Stock Definition in Atlantic Herring (Clupea harengus harengus): Genetic Evidence for Discrete Fall and Spring Spawning Populations

Abstract

Migratory Fish Research Iflsritufe and Depcaras~serzb o j ' Z o~&~g y , U~~iversiQ of Maine ar Orcmo, Oroncr, ME 04469, USA KORNPIELD, I., B. B. SIDELL, AND P. S. GAGXON. 1982. Stock definition in Atlantic herring (Clupea haremgrxs haremgcts): genetic evidence for discrete fall and spring spawning populations. Can. J . Fish. Aquae. Sci. 39: 16310-1621.Ripe Atlantic herring (Cbupea harelagrrs harengks~s.) were sampled from seven discrete spawning grounds in the Gulf of Maine and Gulf of St. Lawrence over a period of 3 yr. Genetic polymophisrns were observed at 13 enzyme loci by starch gel electrophoresis. Five highly polymorphic loci were used to assess population structure of herring stocks by ctantingency analysis of log-likelihood differences in gene frequencies. Significant temporal variation was observed at several localities. Within both spring spawning and faII spawning populations, significant spatial heterogeneity was noted for particular years, but was not temporally stable. By contrast. overall heterogeneity between spring and fall spawning populations was highly significant indicating genetic isolation of spring spawning populations in the Gulf of St. Lawrence frcxn fa11 spawning aggregates in the Gulf of St. Lawrence and Gulf of Maine. The low levels of genetic heterogeneity and absence of both temporal stability within fall spawning samples aand spatial stability among sansples is not consistent with the existence of more than a single genetic population of fall spawning herring in the northwest Atlantic. KORNAELD, I., B. D. SIDELL, AND P. S. GAGNON. 1982. Stock definition in Atlantic herring (Clupea harengus harengus): genetic evidence for discrete fall and spring spawning populatioass. Can. J . Fish. Aquat. Sci. 39: 1618-1621.Nsus avons prblev6 des 6chantillons de harengs de I'Atlantique (CCupen hur-engm hurengus) sur le point de frayer a hept fray2res distinctes dta golfe du Maine et du golfe da~ Saint-Laurene sur une pCriode de 3 ans. L'klectrophorese sbnr gel d'amidsn a perrnis d9obser-vcr un plymorphisme gCnCtiquc 5 13 loci d'enayrne. NOUS en VOWS choisi cinq nettement poiyrnnrphes pour tvaluer la structure de population de stocks de harengs par analyse Je contingence des diffkreances de prokabilitb dans la fr@quence des gkneb. On a trouwC une variation temporelle significative B plusieurs endroits. Dans des annkes particuli?res, nous avons not6 une h6tCrogdnCit6 spatlak significative tant dans Ies populations de repr06iucteurs de printen~ps qlac dam cellcs des reproducteurs d'aueomne. Cette hCtCrogenCit6 n9est toutefois pas stable dans le temps. Par contre, 19hCtCrogCn6itC entre reprcpducteurs de prineernps ea rcproducteurs d9automne est trcs significative, signc d'une skparation g6nCtique entre les populations de reproducteurs de printernps du golfe du Saint-Lauren1 et tobates Ies agglomkrations reproduetrices du golfe du Saint-Laurent ct du goIfe du Maine. La faible hCeCrog6w6itk gCnktique 28 19absence, a la fois de stabilitk ternporelle dans les 6chantillons de reproducteurs d'autornne et d...

Genetic Differentiation, Temporal Stability, and the Absence of Isolation by Distance among Atlantic Herring Populations

“…However, where Kornfield et al (1982) did not demonstrate temporal stability among annual collections from the Gulf of St. Lawrence and Gulf of Maine, King et al (1987) did demonstrate temporally stable patterns of genetic variation in North Sea herring when comparisons were based on year-classes. The contrasting results and interpretations of King et al (1987) and Kornfield et al (1982) may simply reflect the different protocols used to assess temporal variation. Although a test of hypotheses related to stability would optimally include samples from each year-class sampled across years (thus allowing a comparison among year-classes through time), the requisite material would be difficult to obtain.…”

“…The correlation between allele frequencies of replicate samples and the genetic homogeneity among cohorts from the same location (and in most cases between collections in subsequent years) are consistent with genetic temporal stability at the scale of the spawning group. Kornfield et al (1982) concluded that it was doubtful that generational or year-class differences contributed significantly to population differentiation due to the presence of overlapping generations in the collections and the fact that Atlantic herring are iteroparous. However, where Kornfield et al (1982) did not demonstrate temporal stability among annual collections from the Gulf of St. Lawrence and Gulf of Maine, King et al (1987) did demonstrate temporally stable patterns of genetic variation in North Sea herring when comparisons were based on year-classes.…”

“…Kornfield et al (1982) concluded that it was doubtful that generational or year-class differences contributed significantly to population differentiation due to the presence of overlapping generations in the collections and the fact that Atlantic herring are iteroparous. However, where Kornfield et al (1982) did not demonstrate temporal stability among annual collections from the Gulf of St. Lawrence and Gulf of Maine, King et al (1987) did demonstrate temporally stable patterns of genetic variation in North Sea herring when comparisons were based on year-classes. The contrasting results and interpretations of King et al (1987) and Kornfield et al (1982) may simply reflect the different protocols used to assess temporal variation.…”

“…Far less consideration has been given to the ecological mechanisms that may be responsible for producing patterns of differentiation. The majority of previous genetic studies on herring have used indi-viduals of uncertain spawning status (which is arguably insufficient for effective tests of genetic isolation) and have generally concluded that despite the existence of apparently discrete spawning components (Sinclair and Tremblay 1984) and the presumed high degree of spawning site fidelity thought to be characteristic of herring (Iles and Sinclair 1982), gene flow has been sufficient to prevent Atlantic herring populations from becoming reproductively isolated (e.g., Kornfield et al 1982). Alternatively, it has been postulated that herring may only have begun the process of differentiation in their recent evolutionary history, such that resolvable genetic differences have yet to evolve (e.g., Grant 1984), though this contention appears difficult to test.…”

Genetically different Atlantic herring Clupea harengus spawning waves

“…This can occur even when the sampling strategy is considered optimal (e.g. spawning Atlantic herring Clupea harengus collected on the spawning grounds; Kornfield et al 1982). …”