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Research Article
Aug 01, 2016
To Reduce Mortality of Fry Fish (Oncorhynchus mykiss) Caused with Viral Infection (IPNV and VHSV) b ... y Water Treatment with Chloramin-T as Disinfectant
In winter of 2015 we observed gross mortality of fry fish in some tanks of a hatchery in Iran. They had dissonant swimming, spiral swimming, skin darkness, abdominal distension, and anorexia. At the beginning, mortality was low but it increased more and more during the several days. The fry were in fiberglass tanks with 1000 litres of water. It was about 20000 fry in each tank at the beginning. Two activities did synchronously while mortality observation. At the first, some fry sampled from each tanks and sent to laboratory for pathogen detection. The next, 9 tanks selected and grouped as 3 treatments (control, treatment-1 and treatment-2). Control treatment was consisting of 3 tanks that they had not mortality. Treatment-1 and Treatment-2 have the highest mortality and each of them was consisting of 3 tanks. Then, 10 ppm chloramin-T as disinfectant compound added to each tanks of treatment-1 during 1 hour in 3 continuous days (3 times). The tanks of treatment-2 added no drug. After 7 days mortality of fry in each tank estimated and compared with each other. Survival in tanks of treatment-1 was about 76% while survival in tanks of treatment-2 was about 27% while survival in control tanks was about 98%. One month later, results of laboratory tests reported. We found that fish of control tanks were safe (without pathogen) while fish of treatment-1 and treatment-2 were infected with IPN-virus and VHS-virus based on RT-PCR test. Totally 36 fry had been examined by RT-PCR. We founded that 10 fry were IPN+ and 2 of them were VHS+. Clearly; results showed that chloramin-T is able to control the viral infection of Oncorhynchus mykiss (p<0.05) in statistical comparison, it confirmed with SPSS software by using Anova-test. Chloramine-T increased surveillance from 27% to 76% while viral contamination had been confirmed.
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Research Article
Jul 25, 2016
Marketing and Livelihood Contribution of Fishermen in Lake Tana, North Western Part of Ethiopia
The study area was conducted in the North Western part of Lake Tana which are three commercially fish species are found (Tilapia, Catfish and Barbus species). The study was focused on fish production and marketing system. Three landing sites were selected purposively for the survey based on the experience of fishing practices. A total of 95 fishers were interviewed: from each landing site (“Delgie 27”, “Goregora 35” and “Infranze 33.”). The data collection was conducted from October 2012-June 2013. This consists of both form primary and secondary source. A simple random sampling technique was employed covering fishers. Descriptive and statistical package for social sciences (SPSS V-17) was used in analysing. From sample respondents, 100% were reed boat owners. All sampled fishers from the three fish landing sites were used to catch Nile tilapia (Oreochromis niloticus), African catfish (Clarias gariepinus) and large barbs (Labeobarbus spp.). Fishing, crop production, animal husbandry, petty trade and causal labourer contributed 60%, 21%, 12%, 2% and 5% of fisher’s livelihood, respectively. Fisheries development interventions should be aimed at addressing both fish production and marketing problems. The study further suggested that fish quality, fish supply, education and training, licensing of the fishers and improving access to services should receive due attention to improve fish marketing and production system.
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Research Article
Jul 08, 2016
The Beneficial Reuse of Hypersaline Waste Water from Desalination Plants to Treat Harmful Algal Blo ... oms
A number of technologies exist that oوٴer the potential to control Harmful Algal Blooms (HABs). Many of these technologies involved the discharge of solids, chemicals, biological agents, or other foreign materials into waters experiencing HABS. Other technologies are also available that could control HABS through the manipulation of environmental conditions such as water salinity, temperature, light intensity and stratification Нese potential control technologies would essentially accelerate or amplify the development of natural processes that terminate HABs. Нese technologies can be implemented over the entire range of conditions under which HABs occur and could limit the adverse environmental impacts to other organisms in the HAB impacted area. One of these potential technologies involves the application of the hypersaline concentrate waste water from desalination plants over an area impacted by a HAB. Нe near surface discharge of the desalination plant hypersaline waste water could an eوٴective means of HAB control by inducing rapid changes in water salinity and stratification Нe expected environmental impacts would be temporary, limited in both duration and areal extent. No foreign chemicals, materials, substances, organisms or biological agents would be introduced into the environment. Added benefits would include the beneficial reuse of the hypersaline waste water from desalination plants, reduction of waste water loading to the local area of the desalination plant, and the potential to generate revenue for the desalination plants by the sale of waste water.
