Stock enhancement and density-dependence of Caspian kutum (Rutilus kutum Kamensky, 1901) in Iranian waters of the Caspian Sea

The Caspian kutum (Rutilus kutum Kamensky, 1901) is an important economic species in the southern, uniquely Iranian waters of the Caspian Sea. The present study aimed to assess the desirable levels of the Caspian kutum for stock enhancement with two scenarios using fingerlings released (FR) and recruitments (R) density-dependence and macrobenthic production (P). Based on the results, in the years 1989-2018, the FR increased from 72 million in 1989 to 400 million in 2009 and then declined to 176 million in 2018. In contrast, the R with a lag of 2 years declined from 44.53 million in 1991 to 25.77 million in 1998, increased to 65.07 million in 2005, and then collapsed to 25.01 million in 2018. Based on FR-R relationships of Ricker and segment regression models, the lowest level of FR, which resulted in the highest R (39 million), was about 200 and 150 million fingerlings, respectively. Based on the P/Biomass ratio of macrobenthic species, the annual production was 241.6 thousand mt. It concluded that the desired number of the Caspian kutum fingerling concerning stock enhancement could be lower than 150 million to prevent overcompensation in the Iranian waters of the Caspian Sea

Hubungan persekitaran sekolah dengan penglibatan pelajar dalam aktiviti kokurikulum di Sekolah Menengah

Kajian ini bertujuan mengkaji hubungan persekitaran sekolah dengan penglibatan pelajar dalam aktiviti kokurikulum di sekolah menengah daerah Klang. Kajian kuantitatif ini menggunakan kaedah tinjauan melalui soal selidik. Seramai 291 orang ketua guru penasihat telah dipilih secara rawak dari 31 buah sekolah menengah. Kajian ini menggunakan instrumen soal selidik yang diubah suai berdasarkan “School-Level Environment Questionnaire” untuk mengukur persekitaran sekolah dan “National Survey of Student Engagement 2011” untuk mengukur penglibatan pelajar dalam aktiviti kokurikulum. Analisis korelasi menunjukkan wujud hubungan yang signifikan (r=0.294, p=0.00) antara persekitaran sekolah dengan penglibatan pelajar dalam aktiviti kokurikulum. Hasil kajian menunjukkan bahawa persekitaran sekolah adalah faktor signifikan bagi meningkatkan penglibatan pelajar dalam aktiviti kokurikulum

Assessing the stock status of Atlantic bumper, Chloroscombrus chrysurus, Linnaeus 1766, from the coastal waters of Ghana

The main objective of this study was to examine the growth, mortality, and exploitation rate of Chloroscombrus chrysurus from the continental shelf of Ghana, West Africa between July 2018 and June 2019. This study provided results on fishery dynamics parameters to contribute to estimating the stock assessment of these fish species. Monthly length-frequency data were collected from 697 samples and analyzed using fisheries models fitted in TropFish R. The von Bertalanffy growth parameters were utilized to analyze the population dynamics of these species using ELEFAN Simulating Annealing. The estimated asymptotic total length (L∞), coefficient of growth (K), and growth performance index (Φ′) was 24.9 cm, 0.84 year-1, and 2.72, respectively, with a Response surface (Rn) value of 0.79. The total mortality (Z), natural mortality (M), and fishing mortality (F) rates C. chrysurus from the continental shelf of Ghana were 3.27 year-1, 1.31 year-1, and 1.96 year-1, respectively. The exploitation rate (E) estimated was above the optimum level of 0.5 which indicates that the species is overexploited. Based on the Emsy (0.69) value, analyses show that the exploitation rate has exceeded the sustainable limit and hence the need for proper fisheries management measures

Growth and condition factor of Capoeta damascina in the Azad dam Lake and the Komasi River in Kurdistan Province, Iran

