Trout Fish Farm Research Articles

Use of fish farms to assess river contamination: Combining biomarker responses, active biomonitoring, and chemical analysis

Here we addressed the possible effects of trace levels of contaminants on fish by means of a combination of biomarker responses, active biomonitoring (ABM), and chemical analysis. In environmental studies, cytochromes P4501A (Cyp1A) and Cyp3A and related enzyme activities (7-ethoxyresorufin-O-deethylase, EROD, and benzyloxy-4-[trifluoromethyl]-coumarin-O-debenzyloxylase, BFCOD, respectively) are commonly used as biomarkers for evidencing exposure to a variety of contaminants. In a rainbow trout (Oncorhynchus mykiss) fish farm that is routinely sampled to obtain references regarding normal levels of such enzyme activities in freshwater fish, we observed a strong and punctual increase in these activities at the end of 2011. In order to shed light on the causes of this induction, we transferred some fish to a fish farm with controlled conditions and examined them using an active biomonitoring (ABM) approach. EROD activity showed a decrease of 80% from the original values after 7 days in the control farm, while BFCOD activity was also reduced after 15 days. Although not significant, a decrease in cyp1A and cyp3A mRNA levels was also observed. To determine the presence of pollutants, water and sediment samples from the river feeding the fish farm were analyzed by two-dimensional gas chromatography–time-of-flight mass spectrometry (GC×GC–TOF–MS). The screening study reflected a weak inflow of pollutants in the monitored area, which is located far from any industrial activity or densely populated cities. Trace levels of polyaromatic hydrocarbons (PAHs) and personal care products (the polycyclic musk fragrance HHCB, and triclosan) were detected in sediments, at concentrations ranging from 0.01 to 38ng/g dry weight, and in water from 4 to 441ng/L. The approach followed in this study proved useful as a biomonitoring technique for the early detection of trace contaminants.

Evaluation of physicochemical parameters of waste water from rainbow trout fish farms and their impacts on water quality of Koohrang stream – Iran

Physicochemical parameters of rainbow trout farm water were evaluated to assess the potential of fish farm effluents on stream water quality. Seven fish farms were selected at Rostamabad region located on 70 km at south-west of Shahrekord-Iran. Water samples were collected from fish farms inlet and outlet at first and second sampling point. Significant differences were observed in some water factors such as total hardness, total dissolved solid, total suspended solid, COD, BOD5, dissolved oxygen, phosphate, nitrite, nitrate and total ammonia between inlet and outlet water of fish farms where as there were no significant changes in pH, sodium chloride and water temperatures. All of the water factors because of self-purification potential of the stream were in desirable amounts in third sampling point. Feasibility study carried out to assess the distance for making consecutive fish farm along the stream. It was observed that it is possible to make consecutive fish farms at around 1500 m distance but it is depended on stream water discharge and self-purification of the stream. Key words: Water pollution, trout farm effluents, environmental impact, Koohrang stream.

Antibiotic susceptibility of Lactococcus garvieae isolated from rainbow trout (Oncorhynchus mykiss) in Iran fish farms

The rates of antibiotic susceptibility and resistance were investigated in Lactococcus garvieae isolates obtained from diseased rainbow trout. A total of 250 clinically suspected fishes were obtained from 10 rainbow trout fish farms in Chaharmahal and Bakhtyari Provinces Iran which is a major trout producing area. L. garvieae strains were isolated from fish tissues such as kidney, spleen and heart, and were identified by biochemical tests and polymerase chain reaction (PCR). All the isolates were found to be resistant to commonly used antibiotics. Resistance to different antibiotics ranged from 25 to 100% of all 52 isolates. These findings revealed a high rate of antibiotic resistance among the strains of L. garvieae which can be transferred to other bacteria.

Use of RT-PCR in diagnosis of infectious hematopoietic necrosis in rainbow trout hatcheries, Iran.

