Judith S. Weis, Department of Biological Sciences, Rutgers University
Bluefish, Pomatomus saltatrix are the subject of valuable and popular recreational and commercial fisheries around the world, and populations have shown dramatic fluctuations in abundance. Consistently ranking in the top ten species harvested by weight by recreational marine anglers in the Mid-Atlantic, landings averaged 22,000 metric tons per year from 1974-2001 and commercial landings averaged an additional 14 million lbs per year (Lewis 2002). Substantial declines in catch over the past decade have triggered concerns. Recruitment has been declining since 1989, but the cause of the decline is still unknown (Lewis 2002). Possible causes include overfishing, declining habitat quality and reproductive success, and shifts in feeding ecology (MAFMC 1998).
Estuaries along the Mid-Atlantic Bight are considered “essential fish habitat” for young of the year (YOY) bluefish (Fahay et al. 1999, NOAA 2006). Their health at this life stage is an important factor determining the stock size of fish (Gartland et al. 2006). Their residence in contaminated estuaries during critical periods of growth, their high lipid content, and their piscivory make bluefish likely to acquire high levels of contaminants that biomagnify up the food chain (O’Connor et al. 1982, Kennish and Ruppel 1998, Buckel et al. 1999, Deshpande et al. 2002). We have previously shown in a lab experiment that YOY bluefish from Tuckerton, NJ (a relatively clean estuary) accumulate very high levels of PCBs and chlorinated pesticides when fed prey from the contaminated Hackensack River, NJ. Feeding on the contaminated prey resulted in a significant reduction in appetite, swimming activity, and growth (Candelmo 2005, Candelmo et al in preparation). Thus, fish from contaminated sites like Hackensack would be migrating out of the estuaries slower and smaller, and therefore potentially more vulnerable to predation and starvation (Buckel et al. 1999) than fish that had been in cleaner estuaries.
The Fishery Management Plan for bluefish reported in 2002 that future research needed to include the study of contaminants on their survival, and include studies on predator/prey relationships (Lewis 2002). This project will provide better insight into the foraging ecology and recruitment success of young-of-the-year bluefish residing in polluted habitats such as the Hackensack River. It is important to assess how characteristics of a habitat might affect the quality of the YOY, creating a linkage between habitat quality and year class strength. The study will foster collaborations among Rutgers professor Weis, graduate student Allison Candelmo, the NOAA Fisheries Lab in Sandy Hook, and the MRRI lab, and provide data for future proposals to NOAA or other federal agencies.
PCB fingerprints can provide a means to identify which estuary the fish migrated out of after they have joined the adult population, and possibly how much these fish from contaminated estuaries are contributing to the stock. Mid-Atlantic estuaries have varying degrees of contamination, and other commercially and recreationally important fish use them as nursery grounds. It is important to identify effects of contaminants on their health and survival, because changes in behavior and possible decreases in juvenile survival may alter community dynamics as well as cause an overall decline in stocks.
The research will also provide data for the improvement of fish advisories. The human health risk from consuming fish, especially self-caught fish is an important issue. Relationships have been reported between mercury and PCB levels in fish, fish consumption by pregnant women, and deficits in neurobehavioral development in children. In order for fish advisories to be effective it is necessary to have information on contaminant loads in the fish that subsistence and recreational fishermen are catching. Because bluefish are migratory, the location of catch does not denote prior residency and won’t indicate contaminant exposure (Gartland et al. 2006). Overall, a better understanding of the condition of the young-of the year bluefish when they migrate from contaminated estuaries will help implement improved management plans and fishery advisories for this species.