Assessing the Magnitude of Effect of Hydroelectric Production on Lake Sturgeon Abundance in Ontario

Abstract

The presence of hydroelectric power generating facilities has been identified as the primary factor affecting the variation in relative abundance of Lake Sturgeon Acipenser fulvescens in rivers across Ontario. Qualitatively, these facilities are known to have impacts on the aquatic environment, and they can be inferred to have effects on Lake Sturgeon; however, few studies quantifying these effects are available. Our objectives were to (1) determine and compare the magnitude of effect (d) of hydroelectric facility operating regimes on Lake Sturgeon abundance;(2) compare Lake Sturgeon biological responses among river systems with different operating regimes in order to understand the potential limiting factors within these systems; and (3) assess the effectiveness of mitigation efforts where they have been employed. A standardized index netting program targeting juveniles and adults was conducted over two field seasons at 23 river sites across Ontario. The magnitude of effect on abundance (as indicated by d) was lowest in run-of-the-river systems and was considered large in peaking systems and winter reservoir systems. Relative abundance was significantly greater in unregulated rivers than in regulated rivers. Juvenile abundance was significantly greater in run-of-the-river systems than in peaking systems and winter reservoirs and was significantly greater in peaking systems than in winter reservoirs. Adult abundance did not significantly differ among operating regimes. Growth was faster and condition was significantly greater in unregulated systems than in regulated systems. Recruitment of Lake Sturgeon was highly variable in both regulated and unregulated systems, whereas recruitment failure was more evident in regulated systems, particularly in peaking systems.

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

“…Fragmentation has contributed to local extirpation of sturgeon in numerous rivers (Bemis & Findeis 1994, Ferguson & Duckworth 1997, Hensel & Holcik 1997. Dams act as barriers to upstream move ment to historic spawning areas (Bir stein 1993, DeVore et al 1995, Wei et al 1997, congregating migrating sturgeon and exposing them to harvest and the perils of poaching (Cohen 1997, Fernández-Pasquier 1999, and altering flows, affecting the success of natural sturgeon recruitment within rivers (Khoroshko 1972, Ivanov et al 1999, Jager et al 2002, Goto et al 2015, Haxton et al 2015. Moreover, variation in sturgeon abundance across the landscape has been attributed to the presence of hydroelectric generating stations (DeVore et al 1995, Haxton & Findlay 2008, Haxton et al 2014, demonstrating that dams can play a significant role in limiting the recovery processes for sturgeon.…”

Evaluating Population Recovery Characteristics and Potential Recovery Actions for a Long‐Lived Protected Species: A Case History of Gulf Sturgeon in the Apalachicola River

“…Hydroelectric dam operations may have an effect of both sturgeon spawning behavior (Auer ) and abundance (Haxton et al. ), with run‐of‐river flows likely less detrimental to populations than peaking flows. Studies have suggested that recruitment of Gulf Sturgeon in the Suwannee River (Randall and Sulak ) and Atlantic Sturgeon in the Altamaha River, Georgia (Schueller and Peterson ) may be sensitive to autumn river discharge, which is possibly related to rearing habitat or fall spawning.…”

Dynamics of Lake Sturgeon (Acipenser fulvescensRafinesque, 1817) in a ‘pristine’ river

“…While Auer (1996) suggests that a barrier-free range of 250-300 km is the minimum distance to support Lake Sturgeon populations, they often survive within fragmented rivers (Anderson, Barth, Henderson, & Peake, 2011;Findlay & Haxton, 2008;Brousseau & Threader, 1986), and support seemingly robust populations . However, their productive capacity may be reduced (Cano, Friday, Haxton, & Hendry, 2015), meaning their current observed abundance might only be a fraction of their historical abundance. Although habitat may seem to be available within a relatively small, fragmented reach (e.g., Barth, 2011), species movement and habitat use may signify an ecological Verdon et al, 2013) and could be flushed out of turbulent flows and settle within the first pool (i.e., close to the dam).…”