Distribution of Infectious Hematopoietic Necrosis (IHN) was studied in rainbow trout fish farms in Chaharmahal and Bakhtyari Province which is a major trout culture region in Iran. Overall 150 suspected rainbow trout fry with less than 3 g body weight from 30 fish farms in Chaharmahal and Bakhtyari Province, Iran, were studied and fishes of 10 hatcheries (33.3% of all studied farms) found to be infected with IHNV. Reverse transcriptase polymerase chain reaction (RT-PCR) was applied to the detection of infectious hematopoietic necrosis virus (IHNV) using primer pairs. The product of 371 bp was amplified from the RNA extracts of infected organs of suspected fish. DNA sequencing of the PCR products demonstrated specificity of the amplification. The RT-PCR was found to be a simple, highly specific and sensitive method allowing diagnosis of IHN in a short time. Key words: Reverse transcription-polymerase chain reaction (RT-PCR), IHN, rainbow trout.

Otter predation in a trout fish farm of Central–East Portugal: preference for ‘fast‐food’?

AbstractThe Eurasian otter (Lutra lutra) is a known piscivorous predator throughout its distribution range, although in some regions a more generalist behaviour emerged, such as in southern European latitudes. We evaluated otter feeding preference/avoidance towards the elements of the fish guild inhabiting a Mediterranean environment (Côa River, Central Portugal) and assessed the influence of proximity to a surplus of trophic resources (a rainbow trout production farm) on the species diet. Almost two years of collected spraints revealed that otters subsisted by consuming almost exclusively fish (94% of consumed biomass), especially the rainbow trout (87% of consumed biomass), although in summer this consumption is complemented with reptiles and amphibians. Due to the presence of the trout farm, and the consequent constancy in the availability of trout, the observed otter specialization in rainbow trout represents an extreme opportunistic behaviour. Copyright © 2007 John Wiley & Sons, Ltd.

Effects of artificial aeration, macrophyte species, and loading rate on removal efficiency in constructed wetland mesocosms treating fish farm wastewater

We studied the contribution of artificial aeration, loading rate, and macrophyte species on pollutant removal in horizontal subsurface flow constructed wetlands (HSSFCWs) treating reconstituted trout farm wastewater. Twelve 1 m2 mesocosms located in a controlled greenhouse environment were used to test two species of macrophytes (Phragmites australis, Typha angustifolia), three loading rates (30, 60, and 90 L·m–2·d–1), and presence or absence of artificial aeration at the intermediate loading rate. There was no effect of any variable (macrophytes, loading, aeration) on total suspended solids (TSS) or chemical oxygen demand (COD) removal. Artificial aeration improved nitrogen removal while higher loading rates diminished removal of nitrogen and phosphorus. Macrophytes improved nitrogen and phosphorus removal, but this effect varied depending on loading rates and presence or absence of artificial aeration. We found no differences between Phragmites and Typha for treatment of trout fish farm wastewater. Under summer conditions, our results suggest that artificial aeration could be used to improve nitrogen removal by HSSFCWs. Key words: horizontal subsurface flow constructed wetlands, artificial aeration, loading rates, Phragmites australis, Typha angustifolia, fish farm wastewater.

Seasonal occurrence of actinosporeans (Myxozoa) and oligochaetes (Annelida) at a trout hatchery in Bavaria, Germany.

A systematic inventory of actinosporeans and oligochaetes conducted over 3 years at a trout fish farm in Bavaria, Germany, allowed the identification of 12 actinosporeans from five collective groups: four Triactinomyxon (Triactinomyxon nov. types 1-4), two Raabeia (Raabeia nov. types 1, 2), two Echinactinomyxon ( E. radiatum, Echinactinomyxon nov. type 1), two Aurantiactinomyxon ( A. pavinsis, Aurantiactinomyxon nov. type 1) and two Neoactinomyxum (Neoactinomyxum nov. types 1, 2). Nine forms are novel but can be placed within existing collective groups. All 12 forms were detected in the laboratory in aquarium water associated with farm sediment. However, only four of these could be linked with an oligochaete host. Three families of oligochaetes were identified from the sediment: Tubificidae, represented by eight species, Lumbriculidae with one species and Naididae with two species. Only tubificid oligochaetes were found to host actinosporeans.

Carotenoids in fish. XX. Carotenoids in Salmo gairdneri rich. And Salmo trutta morpha fario L.

The author investigated the presence of various carotenoids in Salmo gairdneri Rich. and Salmo trutta morpha fario L. from the trout fish farm (artificial food) and from the river as the natural conditions (natural food).