Influence of hatch duration and individual daily growth rates on size structure of age‐0 smallmouth bass cohorts in two glacial lakes

Abstract

– We assessed hatch dates and daily growth rates of age‐0 smallmouth bass from two glacial lakes over a 3‐year period. Hatching durations (19–27 days among years) of smallmouth bass occurred from late May until late June. Mean daily growth rate of age‐0 smallmouth bass ranged from 0.56 to 1.56 mm·day−1. Correlation analysis indicated that hatch date had little effect on daily growth rates. Hatch date was significant in explaining variation in total length (TL) of age‐0 smallmouth bass at time of capture in only three of six cases and hatch date never explained >50% of the variation in bass length. Daily growth rate significantly explained variation in smallmouth bass TL at time of capture in all six models, accounting for 31–86% of the variability in bass length. Our findings suggest that size structure of age‐0 cohorts in some populations may be more strongly regulated by variation in individual daily growth rate than by hatch timing.

Spatiotemporal Spawning Patterns of Smallmouth Bass at Its Upstream Invasion Edge

“…Smallmouth Bass reproductive success is contingent on a number of factors that include temperature-mediated processes such as spawn timing (Ridgway et al 1991), parental care (Ridgway and Friesen 1992), offspring development rates (Shuter et al 1980), and brood survival (Lukas and Orth 1995). Despite a wealth of research on these processes in their native range (e.g., Raffetto et al 1990;Rejwan et al 1997;Scott et al 1997;Wiegmann et al 1997;Phelps et al 2008;Steinhart and Lunn 2011), surprisingly little is known for nonnative populations in headwater rivers that are subjected to thermal regimes defined by short growing seasons, variable summer growth temperatures, and long winters. Such environmental conditions in its native range can cause Smallmouth Bass to exhibit significant variation in reproductive strategies (Dunlop et al 2005), and current models that predict reproductive success often perform poorly outside of the native populations for which they were developed (Dunlop and Shuter 2006).…”

Otolith Daily Increment Deposition in Age‐0 Smallmouth Bass Reared in Constant and Fluctuating Water Temperatures

“…The potential bias caused by the assumption that firstincrement deposition in Smallmouth Bass begins at swim-up rather than hatching depends, in part, on the specific use of otolith information. The range of time from hatch to swim-up was reported as 7-11 d (Graham and Orth 1987;Ridgway and Friesen 1992); time to swim-up in our study was 9 d at 20 • C. Thus, estimation of hatch dates based on subtracting incrementbased fish ages from fish capture date could be biased by as much as 7-11 d and affect comparisons of hatch timing in disparate geographic areas, such as Virginia, South Dakota, and Ontario (e.g., Ridgway and Friesen 1992;Sabo and Orth 1995;Phelps et al 2008). Further, estimation of growth rates based on the size of fish at capture could be biased low, again if changes in fish length posthatching (about 5.5 mm TL) are divided by the number of daily increments counted and inflated by adding an additional 7 (or up to 11) d. The relative bias would be greatest for relatively young fish and decrease for older fish since the proportion of days before swim-up to total age would decrease over time.…”

“…Further, estimation of growth rates based on the size of fish at capture could be biased low, again if changes in fish length posthatching (about 5.5 mm TL) are divided by the number of daily increments counted and inflated by adding an additional 7 (or up to 11) d. The relative bias would be greatest for relatively young fish and decrease for older fish since the proportion of days before swim-up to total age would decrease over time. The bias induced by this method would be increased if the length at swim-up (8.5 mm TL), rather than the length at hatching (5.5 mm TL), was used to determine the change in length to capture, as was done by Phelps et al (2008), because the divisor for the daily growth calculation was the number of days between hatching and capture, not swim-up and capture. Regardless, investigators may wish to assess if potential aging bias for young Smallmouth Bass affected the conclusions of previous studies.…”

GROUNDWATER INFLUENCES ON THE DISTRIBUTION AND ABUNDANCE OF RIVERINE SMALLMOUTH BASS, MICROPTERUS DOLOMIEU, IN PASTURE LANDSCAPES OF THE MIDWESTERN USA

“…Sabo and Orth () found age 0 smallmouth bass in a Virginia stream grew faster when hatched later (in warmer water temperatures) than those that hatched earlier in the year (in cooler water temperatures); however, by the end of the summer growing season, there were no differences in the length distributions of each cohort. Size structure of age 0 smallmouth bass was more strongly correlated with daily growth rate than hatch date in South Dakota glacial lakes (Phelps et al ., ). These results suggest hatch date may be less important in determining overall TL during the growing season.…”