斑節蝦養殖池之生態調查與其水質基準之研究

Abstract

斑節蝦(Penneus japonicus, Bate)為斑節蝦屬中最名貴的一種，台灣的斑節蝦養殖近年來在病害的侵襲下，活存率不到二成甚至更低；然而仍有少部份的業者在養殖技術之輔導下年年養殖成功，另外在日本的斑節蝦養殖亦已開始回復，足證斑節蝦養殖若能有新穎的觀念與進步的技術，仍然確有可為。本實驗從2005年8月至隔年1月，每三個星期前往宜蘭當地的兩個班節蝦養殖池做水質與生物的基本調查與採樣分析並紀錄收成量，另外在實驗室對斑節蝦苗進行台灣常用四種農藥之急性毒試驗，加上其他資料收集，希望能夠提出對養殖斑節蝦的水質基準，供業界參考。 水質調查研究的結果發現，在水質環境因子兩池都沒有太大的差異時，但鹽度越接近海水的斑節蝦養殖池其收穫量越高，管理較好的蝦池，經過間捕的過程，每分地生產1.1公噸之收穫量，相當成功且其池蝦大小為8~12克。從葉綠素a、BOD、磷酸鹽、矽酸鹽、浮游動植物等方面可用來研判養殖池水質的好壞，一般都有隨養殖日期而增加，且都發現到池水有嚴重的優養化與有機污染的情形，顯示換水的頻率需要增加，以維持較好的水質提供池蝦生長，而在水中、土壤、與蝦體重金屬含量的方面則是比過去的數據要來得低，顯示重金屬的使用已經減少。 由急性毒試驗的結果，四種農藥甲基巴拉松、達馬松、巴拉刈、丁基拉草對斑節蝦在生物之安全濃度分別為0.0013、5、64、5.1μg/L，加上養殖的數據及多人之研究報告，彙整提出養殖斑節蝦時之水質基準供水質管理之用。

Kuruma prawn Penneus japonicus is the most precious specie in penaeid shrimps, Survival rate of its aquaculture in Taiwan has been due to disease attack only about twenty percent in recent years; However farming Penneus japonicus still can success, provided with novel idea and the progress technology. In Japan the aquaculture of Penneus japonicus regain its production year after year. The present study regularly investigated the ecology of two different kuruma shrimp ponds, including shrimp growth and unit production in I-Lan country. Two ponds with stock density of 100~120 individuals per square meter were used in June and July. Sophisticated cultivating technology including better pond bottom preparation, good water management, feeding with more nutritious food, and providing more facility were applied. Moreover acute toxicity of four kinds of agricultural pesticides, methyl-parathion, methamidophos, paraquat and butachlor to juvenile shrimp was carried out, trying to find out their safe concentrations for the purpose of offering water quality criteria for farming with other published results. It is found out that water quality of two ponds did not significantly differ in many ecological factors, apart from salinity. Shrimp production is higher in slightly higher salinity pond(29.3‰) then lower salinity one(21.7‰), the former can produce 1.1 tones of shrimp per hectare, with 10-12 grams in harvest size and 90% survival rate, by 8 partial harvests. BOD, Chlorophyll a, phosphate, silicate, phytoplankton and zooplankton increase with cultural times, all can be used to judge the water quality, especially NH3 and dissolved oxygen. It is suggest that water exchange must be intensified and peddle wheel be installed more to maintain good dissolved oxygen. As do the metal contents of shrimp body, it decreased compared with that in many years, showing usage of copper algaecides is reduced. From the result of acute toxicity, it shows that the biologically safe concentration for methyl-parathion, methamidophos, paraquat and butachlor were 0.0013, 5.0, 64, and 5.1 μg/L respectively. Therefore, water quality criteria for farming the kuruma prawn are discussed and proposed, with other published data for the ease of managing pond water.