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人工藻場技術開發與應用

  • 日期:110-08-02
  • 計畫編號:109農科-20.2.1-水-A3
  • 年度:2020
  • 領域:農業綠能多元發展之整合性關鍵技術研發與推動
  • 主持人:葉宇庭
  • 研究人員:冼宜樂、呂逸林、陳俊廷

表層藻場做為種苗放流中間育成效益評估

    為離岸風場「類保護區」漁業資源的增裕,本計畫模擬在澎湖海域建置表層藻 場,探討其對漁業增裕外溢與應用之可行性。於2019年12月中國半葉馬尾藻( Sargassum hemiphyllum var . chinense)生長期間建置5組藻床,經5個月生產 1,500kg的藻體,推估藻場所依附的生物量達14.4百萬隻,以橈腳類(Copepods)所 占比例最高達81.0%,其次依序分別為跳蝦科(Talitridae)占16.0%,麥稈蟲科 (Caprellidae)占3.0%;棲息在藻場的魚苗近9,000尾,以4cm以下的幼稚魚為主 ,魚種計有10科12種,以六線雞魚(Pelates sexlineatus)、八線雞魚(Pelates sp.)、臭都魚(Siganus fuscescens)及鯔科(Mugilidae)4種魚類最優勢。表層 藻場在3月底覆蓋率已達70%,於4月6日將5萬尾的蟹苗放流藻場,平均甲殼寬為 4.3mm,經25日後,因多層次空間的藻體,提供蟹苗躲棲的環境,降低殘食現象;豐 富的餌料生物可使蟹苗快速成長,降低育苗成本等優勢;平均甲殼寬已達放流適正 甲殼寬20mm以上,棲息藻體上的蟹苗可藉由藻體的脫落隨海流移動至鄰近海域,達 到族群擴散之效。從結果顯示表層藻場對漁業資源具增裕之效,也可應用於蟹苗放 流中間育成用。

粉葉馬尾藻受精卵採集、附苗與培育藻苗技術開發    

本年度成熟藻體較晚,以至所採收的受精卵量較少,為有效採集量多質優馬尾 藻族群的受精卵,需先調查掌握野外各種馬尾藻的生殖週期。受精卵的採集目前多 採「震盪法」,費時耗力僅適合實驗室少量採集實驗用,未來應更精進受精卵的採 集與附苗的作業方法,才能更進一步達到量產的目的。於常溫環境育苗,約需110天 可發展成多葉葉狀體。

底層藻場建置初探    

本研究於2019年12月20日首次以「無性增殖」的方式成功附苗於藻磚上,共完 成100塊,同時也外移天然海域,生長狀況良好,於今年4月底藻體開始脫落,將僅 剩附著器的藻磚攜回育苗池觀察,至7月中旬僅有附著器的藻磚重新再長出藻苗。也 使藻場建置從傳統的表層藻繩,增加底層藻場的類型,使藻場的應用可以朝向更多 元化。「有性生殖」法分別於今年5月11日及7月25日分別進行中國半葉馬尾藻及粉 葉馬尾藻成功的完成受精卵附苗作業,各有326片,2種馬尾藻分別育苗經170日及 112日,藻苗多數發展成多葉葉狀體的階段,並於11月13日外移至紅羅灣海域佈放。

研究報告摘要(英)


Benefit assessment on the surface layer algae field used as an intermediate rearing area for seedling release

To enrich the fishery resources of offshore wind power quasi-protected area, we simulated to establish surface layer algae field in Penghu sea area and discussed its possibility of resource enrichment. We established five sets of Sargassum hemiphyllum var . chinense field during December, 2019. After five months, the production of algae was 1,500 kg. Furthermore, we estimated that there were about 14.4 million pieces of creatures attached in the field. The most abundant is Copepods which accounted for 81.0% of the total abundance and then followe by Talitridae for 16.0%, and Caprellidae for 3.0%. About a total number of 9,000 juvenile fish in 12 species and 10 families inhabited around the algae field. The most dominant species were Pelates sexlineatus, Pelates sp., Siganus fuscescens, and Family Mugilidae. The coverage rate of surface layer algae field reached 70% in March. We released fifty thousand of juvenile crabs with an average carapace width of 4.3mm into the algae field on April 6th. The multidimensional space of algae field which provided hidden spaces for crabs could reduce cannibalism. Abundant organisms in algae field also accelerated the growth of juvenile crabs and reduce the breeding cost. The average carapace width was over 20mm after 25 days, which reached the standard of seedling release. Moreover, some juvenile crabs would float with the fallen seaweed and increased population expansion. The result showed that surface layer algae field could be benefit for fishery resource enrichment and crab breeding release.

Technology development on fertilized egg collection, seedling attachment and cultivation of Sargassum glaucescens

The algae matured relatively late so that the fertilized eggs of Sargassum we collected ware less this year. To collect larger quantity and higher quality of fertilized eggs of Sargassum, the investigation of the reproductive cycle of Sargassum was needed. The method we use to collect fertilized eggs was by shaking; however, we needed to develop a more efficient method of fertilized egg collection and attachment in the future. It took 110 days to develop to thallus from fertilized eggs under an ordinary temperature environment.

A preliminary research on establishing bottom layer algae field

The asexual reproduction algae seedlings were successfully planted on one hundred bricks and move to field on December 20th, 2019. The algae attaching on bricks began to fall in the end of April and only holdfasts remained on the bricks after that. The algae bricks with holdfasts were retrieved and kept being observed in culture tanks. In the middle of July, the new seedlings began to grow from holdfasts on the algae bricks. The success of this method increased a new type of algae field, which could diversify the application of algae field. The sexual reproduction algae seedlings of Sargassum hemiphyllum var . chinense and Sargassum glaucescens were also successfully attached on 326 pieces of tiles each on May 11th and July 25th respectively. It took 170 days and 112 days to develop to thallus from fertilized eggs respectively. All of the algae tiles were move to Hongluo bay on November 13th.