The thesis presents a novel zooarchaeological, statistical, and ecological analysis of fish bone assemblages from early medieval England. Comprehensive evidence is presented of coastal and pelagic fishing of larger bodied, healthier populations in England from the 8th cent.CE, pushing back the assumed rise in marine fishing commonly referred to as the ‘Fish Event Horizon’, or the FEH, by 300 years. The findings are an important contribution to assessing past human impacts on aquatic ecosystems, which to date have not been widely researched.

Atlantic cod (Gadus morhua) was selected as the main focus of the study due to its prominence in modern and historical fishery economies, based on studies of modern and archaeological materials.

Identifications of diverse marine taxa, including cod, were part of the zooarchaeological analysis of a previously unexamined, exceptionally large assemblage from the pre-FEH monastic site of Lyminge. Lyminge was chosen for analysis due to its early occupation dates, which precede the previously theorised onset of marine fishing, and its exceptionally large fish bone assemblage. Fish body sizes were estimated from both newly developed and preexisting regression models. The novel models were constructed from a uniquely large and diverse dataset of modern cod specimens collected for this purpose, and applied to new data from Lyminge and to a legacy dataset from Coppergate. The estimated archaeological cod sizes were further compared to modern trawl survey data. A significant temporal decrease was observed between both archaeological datasets and the modern data. The larger archaeological cod body sizes suggest significantly improved weights, reproductivity, and health of cod populations prior to the onset of commercial fishing in the North Sea. Furthermore, shifts in past food web interactions are also suggested, revealing shifting ecologies of other species interacting in the same food web.

Combined with the positive identifications of other pelagic species, the larger archaeological sizes indicate that the fish were sourced from pelagic environments. The contextualization of these findings in the wider study area of northwest Europe suggests that early medieval communities had the technological abilities and traditional knowledge required to conduct offshore marine fishing as early as 1,300 years ago. The analysis of skeletal elements and butchery patterns of the Lyminge cod further indicate that stockfish was prepared for local consumption, and possibly for trade, in the same era.

Unique statistical tools are presented for estimating past cod sizes, expressed as Total Length (TL), through both newly defined and preexisting measurements of archaeological bones. The robustness and convenience of estimating cod TLs from previously unutilized vertebrae and cranial measurements is demonstrated through the reported accuracy of the developed regression models, and their application to the archaeological case studies where such elements are common but have remained unutilized.

Lastly, the ecological results based on the developed regression models highlight the damaging effects of intensified fishing practices in later periods, a trajectory that has led to diminished health, and even complete collapse, of modern populations.