Mercury Concentrations in Maine Sport Fishes

Abstract

To assess mercury contamination of fish in Maine, fish were collected from 120 randomly selected lakes. The collection goal for each lake was five fish of the single most common sport fish species within the si/e range commonly harvested by anglers. Skinless, boneless fillets of fish from each lake were composited, homogenized, and analyzed for total mercury. The two most abundant species, brook trout Salvelinusfontinalis and smallmouth bass Micropterusdolomieu. were also analyzed individually. The composite fish analyses indicate high concentrations of mercury, particularly in large and long-lived nonsalmonid species. Chain pickerel Esox niger, smallmouth bass, largemouth bass Micropterus salmoides, and white perch Morone aniericana had the highest average mercury concentrations, and brook trout and yellow perch Perca flavescens had the lowest. The mean species composite mercury concentration was positively correlated with a factor incorporating the average size and age of the fish. Lakes containing fish with high mercury concentrations were not clustered near known industrial or population centers but were commonest in the area within 150 km of the seacoast. reflecting the geographical distribution of species that contained higher mercury concentrations. Stocked and wild brook trout were not different in length or weight, but wild fish were older and had higher mercury concentrations. Fish populations maintained by frequent introductions of hatchery-produced fish and subject to high angler exploitation rates may consist of younger fish with lower exposure to environmental mercury and thus contain lower concentrations than wild populations.

Evaluation of Potentially Nonlethal Sampling Methods for Monitoring Mercury Concentrations in Smallmouth Bass (Micropterus dolomieu)

“…Previous studies of smallmouth bass demonstrated increasing Hg concentrations with size, age, or both (May et al 2000;Neumann and Ward 1999;Stafford and Haines 1997). However, and contrary to expectations, concentrations in our fish were poorly correlated with fish size and age.…”

“…Conversely, previously reported Hg concentrations in smallmouth bass from the Big River were lower than in the Current and Eleven Point rivers, which agrees with the lower concentrations in our samples from site 6 ( Table 3). The concentrations in our fish therefore appear typical for Missouri smallmouth bass, but they are lower than those in smallmouth bass from some other areas of the United States (e.g., Brumbaugh et al 2001;May et al 2000;Mueller and Serdar 2002;Neumann and Ward 1999;Stafford and Haines 1997;USEPA 2001). Concentrations in most of our fish exceeded the nationwide mean of 0.34 lg/g ww for smallmouth bass (USEPA 2001), but none approached the maximum reported by the USEPA (>5 lg/g ww).…”

Mercury Contamination of Biota from Acadia National Park, Maine: A Review

“…The fish tissue results also suggest that Hg concentrations in most fish species, with the exception of smallmouth bass, are generally lower on MDI than in other regions of Maine (Stafford & Haines, 1997;Burgess, 1997). Hg concentrations in lake trout from MDI ranged 0.21-0.32 μg/g ww, which is considerably lower than the statewide mean of 0.45 μg/g ww (Stafford & Haines, 1997). Similarly, Hg concentrations in landlocked salmon from MDI ranged 0.11-0.37 μg/g ww, whereas the statewide mean for this species is 0.35 μg/g ww (Stafford & Haines, 1997).…”

Bioaccumulation and Biomagnification of Mercury through Food Webs

“…The relationship between age and Hg concentration has been well documented in fish (e.g., lake whitefish, walleye, northern pike, and lake trout; Jackson, 1991;Evans et al, 2005). Stafford and Haines (1997) found that in particular, age and Hg concentrations were strongly positively correlated in non-salmonid fish species. There are, however, instances where concentrations do not change or actually decrease with age/size, likely due to dietary shifts to herbivory (e.g., some tropical fishes; da Silva et al, 2005).…”