利用生活史資料評估族群永續性─印度太平洋地區之珊瑚礁魚案例分析

Assessing population sustainability with life-history data: a case study of Indo-Pacific reef fishes

宋文傑(Wen-Chieh Sung)

指導教授 ： 王慧瑜

國立臺灣大學/理學院/海洋研究所/碩士(2018年)

https://doi.org/10.6342/NTU201802848

摘要

珊瑚礁魚類是人類重要的食物和經濟來源，並在珊瑚礁生態系中扮演重要的角色。儘管漁業捕撈造成許多珊瑚礁魚族群的衰減，人們對其漁撈永續性的了解仍相當有限。魚類生活史，如成長和繁殖的相關特徵，決定了族群的成長率，能夠幫助吾人了解族群對漁撈行為的反應。具體而言，本研究假設具有“慢”生活史，如成長得慢且晚成熟的魚類，較具有“快”生活史的魚類有更低的漁撈永續性。此外，本研究亦假設，相較於雌雄異體 (gonochoristic) 的魚類，捕捉較大個體的漁撈行為對於雌雄同體中的先雌後雄 (protogynous) 的魚類有更大的衝擊，因體長較大的雄魚被捕撈後，可能導致族群受精率的下降並減少族群入添。
為驗證這些假設，本研究彙整了78種─共108個族群之印度太平洋地區之珊瑚礁魚之生活史及繁殖型態資料，並利用年齡結構模型 (age-structured model) 計算造成未開發之終生產卵族群生量 (lifetime spawning biomass, LSB) 之40 % 之漁撈死亡率 (F40)，做為評估物種漁撈永續性之指標。接著利用線性混和效果模型來探討生活史、繁殖型態、緯度以及科別相關之隨機變異對族群之F40的影響。本研究發現F40受到物種的生活史及繁殖型態影響，即生活史較慢之物種具有較低的F40，而先雌後雄繁殖型態的族群之F40較雌雄異體的族群低。此外，族群科別對F40有顯著影響，而緯度的變化對F40則無顯著影響。本研究結果顯示，族群生活史及繁殖型態資料能夠幫助了解資料較缺乏之珊瑚礁魚類的漁撈永續性，幫助其保育及管理之規劃。

關鍵字

生活史 ； 先雌後雄 ； F40 ； 漁撈永續性 ； 珊瑚礁魚 ； 保育

並列摘要

Reef fishes provide important services to human and reef ecosystem. Despite many reef fishes have declined due to exploitation, there is a lack of understanding of their sustainability. Life histories (e.g., growth and reproductive traits) determine population growth rates, providing insight into population responses to fishing. Specifically, we hypothesize that fishes with slow life histories (e.g., slow growth and late maturation) are less sustainable than those with fast life histories. Further, size-selective fishing could cause a stronger impact on protogynous (i.e., female-first sex-changing) than gonochoristic ones, as removal of large males can decrease fertilization rates and subsequent recruitment. To evaluate these hypotheses, we compiled life-history data and developed a population model to estimate population sustainability (measured by the level of fishing mortality reducing lifetime spawning biomass to 40% of that of an unfished state; hereafter referred as F40) for 78 Indo-Pacific reef fishes. Using linear mixed-effect models, we explored the effects of life history and mating types on F40, simultaneously accounting for potentially confounding latitudinal effects and family-related random variance. We found significant effects of life histories (i.e., a negative correlation between F40 and a fast-to-slow continuum) and mating types (i.e., lower F40 for protogynous than gonochoristic populations) but not latitudes on F40. Also, we found significant family-related random effects on F40. Our results suggest that life-history and mating type data can provide insight into population sustainability for data-poor reef fishes, supporting conservation and management planning.

並列關鍵字

life history ； protogyny ； F40 ； sustainability ； reef fish ； conservation

參考文獻

References:

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Allsop, D. J., & West, S. A. (2003). Constant relative age and size at sex change for sequentially hermaphroditic fish. Journal of Evolutionary Biology, 16(5), 921-929.

Alonzo, S. H., & Mangel, M. (2005). Sex-change rules, stock dynamics, and the performance of spawning-per-recruit measures in protogynous stocks. Fishery Bulletin, 103(2), 229-245.

Alonzo, S. H., Ish, T., Key, M., MacCall, A. D., & Mangel, M. (2008). The importance of incorporating protogynous sex change into stock assessments. Bulletin of Marine Science, 83(1), 163-179.