Coll Marta, Carreras Marta, Ciércoles Cristina, Cornax Maria-José, Gorelli Giulia, Morote Elvira, Sáez Raquel
Institut de Ciències del Mar (ICM-CSIC). Barcelona, Spain ; UMR EME 212 Centre de Recherche Halieutique Méditerranéenne et Tropicale. IRD - IFREMER & Université Montpellier II. Sète Cedex, France.
OCEANA, Madrid, Spain.
PLoS One. 2014 Jan 22;9(1):e85670. doi: 10.1371/journal.pone.0085670. eCollection 2014.
The expansion of fishing activities has intensively transformed marine ecosystems worldwide. However, available time series do not frequently cover historical periods.
Fishers' perceptions were used to complement data and characterise changes in fishing activity and exploited ecosystems in the Spanish Mediterranean Sea and Gulf of Cadiz. Fishers' interviews were conducted in 27 fishing harbours of the area, and included 64 fishers from ages between 20 to >70 years old to capture the experiences and memories of various generations. Results are discussed in comparison with available independent information using stock assessments and international convention lists.
According to fishers, fishing activity substantially evolved in the area with time, expanding towards deeper grounds and towards areas more distant from the coast. The maximum amount of catch ever caught and the weight of the largest species ever captured inversely declined with time. Fishers (70%) cited specific fishing grounds where depletion occurred. They documented ecological changes of marine biodiversity during the last half of the century: 94% reported the decline of commercially important fish and invertebrates and 61% listed species that could have been extirpated, with frequent mentions to cartilaginous fish. Declines and extirpations were in line with available quantitative evaluations from stock assessments and international conventions, and were likely linked to fishing impacts. Conversely, half of interviewed fishers claimed that several species had proliferated, such as cephalopods, jellyfish, and small-sized fish. These changes were likely related to trophic cascades due to fishing and due to climate change effects. The species composition of depletions, local extinctions and proliferations showed differences by region suggesting that regional dynamics are important when analysing biodiversity changes.
CONCLUSIONS/SIGNIFICANCE: Using fishers' perceptions, fishing and ecological changes in the study area were documented. The recovery of local ecological knowledge provides valuable information complementing quantitative monitoring and evaluation surveys.
捕鱼活动的扩张已使全球海洋生态系统发生了深刻变化。然而，现有的时间序列数据并不经常涵盖历史时期。
利用渔民的认知来补充数据，并描述西班牙地中海和加的斯湾捕鱼活动及受开发的生态系统的变化。在该地区的27个渔港对渔民进行了访谈，访谈对象包括64名年龄在20岁至70岁以上的渔民，以获取不同代人的经验和记忆。使用种群评估和国际公约清单，将结果与现有独立信息进行比较讨论。
据渔民称，该地区的捕鱼活动随时间大幅演变，向更深海域和离海岸更远的区域扩展。有史以来捕获的最大渔获量和捕获的最大物种重量随时间呈反向下降。70%的渔民指出了出现资源枯竭的特定渔场。他们记录了上世纪后半叶海洋生物多样性的生态变化：94%的人报告商业上重要的鱼类和无脊椎动物数量减少，61%的人列出了可能已灭绝的物种，其中软骨鱼类经常被提及。数量减少和物种灭绝与种群评估和国际公约的现有定量评估结果一致，可能与捕鱼影响有关。相反，一半的受访渔民称，一些物种数量有所增加，如头足类动物、水母和小型鱼类。这些变化可能与捕鱼和气候变化导致的营养级联效应有关。资源枯竭、局部灭绝和物种增殖的物种组成在不同区域存在差异，这表明在分析生物多样性变化时区域动态很重要。
结论/意义：利用渔民的认知，记录了研究区域的捕鱼和生态变化。恢复当地生态知识提供了补充定量监测和评估调查的宝贵信息。