The objective of the present study was to estimate the population parameters, including length-weight relationship (LWR), condition factor (KF), relative condition factor (Kn), age, growth, and mortality of Capoeta damascina in the Azad Dam and Komasi River in the Kurdistan Province, Iran. Total length and weight were 51-350 (180.6±68.63) mm and W: 2.5-465 (93.3±110.89) g in the river and 120-260 (191.5±30.76) mm and 14.7-216 (75.9±39.89) g in the dam Lake and river, respectively. The length-weight regression was W=0.0122×FL2.9338. The sex ratio (M:F) was 1:0.47, for adult C. damascina which differed significantly from the expected 1:1 (P<0.001). The von Bertalanffy growth parameters were estimated as L∞ = 373.3 mm, K = 0.17 yr-1 and t0 = -0.58 yr. The instantaneous coefficient of natural mortality was estimated as 0.36 yr-1. The average KF values were 1.13±0.14 and 0.98±0.18, and Kn were 1.11±0.12 and 0.98±0.18, in the river and the lake, respectively. In conclusion, C. damascina showed an isometric growth pattern, which the rapid growth is occurred during the two first years of life. The Kn showed that the fish were at suitable welfare conditions in the Azad Dam

Growth and mortality parameters of Caspian kutum, Rutilus kutum, in southern Caspian Sea

The Caspian Kutum, Rutilus frisii, is one of the endemic and most important commercial cyprinid species in the southern Caspian Sea. A detailed study on growth and mortality parameters of this species was conducted based on 700 samples collected from commercial catches of beach seining in Guilan and Mazanderan provinces during fishing season 2017-2018. Females were dominated in both studied populations. Size frequency distributions showed significant variation among same sexes and between different sexes. The different WLRs were observed, positive allometric in Mazanderan, and negative allometric in Guilan. There were significant differences in growth parameters between sexes, females were of much greater asymptotic length than males, while the male fish had a higher growth rate and attained a smaller theoretical L∞ size than females. The theoretical maximum length (L∞) was larger than the maximum one recorded during sampling. Based on the Bhattacharya method, the Caspian kutum from Guilan fishing grounds was more diverse, and included nine cohorts, while the population from Mazanderan Province showed only six cohorts. The linearized catch curve based on age composition data showed that total mortality rates (Z) are 1.32 year-1 and 0.63 year-1 for males and females of Guilan, respectively, that of males in Mazanderan is 1.04 year-1 and of females 0.86 year-1. The natural mortality rates (M) were 0.48 year-1 for males and 0.26 year-1 females in Guilan, and was found to be as 0.26 year-1 and 0.45 year-1 for males and females of Caspian kutum caught in Mazanderan. The exploitation ratio (E) was found to be higher than 0.5 for both sexes from Guilan, and to be lower than the expected optimum level of exploitation in Caspian kutum males and females caught in Mazanderan

Effects of crumb rubber and styrene-butadiene rubber additives on the properties of asphalt binder and the Marshall performance properties of asphalt mixtures

The primary aim of this study is to evaluate the impact of incorporating crumb rubber (CR) and styrene-butadiene rubber (SBR) additives, ranging from 0% to 5% by weight of bitumen, on the performance of a bituminous concrete mixture using the wet process. Laboratory experiments, including the Marshall test, were conducted to establish the optimum bitumen content (OBC) for the hot mix. The study focuses on determining the optimal proportions of CR and SBR to achieve maximum strength. The results show that increasing the proportions of both CR and SBR leads to significant improvements in strength, with the maximum stability recorded at 16.14 kN and a flow of 1.23 mm for a mix containing 5% CR and 4% SBR. The findings further suggest an inverse relationship between CR content and strength, while an increasing SBR content enhances strength. Consequently, the optimal proportions for incorporating CR and SBR additives are identified as 5% and 4%, respectively

