Larval lake sturgeon production and drift behaviour in the Menominee and Oconto Rivers, Wisconsin

Abstract

Lake sturgeon (Acipenser fulvescens) have been negatively impacted by barriers to migration, pollution and overharvest. Biological data such as the timing of spawning activity and larval drift have provided a better understanding of larval production success or failure on a site‐specific basis. However, many river systems that serve as reproductive locations for remnant lake sturgeon populations remain understudied. The objective of this study was to compare and contrast aspects of larval lake sturgeon drift within and between the Oconto and Menominee Rivers over multiple reproductive seasons. Differences in larval drift chronology, the size of drifting larvae during the season and the cross‐sectional profile of drifting individuals as a function of river velocity were evaluated. D‐frame drift nets were deployed at a single transect below spawning sites in the Menominee (2012, 2013 and 2014) and Oconto Rivers (2013, 2014 and 2015). A total of 4,442 larvae were captured across all seasons. Larvae exhibited nonrandom drift profiles related to water velocity, and larvae size was related to horizontal drift location. The seasonal increase in body size of drifting larvae also differed among drift events within and between years and across rivers. This information will provide a better understanding of lake sturgeon early life history and has practical management connections including spawning site protection/enhancement and river flow mitigation.

Reproductive status of a remnant Lake sturgeon (Acipenser fulvescens) population: Spawning and larval drift in the lower Fox River, Wisconsin

“…Furthermore, recent research on the Manistee River, Michigan, documented adult abundance ranging from 22 to 66 individuals and larval catches of 70–726 per year (Madenjian, 2019). Higher larval Lake Sturgeon catch rates and production estimates have also been reported for the major tributaries of Green Bay with similar numbers of spawning individuals (Caroffino et al, 2009; Lawrence et al, 2020; Madenjian, 2019). For example, the Oconto River, with an estimated adult spawning abundance similar or less than that observed in the LFR (Madenjian, 2019), produced catch rates of 135–1,125 larvae and total production estimates ranging between 2,600 and > 24,000 larvae (Lawrence et al, 2020).…”

“…For example, the Oconto River, with an estimated adult spawning abundance similar or less than that observed in the LFR (Madenjian, 2019), produced catch rates of 135–1,125 larvae and total production estimates ranging between 2,600 and > 24,000 larvae (Lawrence et al, 2020). On the Menominee River, adult spawning abundance was estimated to be several hundred fish annually (Madenjian, 2019), and reports of larval catch range between 374–1,289, resulting in estimates of 35,000–150,000 larvae produced (Lawrence et al, 2020).…”

“…In addition, it is thought that the biological cue for larvae to drift is when yolk sacs have become depleted (100% development, see Eckes et al, 2015), and then larvae switch to exogenous feeding and leave spawning substrates. Drifting Lake Sturgeon larvae have been documented at 17–20 mm and near 100% development in local Green Bay tributaries (Caroffino et al, 2009; Lawrence et al, 2020).…”

“…To capture drift phase larvae, D‐framed drift nets (base = 0.85 m, height = 0.55 m, length = 2.5 m in length and an area of 0.57 m 2 ) made of a knotless 1,600 μm mesh netting with a detachable collection bucket of 1,000 μm mesh, were deployed downstream of spawning locations from 10 p.m. to 12 a.m. CST each night (Lawrence et al, 2020; Smith & King, 2005). In 2017, six individual drift nets, fished on the river bottom, were placed ~300 m downstream of observed spawning areas and deployed perpendicular to shore (extending 3–50 m from shore [see Figure 1]).…”

Effects of Stocking Density on Growth Performance and Stress Responses of Bester and Bester ♀ × Beluga ♂ Juveniles in Recirculating Aquaculture Systems

“…; and tertiary levels: related to the changes in growth performance, disease resistance, and behavior that can affect the whole-animal integrity and survival [ 34 ]. Taking all of these into account, the use of blood analysis for monitoring the physiological status of fish under stressful conditions has been suggested as a minimally invasive method, especially when working with economically valuable sturgeons [ 35 ]. In general, sturgeon responses to stressors are not as high as in teleost fish [ 36 ], but these differences—even between closely related species—indicate that there are species-specific variations regarding crowding tolerance among this group of primitive fish [ 37 ].…”