Pollock (Pollachius virens (L.)) in the Bay of Fundy

Abstract

Observations made on the biology of the pollock in the western Atlantic, and primarily in the Bay of Fundy region of the northern Gulf of Maine, are presented. The largest landings of pollock in the western Atlantic are made in this area (ICNAF Division 4X). The best catches of large fish are made at temperatures above 1.1 °C, at depths of 20–100 fathoms (35–185 m) on the edges of shoals and banks where food is abundant. Spawning occurs in the winter and takes place in the southern Gulf of Maine and probably also on the Scotian Shelf, but not in the northern Gulf of Maine. The Bay of Fundy pollock are recruited from spawning in the southern Gulf of Maine and possibly on the Scotian Shelf. The pollock found in the Bay of Fundy appear to remain separate from those of the southern Gulf of Maine and the Scotian Shelf in the summer, but migrate south, spawn and probably mix with those of the southern Gulf of Maine, and possibly also those of the Scotian Shelf in the winter. The offshore pollock have a regular gradient in size across the Bay of Fundy; large fish (65–85 cm) are caught on the New Brunswick side, medium-sized fish (60–75 cm) around Grand Manan and smaller fish (45–60 cm) off western Nova Scotia. Catches with different size compositions are also found in small areas. Segregation by size into schools is therefore an important feature of pollock behaviour. The growth rate of pollock is rapid until the approximate time of sexual maturity, which occurs at ages of 4–7 years (50–65 cm) in the males and 5–7 years (55–70 cm) in the females. The growth rate of the immature and young, mature fish is similar to that recorded for other areas, but the older, mature fish appear to grow more slowly. It is suggested that this discrepancy may be due to biased sampling of the old fish in the Bay of Fundy due to the segregation by size. The 0-class pollock found in the shallow, sublittoral zone feed mainly on algae-inhabiting organisms and to a lesser extent on plankton. The 1-year-olds in the same location have a similar diet but consume a greater proportion of planktonic animals. The larger, offshore pollock in the Bay of Fundy are predominantly plankton eaters, and the euphausiid Meganyctiphanes norvegica is by far the most important organism in the diet. On the Scotian Shelf and in the Laurentian Channel fish is the dominant type of food, except for the smallest sizes of pollock.