h fazli

This study aimed to identify the similarities in the catches of both experimental and commercial fishing efforts along the coast of Greater Accra, Ghana using trawls. Data for fisheries-independent (experimental, INFD) and fisheries-dependent (commercial, FID) catches were sourced monthly from June 2018 to May 2019. The obtained data was analyzed for non-metric multidimensional scaling (nMDS), diversity indices, similarity percentage, and cluster analysis using PRIMER 6 and PERMANOVA+ software. Sixty-seven fish species were obtained from both experimental and commercial catches. Species richness and Shannon-Weaver index (H’) showed no significant difference between INFD and FID catches. SIMPER analysis revealed a high dissimilarity percentage (64.95%) between commercial and experimental catches, with Selene dorsalis, Brachydeuterus auritus, and Galeoides decadactylus contributing the most. The nMDS and cluster analyses showed two distinct groups which indicated that not all grounds are used as fishing grounds by fishermen. Based on the findings, certain areas within the experimental fishing sites should be designated as marine protected areas to safeguard the populations of marine fisheries resources in Ghana.

A dual structural fused system consists of replaceable ductile elements (fuses) that sustain major seismic damage and leave the primary structure (PS) virtually undamaged. The seismic performance of a fused structural system is determined by the combined behavior of the individual PS and fuse components. In order to design a feasible and economic structural fuse concept, we need a procedure to choose the most efficient combination of the PS and fuse systems subject to the stringent constraints of seismic performance and minimum structural cost objectives, simultaneously. In this paper, an efficient method is developed for minimum cost design of dual fused building structures using a performance-based seismic design procedure. The method involves updating a set of reference parameters to find the most suitable combination of PS and fuse structures with satisfactory seismic performance and optimum total structural cost, concurrently. For a set of preselected reference parameters, the structural design variables including primary and fuse structural member sizes are determined through individual linear elastic design processes. Therefore, a limited number of inelastic analyses are required to evaluate seismic response of the combined fused system. The proposed method is applied to seismic design optimization of a moment resisting frame equipped with BRBs as structural fuses. The obtained results indicate that proposed design optimization procedure is sufficiently robust and reliable to design cost-effective structural fuse systems with satisfactory seismic performance.

One of the major sources of impacts on marine resources comes from climate variability and regime shifts. In this context, the present study pinpoints the role of climatic and environmental parameters on the dynamic of kilka in the Caspian Sea. During the last decades, landings and stocks of the main pelagic species of kilka had been changed dramatically in the Caspian Sea. This study focuses on the last three decades of the climate regime and tries to explain the part of the changes in the recruitment (R) and spawning stock biomass (SSB) of three kilka species. Based on the statistical analysis of data series, it is found that regime changes in the global and regional environmental variables started in the mid-1995s, however, the shift of the late 1990s (1998) was more strong in the Caspian Sea. The study further reveals that the global climatic indices changes in the late 1990s are triggering the regional and local indices induced regime shifts in the late 1990s and 2000s. The study concludes that the changes in populations of fish species, especially for kilka, could be due to the regime shift.

In the last three decades, several ecological factors were changed and affected the most important commercial fish stocks in the Caspian Sea. This paper aims to assess the effects of these pressures on the population structure, stock status and the vulnerability risk of stock extinction of the stellate sturgeon (Acipenser stellatus Pallas, 1771) in the Southern Caspian Sea, in the years 1990-2011. For this period, we estimated growth parameters, the age structure of catch, sexual maturity, age at first capture, natural and fishing mortality, biomass and risk of stock extinction of stellate sturgeon by IUCN Red List categories. Fork lengths of individuals ranged from 82 to 206 cm and ages from 4 to 29 years. The growth parameters were L∞=215.0 cm, K= 0.064 year−1, t0=−3.2 years. The majority of the catch (67.4-90.1%, averaged 80.0%) belonged to 9-13 years old. The biomass had a descending trend from 4983.5 mt in 1990-91 declined to 10.6 mt in 2011-12. The generation length was 16 years. Stock status indicators showed that 89% of catch were mature individuals, mature and optimum fish length comprised 74% and 10% of the fish captured comprise mega-spawners. This study revealed that the stock of the stellate sturgeon is being overfished for the whole years and critically endangered.

Biodiversity and structure of the benthic macrofauna communities were studied in the southeast the Caspian Sea (Golestan Province – Iran) during one year from October 2014 to September 2015. Seasonal samplings were done at 6 stations in 3 transects. Depth, temperature, salinity, pH, E.C., total organic matter and grain size were measured. More than 4,037 individuals belonging to five orders, Polychaeta, Oligochaeta, Bivalvia, Diptera and Amphipoda, and eight families including Nereididae, Spionidae, Amphartidae, Tubificidae, Smelidae, Cardiidae, Chironomidae and Gammaridae were identified. In terms of total individuals, Streblospio gynobranchiata, Hypania invalida and Cerastoderma lamarcki, were the most abundant species, and Polychaeta were dominant in the research region. The highest density of all species was observed in autumn (1515 ind m2) and the lowest was observed in summer (698 ind m2). The maximum diversity, richness, and evenness were 1.36, 0.6 and 0.98, respectively. The results of distance-based redundancy analysis (db-RDA) showed that environmental factors such as salinity, depth and substrate type were all important in detecting the distribution pattern of macrobenthic species in the research region. The dominant species, S. gynobranchiata, was distributed in the areas with smaller grain size and higher TOM and muddy sediments and had the most correlation with salinity, temperature, pH and E.C. Species such as T. fraseri. H. invalida and P. robustoides showed more dependency on TOM and mud factors in the spring and summer, while their dependency became lower in autumn and winter. Abra ovate was less influenced by all factors except the substrate.

