ATLANTIC HERRING PROJECT
(Arran McPherson, lead researcher)

Objectives

Microsatellite variability was used to examine population structure of Atlantic herring (Clupea harengus) in the Scotia-Fundy region and the role that oceanographic processes may play in explaining the structure, or lack thereof. Fisheries related genetic studies, until very recently, frequently failed to address oceanographic processes as genetic structuring agents. This prompted Arran to characterize the population structure of Atlantic herring in the region within an oceanographic (and therefore dynamic) framework.

Approach

Working within the Canadian Biotechnology Strategy, Arran developed nine highly polymorphic tetranucleotide microsatellite loci for Atlantic herring, using magnetic bead hybridization selection: Cha 1005, 1014, 1017, 1020, 1027, 1045, 1059, 1202, 1235. She has used these markers and tetranucleotide microsatellites developed for Pacific herring, as her main investigative tools.

(Atlantic herring microsatellite locus Cha1027)

Tissue samples from spawning fish were collected from ~15 spawning locations in the Scotia-Fundy region as well as from many geographically distant locations (eg. Celtic Sea, Iceland, Baltic Sea). In addition, larval herring samples have been collected from two very different oceanographic systems: 1 - offshore in the Western Bank region where there is clear evidence of population resurgence (from commercial extinction); 2 - where circulation might be playing a role and in the Nova Scotia coastal current where there are many putative spawning populations and where there is clear evidence of large scale advection.

Chart illustrates several spawning locations on the Scotian Shelf where spawning stage adult herring were collected. Circle colour indicates inferred associations among spawning groups (e.g. locations with red circles are similar to each other and different from locations represented by circles of a different colour).

Results

Analyses revealed evidence of population structure at the oceanic, basin and shelf scales as herring collected from the Scotia-Fundy region were found to be statistically different from those collected from both the Pacific and northeast Atlantic. Arran also found evidence consistent with differences among spawning groups within the Scotia-Fundy region that appear to have some element of temporal stability. The emergent results are certain to provide insights on genetic structuring processes in Atlantic herring, related retention and dispersal hypotheses, as well as the appropriate scale for population-based exploitation and management.

Arran wishes to thank personnel from St. Andrews Biological Station, L. Sullivan, L. Lewis, D. Ruzzante and many commercial fishers for their assistance in securing samples.