BLOOD LEAD CONCENTRATIONS OF WATERFOWL FROM UNHUNTED AND HEAVILY HUNTED MARSHES OF NOVA SCOTIA AND PRINCE EDWARD ISLAND, CANADA

Abstract

Blood lead concentrations of juvenile American black ducks (Anas rubripes) sampled in unhunted sanctuaries of Nova Scotia (NS) and Prince Edward Island (PEI), Canada, usually were < 30 parts per billion (ppb). Based on gizzard content analyses of juvenile American black ducks from hunted areas, eight (24%) of 33 flightless birds contained ingested lead shot. Blood lead concentrations were > or = 100 ppb in seven of eight juveniles with ingested shot; thus we adopted blood lead concentrations 100 ppb as our threshold indicating exposure to non-background lead. The proportion of both American black ducks and ring-necked ducks (Aythya collaris) with elevated blood lead concentrations (> 100 ppb) exceeded 5% in hunted areas sampled in NS and PEI combined. The Canadian Wildlife Service draft policy is to consider replacing lead shot with non-toxic shot for waterfowl and snipe hunting if 5% of American black ducks exceed a blood lead concentration of 200 ppb. American black ducks significantly (P < 0.05) exceeded this threshold but ring-necked ducks did not. The source of lead in hunted areas may have been lead shot; we recommend that it be eliminated and replaced by an acceptable non-toxic shot for waterfowl hunting. Twenty four (96%) of 25 of American black ducks overwintering in Sullivans Pond, Dartmouth, NS, contained elevated (> 100 ppb) blood lead concentrations and 19 (76%) had detrimental concentrations (> 200 ppb). We believe that the source of lead at Sullivans Pond was automobile emissions.