The recent prehistoric exploitation of edible mussel in Aboriginal shell middens in southern New South Wales

Abstract

A striking but hitherto poorly documented feature of many coastal shell middens in southern New South Wales is the relatively high proportion of edible mussel Mytilus edulis planulatus in their uppermost layers. Poiner (1971) noted an increase in mussel in the upper layers of several shell middens near Sydney, but the phenomenon was particularly remarked upon by Bowdler (1970, 1976) for a site she excavated at Bass Point (Fig. 1). Bowdler recorded an abrupt change to mussel as the dominant shellfish species in the uppermost layers of this midden and proposed a cultural explanation for the change. In terms of both coastal physiography and ecology, the southern coastal region of New South Wales extends over 1000 km from the Hunter River to Mallacoota (Fig. 1). Edible mussel occurs throughout this region (Hum 1970), with the northern limit of its range occurring at Wallis Lake, less than 100 km north. Of about 500 stratified rock platform or estuarine shell midden deposits investigated in this region during a study by Sullivan (1982) at least 20% clearly demonstrated a recent increase in the proportion of edible mussel. Sullivan (1982) observed that this change was widespread but variable in its nature and timing. In some sites edible mussel became the dominant shellfish species in terms of midden volume, but in many others where it did not achieve dominant proportions it made up an appreciable component only of the most recent midden layers. In some middens mussel remained an insignificant component throughout, but nowhere did it decline proportionally in the most recent layers. In some sites the change to mussel was abrupt whereas in others it was gradual. The change, while not synchronous, apparently occurred within the time period between about 1200 and 700 years BP. In this paper causes of the recent prehistoric change to edible mussel are examined. The answer relies essentially on an assessment of the degree to which environmental or cultural factors, or a combination of these, were responsible. On balance the ecological, archaeological and chronological evidence favours cultural rather than environmental explanations.