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TaqMan DNA technology confirms likely overestimation of cod ( Gadus morhua L.) egg abundance in the Irish Sea: implications for the assessment of the cod stock and mapping of spawning areas using egg‐based methods
Author(s) -
FOX C. J.,
TAYLOR M. I.,
PEREYRA R.,
VILLASANA M. I.,
RICO C.
Publication year - 2005
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/j.1365-294x.2005.02439.x
Subject(s) - gadus , haddock , whiting , atlantic cod , fishery , taqman , biology , gadidae , stock (firearms) , irish sea , stock assessment , oceanography , polymerase chain reaction , fishing , fish <actinopterygii> , geography , gene , archaeology , geology , biochemistry
Recent substantial declines in northeastern Atlantic cod stocks necessitate improved biological knowledge and the development of techniques to complement standard stock assessment methods (which largely depend on accurate commercial catch data). In 2003, an ichthyoplankton survey was undertaken in the Irish Sea and subsamples of ‘cod‐like’ eggs were analysed using a TaqMan multiplex, PCR (polymerase chain reaction) assay (with specific probes for cod, haddock and whiting). The TaqMan method was readily applied to the large number of samples ( n = 2770) generated during the survey and when combined with a manual DNA extraction protocol had a low failure rate of 6%. Of the early stage ‘cod‐like’ eggs (1.2–1.75 mm diameter) positively identified: 34% were cod, 8% haddock and 58% whiting. As previous stock estimates based on egg surveys for Irish Sea cod assumed that the majority of ‘cod‐like’ eggs were from cod, the TaqMan results confirm that there was probably substantial contamination by eggs of whiting and haddock that would have inflated estimates of the stock biomass.