The history of sturgeon in the Baltic Sea

Abstract

Aim Migrants of the Atlantic sturgeon, Acipenser oxyrinchus, from North America are thought to have founded the Baltic sturgeon population during the Little Ice Age around 1200 years ago, replacing the European sturgeon, Acipenser sturio. To test this hypothesis and to further elucidate the colonization of the Baltic Sea by A. oxyrinchus, we carried out DNA analyses of ancient and contemporary populations of both species. Location We analysed DNA from 188 specimens of sturgeons collected from archaeological sites and museums in Poland and of 225 contemporary specimens from North American and European populations. Methods Several mitochondrial DNA fragments were sequenced and eight microsatellite loci were genotyped for species identification, polymorphism and population structure analyses. Approximate Bayesian computation was used to estimate when the Baltic Sea was colonized. Results Of 125 ancient sturgeon specimens from the Baltic Sea, only four were classified as A. sturio, the remainder being A. oxyrinchus oxyrinchus. The ancient A. o. oxyrinchus population over two different time periods was highly polymorphic and genetically distant from contemporary populations of this taxon. The time of entry into the Baltic Sea was estimated to be 4000–5000 years ago. We also detected introgression of A. sturio into the A. o. oxyrinchus gene pool, caused by a prior hybridization event. Main conclusions For the past 2000 years at least, A. o. oxyrinchus has been the dominant sturgeon in the Baltic Sea, indicating a much earlier origin than previously suggested. The most similar extant sturgeon populations to the extinct Baltic stock are those from the St John and St Lawrence rivers in Canada. These populations should be considered the best source of breeding material for the ongoing sturgeon restitution programmes in Poland and Germany.

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“…We did not found though any signs of higher relatedness or elevated levels of inbreeding that could explain the differences in body size of fast and slow growing fingerlings. All analyzed sturgeons exhibited lower levels of genetic polymorphism in comparison to the wild (source) population from St. John River (King, Lubinski & Spidle, 2001;Panagiotopoulou et al, 2012;Popović et al, 2014). This reduction arose from a small number of breeders used to obtain the offspring under study, however no genetic differentiation between the slow and fast growing group of sturgeons was detected.…”

“…It is generally accepted that the loss of genetic diversity may result in inbreeding depression leading to fitness decline often manifested by decrease of growth rate (Borrell et al, 2011 and references therein). Genetic polymorphism and kinship can be easily measured using microsatellite loci that are commonly used as markers in fish restitution and conservation programs including sturgeons (Panagiotopoulou et al, 2012;Waldman et al, 2013;O'Leary, Dunton, King, Frisk & Chapman, 2014;Popović et al, 2014 sturgeon (Acipenser oxyrinchus) breeding is to define causes of large variation in sizes of individuals from the same cohort. Atlantic sturgeon, in contrast to other sturgeon species commonly breed in aquaculture, is difficult to rear, due to specific nutritional requirements and high mortality of larvae and juveniles (Piotrowska, Szczepkowska, Kozłowski, Wundrelich & Szczepkowski, 2013).…”

“…This species is currently under restitution in Poland as its native population became extinct in the '60s of the last century. Based on population genetic studies, Atlantic sturgeons from St. John River (Canada) were chosen for the restitution purposes in Polish waters (Kolman, Kapusta, Duda & Wiszniewski, 2011;Popović et al, 2014). Since 2004, fry has been produced through artificial spawning of wild sturgeons, reared under artificial conditions and released into Polish waters (Kolman et al, 2011).…”

Hair, Bone Plates and Coprolites: Ancient DNA Research on Rare Archaeological Materials

“…Only a short while ago, it was believed that the European sturgeon Acipenser sturio was the only sturgeon species in north European waters (Holćik et al 1989;Williot et al 2002). In contrast, today, as a result of studies of archaeological remains and modern specimens, it has been clarified that the Atlantic sturgeon Acipenser oxyrinchus has been the only, or at least by far dominant, sturgeon species in the Baltic Sea (Popović et al 2014). Recent archaeogenetic analyses at the ZBSA of the oldest known sturgeon bone fragment from the Baltic Sea (Fig.…”

Inter- and intraspecific variation in the surface pattern of the dermal bones of two sturgeon species

“…Since 2002, the historical presence of the Atlantic sturgeon, A. oxyrinchus Mitchill, 1815, previously thought to be restricted in its distribution to the east coast of North America, has been demonstrated in the Baltic Sea and along the Atlantic coast of France (e.g. Ludwig et al., , ; Desse‐Berset, , ; Chassaing et al., ; Popović et al., ). Archaeological sturgeon remains from Belgium, the UK and the Netherlands used to be attributed to A. sturio by default, but the possibility that A. oxyrinchus may also have occurred in the North Sea is now acknowledged (E. Thieren, A. Ervynck, D. Brinkhuizen, A. Locker, W. Van Neer, in review).…”