The Effect of the Photoperiod on the Fatty Acid Profile and Weight in Hatchery-Reared Underyearlings and Yearlings of Atlantic Salmon Salmo salar L.

Abstract

The influence of two light regimes, 16:8 h light/dark (LD 16:8) and 24:0 h light/dark (LD 24:0), in comparison to a usual hatchery light regime (HL), on the fatty acids content and weight gain in hatchery-reared underyearlings (at 0+ age) and yearlings (at 1+ age) of Atlantic salmon in the summer–autumn period was studied. The total lipids were analyzed by Folch method, the lipid classes using HPTLC, and the fatty acids of total lipids using GC. The increase in EPA and DHA observed in October in underyearlings and yearlings salmon (especially under LD 24:0) suggests they were physiologically preparing for overwintering. The changes in fatty acids and their ratios in juvenile Atlantic salmon can be used as biochemical indicators of the degree to which hatchery-reared fish are ready to smoltify. These associated with an increase in marine-type specific DHA and EPA, an increase in the 16:0/18:1(n-9) ratio, in correlation with a reduction in MUFAs (mainly 18:1(n-9)). These biochemical modifications, accompanied by fish weight gain, were more pronounced in October in yearlings exposed to continuous light (LD 24:0). The mortality rate was lower in experimental groups of underyearliings with additional lighting. Exposure to prolonged and continuous light did not affect yearlings mortality rate.

Lipids and Fatty Acids of the Gonads of Sea Urchin Diadema setosum (Echinodermata) From the Coastal Area of the Nha Trang Bay, Central Vietnam

“…The TLs were extracted using the Folch method. [ 27 ] The analysis procedure was the same as described in [ 28 ] with the present object of the study performed as follows: the analyzed tissue sample (gonads) was filtered, and the residue retained on the paper filter was rinsed with 10 volumes of solvent according to the Folch method; the extractive mixture was chloroform; methanol (2:1, v/v). To remove water‐soluble impurities, 15 mL of the chloroform‐methanol (2:1, v/v) and 3 mL of 0.74% aqueous potassium chloride solution were added to the extract in the separatory glass funnel (Schott Duran, Germany) until the complete separation of organic phases.…”

“…The analysis procedure was the same as described in. [ 28 ] Qualitative and quantitative determination of individual lipid classes (PL, MAG, DAG, TAG, Chol, Sterol esters, FFA) were carried out using high‐performance thin‐layer chromatography (HPTLC). Fractionation of TLs was performed on ultrapure glass HPTLC silica gel 60 F 254 Premium Purity plates (Merck, Germany).…”

“…The analysis procedure was the same as that described in. [28,32] The fatty acid profile of the TL extracts was analyzed using gas chromatography (GC). The methylation of fatty acids from lipid extracts was made in a glass vial in which 0.1 mL of a solution containing 20 mg 10 mL −1 (behenic FA, C22:0) (Sigma Aldrich, USA) in methanol was added as an internal standard.…”

The Effect of Continuous Light on Growth and Muscle-Specific Gene Expression in Atlantic Salmon (Salmo salar L.) Yearlings

“…It is necessary to note that in our previous study [ 37 ], salmon yearlings exposed to experimental regimes (LD 16:8 and LD 24:0 between July and October) experienced weight loss during the first 2 months, but the growth rate of fish in the HL group decreased in September and October, and yearlings in the experimental groups continued to grow. It has been suggested that yearlings need a period to adapt to new light conditions.…”

“…The effects of the LD 24:0 light regime on the growth and condition of yearlings were studied. The study is a continuation of previous research on the influence of light regimes on the growth of juvenile fish, which was conducted in 2017 [ 37 ]. We continued to monitor fish that grew in the first year in tanks without additional lighting (the control group) and those under the LD 24:0 regime (the experimental group) during August–November 2017 ( Figure 6 ).…”