Population dynamic of bony fishes in the southern part of the Caspian Sea

This study was conducted to determine growth parameters, catch and fishing effort trends, stock assessment and Acceptable Biological Catch (ABC) of bony fishes in the Iranian coastal waters of Caspian Sea in the years 2010-2011 and 2011-2012. According to the result, the numbers of beach seines were 131 and 128 and their fishing efforts were observed 50184 and 42255 beach seining during 2010-11 and 2011-12, respectively. The catch per unit of effort CPUE) was calculated 182.9 and 205.6 kg/haul during two sampling periods, respectively. The total catches (including illegal fishing) were also obtained 16601.5 mt and 17034.1 mt during 2010-11 and 2011-12, respectively. The highest proportion of catch was belonged to kutum and golden grey mullet (86% and 88%, respectively) in two fishing seasons aforementioned above. Growth parameters of kutum were estimated as K=0.21/yr, L_∞ = 60.0 cm, t-0 = 0/yr. The Growth parameters were K=0.18/yr, L_∞ = 61.1 cm, t-0 = -0.14/yr for golden gray mullet and were K=0.12/yr, L_∞ = 73.6 cm, t-0 = 0.92/yr for common carp. Based on catch-at-age data, in the years 2010-2011 and 2011-2012, the total biomass, from the biomass-based cohort analysis were estimated 41700mt and 34400 mt for kutum and 14600 mt and 14400 mt for golden grey mullet, respectively. The reference points of F0.1 and F35% were 0.41/yr and 0.34/yr for kutum and 0.36/yr and 0.33/yr for golden grey mullet, respectively. Stock enhancement plays an important role in recovery of kutum stocks in the Iranian coastal waters of Caspian Sea. There is a significantly negative correlation between fingerlings released and condition factor (CF) and recruitment and CF. The different trends for fingerlings, recruitments and CF suggest that CF may be partly density-dependent, declining at high population sizes due to intra-specific competition. Therefore, more research should be conducted to determine the desirable level of artificial propagation. Food consumed by fish species, Rutilus frisii kutum, Rutilus rutilus caspicus, Cyprinus carpio, Liza auratus and Liza saliens were included Foraminifera, Porifera, Annelida, Mollusca, Arthropoda, filamentous algae, fish eggs and detritus.The results showed that Rutilusfrisii kutum generally feed on Balanus and Cerastorderma. The main food item for Cyprinuscarpio, Liza auratus and Liza salienswas detritus. Based on available models, the ABCs were estimated as 6600-7400 mt for kutum and 2200-2800 mt for golden grey mullet (with precautionary approach 6600 mt and 2200 mt for kutum and mullet, respectively) in 2011-12. Two species (kutum and golden grey mullet) are vulnerable to environmental factors, and these factors should be considered in the stock assessment and management of the fish. For two species, the ABC with a lower andmore accurate value based onmore information, should be selectedfor the implementation of a precautionary management approach

