Bet-hedging bigmouth buffalo (Ictiobus cyprinellus) recruit episodically over a 127-year timeframe in Saskatchewan

Abstract

The bigmouth buffalo (Ictiobus cyprinellus) is an iconic freshwater fish native to North America that is in decline. Recent studies have revealed bigmouth buffalo exhibit a slow pace of life, yet demographic information on bigmouth buffalo outside of North Dakota and Minnesota is lacking. We used otoliths to investigate population demographics of bigmouth buffalo in Canada, and also monitored bigmouth buffalo spawning frequency and reproductive success in the wild. From a sample of 52 fish collected during 2018 – 2021 we found bigmouth buffalo from the Qu’Appelle system more than 125 years old. Only 13 year classes ranging from 1894 – 1997 were evident with only one year class since 1948, indicating recruitment has been episodic. During the past decade (2013 – 2022) bigmouth buffalo have spawned only once (May of 2013) in Buffalo Pound Lake. This spawning effort culminated in recruitment failure because the water-level recession rate was too rapid. Our findings indicate that bigmouth buffalo spawning attempts as well as recruitment occur within a narrow range of water-level fluctuations that may rarely occur, which is enabled by their supercentenarian lifespan, and has direct implications for the conservation of this species.

Bowfishing shoot and release: High short‐term mortality of nongame fishes and its management implications

“…One of the Longnose Gar taken by bowfishing in our study was estimated to be 29 years old, 2 years older than the oldest published age estimate for the species (McGrath et al 2016). Along with these long life spans, native nongame fishes often exhibit delayed onset of sexual maturity (Table 1) and irregular or episodic recruitment (e.g., multidecadal gaps between recruitment cohorts for Bigmouth Buffalo; Lackmann et al 2021, 2022).…”

Intra‐Annual Variability of Common Carp and Bigmouth Buffalo Electrofishing Data in Shallow Lakes

“…Carp spawning behaviors may increase their vulnerability to capture during spring and early summer sampling, while postspawning dispersion may reduce their vulnerability from August through the fall. Although Buffalo spawn in shoreline habitat similar to Carp, they tend to spawn earlier and at a lower, narrower range of temperatures (17-19°C), and consequently they are less vulnerable to late-spring electrofishing (Johnson 1963;Walburg and Nelson 1966;Edwards 1983;Lackmann et al 2023). Scarce Buffalo catches across the summer months may be due to a behavioral response to changes in water temperature, as Buffalo tend to avoid water temperatures above 30°C (Gammon 1973).…”

Precision and Bias of Three Bigmouth Buffalo Aging Structures

“…Using these structures could be a useful approach for determining recruitment patterns (e.g., annual CPUE of age-2 fish), age at maturity, and growth rates early in life. Long-lived fishes have gained considerable attention recently (Koch et al 2009;Lackmann et al 2019Lackmann et al , 2023; consequently, obtaining reliable age and mortality estimates for older fish is critical. While dorsal and pectoral fin rays provided similar age estimates for younger fish compared to lapillus otoliths, they likely underestimate population age structure for older individuals.…”

“…2011; Lackmann et al. 2019, 2023); consequently, obtaining reliable age and mortality estimates for older fish is critical. While dorsal and pectoral fin rays provided similar age estimates for younger fish compared to lapillus otoliths, they likely underestimate population age structure for older individuals.…”

“…Because Bigmouth Buffalo age data and mortality estimates are sparse, it is difficult to estimate or speculate on the average Bigmouth Buffalo mortality rates among populations or within regions. Some populations appear to have very low mortality and are supported by a limited number of recruitment events (Lackmann et al 2019(Lackmann et al , 2023, whereas others have consistent recruitment and have been commercially harvested at high rates (e.g., 333,000 kg/year: Rose and Moen 1952; 373 kg/ha/year: Simonson et al 2022). High harvest of these populations may result in a truncated age structure.…”