User:Generalissima/Fish event horizon

The Fish Event Horizon (FEH) is a historiographic term for the rapid transition of Northern European fish consumption from freshwater to marine sources (especially cod and herring) during a hundred year period centered around 1000 CE.

Early medieval fishing
From the 5th to 7th centuries CE, open sea fishing was generally avoided by many cultures across Northern Europe. Zooarchaeological evidence from sites along the southern coasts of the North Sea and Baltic Sea reveals extremely low quantities of marine fish remains in comparison to later periods, with finds generally limited to coastal locations. Fish bones found at other sites from this period may in fact originate from Roman-era deposits. In Poland and the eastern coast of the Baltic, previously vital fish vanish from the archaeological record during much of the 1st millennium CE, only reappearing as late as c. 1000 CE in Estonia. Pictish sites in Scotland reveal some amount of marine fish consumption, but in dramatically low volumes in comparison to later periods. Only in Scandinavia is significant evidence of marine fishing present during the Migration Period, such as a deposit of over 13,000 herring bones recovered from the 6th–7th century Sorte Muld site on Bornholm.

Different factors likely contributed to the avoidance of marine fishing across this region, but no firm evidence is available due to the corresponding lack of fish remains. The collapse of the Western Roman Empire saw a reduction in urban and elite populations, the ubiquity of ships with low cargo capacity, and an increasing emphasis on high-value items in trade in lieu of staple products. An Iron Age cultural stigma towards fish consumption along the North Sea may have reasserted itself in the post-Roman period.

Reemergence (600s-800s)
The reemergence of small-scale marine fish consumption outside of immediate coastal environments began in the mid-7th century. Evidence of occasional fish consumption emerges in various post-Roman towns in England during this period, possibly deriving from fish collected at coastal feudal and ecclesiastical fiefs. Along the continental North Sea coast, small amounts of sea fish (mainly herring) appear in urban and elite areas, likely caught by coastal settlements and transported upriver. However, fishing villages did not emerge, and coastal communities generally engaged in a variety of other economic activities.

Causes
The beginning of the Medieval Warm Period corresponds to the initial stages of the Fish Event Horizon. While this rise in temperature increased cod and herring stocks in the far north, around the Norwegian Sea, it led to a reduce of fish stocks in the North Sea and the Baltic.