Microsatellite and mtDNA analysis of the population structure of grey seals (Halichoerus grypus) from three breeding areas in the Baltic Sea

Abstract

The growing number of grey seals in the Baltic Sea has led to a dramatic increase in interactions between seals and fisheries. The conflict has become such a problem that hunting was introduced in Finland in 1998 and the Swedish Environment Protection Agency recommended a cull of grey seals starting in 2001. Culling has been implemented despite the lack of data on population structure. Low levels of migration between regions would mean that intensive culling in specific geographic areas would have disproportionate effects on local population structure and genetic diversity. We used eight microsatellite loci and a 489 bp section of the mtDNA control region to examine the genetic variability and differentiation between three breeding sites in the Baltic Sea and two in the UK. We found high levels of genetic variability in all sampled Baltic groups for both the microsatellites and the control region. There were highly significant differences in microsatellite allele frequencies between all three Baltic breeding sites and between the Baltic sites and the UK sites. However, there were no significant differences in mtDNA control region haplotypes between the Baltic sites. This genetic substructure of the Baltic grey seal populations should be taken into consideration when managing the seal population to prevent the hunting regime from having an adverse effect on genetic diversity by setting hunting quotas separately for the different subpopulations.

The Limits of Dispersal: Fine Scale Spatial Genetic Structure in Australian Sea Lions

“…Differentiation between South Australian and Western Australian colonies is not surprising considering the distance (>2200 km) between these two regions. However in comparison to other pinniped studies conducted at similar or larger spatial scales the F ST values reported here between these two regions were higher (Hoelzel et al, 2001;Palo et al, 2001;Coltman et al, 2007;Graves et al, 2009;Andersen et al, 2011;Feijoo et al, 2011). Strong genetic partitioning between South Australian and West Australian colonies is also evident with mtDNA data (significant pairwise ST values ranged from 0.83 to 0.94, Campbell et al, 2008).…”

“…However, significant structuring was also detected between colonies separated by only 120-160 km, well within realistic swimming distances for Australian sea lions. The level of genetic differentiation at these relatively short spatial scales is above that detected in other pinnipeds (e.g., gray seal (Halichoerus grypus) Allen et al, 1995;Graves et al, 2009, Harbor seal (Phoca vitulina) Goodman, 1998 Lancaster et al, 2010). This high level of genetic differentiation has implications in terms of vulnerability to any threatening processes and in particular, local fisheries interactions (Goldsworthy et al, 2009) are likely to have strong regional effects.…”

Control Control Control: A Reassessment and Comparison of GenBank and Chromatogram mtDNA Sequence Variation in Baltic Grey Seals (Halichoerus grypus)

“…The reassessment was based on three different datasets: i) the 40 grey seal haplotypes posted in GenBank (accession numbers AM287215-AM287254) by Graves et al [8]; ii) the raw ABI chromatograms from Graves et al [8], covering three different grey seal breeding sites in the Baltic Sea: the Bay of Bothnia (BB), Estonia (EST), and the Stockholm Archipelago (STA); and iii) an “erroneous” dataset constructed from the GenBank haplotypes and the information on haplotype distribution in Table 5 of the Graves et al study [8]. Specifically, we first downloaded the haplotypes listed in GenBank and assembled them with zero mismatches in order to assess the actual number and types of haplotypes in the data listed in GenBank.…”

“…In our ongoing study of grey seal population dynamics we were interested in using the information of Graves et al [8] and the corresponding mtDNA haplotype data in GenBank to recreate their mtDNA dataset. A closer examination of the GenBank data revealed that several of the haplotypes in the GenBank repository were identical.…”

Detection of grey seal Halichoerus grypus DNA in attack wounds on stranded harbour porpoises Phocoena phocoena

“…For grey seal, we selected the data of Graves et al (2009) re-edited by Fietz et al (2013). In addition, new data were generated using the primer pair ThrL16272 and DLH16750 (Stanley et al 1996) on DNA extracts of 8 grey seals (GenBank accession numbers KM053398−KM053405) and 97 faecal samples of grey seals from various locations in the Dutch North Sea and Wadden Sea (GenBank accession numbers KM066992-KM067088).…”