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  • 1
    Publication Date: 2017-11-27
    Description: This study was conducted to determine length-weight and length-length relationships, relative condition factor (Krel) and Fulton’s condition factor (K) for five species including Scardinius erythrophtalmus, Carassius auratus gibelio, Cyprinus carpio, Tinca tinca and Hemiculter leucisculus belonging to Cyprinidae family. Fish sampling was carried out by gill net and fyke net in the western region of Anzali wetland (SW of the Caspian Sea) between Nov. 2010 and May 2011. 368 specimens were measured and weighed. The values of the exponent b in the length-weight relationships (LWRs) ranged from 2.5358 to 3.3613 and those of the length-length relationship (LLRs) ranged from 0.8717 to 0.9412. Also, relative condition factor (Krel) ranged from 1.00±0.11 to 1.30±0.21 and Fulton’s condition factor (K) ranged from 0.80±0.05 to 1.60±0.18 for all species.
    Keywords: Biology ; Fisheries
    Repository Name: Aquatic Commons
    Type: Article , PeerReviewed
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  • 2
    Publication Date: 2018-11-22
    Description: In this study the effects of two catch methods (gillnet and beachseine) were investigated on some spermatological parameters of Kutum brood stock. For this purpose 8 adult male caught by gill net and beach seine were stripped by applying slight pressure to abdomen section of fishes and sperm samples were transferred to laboratory in ice box for spermatology analysis. Semen volume was measured by scaled syringes and sperm movement duration by faze-contrast microscope. spermatocrit was determined by haematocrit reader. The results showed significant (P〈0.05) differences in spermatocrit levels between fishes that were captured by gillnet and beach seine, but no significant (P〉0.05) differences observed in semen volume and sperm movement duration between the two methods. The results showed that fishes captured by gillnet had more positive index in comparison to fishes captured by beach seine.
    Keywords: Aquaculture ; Biology
    Repository Name: Aquatic Commons
    Type: Article , PeerReviewed
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  • 3
    Publication Date: 2018-11-16
    Description: The CPUE, CPUA and biomass of Pomadasys kaakan was assessed in the waters of the province of Bushehr in 2011. The study area was divided into three areas (Northern, Central and Southern) and depth zones (10-20, 20-30 and 30-50 m).Stratified random sampling was used to collect the data. Samples were taken from 45 stations. The total length and total mean length were calculated to be 27-56 cm and 42.7±4.95 cm, respectively. The total biomass was estimated to be approximately 5943.55 tons. The total CPUE and CPUA were calculated as being 803.25 kg/h and 9269.05 kg/nm^2, respectively. The lowest mean CPUE was observed in the 20-30 m depth zone and was 8.82 kg/h and the highest mean CPUE was observed in the 10-20 m depth zone as 21.45 kg/h. The lowest and highest mean CPUA were calculated in the 20-30 m and 10-20 m depth zones as being 95.91 kg/nm^2 and 259.35 kg/nm^2 , respectively. Also, the central area of Bushehr showed the highest CPUA with an estimate of 8913.9 kg/nm^2. The results of this study demonstrated that the highest distribution and biomass of P. kaakan were concentrated in central areas and 30-50 m depth zones.
    Keywords: Fisheries
    Repository Name: Aquatic Commons
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2017-12-03
    Description: Anesthesia is considered to be the best way to ensure animal welfare during handling etc. Clove oil and electronarcosis are among the most popular chemical and physical anesthetics used in fisheries and biology;however there is a little information available on the effect of anesthesia using direct electric current in fish. In the present study, the impacts of clove oil (30 mg.l-1) and electro-anesthesia (constant direct current, 0.5 v.cm-1) (DC) were assessed in common carp, Cyprinus carpio during narcotic stage in two experimental sets. Experiment 1 was conducted to quantitatively compare induction of anesthesia and recovery time. The biochemical and hematological effects of anesthetics were analyzed as experiment 2. The results revealed that induction and recovery times in fish anesthetized with electric current were significantly lower than clove oil treatment.Significant differences were observed in cortisol concentrations, red blood cells and mean corpuscular hemoglobin concentration between anesthetic methods. Our results suggest that constant direct current electronarcosis was more quickly than clove oil and associated with lower side effects in common carp.
    Keywords: Biology ; Fisheries
    Repository Name: Aquatic Commons
    Type: Article , PeerReviewed
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  • 5
    Publication Date: 2018-06-19
    Description: One of the most visible direct impacts of fishing is the capture of non-target species, known collectively as by-catch. By-catch includes species that are unwanted and discarded (discards) and species that are retained and sold (byproduct) (Stobutzki et al., 2003). Although tuna purse seine fisheries have been shown to be selective, leading to lower levels of by-catch than other fisheries (Alverson et al., 1994; Kelleher, 2005), several species can be incidentally caught and, in some cases, discarded at sea. These include vulnerable and sensitive species such as turtles, mammals, and sharks (Minami et al. 2007; Romanov, 2008b). Tuna purse seine fisheries probably apply the most intensive direct human impact on the tropical epipelagic ecosystems in all oceans. Because of the worldwide scale of purse seine fisheries, an assessment of their impact on associated and dependent species is essential (Romanov, 2002a).
    Keywords: Fisheries
    Repository Name: Aquatic Commons
    Type: Article , PeerReviewed
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  • 6
    Publication Date: 2018-10-19
    Description: The purpose of this study was to find some important biological aspects of Thunnus tonggol in coastal waters of Hormozgan Province (Persian Gulf and Oman Sea). A total monthly data of 4383 individuals ranging from 25 to 124 cm fork length were collected from April 2015 to March 2016. The data were analyzed with FiSAT II software using the ELEFAN1 package to estimate the population parameters. The length-weight relationship was TW=0.00002 FL^2.87 (R^2 =0.97) showing an isometric growth for T. tonggol. Growth parameters were computed as L∞=129.6 cm, K=0.39 year^-1 and t0=−0.28 with the growth performance index, φ’ of 8.7. The total mortality (Z) was estimated 1.58 year^-1 using catch curve method. The natural (M) and fishing mortality (Fcurr) were obtained 0.49 and 1.09 year^-1, respectively. The exploitation ratio was 0.69. Length at first capture (Lc) was estimated as 60.2 cm fork length. The yield per recruit (Y/R) maximized in maximum fishing mortality rate 0.85 year^-1. The biomass per recruit decreased to 17.2% of unexploited biomass (virgin biomass) at Fcurr. The current fishing mortality exceeds optimum fishing mortality (Fopt) and limit fishing mortality (F limit) as biological reference points. The results indicated that population of T. tonggol is overexploited in the Persian Gulf and Oman Sea and there no further scope for improving the exploitation of this species.
    Keywords: Fisheries
    Repository Name: Aquatic Commons
    Type: Article , PeerReviewed
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