This study provides an updated list of fish in the Class Chondrichthyes sampled during all research projects conducted in the north-western Ionian Sea from 1985 to 2020. A total of 36 Chondrichthyes species belonging to 8 orders and 19 families were detected, most of them distributed over a wide depth range, between shelf and slope. For species assessed by the International Union for Conservation of Nature (IUCN), 8 species are listed as Critically Endangered, 3 as Endangered, 6 Vulnerable and 5 as Near Threatened species. The distribution of cartilaginous fish was examined exploring the historical series of MEDITS data (1995–2020. Changes in the species diversity and in their abundance with time and space were detected and some environmental and anthropogenic drivers that could have caused these changes were analysed. An increase in the presence, number of species and biomass of Chondrichthyes was detected from 1995 to 2020. The GAM analyses seem to indicate that the observed increase in species number and biomass is due to the decrease in fishing capacity and increase in salinity and temperature on the bottom. Furthermore, for the most abundant species, , an increase of biomass, size and a deeper distribution over the last 26 years were detected. Significant changes in biomass were also observed for other abundant species in the study area ( and ). The increase in biomass over time, different from several Mediterranean observations, is discussed in relation to the presence of refuge areas in the north-western Ionian Sea.

中文翻译：

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爱奥尼亚海西北部（地中海中部）的软骨鱼：物种多样性、丰度和时空变化

本研究提供了 1985 年至 2020 年在爱奥尼亚海西北部进行的所有研究项目期间采样的软骨鱼纲鱼类的最新清单。总共检测到了属于 8 目 19 科的 36 种软骨鱼，其中大部分分布在在陆架和斜坡之间的较宽深度范围内。在国际自然保护联盟 (IUCN) 评估的物种中，8 个物种被列为极度濒危物种，3 个物种被列为濒危物种，6 个物种被列为易危物种，5 个物种被列为近危物种。通过探索 MEDITS 数据的历史系列（1995-2020），对软骨鱼的分布进行了检查。检测到物种多样性及其丰度随时间和空间的变化，并分析了可能导致这些变化的一些环境和人为驱动因素。从 1995 年到 2020 年，检测到软骨鱼的存在、物种数量和生物量有所增加。GAM 分析似乎表明，观察到的物种数量和生物量增加是由于捕捞能力下降以及海域盐度和温度增加造成的。此外，对于最丰富的物种，在过去 26 年中还观察到了生物量、大小和更深层次分布的显着变化（和）。与一些地中海观测不同，随着时间的推移，生物量的变化与爱奥尼亚海西北部避难区的存在有关。