Search

The present study evaluated the health status of rainbow trout (30.24±5.34 g) acclimated to high-saline water (28‰). Among adaptation procedures, gradually-acclimated (for 48 h) fish showed best performance, which were then introduced to the offshore cage-farm for further monitoring of fish health in marine environment over a long-term period of 100 days, until harvest weight of 319.9±48.51 g. Fish health and welfare was evaluated by means of biochemical parameters (viscerasomatic index, hepatosomatic index, mesenteric fat index, and spleen somatic index), hematological parameters (serum glucose, triglyceride, cholesterol, total protein, albumin, globulin), and immune parameters (lysozyme, myeloperoxidase, respiratory burst and potential killing values). Gradual acclimation to high-saline water did not show any adverse effects on health parameters. No significant differences were found in biometric measures (P>0.05). However, a time-dependent increase was recorded in hematology markers (P<0.05) after seawater transfer, and the health status improved over long term from March 7 to June 14, 2018. All serum biochemical markers, except the total protein showed significant alterations (P<0.05) in long term but without detrimental influence by day 100. Therefore, it seems possible to expand trout farms from brackish water sites to higher saline environments up to 28‰ salinity, with no detrimental impacts on fish health, that in turn may significantly contribute to the extension of potential aquaculture sites to wider areas.

The aim of the present study was to evaluate risk levels of trace elements in gilthead seabream (Sparus aurata) from conventional polymer nets and copper alloy mesh with reference to hazard levels and maximum allowable limits for human consumption. Bioaccumulation of trace metals in muscle tissues of fish from copper-alloy mesh, and antifoulant-coated net presented elevated levels in the order of Fe(5.76) > Zn(5.56) > Cu(0.53) > Mn(0.28), and Zn(5.20) > Fe(3.97) > Cu(0.56) > Mn(0.26), respectively, compared to the untreated polymer net pen as Zn(3.61) > Fe(3.12) > Cu(0.44) > Mn(0.16) mg/kg wet weight. However, metal levels in fish harvested from all experimental cages did not exceed maximum permitted levels for seafood safety. Target hazard quotients and total hazard indexes, calculated for the evaluation of non-carcinogenic health risks via metal intake through the consumption of possibly contaminated fish, were found lower than “one” (THQ < 1; THI < 1). Maximum allowable consumption levels (kg/day/person) were found in the order of Mn(39.27) > Cu(18.87) > Fe(7.81) > Zn(7.19), Mn(42.31) > Cu(17.86) > Fe(11.34) > Zn(7.69), and Mn(68.75) > Cu(22.73) > Fe(15.96) > Zn(11.08) for fish from copper-alloy mesh, antifoulant-treated net, and untreated polymer net pen, respectively. The results of this study showed that the trace metals in the edible muscle of fish from both copper alloy and antifoulant-coated net pens were below human health risk levels, according to the limits suggested by US Food and Drug Administration and EU Regulations for Seafood Consumption.