Assessment of Total Mercury Concentrations in Fish from Rivers, Lakes and Reservoirs in New Jersey: Research Project Summary
Date
2002-07
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Trenton, N.J. : New Jersey Department of Environmental Protection, Division of Science, Research and Technology
Abstract
In 1996-97, Academy Natural Sciences, Philadelphia (ANSP) conducted a study of mercury levels in freshwater gamefish in New Jersey. A total of 258 fish samples from 30 water bodies were analyzed. These included single fillet samples of 58 largemouth bass, 58 chain pickerel and 109 large specimens of other commonly consumed species and 32 whole-body analysis of forage fish species. The results of this study are consistent with ANSP 1992-93 mercury in fish research in New Jersey. The highest mercury concentrations were in fish from the Pine Barrens region and marginal to the Pine Barrens. Mercury levels varied greatly in fish from industrial areas, northern and northwestern waterways and cold-water streams. Mercury concentrations typically increased with species trophic level, but among-species variation within each group was observed. Highest levels were typically found in piscivorous species (e.g., chain pickerel, largemouth bass), as well as in larger and older specimens of all species analyzed. Lower mercury concentrations were seen in a wide variety of commonly consumed species including perch, sunfish, crappie, catfish and bullhead. Mercury levels in samples of forage fish varied by species and location. Elevated mercury concentrations in chain pickerel were explained by models identifying a decreasing gradient from low alkalinity, high DOC, low pH sites (e.g., Pine Barrens), to higher alkalinity, low DOC, high pH sites (e.g.some northern lakes). For chain pickerel, mercury concentrations were typically higher in fillets verses whole body, with median ratios of 1.3 times greater than the whole body. In addition, the results of the 1994-95 NJDEP 15 lake follow-up study (reported herein) are in agreement with the ANSP 1992-93 study and this investigation. Also reported herein is a review of the entire five-study database (1100 samples) showing that mercury is ubiquitous in New Jersey freshwater systems. Although regional differences exist (e.g., Pine Barrens), mercury has been found in freshwater fish from all geographical areas of the state. Mercury levels for the Pine Barrens and non-Pine Barrens fish are consistent over the entire database. Elevated mercury levels are identified in top trophic level species, in individual specimens from each trophic level and in larger and/or older specimens of all species. While mercury concentrations were generally found to be less in lower and bottom trophic level species, mercury concentrations in some of these most commonly consumed species were greater than NJDEP thresholds that can trigger fish consumption advisories
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New Jersey