Murat Yigit

Effect of dietary Ulva and Spirulina on weight loss and body composition of rainbow trout, Oncorhynchus mykiss (Walbaum), during a starvation period.

A study was conducted to determine the effect of dietary algal supplementation on weight loss and proximate composition in rainbow trout, Oncorhynchus mykiss, during starvation. An algae-free control diet (C) and four experimental diets, including varying levels of raw Ulva meal (5% = U5; 10% = U10) and Spirulina meal (5% = S5; 10% = S10) were formulated. Fish were fed to satiation for 12 weeks and then subjected to a 3-week starvation period. Body weight, viscerosomatic index (VSI, %), hepatosomatic index (HSI, %), dress-out (DO, %) and chemical composition of carcass were analysed at the end of each starvation week. The accumulated weight loss of the fish fed dietary algae was almost 50% less than the control group (p < 0.05) after 2 and 3 weeks starvation. No significant differences in weight loss were observed among the fish fed different algal diets during the starvation period. Total body protein and ash contents remained constant in all groups throughout the starvation period. Fish in all treatments lost a significant level of total lipids and changes of liver fatty acid profiles were also observed. Results indicate that low level inclusion of algae in aquafeeds may have economical advantages in terms of reducing weight loss in fish when subjected to a short-term fasting period, that sometimes is necessary after a heavy rainfall or when fish stocks are held back to meet market demand.

Unrefined Peanut Oil as a Lipid Source in Diets for Juveniles of Two-banded Seabream Diplodus vulgaris

AbstractA feeding study with Two-banded Seabream Diplodus vulgaris was conducted to determine the effects of replacement of fish oil (FO) by unrefined peanut oil (PO) on growth performance, feed utilization, body composition, fatty acid composition, and serum biochemical and hematological variables. Three isonitrogenous (35.8%) and isoenergetic (21.15 kJ/g) diets were formulated by replacing dietary FO with PO at levels of level 0% (PO0), 50% (PO50), or 100% (PO100). Fish were fed twice a day until satiation for an experimental period of 8 weeks. The best growth performance was observed in fish fed with the PO0 and PO50 diets. A significant increase was observed in hematocrit and mean corpuscular volume levels of fish fed with PO50 diet compared with the other groups. Hemoglobin, mean corpuscular hemoglobin, total protein, albumin, and globulin were not affected by dietary PO treatment and did not differ among experimental groups. The glucose level was highest in the PO100 group. Triglyceride and choleste...

Bioaccumulation of trace metals in Mediterranean mussels (Mytilus galloprovincialis) from a fish farm with copper-alloy mesh pens and potential risk assessment

ABSTRACT Concentrations of trace metals were determined in the muscle tissue, digestive gland and gills of Mediterranean mussels (Mytilus galloprovincialis) collected from different locations around an offshore copper alloy fish farm. Levels of copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe) as mg/kg wet weight in the edible part of the mussels collected from distant zone (upstream Zn7.33 > Fe2.8 > Cu0.13 > Mn0.07 and downstream Zn9.9 > Fe5.67 > Cu0.18 > Mn0.17) were significantly lower (p < 0.05) than those sampled from the cage zone (bottom panel Zn22.25 > Fe13.75 > Cu2.39 > Mn0.85 and cage frame Zn17.1 > Fe8.74 > Cu1.39 > Mn0.26). Trace metal concentrations in mussels were significantly higher (p < 0.05) in the samples from the frame and bottom panel of the copper alloy mesh pen, compared to those from distant areas, namely the farm affected downstream -and non-affected upstream locations. However, the rates of target hazard quotients (THQ) for all tested trace metals from all locations in the present study were smaller than “one” (THQ < 1), indicating that the consumption of mussels grown around a cage farm with copper alloy mesh pens were within safe limits and did not exceed maximum levels suggested by the US Food and Drug Administration (USFDA) and European Union (EU) regulations for seafood consumption.

