Israel Oceanographic and Limnological Research, The National Center for Mariculture, 8811201, Eilat, Israel.
Department of Life Sciences, University of Trieste, Trieste, Italy.
Sci Rep. 2021 Oct 25;11(1):20990. doi: 10.1038/s41598-021-00466-5.
Aquaculture threatens natural resources by fishing down the sea to supply fishmeal. Alternative protein sources in aquafeeds can provide a solution, particularly those that are waste from other operations and thereby reduce feed production costs. Toward this goal, we examined the waste biomass of marine periphyton from biofilters of an integrated multi-trophic aquaculture (IMTA) system as a replacement for fishmeal in diets of gilthead seabream (Sparus aurata). Four isoproteic (41%) and isolipidic (16.7%) aquafeeds were formulated with increased content of periphyton and a corresponding decrease in fishmeal from 20 to 15, 10, or 0%. The growth and biochemical content of seabream fingerlings (initial body weight 10 g) were examined over 132 days. Replacing 50% of fishmeal by waste periphyton improved feed conversion ratio (1.2 vs. 1.35 in the control diet) without harming fish growth. The complete replacement of fishmeal with periphyton resulted in 15% slower growth but significantly higher protein content in the fish flesh (59 vs. 52% in the control diet). Halving fishmeal content reduced feed cost by US$ 0.13 kg feed and saved 30% in the cost of conversion of feed to fish biomass (US$ 0.58 kg produced fish vs. $0.83 in the control diet). Finally, the total replacement of fishmeal by waste periphyton in the diet reduced the fish in-fish out ratio to below 1 (0.5-0.9) as compared to 1.36 in the control diet. Replacing fishmeal with on-farm produced periphyton minimizes aquaculture footprint through the removal of excess nutrients in effluents and the use of waste biomass to reduce the 'fish in' content in aquafeeds and fish production costs. The present study demonstrates the great practical potential of this dual use of marine periphyton in enhancing the circular economy concept in sustainable fish production.
水产养殖通过捕捞海鱼来供应鱼粉，从而威胁到自然资源。水产饲料中的替代蛋白质来源可以提供一种解决方案，特别是那些来自其他操作的废物，从而降低饲料生产成本。为此，我们研究了综合多营养水产养殖（IMTA）系统生物过滤器中的海洋周丛生物的废生物质，作为饲料中鱼粉的替代品，用于养殖真鲷（Sparus aurata）。四种等蛋白（41%）和等脂（16.7%）的水产饲料配方中增加了周丛生物的含量，同时将鱼粉从 20%降至 15%、10%或 0%。在 132 天内，我们研究了真鲷鱼苗（初始体重 10g）的生长和生化含量。用废周丛生物替代 50%的鱼粉可以改善饲料转化率（对照饲料为 1.35，实验组为 1.2），而不会损害鱼类生长。完全用周丛生物替代鱼粉会导致生长速度降低 15%，但鱼肉中的蛋白质含量显著提高（对照组为 52%，实验组为 59%）。将鱼粉含量减半可使饲料成本降低 0.13 美元/公斤饲料，并节省饲料转化为鱼生物量的 30%的成本（实验组每生产 0.58 公斤鱼的成本为 0.83 美元，而对照组为 0.83 美元）。最后，用废周丛生物完全替代饲料中的鱼粉可将鱼的养殖比降低至 1 以下（实验组为 0.5-0.9，对照组为 1.36）。用农场生产的周丛生物替代鱼粉，通过去除废水中的多余养分，并利用废生物质减少水产饲料和鱼类生产成本中的“鱼含量”，最大限度地减少水产养殖的足迹。本研究证明了在可持续鱼类生产中增强循环经济概念的这种海洋周丛生物的双重用途具有很大的实际潜力。