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Research Article
May 30, 2016
Longitudinal Exploitation of the Transversal Gradient of Oreochromis niloticus (Linné, 1758) Gill ... System by Four Monogenean Species at Melen Fish Station (Yaounde, Cameroon)
From February 2012 to February 2013, 406 fish were caught in the Melen fish station, then fixed in 10% formalin solution and taken to the laboratory to be examined. Mounting of monogeneans carried out under binocular magnifying glass; the determination of the various species was further done using the optical microscope. The colonization of the four pairs of gill arches by C. thurstonae occurred in the anterio-posterior direction. The other three species showed non-specific model of occupation of the transversal gradient. These different patterns have undergone permanent modifications. The results obtained in this study could be explained based on the heterogeneity of the gill system, the ventilation of current flow, the model of gills colonization by the oncomiracidiums of the Monopisthocotylea. The low diversity values obtained within seasons indicate that this period is harmful for the parasites studied. The species C. halli has exploited the resource space better in all. The populating of arches II and III were the best organized.
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Research Article
May 16, 2016
The Proximate of Natural Foods Gracilaria lichenoides and Ulva fasciata for Abalone Haliotis squama ... ta Culture
The aim of this research was to analyse the proximate in natural foods Gracilaria lichenoides and Ulva fasciata for abalone Haliotis squamata. The proximate analysis included water, ash, protein, crude fibre, and lipid components. The proximate of Ulva fasciata were 82.0% of water, 25.7% of ash, 3.5% of protein, 4.8% of crude fibre, and 1.7% of lipid, while in Gracilaria lichenoides were 92.5% of water, 50.3% of ash, 2% of protein, 4.4% of crude fibre, and 1.2% of lipids. Natural food Ulva fasciata provides better result of growth of abalone due to the nutrients contained in it particularly the higher value of amino acids and fatty acids compared to natural food Gracilaria lichenoides.
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Research Article
May 12, 2016
A Review on Feeding and Reproductive Biology of Cirrhinus reba (Hamilton, 1822), A Threatened Fres ... hwater Fish of Indian Subcontinent with an Emphasis on its Conservation
Cirrhinus reba is a commercially important freshwater cyprinid fish which has good demand as a table fish due to good amount of protein, fat and carbohydrate content in its flesh. Recently due to numbers of reasons like over harvesting, loss of habitat and ecological changes in its habitat, populations of this fish species have been declined in their nature. This fish species has already been enlisted as vulnerable species both in India and Bangladesh. Earlier considerable research has been conducted on different aspects of feeding and reproductive biology of this fish species but so far no such consolidated report is available on these two aspects. This review report aims to sum up the so far available information on these particular aspects of this threatened fish species as well as to point out some possible measures that to be considered to promote its conservation.
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Research Article
May 10, 2016
In-season Forecast of Chum Salmon Return Using Smoothing Spline
We developed an in-season forecast model of return of chum salmon for the population off the Honshu region in the Sea of Japan using the smoothing spline based on catch data obtained in fishing season. The optimal in-season model was constructed using adult return in season 8 (middle October) as an explanatory variable. Residual sum of squares of the optimal in-season model was lower than that of the pre-season forecast (sibling) model, indicating the former was more accurate than the latter. The relationship between forecast error rate in the optimal model and the cumulative proportion of return until season 8 (middle October) was positive. Yearly variation in the forecast error rate may be affected by variability in the timing of return. We provide a new and accurate forecast model of chum salmon return.
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Research Article
May 09, 2016
Is There Any Species Specificity in Infections with Aquatic Animal Herpesviruses?–The Koi Herpesvi ... virus (KHV): An Alloherpesvirus Model
Most diseases induced by herpesviruses are host-specific; however, exceptions exist within the family Alloherpesviridae. Most members of the Alloherpesviridae are detected in at least two different species, with and without clinical signs of a disease. In the current study the Koi herpesvirus (KHV) was used as a model member of the Alloherpesviridae and rainbow trout as a model salmonid host, which were infected with KHV by immersion. KHV was detected using direct methods (qPCR and semi-nested PCR) and indirect (enzyme-linked immunosorbant assay; ELISA, serum neutralization test; SNT). The non-koi herpesvirus disease (KHVD)-susceptible salmonid fish were demonstrated to transfer KHV to naïve carp at two different temperatures including a temperature most suitable for the salmonid (15°C) and cyprinid (20°C). At 20°C KHVD was induced in carp cohabitated with infected trout. KHV was also detected virologically and serologically at the end of the experiment in both rainbow trout and carp.
