Weakfish (Cynoscion regalis)

Description

Weakfish (Cynoscion regalis) have long, compacted bodies and grow to approximately 5 kilograms in weight and 90 centimeters in length (Grosslein and Azarovitz 1982, Weiss 1995). Coloration is typically an iridescent, dark olive green with dark spots on dorsal and lateral sides and white to silver on the ventral surface. Their long heads bear pointed snouts, large mouths, and projected lower jaws. The name weakfish describes these brittle, easily broken jawbones. Weakfish have a pair of large canine-like teeth along the upper jaw and a row of teeth on the lower jaw (Mercer 1989). As members of the family Sciaenidae, commonly known as drum fishes, weakfish produce a drum-like sound by vibrating their swim bladders (Grosslein and Azarovitz 1982).

Background

Distribution. Weakfish are distributed from Florida to Massachusetts Bay and sometimes to Nova Scotia; the species has also been identified in the Gulf of Mexico (Mercer 1989). Younger fish (less than four years) migrate south in the winter and north during spring. Adults tend to migrate offshore in the fall as temperatures decline and return to their inshore grounds in the spring when the coastal waters begin to warm (Grosslein and Azarovitz 1982, Mercer 1989).

Berg and Levinton (1985) indicate that weakfish are the ninth most abundant species in the Lower Bay area and seventh in the Lower Hudson River. They have been identified in most portions of New York/New Jersey Harbor (Dowhan et al. 1995); they reside in Raritan Bay and use the bay as a spawning and nursery area (MacKenzie 1990). Weakfish are also abundant in the lower regions of the Arthur Kill.

Feeding. Weakfish feed mainly between dusk and dawn, which coincides with feeding habits of their prey. Younger (smaller) weakfish eat invertebrates and smaller fish, while older (larger) fish are piscivorous, (Grosslein and Azarovitz 1982; Mercer 1989). Fish food species include the anchovy, killifish, silversides, young herring, porgies, and smaller conspecifics. Invertebrate prey include mysid shrimp, small crabs, worms, and clams (MacKenzie 1992).

Fishery. Weakfish are important in both the commercial and recreational fisheries. Landings for both commercial and sport fisheries were relatively equal during the 1960s and 1970s, though the NY Bight population declined from 1910 to 1960, then recovered in the 1970s (Grosslein and Azarovitz 1982). According to the National Marine Fisheries Service (1999), landings reached a peak in 1980 and then began to decline again. Heavy fishing by both commercial and sport fisheries is believed to be the principal cause of population decline in recent years.

Life Cycle

The weakfish spawning period occurs along the coast and in estuaries from May to October, peaking in the New York Bight population from May to mid-July. Females can produce more than 300,000 buoyant, spherical eggs (Mercer 1989), which average 0.9 to 1.0 millimeters in diameter (Grosslein and Azarovitz 1982). Larvae hatch in approximately 48 hours and take up residence in estuaries from April to August. By their fifth month, larvae reach approximately 180 millimeters in length and migrate out of their estuarine nursery areas. Weakfish are found frequently on intake screens of power generators in NY/NJ Harbor at the time of their migration out of the bay (Berg and Levinton 1985). Adults migrate offshore in the fall, but juveniles spend their first year in the protection of the Harbor. Sexual maturity is usually attained at one year, but some begin spawning in their second year (Grosslein and Azarovitz 1982). Weakfish typically live to an age of nine years (MacKenzie 1992).

Environmental Influences

Salinity. Weakfish are euryhaline and have been found at various salinities (Dowhan et al. 1995).

Predation. Weakfish are top predators and are primarily consumed by humans and larger predatory fish.

Pollution. Weakfish are susceptible to pollution-induced disease such as fin rot, which can be pervasive in the New York Bight area. While pollution can affect weakfish populations, the fish are able to recover quickly when the pollution source is removed (Mercer 1989).

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