BIOLOGICAL PARAMETERS AND FISHERIES INDICES OF BELUGA STURGEON Huso Huso IN THE SOUTHERN CASPIAN SEA

Postoji značajan nedostatak podataka o biološkim parametrima morune Huso huso, najveće ribe u Kaspijskom moru. Ovim istraživanjem određivala se dob i indeksi rasta morune u svrhu procjene stanja njenog fonda u južnom Kaspijskom bazenu Irana od 1990. do 2011. Duljina vilice kretala se u rasponu između 113-420 cm, a masa od 8,0 do 725,0 kg. Parametri rasta bili su L∞ = 440 cm, K = 0,027 godina−1, t0 = - 5,8 godina. Dob pri prvom ulovu (tc) bila je 13,1 godina. Podaci o dugoročnoj strukturi dobi morune ukazali su na dob do 63 godine, a jedinke u dobi od 12-19 godina sačinjavale su 76,7% ukupnog ulova. Dužina generacije bila je 33 godine. Vrijednosti KF indeksa bile su blizu 1 ili > 1, što ukazuje da je moruna u povoljnom kondicijskom stanju u južnom Kaspijskom moru. Raspodjela vrijednosti dužine morune ukazala je kako 24,2% ulova čine juvenilni primjerci. Natemelju dobne strukture i dobi pri spolnom sazrijevanju, novačenje i prekomjerni ribolov utjecali su na zalihe morune. Ovim se, u budućim ribarstvenim politikama, preporuća povećati dužinu ili starost morune pri ribolovu. Mega-mrijesni primjerci morune su predstavljali 4,4% ulovljene ribe, što ukazuje na neujednačenu strukturu populacije.There is a significant lack of data for the biological parameters of beluga or great sturgeon, the largest fish in the Caspian Sea. The age, growth and fisheries indices for the stock status of beluga was investigated in the south Caspian Basin of Iran between 1990 and 2011. Fork lengths ranged between 113-420 cm and weights from 8.0 to 725.0 kg. The growth parameters were L∞ = 440 cm, K = 0.027 year−1, t = − 5.8 years. The age at first capture0(tc) was 13.1 years. The long-term age composition data showed age up to 63 years, and the ages 12-19 years comprised 76.7% of the total catch. The generation length was 33 years. The values of “KF” were close to 1 or >1, indicating that beluga sturgeon is in a favorable condition in the southern Caspian Sea. The length distribution showed that 24.2% of the catch is comprised of juveniles. Based on the age structure and age at first maturity, recruitment and growth overfishing occurred in beluga stocks. Therefore, increased length or age at first capture in future fishery policies should be implemented. The mega-spawners represented 4.4% of the fish captured and revealed an unhealthy population structure

Genetic variation of Clupeonidae (Clupeonella caltriventris, C. engrauliformis and C. grimmi) in southern part of Caspean Sea as revealed by RFLP Analysis

In this study genetic variation of clupeonidea using restriction fragment length polymorphism (RFLP) of the mtDNA control region. Samples were collected from Amirabad port (50 individuals for each species) and Anzaly port (50 individuals for each species) regions in East and west of southern part of Caspian Sea. DNA was extracted from fin tissue by phenol - chlorophorm method. PCR was performed using D- Loop region, as result PCR product was about 1015 bp in all samples. The PCR products of samples ware digested by 19 restriction endonuclease enzymes. Ten out of nineteen restriction enzyme were polymorphic for D- Loop region. 12 different haplotypes were detected in C. engrauliformis and 9 haplotypes in C. grimmi and C. cultriventris. The mean value of haplotypes diversity among 71 Populations Was 0/786, 0/734, 0/426 and nucleotide diversity was 0/0092, 0/0099 and 0/0079, respectively. The nucleotide divergence among populations in C. engrauliformis, C. caltriventreis and C.grimmi was 0/01%, 0/01% and 0/003%, respectively. The results showed that the hoplotype differences in C. engrauliformis and C. cultriventris were significant (p0.01)

Length-weight relationship, condition factor and relative condition factor of Alosa braschnikowi and A. caspia in the southeast of the Caspian Sea (Goharbaran)

The main objectives of the present study were to determine the species composition of Caspian shad, genus Alosa and to estimate the LWR, CF, and Kn of A. braschnikowi and A. caspia during different months in the southeastern coast of the Caspian Sea. Two fishing methods, small mesh size beach seine and gillnet were used from December 2013 through July 2014. A. braschnikowi and A. caspia, were distinguished in the southeastern part of the Caspian Sea (Goharbaran), consisting of 57.1% and 42.9% of the Alosa catch, respectively. The slopes (b values) of the length-weight regression were 3.241 and 2.844 which were significantly different from 3 (P<0.05), indicating positive and negative allometric growth, respectively. The average CF of A. braschnikowi and A. caspia were calculated as 0.72 ± 0.12 and 0.83 ± 0.13, respectively. The average CF for both species were significantly different among months (P<0.001). There was a significantly negative correlation between size classes and CF of A. caspia. The Kn was greater than 1 for A. braschnikowi and lower than 1 for A. caspia indicating good well-being of A. braschnikowi as opposed to A. caspia in the southeastern Caspian Sea