Capelin ( Mallotus villosus ) Spawning on the Southeast Shoal: Influence of Physical Factors Past and Present

Capelin Mallotus villosus is the most abundant pelagic fish species in boreal and subarctic waters. The ecological and commercial importance of capelin emphasizes the need for a better understanding of the genetic population structure of the species and the mechanisms underlying its population dynamics. With this aim, 1155 capelin from the entire distributional range of the species were genotyped using 9 recently-developed microsatellite markers. The genetic analyses clearly demonstrated that the circumpolar capelin population can be divided into 4 regional groups: (1) West Pacific, (2) East Pacific, (3) Newfoundland, and (4) Northeast Atlantic and West Greenland. Highly significant genetic differentiation was observed between capelin from the western and eastern Pacific, and a high assignment success within both regions indicated minimal gene flow between these populations. Within the Atlantic Ocean, the Newfoundland population was differentiated from all the other samples. Among the remaining samples within the Atlantic Ocean the microsatellite data were less conclusive. Comparison of our results with studies of species with similar distribution, duration of planktonic stages and dispersal capacity suggests that genetic structuring of capelin within the complex system of the Northeast Atlantic Ocean cannot be ruled out. KEY WORDS: Mallotus villosus · Population structure · Genetic differentiation · Microsatellite markersResale or republication not permitted without written consent of the publisher

Section: Introductionmentioning

confidence: 99%

Circumpolar genetic population structure of capelin Mallotus villosus

Præbel

Westgaard²,

Fevolden³

et al. 2008

“…Capelin overwinter in offshore feeding areas near the shelf edge off Newfoundland. They undergo extensive migrations inshore during March to April in order to spawn, primarily on coastal beaches (Carscadden et al 1989). Capelin first arrive inshore near SE Newfoundland during May , after which they migrate north along the east coast during June and spawn on or near beaches during July (Nakashima 1992).…”

Section: Introductionmentioning

confidence: 99%

Scale-dependent associations of predators and prey: constraints imposed by flightlessness of common murres

Davoren

Montevecchi²,

Anderson³

2002

We examined the behavioural interactions of a mobile marine predator, the common murre Uria aalge, and its prey in a cold ocean regime in the context of shifting foraging constraints of the predator during various periods of the year. To do this, we explored the scale-dependent distribution patterns of murres in relation to their prey under 2 mobility regimes: (1) during the pre-breeding period when murres can fly and (2) during the post-breeding or moulting period when murres are flightless and are accompanied by flightless juveniles. In addition, we documented for the first time the relative contributions of different prey types in the diets of murres during moult using stable isotopic analysis. Flightless adult and juvenile murres were concentrated on a meso-scale (>100 km) in an area (nursery area) where significantly greater amounts of non-capelin, mainly crustaceans, were located in closely spaced aggregations. Accordingly, flightless murres had variable proportions of fish (capelin Mallotus villosus) and crustaceans in their diet, whereas breeding murres exclusively ate capelin. At fine-and coarse-scales (0.1 to 100 km), murres that could fly during pre-breeding tracked prey at smaller spatial scales (3 to 4 km) than flightless murres (6 to 9 km). We hypothesize that varying mobility regimes and energetic demands (activity levels) of murres during these 2 periods resulted in divergent perceptions of the foraging environment and subsequently in varying tracking scales of prey. This has important implications for the scale of study during different periods of the annual cycle of a predator, when varying constraints and trophic levels may interact to produce diverse behavioural responses to prey distribution and densities.

“…As the glaciers melted and receded about 12000 yr ago, the Grand Banks were flooded. Geologic evidence indicates that the shallow Southeast Shoal was once a beach and Carscadden et al (1989) proposed that the Southeast Shoal stock was once a beach-spawning stock. The Avalon ice cap extended over Newfoundland onto the Grand Banks and as a result, present day capelin spawning beaches were ice covered.…”

Section: Introductionmentioning

confidence: 99%

“…The Avalon ice cap extended over Newfoundland onto the Grand Banks and as a result, present day capelin spawning beaches were ice covered. Thus, a logical hypothesis arising from Carscadden et al (1989) is that all of the stocks now spawning on beaches in the northwest Atlantic originated from the once beach-spawning Southeast Shoal stock during glacial retreat. Thus, present-day NW Atlantic capelin stocks would represent a monophyletic group derived from a common ancestral stock no more than 10000 to 12000 yr ago.…”

Section: Introductionmentioning

confidence: 99%

Relationship between spawning mode and phylogeographic structure in mitochondrial DNA of North Atlantic capeiin Mallotus villosus

Dodson¹,

Carscadden²,

Bernatchez³

et al. 1991

Capelin Mallotus villosus spawn on beaches in Alaska and British Columbia, but spawn offshore in Icelandic waters and the Barents Sea. Both modes of reproduction CO-occur In the northwest Atlantic. The Southeast Shoal population spawns on the Grand Banks 350 km to the SE of Newfoundland at the same time as other stocks, all of which are beach spawners. These observat~ons gave rise to 2 alternative hypotheses concerning the zoogeography and evolution of life cycle in capelin. First, the Southeast Shoal population was originally a beach-spawning population during the late Wisconsinian glaciation and is ancestral to all other northwest Atlantic capelin stocks. In such a case, present-day stocks from this area would represent a monophyletic group derived from a common ancestor no more than 10000 to 12000 yr ago. The alternative hypothesis is that the 2 modes of reproduct~on onginally evolved in ~solatlon. Beach spawners are hypothesized to have originated in the north Pacific and recolonized Canadian Arctic waters and the northwest Atlantic following glaciation Bottom spawners originated in the North Atlantic and continued to reproduce where environmental conditions permitted. In such a case. genetic divergence among bottom-spawners and among beach-spawners from across the North Atlantic would be less than that between beach-and bottom-spawners. We tested these hypotheses by comparing mitochondrial DNA (mtDNA) restriction fragment length polymorphisms among 6 stocks of beachspawning capelin (St. Lawrence estuary; Gulf of St. Lawrence; Placentia Bay, Conception Bay and Notre Dame Bay, Newfoundland; Nain, Labrador) and 3 stocks of bottom-spawning capelin (Southeast Shoal; Iceland; Barents Sea). We observed 2 major mtDNA genotype groups separated by a mean sequence divergence of 3.42 O/O, clearly reflecting the genetic separation of the Iceland and Barents Sea stocks from the northwest Atlantlc stocks. No geographical heterogeneity in the frequency of mtDNA genotypes was observed among the northwest Atlantic sampling sites. However, differences in nucleon diversities among sites did not support the view that capelin form one large panmictic population in the northwest Atlantic. Although our results do not permit the identification of the Southeast Shoal stock a s ancestral to northwest Atlantic capelin, these observations refute the hypothesis that the beach-and bottomspawning stocks evolved in isolation long before the end of the Wisconsinian glaciation.