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Research Article
Apr 28, 2016
Livelihood Status of Hilsa (Tenualosa ilisha) Fishermen of Greater Noakhali Regions of Bangladesh
The present study aimed to elucidate the livelihood status of Hilsa (Tenualosa ilisha) fishermen at Lakshmipur and Noahkali Districts in Bangladesh during August, 2014 to January, 2015 through questionnaire survey method. During Hilsa fishing, Pangas (Pangasius pangasius), Koral (Lates calcarifer) and Poa (Johnius coitor) were also found to capture as by catch using Chandi jal (set gill net). 85% fishermen were observed to use mechanized (5-40 HP; Horse Power) boats in the study areas. Hilsa fishing was noticed mostly during October-November while such activities was almost absent during February-May (off period) which made fishermen to start migrating temporarily to the nearest urban areas for their livelihood. Although the Government of Bangladesh formulates an act to have fishing license yet 20% of the fishermen were found having valid fishing license in the study areas. Average daily net income of the fishermen during fishing period was 600 BDT whereas their real field daily income through fishing supposed to be 1695 BDT if they are supported by nets, boats, fuels etc., which means almost 64% of their daily income is taken by the aratdars. Therefore, subsidy as a means of nets, boats, fuels, engines etc., might be recommended for the better livelihood of the fishermen in greater Noakhali region.
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Research Article
Apr 22, 2016
Shift of Small Scale Fishing Impacts on Fish Trophic Levels in Lake Iro Revealed by Species-based ... Indicators
A fisheries management plan was required in Central Africa, which integrated a reduced regional hydrographical network and limited amounts of data in the overall regime. The current data and knowledge on fish populations and fisheries impacts are very poor in this region, particularly in Chad. Therefore, any new knowledge, especially on the structure of the ichthyological stands can be considered as valuable. Information on the status of Lake Iro fisheries resources was thus established by this study, which can serve as a model fisheries management regime in Central Africa. We performed assessment of fish resources in Lake Iro, Chad, achieved by a characterization of the exploited ichthyofauna, and the location of nursery and fishing areas. Results indicated that the overall size range of fish species showed negative effects of fishing pressure on size structure of the fish resources. Fishing has increasingly exerted pressure on fish species and affected the primary consumer species. We hypothesized at Lake Iro fish catches were below optimal fish production levels, essentially due to excessive localized fishing efforts, and selective fishing techniques by fisherman. Such reports call for the development of an integrated plan for sustainable management of Lake Iro fisheries resources. Sustainable and equitable exploitation of Lake Iro resources can be promoted by implementation of the following recommendation: a protected area at the lake inlet to limit excessive juvenile fish catches, which disturbs the aquatic food chain and prevents juvenile fish supply and growth in Lake Iro.
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Research Article
Apr 21, 2016
Production and Purification of Recombinant Somatolactin and its Effects on Insulin-like Growth Fac ... tors Gene Expression in Tilapia Hepatocytes
Somatolactin (SL), the member of the growth hormone (GH)/prolactin (PRL) family, is fish-specific pituitary hormone with diverse functions. However, little is known about its biological function in fish hepatocytes. Using tilapia as a model, SL transcripts were shown to be widely expressed in various extrapituitary tissues with the relatively high expression level in liver. To explore the biological action of SL in hepatocytes, we produced and purified recombinant tilapia SL protein which could induce pigment aggregation in tilapia melanophores. Further, the antiserum for the SL was produced and its specificity was confirmed by antiserum preabsorption. During 4 week starvation, hepatic SL transcripts in starved fish were significantly higher than the control fish starting on the 1st week of starvation until 4th week. After re-feeding, the SL transcripts level returned to normal. Using primary cultures of tilapia hepatocytes, insulin-like growth factors (IGF1 and IGF2) gene expression were elevated by static incubation with recombinant tilapia SL. In contrast, removal endogenous SL by immunoneutralization using SL antiserum was shown to inhibit IGF1 and IGF gene expression. These findings, taken together, provide evidence for the first time that SL may serve as a novel regulator in fish stimulating IGF1 and IGF gene expression in hepatocytes
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Research Article
Apr 20, 2016
Inventory of Ichthyofaunal Diversity, Fishing Gear and Craft in Turag River, Dhaka, Bangladesh
Biodiversity of many Bangladesh Rivers is seriously threatened by industrial and municipal pollution. The study was conducted in the Turag River starting from Amin Bazar bridge (23°47’ N 90°20’E) to Kamarpara bridge (23°53’ N 90°23’E). This inventory survey was sampled at a fortnightly interval usually between 7.00 am to 5.00 pm by a team using a boat from December 2012 to November 2013. Detailed information on catch by species, fish length and weight, different types of gear and craft were collected through direct observation. A total of 71 (65 indigenous and 6 exotic) fish species (under 25 families of 9 orders) have been identified. 17 different types of gears of two categories (active and passive gear) and 8 different types of crafts were observed to harvest fish in the study area. The survey revealed that rising floodwater stimulated an increase in fishing activities in the study area from July to October. Fish numbers were recorded lower from November to July (dry and pre-monsoon period) likely due to reduced water flow and adverse water quality of this river. A paired t-test indicate that fish species numbers were significantly difference between Dry and pre-monsoon (P=0.02), Dry and monsoon (P=0.02) and Dry and post-monsoon season (P=0.03) respectively. However, fisheries resources contribution is very limited for livelihood of the surrounding people.
