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  • 1
    Publication Date: 2018-09-06
    Description: An artificial Reef is a fabricated, underwater structure, typically built for promoting marine life in areas of generally featureless bottom. Creating artificial reefs began from 2000 in southern provinces in Iran. This study has surveyed about the Bushehr and Khozestan states. The objective is to determine the effectiveness of artificial reefs in attracting and enhancing the production different aquatics through increasing of fish assemblage and fishery. The performance of artificial reefs deployed off the coast of the Persian Gulf in 10 to 15m, was evaluated. The reefs comprised of seven artificial and one control (natural) statistical tests plan in three replicates. Three types of artificial reefs were used in this study. That two were designed reefs and one was not designed or used material. The experimental plan consisted (i) Reef ball (R), designed hemispherical shaped; (ii) Laneh Mahi (L), designed pyramid shaped; (iii) Used material (U); (iv) mixed (RL); (v) mixed (RU); (vi) mixed (LU); (vii) mixed (RLU); and (viii) control site (CS). Trap nets and under-water visual census surveys were adopted for seasonal sampling of fish aggregation. Results of statistical analysis using ANOVA and T-test of the mean Catch per Unit Effort (CPUE) showed significant difference (p〈0.05) in term of computing number of fish for aggregation of fishes. The study has concluded that reef deployments have influenced favorably the fish communities and fish harvests. Therefore, the artificial reefs, especially the mixed RLU, are appropriate tools for future fishing enhancement in the Persian Gulf of Iran.
    Keywords: Aquaculture
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
    Format: application/pdf
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  • 2
    Publication Date: 2018-10-08
    Description: For the first time white spot disease (WSD) was reported in shrimp farms of khoozestan province, in southwest of IRAN in 2002. Then in 2005 the neighbor province, boushehr, was contaminated. In 2008 WSD outbreak reported in sistan-bloochestan province in southeast of Iran. In 2015 all of southern shrimp farms of country except Hormozgan, the middle southern province, which has remained free of WSD, are being contaminated. White Spot disease suspended shrimp culture in thousands hectares of shrimp farms. Considering that white spot disease has not been observed in Hormozgan province yet, the question is; to what extent environmental and management factors participated in preventing WSD outbreak or cause WSD outbreak. In this study (20102012), the effects of environmental factors and management, stressors that decrease immune system function of shrimp are discussed. In addition, the role of pathogen as the main factor of outbreak is discussed. The goal of this study is to define environmental parameters and management practices associates with outbreak of white spot disease in affected provinces and discover reasons of being Hormozgan province free of this disease. In this study the role of the local environmental factors and management practice stressors in susceptibility to WSD was determine. Both the effects of environmental factors in water of ponds including total ammonia, nitrogen, dissolved oxygen, pH, salinity, transparency, and temperature and management issues related to biosecurity are studied. There were overlaps on physical and chemical parameter values obtained in clear areas with contaminated areas .Results of the data analysis suggest that lack of association with WSD incidence was 7 times greater than WSD incidence despite of disease outbreak in sistan-bloochestan province, so other sources of white spot disease virus incidence was suspected in affected areas. Histopathological examinations and polymerase chain reaction (PCR) tests during project performance did not reveal white spot disease virus evidences in post larvae examined from khoozestan province stocked in farms but disease outbreak was happened in that farms , so we suspected to management practice include feed , pond preparation and carrier of disease. Recorded values of temperature and salinity in some months during inspection in Hormozgan province specified stressful condition that may lead to WSD outbreak, however the disease did not appear. Therefore the hypothesis that the water physical and chemical conditions are reasons to prevent disease outbreak in Hormozgan province is being rejected. The policy of Hormozgan’s fishery authorities, to replaced Fenneropenaeus indicus with specific pathogen free Litopenaeus vannamei, that is more resistant to some of diseases, before incidence of WSD in farms and to before being endemic in the Hormozgan province, made an advantage compare to affected southern provinces that introduced Litopenaeus vannamei after WSD prevalence to their farms. However it does not guarantee to maintain current trend of being Hormozgan province farms free of white spot disease. Therefore establishing the principals of biosecurity are strongly emphasized. Strategies taken by the proficient authorities in preparation of SPF shrimp broodstock can be the most important factor in preventing WSD. Regarding biosecurity principals purchased feed must be free of shrimp head powder. Construction the new shrimp farms should be as far as it could be away from contaminated areas.
    Keywords: Aquaculture ; Ecology ; Health
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
    Format: application/pdf
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  • 3
    Publication Date: 2018-08-26
    Description: Biology aspects of cobia (Rachycentron canadum) were investigated from October 2005 to December 2006 in Northern waters of Persian Gulf (Hormozgan province).The reproduction cycle, sexual maturity, sex ratio, Fecundity, Lm50, feeding, length frequency, growth parameters and mortality of cobia were studied from total of 509 specimens ranged from 19 to 159 fork length. Gonadosomatic index peaked during spring and summer with main peak in June. Spontaneous spawning occurs around the year with peak in June. The overall female to male ratio was significantly 1 : 1.49 (P〈0.05). Batch fecundity were estimated 1684954±118990 in 15 females. Relationship between total length and fecundity were calculated F=1.3717TL 2.9567 (r^2= 0.82). Feeding studies indicated that the bony fishes were main food of cobia (76%) and followed by crustaceans (25%) and mollusks (11%). Rays were least food items (22%). Maximum and Minimum GaSI were observed in March (33%) and August (0.07%) respectively. Females reached 50% sexual maturity at 81.25 cm TL. The total length -weight relationship was W=0.0042L3.1162 (r^2=0.9852). Thetotal length-fork length relationship was TL= 1.1561FL-2.533 (r^2= 0.9933). Growth parameters K, L, and t_0 were calculated by von bertalanfy growth equation: 0.11 (year1), 168.65 cm, 3.49 and -0.97 respectively. The instantons rate of total mortality (z), natural mortality (M) and fishing mortality estimated by catch curve analysis were 0.30, 0.25, 0.14 (year1). Exploitation rate and Tmax were 0.36 and 28 year respectively.
    Keywords: Biology
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
    Format: application/pdf
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