Food Consumption, Growth, And Ecological Conversion Efficiency Of The Two Key Middle-to-Up Layer's Fishes Of Bohai And Yellow Sea

The ecological energetic parameters of two marine pelagic fish species, Ammodytes personatus and Engrauli japanicus, such as food consumption, growth and ecological conversion efficiency, were determined by using in situ stomach content method given by Eggers. The two fishes' experiments have been carried out in laboratory and in situ respectively.The research on Engrauli japanicus has been done in two periods, and the results shown that: Relationship between instantaneous food content in stomach and corresponding time could be described as St = 11.895e-0.1397t, St = 6.7395e-0.1464t, and instantaneous gastric evacuation rate calculated by above formula was Rt = 0.1397 gWW /100g/h, Rt = 0.1464 gWW /100g/h; Food consumption calculated according to Eggers' formula was Cd = 10.18 ±3.14 gWW/100g/d or 45.63± 14.05 KJ/100g/d, Cd = 12.35± 0.60 gWW/100g/d or 55.36± 2.71 KJ/100g/d; Because real determining value of growth was Gd = 4.29 gWW /100g/d or 18.85 KJ/100g/d, Gd = 1.04 gWW /100g/d or 4.56 KJ/100g/d, ecological conversion efficiency could be evaluated, which was Eg =42.12% WW or 41.31 % KJ, Eg= 8.39% WW or 8.23 % KJ.The research on Ammodytes personatus has been carried out under different ecological factors, such as body weight, diet species and diet size. The results showed that: The rate of food consumption and growth, and ecological conversion efficiency tended to decrease with the body weight increase; With comparison among three diets such as Themisto gracilipes, artemia nauplii and fish mud, the result showed that artemia nauplii was very applicable to the Ammodytes personatus laboratory experiment; The experiment of different food size showed that mature artemia nauplii was fitter than larva.During above experiment, the gastric evacuation rate (GER) has been studiedwith different ecological factors such as temperature, body weight and different diets. The results showed that: GER tended to increase with temperature rise; Relation between GRE and temperature could be described as Rt= -0.00l2t2+0.0579t-0.5456 (R2 = 0.9818) with Ammodytes personatus, R, = 0.0253e0.0908t (R2 = 0.9863) with Engrauli japanicus; With body weight increase, the Ammodytes personatus' GER changed unremarkably. The food evacuation speed of artemia nauplii was the fastest of the three diets, the speed of fish mud was slow, and that of Themisto gracilipes was the slowest.