Bluefish Habitat Model
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Bluefish, Pomatomus saltatrix
Use of Study Area Resources:
Juvenile and adult growth, migration. The bluefish is a pelagic marine fish of the warmer parts of all oceans. On the east coast of North America bluefish range from Florida to mid-coast Maine, generally west of Penobscot Bay (Bigelow and Schroeder 1953, Jury et al. 1994). Creaser and Perkins (1992) confirmed one collection as far east as Little Kennebec Bay, near Maine's eastern border. Bluefish are sought in both recreational and commercial fisheries. Adult bluefish inhabit both inshore and offshore areas of coastal regions with young fish often frequenting estuaries and river mouths (Bigelow and Schroeder 1953).
Spawning occurs over the continental shelf in the mid- and south Atlantic Bight; eggs and larvae may be found from Cape Cod to Florida. Young belong to one of two distinct cohorts; the predominant spring-spawned cohort results from spawning in the south Atlantic Bight in March and April. A second less abundant cohort results from summer-spawning in the mid-Atlantic Bight, and recruits to inshore areas in August (Juanes and Conover 1995). The fry are carried northward on the edges of the Gulf Stream.
Bluefish populations are highly variable, and have been described as nearly irruptive (Bigelow and Schneider 1953). No doubt this is due to the variability in survival of eggs and larvae which are stongly influenced by the circulation patterns of currents on the continental shelf. If they are moved shoreward to suitable habitats, many survive; if they are swept of the continental shelf, higher mortality may result. (Ross 1991).
Juvenile bluefish, known as snappers, feed on small fish, crustaceans, molluscs and polychaetes. Juveniles < 10 cm in length feed mostly on crustaceans (Bigelow and Schroeder 1953, Creaser and Perkins 1992). Adults feed opportunistically on fish, squid and eels. They normally travel in large schools and their feeding behavior is legendary, as described by Ross (1995): Bluefish dash wildly about within schools of prey species, biting, crippling, and killing numerous small fishes, most of which are subsequently eaten. They frequently drive schools of prey species into shallow inshore areas where it is easier to cripple or catch individuals trying to escape. (Infrequently) during particularly frenzied feeding activity, schooling fishes such as menhaden will literally be driven to shore, leaving a number of individuals beached along the wave line. Males and females mature within two years, and may live as long as twelve years (Fahey et al. 1999)
Bluefish appear in northern waters as warm season migrants only (Bigelow and Schroeder 1953). Both adults and juveniles are found predominantly in waters less than 20 m deep (Fahey et al. 1999). Adults inhabit both inshore and offshore areas of the coast, while juveniles are dependent upon shallower habitats in estuaries and river mouths (Ross 1991, Juanes and Conover 1995). Temperature and photoperiod are the principal factors directing activity, migrations, and distribution (Olla and Studholme 1971 in Moore 1989). .
While adult bluefish are largely oceanic, Creaser and Perkins (1992) collected juveniles in salinities ranging from 9 to 27 ppt. Smale and Kok (1983 in Creaser and Perkins 1992) reported occurrences in 12 to 25 ppt.
Habitat was mapped using the Essential Fish Habitat designations of NOAA/NMFS, which are based on available occurrence information and environmental characterizations of major estuaries. The narratives from the www site: "Guide to Essential Fish Habitat Designations in the Northeastern United States", http://www.nero.nmfs.gov/ro/doc/newefh.html [as of 7/00] were used to indicate the appropriate zones , by coastal embayment, throughout the study area. The zones were actually delineated from a GIS coverage of fresh, mixing, and seawater estuarine zones for the Northeast (provided by Kenneth Buja, NOAA), with boundaries adjusted to conform to 'local' salinity data sets with higher resolution. In addition, inshore areas between these Essential Habitat polygons with depths from mid-intertidal to -30 m were mapped as "corridors".
Habitat suitability for this model is scored on the basis of probability of use. Essential Fish Habitats were scored 1.0, while the connecting inshore areas were scored 0.5.
Model testing: Occurrences of juvenile bluefish were digitized from tables in Creaser and Perkins (1992), and adult occurrences were added from NOAA/NMFS inshore trawl surveys. We examined the association of habitat, based on the model, with occurrences at these 37 sites. Similarly, we examined the coincidence of bluefish habitat with randomly distributed sites. Of the 37 sites with birds, 30 had mapped habitat, while only 32 out of 382 randomly distributed sites in coastal and offshore waters of the Gulf of Maine had habitat. A Chi-square analysis comparing these proportions showed them to be significantly different, indicating that this model does indicate localities useful for bluefish.
Bigelow, H.B. and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. U.S. Fish. Wildl. Serv. Fish. Bull. 74(53), 577 p.
Creaser, E.P. and H.C. Perkins. 1992. The distribution, food and age of juvenile bluefish, Pomatomus saltatrix in Maine. Final Report F-36-R-2 to Maine Dept of Marine Resources, West Boothbay Harbor, ME. 56 p.
Fahey, M.P., P.L. Berrien, D.L. Johnson and W.W. Morse. 1999. Essential Fish Habitat Source Document: Bluefish, Pomatomus saltatrix, Life History and Habitat Characteristics. NOAA Technical Memorandum NMFS-NE-144, September 1999, 68 p.
Juanes, F. and D.O. Conover. 1995. Size-structured piscivory: advection and the linkage between predator and prey recruitment in young-of-the-year bluefish. Marine Ecology Progress Series 128:287-304.
Jury, S.H., J.D. Field, S.L. Stone, D.M. Nelson and M.E. Monaco. 1994. Distribution and abundance of fishes and invertebrates in North Atlantic estuaries. ELMR Rep. No. 13. NOAA/NOS Strategic Environmental Assessments Division, Silver Spring, MD. 221 p.
Moore, C.M. 1989. Fishery Management Plan for the Bluefish Fishery, Mid-Atlantic Fishery Management Council. Fishery Management Report No. 14 of the Atlantic States Marine Fisheries Commission.
Ross, M.R. 1991. Recreational Fisheries of Coastal New England. University of Massachusetts Press, Amherst, MA. pp 185-189.