THE DISTRIBUTION, FOOD, AND AGE OF JUVENILE BLUEFISH, POMATOMUS-SALTATRIX, IN MAINE

The bluefish, Pomatomus saltatrix (Linnaeus), is abundant in the South and Middle Atlantic Bights, where more than 75% of the shore-based ca tches are juveniles (age 0). No information is available on the distri bution, food, and age of juvenile bluefish north of the Middle Atlanti c Bight. The objectives of the present study were to review and summar ize unpublished records of catch locations, to characterize the diet o f juvenile bluefish, and to derive parent spawning dates (and possible spawning locations) for juvenile bluefish in Maine. Most observations of juvenile bluefish were from southwestern Maine. The most northeast erly site was Little Kennebec Bay (near Machiasport, Maine). During th is study juvenile bluefish were collected from three locations: Marsh River (1990-1991), Sagadahoc Bay (1990), and Merepoint Bay (1991). The diet of juvenile bluefish varied with size. Fish from Sagadahoc Bay, measuring 37-64 mm fork length (FL), fed predominantly on mysids and c opepods. Fish from the Marsh River, measuring 81-200 mm FL, fed on fis h and large crustaceans. Daily growth rings were counted on the sagitt a of juvenile bluefish. Spawning dates, backcalculated from these coun ts, suggest that fish captured in the Marsh River (1990-1991) originat ed from a spring spawning (March-May), and fish captured in Sagadahoc Bay (1990) originated from a summer spawning (predominantly June). We do not believe that these spring and summer spawned fish originated fr om the known major spring and summer spawning grounds in the South and Mid-Atlantic Bights, respectively. The time required to swim from eve n the northern portion of these major spawning grounds to the site of capture exceeds the known age of the fish derived from counting daily growth rings. The results suggest that both major spawning areas have been extended to the northeast, or unknown spawning areas exist closer to Maine.