阿根廷魷魚之食性分析與人造物攝入

Abstract

頭足類（Cephalopods）在生態學與漁業皆扮演重要角色，為全球重要漁獲資源之一，年產量約占總漁獲量的4%。頭足類中的魷類（Squids）具有多樣化的食性以及豐富的族群量，在食物網中做為高級消費者提供不同營養階層間高度交互作用及能量流動。過去研究已顯示在氣候變遷衝擊下，魷類的主要食物來源如磷蝦也因海冰溶化導致棲地改變而降低生物量。然而，對於快速生長過程中須攝食大量食物的魷類而言，目前尚未有研究探討魷類是否會因上述原因影響其食性，以及近年的海洋塑膠汙染對其攝食的影響。在本研究中，利用2018及2019年2月到4月在西南大西洋所採集之300尾阿根廷魷（Illex argentinus），解剖個體胃內容物，進行食性分析與人造物檢測。由食性分析結果顯示，在2018年有97.60%的阿根廷魷個體胃內容物中含有甲殼類、14.90%含有魚類以及2.40%含有頭足類；在2019年有96.23%的阿根廷魷魚個體胃內容物中含有甲殼類、18.87%含有魚類以及20.75%含有頭足類，可以發現阿根廷魷魚在2019年攝食頭足類的比例明顯較高，攝食甲殼類的比例明顯較低。由人造物檢測結果顯示，阿根廷魷魚個體的人造物攝取比例在2018年為17.92%、在2019年為28.33%，但阿根廷魷個體平均攝取人造物數皆小於0.5個，並且由FTIR分析結果顯示大部分人造物並非塑膠但可能為似衣料纖維的聚醣材質。整體而言，阿根廷魷魚的食性雖因年度有部分差異，但攝食內容整體比例仍與前人研究相近，顯示其食性應未隨氣候變遷改變，而人造物檢測結果也顯示西南大西洋海域僅輕微污染，可提供國民對於此類食品安全的參考。

Cephalopods play an important role in ecology and fishery. The variation in the diet of large squid population promote high interaction of individuals between different trophic levels in the marine ecosystem. As a consequence of global climate change, previous research has indicated that alteration of environment impacts the availability of the prey. Due to marine pollution, the squids are under the risk of artifact ingestion. However, no clear understanding about the effect of climate change and marine pollution on squid diet selection. This study examined 300 stomachs from Illex argentinus. The sample were collected through commercial catches across the Southwest Atlantic from February to April of 2018 and 2019. In the result, the percentage of frequency of occurrence (FO%) of squid diet in 2018 comprised of 14.90% fish, 2.40% cephalopod and 97.60% crustacean taken from 208 stomachs. Meanwhile, a relatively higher FO% for squid diet in 2019 was observed comprising of 18.87% fish, 20.75% cephalopod and 96.23% crustacean examined from 53 stomachs. Also, the Fourier-Transform Infrared Spectroscopy (FTIR) showed that artifacts examined were composed of plastic and non-plastic materials. Subsequently, FO% of artifact ingestion was higher in 2019 (28.33%) than in 2018 (17.92%), thus mean number of artifact ingestion from two years were less than 0.5. The results indicate that the main diet of Illex argentinus is crustacean. Also, climate change has no direct impact to the squid diet. The results of artifact detection showed that the Southwest Atlantic is less polluted. Thus, it is suggested to continue a monitoring study of squids in this area, particularly on food safety and diet to well manage the biodiversity and squid biology.