% and 15.44 to 10.78%, respectively. Palmitic acid (C16: 0, 27.42% of total fatty acids) and stearic acid (C18: 0, 12.62%) were the dominant saturated fatty acids. The major unsaturated fatty acids were determined as docosahexaenoic acid (C22: 6n3, 5.76%), oleic acid (C18: 1n9, 25.76%) and linoleic acid (C18: 2n6, 4.38%). As a result of the frozen storage (up to 6 months), marked content decreases were found in fatty acid groups such as monounsaturated, polyunsaturated and n-3 polyunsaturated, as well as in the n-3/n-6 ratio and it means that the nutritional value of Cobia has decreased.

There is no available adequate information on the biology and genetics of the Caspian salmon (salmo truta Caspiu) living in the Caspian Sea with other species such as common carp families, sturgeons and etc., therefore we are interested in knowing whether selection for rapid growth rate in salmo trutta Caspius will potentially lead to correlated genetic response in body weight and length. The potential for correlated responses was evaluated by the heritability estimation, estimating heritabilities of body weight and length. The genetic parameter estimations were obtained for different stages of growth from 5400 fish consisting 27 unrelated families that reached maturity at 36 months of age. The parent which used to produce separate family groups had been caught from the Caspian Sea and spawned during the autumn season. The estimated heritability of body weight and length was 0.42±0.13 and 0.49±0.01, respectively based on differential and selection response between parent pairs and their offsprings. Several factors may have affected the creation of this high level of estimation, dominant effect, inherited from different breeders to offspring.

Fish egg poisoning is a public health hazard although usually the incident rate, mortality and fish species involved are not well reported (Halstead, 1970). Four species of Cyprinidae in Iran have been suggested as ichthyotoxic by Coad (1979).namely Abramis brama. Cyprinus carpio. Schizothorax zarudnyi and Tinca tinca and it was thought that other species may be discovered subsequently. Najafpour and Coad (2002) reported ichthyotoxin in the cyprinid Barbus luteus from Iran, and the study records another species. The Cyprinid fish Capoeta capoeta known as Siah mahi or gara balig in Iran.

According to the data recorded from Cadiz area located in the Mediterraneans (Cardenas. et al., 1997) the red cornet fish Fistularia petimba Lacepede, 1803 is a large fish typically found along soft bottom coastal areas and usually at a depth of over 10m (Banon and Sande, 2008). Fistularia commersonii is often misidentified as Fistularia petimba Lacepede (Randall, 1992). Cornet fish distribute in the tropical waters of the Atlantic and Indo pacific.