A series of cruises carried out from 1989 to 2009 each November on the INA-K
in the Thames Estuary. The aims of which were to assess the state of herring
(Clupea harengus) stocks through measurements of length samples and by
ageing a stratified selection of fish. The latter was also to determine the
stock split between North Sea and Thames fish as there is a great deal of
mixing of stocks in the area. Stock identification was done by a combination
of first year growth observed in the otolith and the maturity stage of the
fish.