Spawning and year-class strength of northern cod (Gadus morhua) as measured by pelagic juvenile cod surveys, 1991-1994

Distribution and abundance of pelagic juvenile northern cod (Gadus morhua) were studied during four years following stock collapse. We nominally rank year-class strength as 1994 > 1993 >= 1992 > 1991. Pelagic juvenile cod were mostly absent within the inshore area in 1991 along the northeast coast of Newfoundland (NAFO 2J3KL) whereas in 1992-1994, cod were observed throughout the inshore. Offshore, cod were observed infrequently during 1991-1993. However, in 1994, a large concentration of cod was observed offshore on the Northeast Newfoundland Shelf. The offshore distributions reflect changes in the spawning distributions of adults. The inshore distributions are believed to reflect inshore spawning. Successful spawning was limited to 1-2 mo duration, although the spawning period differed among years. Larvae hatched primarily during August in 1992, July-August in 1993, and June in 1994. We estimate that spawning in 1994 occurred from late April through May, similar to the historical median spawning time, whereas spawning in 1992 and 1993 was late. The differences in spawning times are interpreted to reflect changing spawning behaviour by adults.