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Research Article
Mar 28, 2016
Retention of Fillet Coloration in Rainbow Trout After Dietary Astaxanthin Cessation
This study was conducted to determine the retention time of rainbow trout (Oncorhynchus mykiss) fillet coloration, as indicated by hue, chroma, and entire color index (ECI) values, after the cessation of dietary astaxanthin. After 12 weeks of receiving a diet containing astaxanthin, rainbow trout [mean (SD) length 240 (26) mm, weight 194 (65) g] were either switched to a non-astaxanthin diet or continued to receive the same astaxanthin diet for 55 d. In addition, a control group was fed a non-astaxanthin diet for the entire duration of the study. Digital coloration measurements (L*, a*, and b*) were recorded on fillets and used to calculate hue, chroma, and ECI values. Hue, chroma, and ECI did not significantly change within any of the treatments over the course of the study. Hue, chroma, and ECI were also not significantly different between the fillets of those fish that either continued to receive astaxanthinsupplemented feed compared to those that were switched from an astaxanthin diet to diet free of astaxanthin. However, ECI, hue, and chroma were significantly different in fillets from the fish that had never received dietary astaxanthin compared to fillets from the other two treatments. These results indicate that catchable-sized rainbow trout stocked into recreational fishing waters with minimal natural feed should retain fillet coloration for at least 55 d after stocking, making astaxanthin supplementation in recreational hatcheries a viable tool to improve angler satisfaction.
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Research Article
Mar 15, 2016
Influence of Dietary Sorghum Starch on Growth Performance, Digestibility Coefficient and Some Hepa ... tic Enzyme Activities in Hybrid Red Tilapia (Oreochromis mossambicus × Oreochromis niloticus) Fingerlings
A 120-day feeding trial was conducted to investigate the effects of dietary sorghum starch on growth performance, feed utilization, apparent digestibility coefficient (ADC) and some hepatic enzyme activities regulating glycolytic and gluconeogenic metabolic pathways of fingerlings hybrid red tilapia (Oreochromis mossambicus × O. niloticus) with mean initial body weight of 10.9 ± 0.2 g. Five diets containing graded levels of sorghum starch (15%, 20%, 25%, 30% and 35%) were formulated. The results demonstrated that weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and net protein utilization (NPU) values increased with increasing dietary sorghum starch up to 30%. Hepatosomatic index, plasma glucose, triglycerides, liver glycogen and liver lipid concentration of fish significantly increased with increasing dietary sorghum starch level (P<0.05). ADC of starch decreased significantly with increasing sorghum starch level over 30%. However, whole body compositions and ADC of protein and lipid showed no significant differences. Dietary sorghum starch supplements tended to enhance gluconokinase and pyruvate kinase activities of the liver but insignificant differences were observed in activities of hexokinase, phosphofructokinase-1, fructose-1, 6-bisphosphatase and glucose-6-phosphatase in the liver for all dietary treatments. Based on WG and FCR results, the appropriate dietary sorghum starch supplementations of fingerlings hybrid red tilapia (O. mossambicus × O. niloticus) can be incorporated up to 30% of diet.
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Research Article
Mar 10, 2016
Potential Use of Mussel Farms as Multitrophic On-growth Sites for American Lobster, Homarus americ ... anus (Milne Edwards)
Mussel (Mytilus edulis) farms in Newfoundland, Canada were investigated as potential sites to hold adult lobsters Homarus americanus in inshore benthic cages. The goals of this project were to determine if lobsters can be maintained for prolonged periods in cages and survive and grow by feeding on mussels dropping-off culture lines. The effects of biotic and abiotic factors on the moulting, growth rates and serum protein concentrations were monitored at regular intervals in both the field and the lab over 6 months. Although survival rates were high under mussel lines, the moulting rate was low and analysis of serum protein concentration showed they were in a poorer condition than fed lobsters in lab experiments. In the laboratory diet type, temperature, feeding frequency and compartment size were manipulated to determine possible factors influencing survival and growth of the lobsters in the field. In the lab, moulting was highest at 15°C and survival lowest at 5ºC; lobsters fed a mixed versus a mussel only diet were healthier. In a separate lab experiment, lobsters that were fed twice weekly attained a larger size at post-moult than those fed once per month. However, feeding frequency did not affect survival or the number of animals moulting. The lab experiments suggested that the combination of low temperature and infrequent food input was the cause of the low moulting rate and overall quality of the lobsters in the field. This project showed although lobsters can be stored in benthic cages in the field for up to 6 months, relying on mussel drop-off alone is limited, and lobsters may need supplemental feeding in order to produce a larger, higher quality product for market. Initial results also suggest the promise of incorporating lobsters into a multitrophic aquaculture system as a means to remove moribund mussels underneath culture lines
