淡水水体渔业碳移出之估算

Evaluation of the carbon removal by fisheries and aquaculture in freshwater bodies

中文关键词: 淡水  渔业  碳移出

英文关键词: Freshwater  Fisheries and aquaculture  Carbon removal

中文摘要:

      鱼类和甲壳类等水产品是淡水生态系统碳移出的主要方式。2009年，全国淡水鲢产量348万t，鳙产量243万t，草鱼408万t，鲫206万t，鲤246万t。鲢、鳙的食物主要是天然饵料，鳜鱼摄食鱼类，其饵料鱼则摄食天然饵料，假设草鱼、鲫鱼、鲤鱼、团头鲂等产量的20%来自天然饵料(如不计算施肥等碳输入)，通过计算，淡水水产每年总的碳移出约155万t，另外通过粪便等形式沉积的碳约186万t。如按淡水捕捞产量214万t计算，则移出碳27.8万t/yr。 比较了不同湖泊的碳移出和沉积力，鄱阳湖为大型浅水湖泊，从20世纪50年代~90年代，其通过渔业移出的碳为11.8~27.6kg/hm2•yr，总移出碳为3 890~9 061 t/yr，总固定的碳为8 558~19 935 t/yr。梁子湖为中型浅水湖泊，渔业碳移出为24~38 t/hm2•yr，总移出碳约700~1 100 t/yr。武汉东湖为典型的富营养化湖泊，其渔业的碳移出约为78 kg/hm2•yr，通过渔业输出的碳约260 t/yr，总固定碳约600 t/yr。长江中下游湖泊面积1971年为1.67万km2，2000年为1.3万km2，如果平均碳移出按10~30 kg/hm2•yr计算，总碳移出分别为1.67~1.3万t/yr和5.01~3.9万t/yr。 淡水渔业不仅可以移出水体的碳，而且还可以为人类提供大量的优质食物。各种计算方法之间存在一定差异。

英文摘要:

      Fish and crustaceans are the main ways removing carbon from freshwater ecosystems. In 2009, the total fishery and aquaculture production in China was 3.45 million tonnes for silver carp Hypophthalmichthys molitrix, 2.43 million tonnes for bighead carp Aristichthys nobilis, 4.08 million tonnes for grass carp Ctenopharyngodon idella, 2.06 million tonnes for crucian carp Carassius auratus and 2.46 million tonnes for common carp Cyprinus carpio. Silver and bighead carp are filtering fish and live on natural food. Mandarin fish Siniperca chuatsi is piscivorous fish and lives on natural fishes that feed on natural food. Assuming that 20% of the total production of grass carp, crucian carp, common carp and blunthead bream Megalobrama amblycephala from aquaculture feeding on the natural food, the carbon removal by freshwater aquaculture is around 1.55 million tonnes and about 1.86 million tonnes of carbon is deposited in feces(the carbon input was not calculated). There are also 0.278 million tonnes of carbon removed from natural capture fisheries as the production is around 2.14 million tonnes. Different lakes are varied in ecosystem characteristics and show different ability of carbon removal. The Poyang Lake is a large shallow lake. The carbon removal from Poyang Lake by fisheries was 11.8~27.6 kg/hm2•yr and its total removal was 3 890~9 061 t/yr, and its total carbon sequestration was 8 558~19 935t/yr during 1950s to 1990s.The Liangzi Lake is a medium shallow lake. Carbon removal by fisheries from Liangzi Lake is around 24~38 t/hm2•yr and total removal is 700~1 100 t/yr. The Donghu Lake is a eutrophic lake and its fisheries carbon removal is 78 kg/hm2•yr and total carbon removal is 260t/yr. The total lake area in the middle and lower reaches of Yangzi River is 16 700 km2 in 1971 and 13 000 km2 in 2000, of which average carbon removal by fisheries is 10~30 kg/hm2•yr and the total carbon removal by fisheries from all these lakes is 16 700~13 000 t/yr and 50 100~39 000 t/yr. Freshwater fisheries and aquaculture could remove carbon from freshwater, but also provide food for the human beings.There are still some differences in carbon removal via different calculations.