White hake (Urophycis tenuis) in the Gulf of Maine: Population structure insights from the 1920s

White hake (Urophycis tenuis) provides an important fishery in the Gulf of Maine (GOM) that is currently depleted. Even though several year classes are present, there is little evidence of white hake reproduction occurring along the northern coastal shelf. Based on survey indices of early life history stages, researchers concluded that they reproduced at one of the two population centers located either from the Scotian Shelf area in eastern GOM or from the Georges Bank-Mid Atlantic Bight area. White hake have been absent from large areas of the GOM for more than 15 years and this suggests substantive changes may have occurred in their distribution since the 1920s. Various factors may have contributed to this observation, including the loss of spawning aggregations. This study examined the historical population structure of white hake in the Gulf during the 1920s, a period when stocks were more abundant. Their seasonal distribution, movement patterns and the behavior of individual population components were derived from relevant scientific literature and surveys of fishermen gathered during the period. The study identified several resident groups of white hake near the coastal shelf that displayed cyclic movement patterns to fishing grounds that have been abandoned for decades. The comparison of historical distribution patterns to recent white hake surveys revealed the loss of resident white hake groups from grounds bordering the northern GOM coastal shelf that apparently were undetected spawning components. Significance of the predator–prey linkage with alewives is discussed.

► Gulf of Maine (GOM) maps show 1920s white hake distribution and movements.
► Maps show the population structure of 1920s white hake in the GOM.
► White hake and alewife movement patterns are compared.
► Predation is linked to alewives and the formation of coastal white hake groups.