Aquatic Science and Technology
Latest Publications

Microalgae culture media must be efficient, give high growth, meet micro-requirement, and be available. The effect of different levels of brown lentil infusion and use at [25, 50 and 75%] levels on the chemical composition (protein, carbohydrates, fatty acids, and amino acids) in N. oceanic was evaluated. Compared to the standard F/2 Guillard. The obtained results indicated that the chemical components of N. oceanica were affected by these levels. The highest protein and carbohydrate content and the highest EAA content (55.92%) were obtained using OB3 medium (75% SBL) compared to the control group (100% F/2). The highest biomass production was obtained in OB3 medium. The highest TSFA and USFA were recorded for N. oceanica by the OB3 mean. The present study recommended that it is possible to use microalgae grown on OB3 and OB2 medium as a lipid and protein inducer in aquaculture.

Aquatic Science and Technology (AST) would like to acknowledge the following reviewers for their assistance with peer review of manuscripts for this issue. Many authors, regardless of whether AST publishes their work, appreciate the helpful feedback provided by the reviewers. Their comments and suggestions were of great help to the authors in improving the quality of their papers. Each of the reviewers listed below returned at least one review for this issue.Reviewers for Volume 9, Number 2Analía Ale, Instituto Nacional de Limnologia (CONICET, UNL), ArgentinaIgor Z. Zubrzycki, Hanyang University, PolishTai-Sheng Cheng, National University of Taiwan, Taiwan Maggie LiuAquatic Science and TechnologyMacrothink Institute*************************************5348 Vegas Dr.#825Las Vegas, Nevada 89108United StatesTel: 1-702-953-1852 ext. 524Fax: 1-702-420-2900E-mail 1: [email protected] 2: [email protected]: http://ast.macrothink.org

Ages of whitebone porgy (Calamus leucosteus) (n = 559) from southeastern U. S. commercial and recreational fisheries from 1975 – 2017 were determined using sectioned otoliths. Opaque zones were annular, forming April – July (peaking in June). Ages ranged from 2 – 19 years, and the largest fish measured 513 mm TL (total length, mm). Body size relationships were: TL = 1.09 FL + 16.07 (n = 469, r2 = 0.97), FL = 0.89 TL – 6.39 (n= 469, r2 = 0.97), W = 2.8 x 10-5 TL2.91 (n = 462), and W = 6.8 x 10-5 FL2.82 (n = 417) where W is total weight (grams, g) and FL is fork length (mm). The von Bertalanffy growth equations were Lt = 365 (1 - e-0.35 (t + 1.37)) (n = 559) for all areas combined, Lt = 365 (1 - e-0.55(t + 0.00)) (n = 185) for fish from North Carolina through Cape Canaveral, Florida, and Lt = 368 (1 - e-0.25 (t + 2.51)) (n = 374) for fish from southeast Florida. Mean size-at-age was significantly different between regions for ages 4 – 9, (92% of total samples). Point estimates of natural mortality were M = 0.22 and M = 0.30 for northern- and southern-region fish, respectively, while age-specific estimates of M were 0.85 – 0.55 y-1 for ages 2– 19 for the northern region and 0.41 – 0.26 (ages 2-14) for southern region fish. This study presents updated life history parameters for whitebone porgy from the Atlantic waters off the southeastern United States.

Walleye (Sander vitreus) fingerlings (30 to 35 mm) are commonly reared in ponds filled with surface (i.e., lake) water, but the use of ground (i.e., well) water would provide increased biosecurity. We assessed the potential for using well water to rear walleye by comparing plankton and water quality over 30 days between organically fertilized lined ponds that were filled with either unfiltered lake or well water. All ponds were inoculated with plankton that originated from Blue Dog Lake, filled by May 15, 2020, and remained fishless. Zooplankton density and body size were consistently reduced in well ponds suggesting that fry survival and growth would be reduced. Initially, well ponds exhibited higher ammonia-nitrogen and alkalinity, but lower pH owing to the inherent chemistry of the well water. Later, reduced ammonia-nitrogen combined with increased dissolved oxygen and pH suggest that decomposition of the organic fertilizer occurred slower in well ponds. A phytoplankton bloom was successfully initiated but was difficult to maintain despite consistently lower zooplankton density in well ponds. While the use of well water would enhance biosecurity, these data suggest that walleye fingerling production would be reduced relative to lined ponds filled with productive, lake water. Increasing organic fertilizer, supplementing with liquid 28N:0P:0K, and/or filling ponds earlier (e.g., 30 days) may provide a more favorable environment for walleye culture in lined ponds filled with well water.

The study was conducted at the fish farm of the Department of Fish Sciences, Faculty of Agricultural Technology and Fish Sciences, Al-Neelain University. The purpose of the study is to compare the growth performance of different local strains of Nile tilapia (Oreochromis niloticus) to provide the necessary information for conducting research leading to genetic improvement of the locally farmed Nile tilapia. Fish fry used in the study were spawned by brooders collected from, Jebel Aulia Dam Reservoir (White Nile strain A) , Sennar Dam Reservoir (Sennar strain B), Lake Nubia (Halfa strain C) and khashm elgirba reservoier( Khashm elgirba strain D). The study was conducted for six weeks in twelve happas, each stocked with 30 fry in three replicates for each strain, averaging 5 g. Fish were fed by diet with a protein level of 35%. Statistical analysis showed Sennar strain was the best growth rate with a percent weight gain of 1529%, followed by white nile strain with a percent weight gain of 1114%, followed by khashm elgerba strain with a percent weight gain of 993% and finally Halfa strain with a percent weight gain of 829%. Daily Growth Rate gain was 0.9g/day for sennar strain, followed by other strain with no significant(≥0.05). Food Conversion Ratios (FCR) were best in sennar and white nile strain ,survival rate with the same no significant(≥0.05) between treatments. finally results indicated that there is significant( ≤ 0.05) between treatments so sennar and white nile strains is better than two strains in this study.

