Deterministic Signals in Scottish and Irish Herring (Clupea-Harengus) Catches

The Scottish herring fishery which began in the early nineteenth century was accompanied by detailed record keeping. Here we provide a shea summary of technical changes in this fishery up to 1900 A.D., and the results of maximum entropy spectral analysis (MESA) of five east coast and five Clyde Sea port records. A similar analysis of some Irish herring records is also given. Most series provide clear evidence of the nodal tide and solar signals of 18.6 year and 11 year periods respectively. It is suggested that the former may modulate productivity through systematic changes in mixing depth.