CONSTRUCTION, ASSEMBLY AND SYSTEM DEPLOYMENT OF A FISH CAGE WITH COPPER ALLOY MESH PEN: CHALLENGING WORK LOAD AND ESTIMATION OF MAN-POWER

In the present study, a 150 cubic m net pen was designed as part of a collaborative research effort between the International Copper Association (ICA-USA), the University of New Hampshire (UNH-USA) and Cannakale Onsekiz Mart University (COMU-Turkey) in August 2011. The fish cage was developed to support the creation of a small scale demonstration farm, located in the Strait of Canakkale, off the coast of Guzelyali town in Turkey. The surface gravity-type, octagonal shaped fish cage was designed to have a diameter of 6 m and a copper alloy mesh chamber depth of 5 m. The present study details the cage construction and system deployment of one fish cage utilized a chain link mesh net chamber with a copper alloy developed by Wieland-Werke in Germany, with reference to work load challenge and estimation of man-power necessary for the partial and total work efforts. As a conclusion, one cage equipped with copper-alloy mesh pen was brought to a final shape with the net chamber assembled and attached to the cage frame in 3 days and 90 man-hours. The HDPE (high density polythylene) cage frame was assembled by an outside company, therefore detail of the main cage frame is not discussed in this paper.

THE INTEGRATION OF FISH AND PLANT PRODUCTION: NILE TILAPIA (Oreochromis niloticus) AND BASIL(Ocimum basilicum) CULTURE IN RECIRCULATING AND AQUAPONIC SYSTEMS

In the present study, tilapia and basil production was performed in an aquaponic system developed with the integration of fish and plant production in the same culture environment. The variation of elements in the water was monitored and their effects on fish growth performance and feed utilization together with the plant growth were recorded. Triplicate groups of fish tanks were used in two different culture systems (recirculating-RS and aquaponic system-AS). The RS consisted of a water filtration unit whereas the AS was set with the incorporation of basil ( Ocimum basilicum ) production with the roots in water instead of soil, absorbing the discharge water from fish tanks through their roots. Nile tilapia ( Oreochromis niloticus ) with an initial mean weight of 5.65 g were introduced into both RS and AS systems and fed a commercial diet (50% protein) for a period of 75 days. At the same time basil was set into the AS with roots in water, a photoperiod of 12:12 dark:light regime was applied for the monitoring of plant growth. Water physico-chemical parameters were recorded in both culture environments throughout the study period. Based on the findings in both culture systems, at the end of the experiment, it was found that the variations of amonium (NH 4 ), nitrite (NO 2 ) and nitrate (NO 3 ) recorded in the AS were lower then those measured in the RS culture unit.

THE USE OF GARLIC (Allium sativum) MEAL AS A NATURAL FEED SUPPLEMENT IN DIETS FOR EUROPEAN SEABASS (Dicentrarchus labrax) JUVENILES

The incorporation of garlic meal (GM) in diets for European seabass juveniles were evaluated with a diet containing 43% protein and 17% lipid (gross energy 19kJ/g diet). Experimental diets with GM incorporation of 0, 2, 4, and 6% were fed to fish (10.60 ±0.16 g) until satiation for 60-days. Significant differences ( p<0.05 ) were recorded for growth performance, with the highest rate in the 4% GM group, followed by the control group. Improved feed conversion (FCR) and protein efficiency rates (PER) were observed in the GM4 group compared to the other treatments. Nitrogen retention as a percent of intake was highest in the in GM4 group. Significantly higher values ( p<0.05 ) were found for body protein and lipid, and lower values ( p<0.05 ) for the hepatosomatic, viscerasomatic or mesenteric fat indexes in the GM4 group compared to the other treatments. Fish fed garlic supplemented diets showed lower saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA), but higher polyunsaturated fatty acids (PUFA) compared to the control group with no garlic treatment. Results indicate that dietary GM inclusion of 4% can improve fish growth and nutrient utilization with an increase of fish muscle quality by elevated PUFA concentrations, and a reduction of total nitrogen excretion.