Recruitment of the 1987 Year Class of Georges Bank Haddock (Melanogrammus aeglefinus): The Influence of Unusual Larval Transport

Abstract

Unusually strong along-shelf surface flow in the spring of 1987 transported haddock (Melanogrammus aeglefinus) larvae westward from spawning grounds on Georges Bank into the Middle Atlantic Bight, some as far as 400 km beyond the limits of their normal distribution. 0-Group haddock survived in the Bight in record numbers. Their center of abundance occurred along the outer half of the shelf from Delaware Bay to Martha's Vineyard where more than 97% of the 0-group fish resided in the fall of 1987. Juveniles remained more abundant in the Bight than on the bank through the spring of 1988. Collective evidence suggests that survivors returned to Georges Bank during the late spring/early summer of 1988. The estimated number of 0-group fish in the 1987 year class exceeded all previous estimates from a 27-yr time series which included the 1963 year class, the largest recruited to the fishery since record keeping began in 1931.

Modeling the connectivity between sea scallop populations in the Middle Atlantic Bight and over Georges Bank

“…However, drifters deployed on GB have drifted down to the MAB, with a maximum velocity of 80 km d -1 (Lozier & Gawarkiewicz 2001). Fish larvae have also been found to drift from GB to the MAB (Polacheck et al 1992). The along-shelf current has considerable interannual variability, leading to fluctuations in larval dispersal.…”

“…The tidal-mixing-front recirculation is believed to play a key role in larval retention and population maintenance on GB (Tremblay et al 1994). The along-shelf current, however, can transport larvae away from the region (Polacheck et al 1992, Lozier & Gawarkiewicz 2001. These currents are subject to local forcing such as wind (Noble et al 1985, Houghton et al 1988 as well as remote forcing such as the coldwater intrusions from the Nova Scotian Shelf (Greene & Pershing 2003) and warm core rings from the Gulf Stream (Beardsley et al 1985).…”

Hatch date distributions of young-of-year haddock Melanogrammus aeglefinus in the Gulf of Maine/ Georges Bank region: implications for recruitment

“…Due to their commercial and ecological importance, there is a large body of literature examining recruitment processes of haddock and other gadoid species. This literature focuses on a variety of factors including the effects of egg and larval transport (Polacheck et al 1992), larval and early juvenile growth (Campana 1996), density-dependent growth and mortality (Ross & Nelson 1992), and habitat selection ) on recruitment variability. These studies highlight the complexity of recruitment processes and the great difficulty of predicting year-class strength.…”

Short term variability in larval fish assemblages of the Sydney shelf:tracers of hydrographic variability

“…In addition, recruitment patterns of post-larvae indirectly implicate the importance of physical processes in larval advection (e.g. Cowen 1985, Polacheck et al 1992, Castillo et al 1994, Fechhelm et al 1994, Sponaugle & Cowen 1996, Jenkins et al 1997.…”