School of Environment and Life Sciences, University of Salford, Greater Manchester, UK.
School of Biology & Environmental Science, Science Education and Research Centre-West, University College Dublin, Belfield, Dublin, Ireland.
PeerJ. 2013 Aug 13;1:e129. doi: 10.7717/peerj.129. eCollection 2013.
Skates are widely consumed across the globe, but many large species are subject to considerable concern regarding their conservation and management. Within Europe such issues have recently driven policy changes so that, for the first time, reports of skate landings now have to be made under species-specific names. Total allowable catches have also been established for many groups, which have been set to zero for a number of the most vulnerable species (e.g., Dipturus batis, Raja undulata and Rostoraja alba). Whilst accurate species identification has become an important issue for landings, the sale of skates is still usually made under a blanket term of "skate" or "ray". The matter of identifying species of skate is further complicated by their morphologically conservative nature and the fact that they are commercially valued for their wings. Thus, before sale their bodies are usually discarded (i.e., "winged") and often skinned, making morphological identification impossible. For the first time, DNA barcoding (of the mitochondrial COI gene) was applied to samples of skate wings from retail outlets across the British Isles, providing insight into which species are sold for consumption. A total of 98 wing samples were analysed, revealing that six species were sold; blonde ray (Raja brachyura), spotted ray (Raja montagui), thornback ray (Raja clavata), cuckoo ray (Leucoraja naevus) small-eyed ray (Raja microocellata) and shagreen ray (Leucoraja fullonica). Statistical testing demonstrated that there were significant differences in the species sold in the distinct retail groups which suggests complex drivers behind the patterns of sale in skates. The results also indicate that endangered species are not commonly being passed on to consumers. In addition, the practice of selling skate wings under ambiguous labels is highlighted as it makes it extremely difficult for consumers to exercise a right to avoid species of conservation concern. Interestingly, a single retailer chain labelled their wings as originating from three smaller-growing species (generally to be considered of lower conservation concern); of the six samples analysed from this company a third were mislabelled and originated from the thornback ray (a larger species that is currently undergoing population declines).
在全球范围内，鳐鱼被广泛食用，但许多大型鳐鱼物种的保护和管理仍令人高度关注。在欧洲，这些问题最近推动了政策的改变，以至于首次要求按照具体物种名称报告鳐鱼的上岸量。许多群体的总可捕捞量也已确定，其中一些最脆弱的物种（例如，Dipturus batis、Raja undulata 和 Rostoraja alba）的总可捕捞量已设定为零。尽管准确的物种识别已成为上岸量的一个重要问题，但鳐鱼的销售仍通常以“鳐鱼”或“射线”的统称进行。由于它们形态保守，并且其翅膀具有商业价值，因此确定鳐鱼物种的问题更加复杂。在出售之前，它们的身体通常被丢弃（即“带翅膀”），并且经常被剥皮，从而无法进行形态学识别。首次将 DNA 条形码（线粒体 COI 基因）应用于不列颠群岛各地零售店的鳐鱼翅膀样本，深入了解哪些物种被用于消费。总共分析了 98 个翅膀样本，结果表明有六种物种被出售，分别是：短吻鳐（Raja brachyura）、斑点鳐（Raja montagui）、棘背鳐（Raja clavata）、库氏棘鳍鳐（Leucoraja naevus）、小眼鳐（Raja microocellata）和粗皮真鲨（Leucoraja fullonica）。统计检验表明，不同零售群体出售的物种存在显著差异，这表明鳐鱼销售模式背后存在复杂的驱动因素。结果还表明，濒危物种并未普遍传递给消费者。此外，销售鳐鱼翅膀时使用模糊标签的做法也突显出来，因为这使得消费者极难行使避免关注保护的物种的权利。有趣的是，一家零售商连锁公司将他们的翅膀标记为来自三个较小的生长物种（通常被认为保护关注程度较低）；从该公司分析的六个样本中，有三分之一被误标记，来自棘背鳐（一个较大的物种，目前正在经历种群数量下降）。
