Genetic assessment of lake sturgeon (Acipenser fulvescens) population structure in the Ottawa River

Abstract

Lake sturgeon (Acipenser fulvescens) are of conservation concern throughout their range. Many populations are dependent on fluvial habitats which have been increasingly impacted and fragmented by dams and human development. Although lake sturgeon were once abundant in the Ottawa River and its tributaries, historical commercial harvests and other anthropogenic factors caused severe declines and low contemporary numbers in lake sturgeon populations. Contemporary habitat fragmentation by dams may be increasing isolation among habitat patches and local rates of decline, raising concerns for persistence of local populations. We used microsatellite DNA markers to assess population structure and diversity of lake sturgeon in the Ottawa River, and analyzed samples from 10 sites that represent more than 500 km of riverine habitat. To test for evidence of anthropogenic fragmentation, patterns of genetic diversity and connectivity within and among river segments were tested for concordance with geographic location, separation by distance and obstacles to migration, considering both natural and artificial barriers as well as barrier age. Despite extensive habitat fragmentation throughout the Ottawa River, statistical analyses failed to refute panmixia of lake sturgeon in this system. Although the long generation time of lake sturgeon appears to have effectively guarded against the negative genetic impacts of habitat fragmentation and loss so far, evidence from demographic studies indicates that restoring connectivity among habitats is needed for the long-term conservation and management of this species throughout this river system.

A global perspective of fragmentation on a declining taxon—the sturgeon (Acipenseriformes)

“…However, many populations have become decimated despite their historical abundance and widespread distribution across the Northern Hemisphere (Birstein 1993, Bemis & Findeis 1994, DeVore et al 1995. Nonregulated harvests for the highly sought caviar and meat of many sturgeon species initiated their decline in the mid-1800s in North America (Birstein 1993, Bemis & Findeis 1994, Pikitch et al 2005, exacerbated stock declines from the Caspian Sea in the early 1960s (Khodorevskaya et al 1997, Ivanov et al 1999, Khodorevskaya & Krasikov 1999) and continue to depress or limit the recovery of some populations (Khodorevskaya et al 1997, Williamson 2003, Peterson et al 2007, Johnson & Iyengar 2015. Major alterations to many rivers were concurrent with, or subsequent, to overharvests.…”

“…More recently, water quality conditions in many regions have improved (Hensel & Holcik 1997, Schram et al 1999, Kampa et al 2014) and stricter harvest controls have been implemented (Khodorevskaya et al 1997, Baker & Borgeson 1999, Peterson et al 2007) in addition to the enforcement of import restrictions on many sturgeon species through the Convention on International Trade in Endangered Species (Williamson 2003, Lenhardt et al 2006, Ludwig 2006. However, poaching purportedly remains a conservation concern for all sturgeon species, given the exorbitant prices of caviar (Cohen 1997, Pikitch et al 2005; this seems to be especially relevant for European stocks (Khodorevskaya et al 1997, Ivanov et al 1999, Ludwig 2006).…”

Validation of 12 species-specific, tetrasomic microsatellite loci from the Russian sturgeon, Acipenser gueldenstaedtii, for genetic broodstock management

“…The magnitude of genetic population differentiation strongly depends on the population status (wild or farmed) as well as the geographical scale of sampling (i.e., a stronger differentiation can be expected if the whole distribution range is covered compared to sampling within a single river, lake, or sea basin). Therefore, a comparison with available population genetic studies on lake sturgeon (McQuown et al 2003;Welsh et al 2008;Wozney et al 2011) and Siberian sturgeon (Barmintseva and Mugue 2017) would be suspect and was not attempted.…”

Evaluating the genetic consequences of river fragmentation in lake sturgeon (Acipenser fulvescens Rafinesque, 1817) populations

“…Genomic DNA was extracted using a simple isopropanol precipitation Wozney et al, 2011). Samples were amplified and genotyped at 14 microsatellite loci (McQuown et al, 2002;Welsh et al, 2003;Welsh and May, 2006) to enable direct comparison between datasets and integration into the growing, range-wide database for Lake Sturgeon.…”

“…For some long-lived threatened and endangered fish species, however, observed anthropogenic declines in population abundance have not been mirrored by similar genetic changes (DeHaan et al, 2006;Lipp e et al, 2006;Reid et al, 2008;McDermid et al, 2011;Wozney et al, 2011). The long generation times of these species may buffer against genetic loss within and among river fragments over the time scales studied to date (Lipp e et al, 2006;Reid et al, 2008;McDermid et al, 2011;Wozney et al, 2011).…”