PCR-RFLP analyses of formalin-fixed fish eggs for the mapping of spawning areas in the Eastern Channel and Southern North Sea

• Published in: Journal of Plankton Research
• Main Authors: Lelièvre, Stéphanie, Verrez-Bagnis, Véronique, Jérôme, Marc, Vaz, Sandrine
• Format: Text
• Language: English
• Published: Oxford University Press 2010
• Subjects: Article; Gadus morhua
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/fbq067v1; https://doi.org/10.1093/plankt/fbq067

A better knowledge on spawning grounds of principal commercial fishes in the North Sea is necessary for their monitoring. Fish egg taxonomic identification based on morphological characters cannot always be carried out effectively. This is particularly the case for the eggs of a number of species of the Gadidae (i.e. cod, haddock and whiting and three rockling species) which have the same range of size and for which molecular-based techniques can help improve the accuracy of taxonomic identification of eggs, and hence the reliability of studies on spawning areas. In this study, formalin fixation, egg conservation and DNA extraction were optimized in order to develop a specific polumerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Based on the sequence of the cytochrome b gene of reference specimens, a PCR-RFLP method was developed to distinguish eggs of cod, haddock and whiting on the one hand, and between eggs of three species of rocklings on the other. Among the 404 eggs tested, 80% of positive amplification was obtained for rocklings eggs and 86.36% for Gadidae eggs. Eggs of Enchelyopus cimbrius, Ciliata mustela and Ciliata septentrionalis, and Gadus morhua, Merlangius merlangus and Melanogrammus aeglefinus were distinguished with this method. Based on morphological characters, the percentage of misidentification was less for cod than for whiting.