Aquatic Science and Technology (AST) would like to acknowledge the following reviewers for their assistance with peer review of manuscripts for this issue. Many authors, regardless of whether AST publishes their work, appreciate the helpful feedback provided by the reviewers. Their comments and suggestions were of great help to the authors in improving the quality of their papers. Each of the reviewers listed below returned at least one review for this issue.Reviewers for Volume 9, Number 1Analía Ale, Instituto Nacional de Limnologia (CONICET, UNL), ArgentinaDeniz Anıl Odabaşı, Çanakkale Onsekiz Mart University, TurkeyForat Yasir AlJaberi, Al-Muthanna University, IraqIgor Z. Zubrzycki, Hanyang University, PolishLevent BAT, Sinop University Fisheries Faculty, TurkeyTai-Sheng Cheng, National University of Taiwan, Taiwan Maggie LiuAquatic Science and TechnologyMacrothink Institute*************************************5348 Vegas Dr.#825Las Vegas, Nevada 89108United StatesTel: 1-702-953-1852 ext. 524Fax: 1-702-420-2900E-mail 1: [email protected] 2: [email protected]: http://ast.macrothink.org

Pollution of aquatic ecosystems often results in adverse environmental disturbances, including individual and/or sub-individual changes in fish. The aim of the present study was to examine possible reproductive health effects in male and female, based on a histological assessment of Clarias gariepinus sampled in Bagoue River impacted by mercury from the artisanal gold mining. Fish were collected between August 2018 and April 2019 during two seasons from four stations differently impacted. A histological assessment was done on three target fish organs (liver, ovary and testis). Water and sediment samples were analysed for total mercury (T-Hg) concentration. Histological alterations were semi-quantitatively assessed, and the results were classified according to the severity of the histological response identified. Microscopic assessment revealed alterations of the gonads and liver tissues. A higher incidence of reaction pattern (Regressive changes, Inflammation and Circulatory disturbance) was found in liver tissues than in gonads tissues (Regressive changes). T-Hg levels were higher upstream than downstream in ovaries and testis tissues. Paradoxically, the lesions observed in these organs were more pronounced downstream than those found in fish from upstream during rainy season. According to total index, the organs examined downstream suffered severe damage unlike upstream sites. Also, comparison of degree of alteration between testes and ovaries indicates a greater impact of ovarian structures especially on downstream sites. The effect of anthropogenic impact appears to be visible downstream as the concentration of chemical pollutants and exposure time determine the severity of the damage. Alterations in ovarian follicles, spermatogenic cells and liver tissues may reflect damage to the process of gametogenesis, which may reduce the reproductive capacity of individuals over the long term.

The aquatic environment is particularly vulnerable to the effects of contaminants as effluents from municipal and industrial wastewater continually add numerous harmful exogenous compounds. Lake Manyame is a peri-urban freshwater reservoir that is subject to municipal and industrial discharge as well as agricultural run-off. Adult Nile tilapia (Oreochromis niloticus) were sampled from L. Manyame during low-flow and high-flow seasons from selected locations. The samples were processed in the field for histology and biochemical analysis of selected biomarkers of oxidative stress. Induction of reduced glutathione (GSH), carboxylesterase (CES) and malondialdehyde (MDA) was evident at all the sites. There were no significant variations between sites except in the last low flow season and there was an upward trend between the first season and the subsequent sampling periods. Gonadal histology did not show occurrence of any intersex as a sign of endocrine disruption. The prevalence of histological lesions in the gonads was highest in the last sampling seasons, suggesting a progressive deterioration of water quality over time.

Feral spawning fall Chinook salmon (Oncorhynchus tshawytscha) in Lake Oahe, South Dakota, are captured using a fish ladder and catch raceway at Whitlock Bay Spawning Station. The number of salmon that escaped the catch raceway and descended the fish ladder prior to spawning was unknown. During October 2017, all salmon that ascended the fish ladder at the spawning station were tagged. Tagged males remained in the catch raceway. Tagged females were moved to other secure raceways and used to estimate tag retention. Of the 383 tagged males, 159 (41.5%) were initially designated as escaped from the catch raceway. Tag loss in the females was 3.9%. Thus, the estimated male salmon escapement rate from the catch raceway was 37.6%. Male salmon remained in the catch raceway for one-to-three days before escaping. The escapement rate decreased over the month-long spawn, with nearly 60% of the males going back down the fish ladder in the first week of October, compared to less than 20% escapement by the final week. Such high rates of escapement from the spawning station may be negatively impacting the spawning efficiencies. Possible solutions include re-engineering of the fish ladder or daily removal of the salmon in the catch raceway to other more secure locations at the spawning station.

The environmental resilience is strictly dependent of water availability. The identification of priority areas is important to conservation aid land-use planning and urban expansion, conservation, and policy strategy. The goal was to identify priority areas aiming water provision and environmental conservation at the “Canal do Rio Guandu” watershed in Rio de Janeiro, Brazil. To address the goal four micro-basins included in the watershed were selected to optimize collect field data and create the criteria to define the priority levels. Based on prior literature, legacy and field data, an assessment method was proposed based on map algebra with support of Geographical Information System, gathering professional tacit knowledge with spatial data to support the selection of strategic areas. The approach based on was successful to select primarily priority areas and can contribute to regulate the local policies, pointing out areas that can connect legally protected areas with forested fragments, which presents great importance to urban and rural supply.