中国水产养殖种类组成、不投饵率和营养级

根据1950–2014年水产养殖种(类)有关统计和调研数据,并在对养殖投饵率、饲料中鱼粉鱼油比例、各类饵料(配合饲料、鲜杂鱼/低值贝类/活鱼、天然饵料等)营养级等基本参数进行估算的基础上,研究分析了中国水产养殖种类组成、生物多样性、不投饵率和营养级的特点及其变化。结果表明:中国水产养殖结构相对稳定,变化较小,其显著特点是种类多样性丰富、优势种显著、营养层次多、营养级低、生态效率高、生物量产出多。其中:(1)养殖种类296个、品种143个,合计为439个。种类组成区域差异明显,淡水养殖鱼类占绝对优势,如2014年草鱼、鲢鱼、鳙鱼、鲤鱼、鲫鱼和罗非鱼排名前6个种类的养殖占淡水养殖产量69.6%,其次为甲壳类、其他类、贝类及藻类,而海水养殖则以贝藻类为主,如2014年牡蛎、蛤、扇贝、海带、贻贝和蛏6个种(类)的养殖占海水养殖产量71.3%,其次为甲壳类、鱼类及其他类;(2)养殖种类多样性特征显著,与世界其他主要水产养殖国家相比,独为一支,具较高的多样性、丰富度和均匀度,发展态势良好;(3)由于养殖方式从天然养殖向投饵养殖转变,不投饵率呈明显下降趋势,从1995年90.5%降至2014年53.8%(淡水35.7%,海水83.0%),但与世界平均水平相比,仍保持较高的水准;(4)与世界相比,营养级低且较稳定。由于配合饲料的广泛使用及其鱼粉鱼油使用量减少,近年营养级略有下降,从2005年较高的2.32降至2014年2.25(淡水2.35,海水2.10)。营养级金字塔由4级构成,以营养级2为主,近年占70%,表明其生态系统有较多的生物量产出。中国水产养殖未来发展需要遵循绿色、可持续和环境友好的发展理念,探讨适宜的、特点各异的新生产模式,发展以养殖容量为基础的生态系统水平的水产养殖管理,建设环境友好型的水产养殖业,为保障国家食物安全、促进生态文明建设作出更大贡献。

Species composition, non-fed rate and trophic level of Chinese aquaculture

Based on Chinese aquaculture (including species and species group) statistics and investigation data during 1950–2014, combined with the estimate on the feeding rate in aquaculture, the percentage of fishmeal and fish oil of compound aquafeed, the trophic level of all kinds of diet (compound aquafeed, trash fish/low-valued molluscs/live fish, natural diet, etc.), the characteristics and changes of species composition, biodiversity, non-fed rate and trophic level in Chinese aquaculture were analyzed. The results were as follows: Chinese aquaculture structure was relatively stable, just less changes during the past decades, and was distinctively characterized by species-rich diversity, dominant species concentration, multi-trophic levels, lower trophic level, high eco-efficiency and more yields. The details were: (1) A total of 439 species and varieties in Chinese aquaculture, including 296 aquaculture species and 143 varieties. Species composition significantly varied with regional differences, and fish were the absolutely dominant species in freshwater aquaculture, e.g. in 2014, the top 6 species (grass carp, silver carp, bighead carp, common carp, crucian carp and tilapia) yields accounted for 69.6% of total yields in freshwater aquaculture, followed by crustaceans, others, molluscs and al-gae. However, molluscs and algae were the dominant species in mariculture, e.g. the top 6 species (oyster, clam, scallop, kelp, mussel and razor clam) yields accounted for 71.3% of total mariculture yields in 2014, followed by crustaceans, fish and others. (2) Biodiversity was characterized by species-rich diversity, high richness and evenness, not a paralleled aquaculture countries have been found in the world, meanwhile, Chinese aquaculture showed a better development trend. (3) The non-fed rate of Chinese aquaculture showed an obvious decreasing trend, and varied markedly during the different aquaculture development period. The higher non-fed rates were found before the 1990s, were about 96.7%–100%, which was mainly attributed to aquaculture model with natural diet. Meanwhile, with the aquaculture models from natural farm to feeding farm, the non-fed rate greatly decreased from 90.5% in 1995 to 53.8% in 2014 (35.7% for freshwater aquaculture and 83.0% for mariculture in 2014), which still remained the higher level when compared with the average non-fed rate of the other countries in the world. (4) The trophic level of Chinese aquaculture was lower and more stable (range from 2.12 to 2.33). There were three periods in the trophic level changes of Chinese aquaculture: the trophic level decreased from 2.33 to 2.12 during 1950–1980, then showed an increase–decrease– in-crease changing trend (range from 2.17–2.32) until 2005, and slightly decreased since 2005 for the popularization of compound aquafeed and the percentage decrease of fishmeal and fish oil of compound aquafeed, e.g. the trophic level was 2.32 in 2005, and decreased to 2.25 (2.35 for freshwater aquaculture and 2.10 for mariculture) in 2014. The trophic level pyramid of Chinese aquaculture was composed of 4 levels, and dominated by trophic level 2 (accounted for 70% of total yields in recent years), which means the more yields in Chinese aquaculture ecosystem. In the future, the de-velopment of Chinese aquaculture orientates by green, sustainable and environment-friendly development concept, de-velop the new aquaculture model with suitable and different characteristics, combine with the ecosystem-based aqua-culture management based on carrying capacity, and finally realize the environment-friendly aquaculture. Chinese aqua-culture is destined to greatly contribute the national food security and ecological civilization construction.