Nutritional Data on Six Oceanic Pelagic Fish Species from New Zealand Waters

Abstract

Proximate composition, fatty acid profiles and concentrations of 22 elements of the edible muscle of six oceanic pelagic fish species from the New Zealand Exclusive Economic Zone were determined from samples of surface longline catches. The species analyzed were albacore tuna ( Thunnus alalunga), butterfly tuna ( Gasterochisma melampus), short-finned mako shark ( Isurus oxyrinchus), moonfish ( Lampris guttatus), porbeagle shark ( Lamna nasus), and swordfish ( Xiphias gladius). Protein content of all species exceeded 20%, except swordfish, which ranged between 16.4 and 19%. In all species except swordfish and a single albacore tuna, the mean oil content was less than 5.0%. The soluble carbohydrate content varied between 0.21 and 0.36 g/100 g wet wt in all species, with albacore tuna the highest measured. The Zn concentration of swordfish (1.3 mg/100 g wet wt) was substantially higher than that in other finfish from the New Zealand fishing area. No marine wax esters were present in any of the fish examined; triacylglycerols (70-80%) and phospholipids (10-15%) were the main constituents of the glycerol esters. Omega-3 polyunsaturated fatty acids (ω-3 PUFA) ranged from 0.3 to 1.6 g/100 g wet wt, the highest being swordfish and albacore tuna (1.1 g/100 g wet wt). Total mercury concentrations were lowest in butterfly tuna (33 μg/100 g) and highest in mako (216 μg/100 g). A strong linear relationship existed between total mercury and methyl mercury concentration and fish length in porbeagle and swordfish. Regression equations for length versus total and methyl mercury concentration were determined for porbeagle and swordfish as was the regression between methyl and nonmethyl mercury concentrations for all specimens.