HMAP Dataset 22: Catch and Fishing Effort in the Limfjord Fisheries

The research that generated Dataset 22 focuses on the long-term development of the herring fishery, the largest of the Limfjord’s fisheries in the early modern era. It seeks to establish whether the collapse of the herring fishery around 1830 was caused by the ‘Agger Breach’, as most commentators have assumed, by charting the pattern of herring catches and fishing effort from 1667 to 2000. Measuring these variables over a 340-year period not only indicates the degree to which herring stocks fluctuated over time, but also suggests that the Limfjord herring did not, as conventionally believed, collapse because of the ecological impact of the breach of Agger Tange. Rather, this research infers that commercial fishing activity greatly impaired herring reproduction - through damage inflicted by gear on eggs and spawning habitats, the capture of immature herring, and the overexploitation of adults. This is the first documented case in Denmark of the decisive impact that a pre-industrial fishery could have on a large marine resource.