The Effect of Seafood Processing Plant Effluent on Sentinel Fish Species in Coastal Waters of the Southern Gulf of St. Lawrence, New Brunswick

Abstract

Abstract This study evaluated effects of effluents discharged by seafood processing plants on populations of fish living in shallow estuarine waters of the southern Gulf of St. Lawrence. To monitor potential nutrient and/or toxicity impacts on fish populations living and possibly feeding in the effluent, we measured indices of survival (age), growth (weight-at-age), reproduction (gonad weight), and energy storage (liver weight, condition factor) on mummichog (Fundulus heteroclitus) and Atlantic silverside (Menidia menidia) in spring, summer, and fall. Fish exposed to effluents in three bays were compared to fish from a local reference site within the same bay and from regional reference sites in bays without seafood plants. Mummichog caught near seafood processing plants showed a number of differences from reference fish consistent with a localized nutrient enrichment effect including elevated growth (3 of 3 plants), liver size (2 of 3), and condition factor (1 of 3) in at least one of the months sampled. Female silverside caught near one of the three fish plants showed an elevated condition factor in spring, but otherwise silverside did not differ significantly from all four reference sites. In a number of cases, fish exposed to effluent differed from reference fish sampled from bays without fish plants but not from the local reference site, implying that the entire bay was affected either by the seafood processing plant or by some other factors. No harmful impacts such as reduced growth or survival were found in our study, possibly because the processing plants studied were relatively small and the amounts of waste discharged could be flushed by tides and currents and/or assimilated by the fish and other biota in the receiving environments.