Reappearance of Spawning Atlantic Herring (Clupea harengus harengus) on Georges Bank: Population Resurgence not Recolonization

Abstract

Spawning Atlantic herring (Clupea harengus harengus L.) have been recorded on Georges Bank for the first time since the collapse in 1977 of what had once been the largest herring fishery in the Northwest Atlantic. The reappearance after almost a decade could have resulted from resurgence of a residual extant Georges Bank population or from recolonization by fish from neighboring spawning groups. Three independent lines of evidence are consistent with the resurgence hypothesis: the Georges bank fish differed in age composition and isozyme characteristics from neighboring populations, and the reappearance was later than expected for recolonization. The degree of isozyme variability and of mitochondrial DNA lineage diversity gave no indication that stochastic events influenced the genetic structure of the herring population at Georges Bank after the collapse. The persistence of this population, in spite of considerable potential for recolonization, supports the discrete population concept in herring.