The aim of the present study was to estimate the population parameters including length-weight relationship (LWR), condition factor (KF), relation condition factor (Kn), age, growth and mortality of Alburnus mossulensis in Azad dam and Komasi River in Kordestan Province, Iran. Of 522 specimens, the fork length, total length and weight of A. mossulensis ranged from 70 to 164, 75-175 mm, and 4.3 to 48.1 g and averaged (±SD) 114.0 (±15.97), 127.5 (±25.29) mm and 18.2 (±5.61) g, respectively. The length-weight regression was W=0.0003×FL2.7434 indicating a negative allometric growth. The sex ratio (M:F) was 1:0.49, for adult A. mossulensis (n=134) which differed significantly from the expected 1:1 ratio (p<0.001). The von Bertalanffy growth parameters were estimated as L∞=170.3 mm, K=0.46 yr-1, t0=-0.59 yr. The instantaneous coefficient of natural mortality was estimated as 0.85 yr-1. The average of condition factor (KF) was 1.27(±0.161). Statistically significant differences were found in KF during different seasons (p<0.001). There was a significantly negative correlation between FL and KF (r2=0.60). The average of relative condition factor (Kn) was 1.06±(0.130). In the present study, the Kn of A. mossulensis were close to 1 and greater than 1 in Komasi River and reservoir, respectively. These results suggested the well-being of the fish was good in Azad Dam region.

Disregarding the degraded ecosystems, especially the regional rivers, threatens biodiversity in the Caspian Sea basin. The purpose of this study is to promote the co-ordination of research, implementation, promotion and education on the conservation of natural reproduction of Caspian Sea fish in the Kheirud River. This study was conducted in the Kheirud River in the years 2017-2018 as a model site from September 2017 in one year. The Kheirud River with a latitude of 51 ° 34 ° 51 and a latitude of 40 ° 37 ° 36 are divided into three upper parts of the hands, the middle section and the lower part. In this survey, 15,000 Rutilus kutum breeder entered the river, which female numbers were of at least 5000-3000. On average, the capacity of 10 million larvae (7.5-7.5 million) from natural reproduction entered the production chain. The penetration rate of the river reached about 0 to 7.5 million larvae. More than 70 fishermen were covered by this study, with a penetration rate of from 0 to 3.5%. More than 450 women and 500 students and teenagers were covered by this study and their penetration rate in this region was estimated at 30% and 16%, respectively. With this view, and in light of the experience gained from the present study, the importance of the greater participation of the public and the public in the pursuit of the goals of similar studies becomes more eviden

A total of 148 specimens of Capoeta trutta caught from Azad Dam Lake, Kurdistan Province, northwest of Iran were examined during 2015-2016 for assessing growth parameters. The total length (TL) and weight (W) of C. trutta ranged from 4.0 to 29.0 cm and 0.9 to 274.0 g, average (± SD) = 19.3 (± 4.0) cm and 80.3 (± 44.7) g, respectively. The length-weight regression was W = 0.0121 × TL2.9317 indicating isometric growth. The sex ratio (M:F) was 1:0.33, differed significantly from the expected 1:1 (P < 0.001). The von Bertalanffy growth parameters were estimated as L∞ = 29.6 mm, K = 0.33 yr-1, t0 = -0.57 yr. The instantaneous coefficient of natural mortality was estimated as 0.58 yr-1. The averaged condition factor (KF) was 1.00 ± 0.11, by significantly differences among seasons (P < 0.001). In the present study, the relative condition factor (Kn) of C. trutta were close to 1 suggesting the well-being condition of the fish in Azad Dam region.

Reproduction period, spawning peak and sexual maturity in anchovy kilka were investigated during the year 2006 for sustainable yield assessment in Iranian waters of the Caspian Sea. The mean fork length, total weight and age were 118±5.9mm, 11±1.7g and 4.6±1.2 year, respectively. Mean (±SD) absolute fecundity was 12625±5533 ovules. More than 50 percent of the fish specimens matured when their length exceeded 92.5mm. The results showed that reproduction of anchovy kilka occurred in autumn, and spawning occurred throughout the year and especially in winter. The length and age ranges were found to be shortened compared to the past years with many older fish and less younger ones (< 2 years) in the catch which sharply decreased recruitment. This phenomenon is thought to be due to overfishing synchronized with invasion of M. leidyi pushing kilka to spawn in winter, which all cause collapse of anchovy kilka stocks in the Caspian Sea. We postulate that anchovy kilka has adopted the strategy of spawning year round to mitigate the negative effects of overfishing and invasion of M. leidyi.