台灣周圍海域人工魚礁區魚類群聚結構之探討

Abstract

為了培育資源、增加漁獲，台灣周圍海域自民國60年代起開始進行人工魚礁的設置。長期以來，雖然已經陸續收集了許多魚礁區的魚類群聚資料，不過對人工魚礁魚類資源培育的機制與所受的限制，並不是很清楚。在自然環境中，魚類的群聚結構多受到生物性和非生物性的環境因子所影響，而魚類的食性組成則可反映生態體系中的能量供給及其傳遞情形，本項人工魚礁區魚類群聚的分析，也是基於此一概念。經收集2008-2010年在台灣周圍人工魚礁區實地潛水調查所登錄的魚類群聚、底棲生物相與環境因子資料，共135筆，經過魚類群聚結構、生物群聚指標、總尾數與生物量的分析，顯示人工魚礁區的魚類群聚明顯可依地理上的差異分成4個分支，而礁型的影響則較小。BIO-ENV與排序分析結果顯示，整體而言，可能影響魚類群聚的因子為緯度、能見度、底質類型、沈積物厚度、藻類覆蓋率與總生物覆蓋率，其中非生物性的環境因子與魚類群聚的相關性較高。食性組成分析顯示：以總生物量而言，人工魚礁區中以攝食無脊椎動物的魚類佔最多；另外，西南海域礁區的小型魚類數量豐富，因此區內亦多食魚性魚類；離島礁區則多攝食浮游動物的魚類；東南及離島礁區藻類覆蓋率較高，藻食性魚類所佔的比例亦較高。若以生物量當做指標，北部魚礁區的漁業資源以三線雞魚 (Parapristipoma trilineatum)、鞍帶石斑魚 (Epinephelus lanceolatus)、條石鯛 (Oplegnathus fasciatus) 佔優勢；西南為銀紋笛鯛 (Lutjanus argentimaculatus)、單斑笛鯛 (Lutjanus monostigma) 與花軟唇 (Plectorhinchus cinctus)；東南為鋸尾鯛 (Prionurus scalprum) 與四帶雞魚 (Pomadasys quadrilineatus)；離島為尖翅燕魚 (Platax teira) 與六棘鼻魚 (Naso hexacanthus)。儘管北部、西南礁區魚種豐富度不若東南與離島，但對於經濟性魚種資源的培育，卻較東南與離島明顯。

Artificial reefs (ARs) have been deployed in the coastal waters of Taiwan for fisheries enhancement since the 1970s. Information on fish communities around ARs has been available for many AR sites. However, we still don’t have enough knowledge on mechanisms accounting for the resource enhancement and the limitations of the AR application. In a natural environment, fish communities are opted to be affected by both biological and non-biological environmental factors. And the trophic composition of the organisms basically implies the supply of energy and its transfer in an ecosystem. Stemmed from these perceptions, the present study has launched a wide spectrum of analysis on fish communities. Data of fish assemblages collected during 2008-2010 from 135 AR sites by scuba divers in waters around Taiwan, along with data of epibenthic cover and environmental factors, were used for analyses on community characteristics, fish abundance and fish biomass. Dendrograms from cluster analysis showed 4 clear clusters of fish assemblages, which could be attributed to geographical areas. In contrast, the effect of AR types was less evident. BIO-ENV and ordination analysis revealed that the structure of overall fish communities were affected more by latitude, water transparency, substratum type, sedimentation, algal coverage and total live cover. Non-biological factors apparently predominated over biotic factors. Trophic analysis showed that invertebrate feeders were common at most AR sites. Besides, in southwestern waters, with the abundant cardinal fishes and damselfishes, a higher proportion of carnivores and piscivores occurred. At offshore islands, planktivores predominated. In both southeastern waters and offshore islands, higher biomasses of herbivores occurred in parallel to higher algal coverages in these regions. Using biomass as an indicator, Parapristipoma trilineatum, Epinephelus lanceolatus and Oplegnathus fasciatus were regarded as the major fishery resource for the AR sites in northern waters; Lutjanus argentimaculatus, L. monostigma and Plectorhinchus cinctus in southwestern waters; Prionurus scalprum and Pomadasys quadrilineatus in southeastern waters; and Platax teira and Naso hexacanthus at offshore islands. Overall, ARs deployed in northern and southwestern waters were more effective in terms of enhancing the production of economically important fishes when compared with those in other waters, despite that the fish assemblages there were less diverse.