Reproductive Longevity and Fecundity Associated with Nonannual Spawning in Cui-ui

Abstract

The cui-ui Chasmistes cujus, a long-lived (40 years or more) and highly fecund catostomid, is often prevented from spawning in drought years. We studied the effect of cui-ui age on egg viability and the effect of nonannual spawning on fecundity in relation to length, age, and growth rate. Egg hatching and survival of swim-up larvae were examined for the offspring of first-time spawners, intermediate-aged females, and old females. Fecundity was tested for three growth categories (fast, intermediate, and slow) in years that were sufficiently wet to allow fish to spawn in the Truckee River and after dry years when fish did not spawn because of river inaccessibility. Females in the fast-growth category were first-time spawners, those in the middlegrowth category were young to middle aged, and those in the slow-growth category were middle aged to old. Females up to 44 years of age still had viable eggs and a reproductive life of at least 29 years. Fecundity was greater after no-spawn years (dry year) compared with a spawn year (wet year), especially for fish in the slow-growth category. This study provides insight into the reproductive adaptation of a long-lived western North American catostomid and suggests possible reasons for the wide variation in fecundity in other long-lived catostomids. Our data will be used to improve the accuracy of an existing cui-ui population viability model. The revised model will have greater sensitivity to cui-ui survival relative to their spawning frequency and, thus, contribute to better management of conditions needed for the long-term survival of endangered cui-ui.

Climate change poised to threaten hydrologic connectivity and endemic fishes in dryland streams

“…out by drying (32). Finally, native sucker species (Catostomus clarki, C. insignis) and roundtail chub (Gila robusta) can make extensive migrations before spawning (33), and evidence from other dryland streams suggests that reductions in hydrologic connectivity can prevent spawning-related movements (34). Although significant decreases in hydrologic connectivity were predicted across all species, small-bodied species with more limited dispersal abilities may be more challenged in the future.…”

“…As habitat fragmentation increases in response to climate-induced changes to streamflow, fish species will be required to disperse through rewetted channels to recolonize suitable habitats containing abundant food resources, meet spawning requirements and access rearing habitats, and avoid predators (32)(33)(34)53). Fish species differ greatly in their mobility, where individuals may rapidly recolonize over many meters or many kilometers from remaining locations of permanent water.…”

Effects of Lake Surface Elevation on Shoreline‐Spawning Lost River Suckers

“…Skipped spawning is a common phenomenon among longlived catostomids when fish are young, when nutritional condition is poor, or when the mortality or energetic costs associated with spawning are high (Quinn and Ross 1985;Scoppettone et al 2000;Rideout and Tomkiewicz 2011). Given the nearly homogeneous age and size of fish in this spawning aggregation (Hewitt et al 2012), young age or small size is very unlikely to be a cause of skipped spawning.…”

“…However, the loss of a single year's egg production may be compensated with future increases in fecundity. For example, Cui-ui Chasmistes cujus reabsorbed eggs in years that they were prevented from spawning, but the older and slower-growing fish compensated with increased fecundity in the following year (Scoppettone et al 2000). Given that the supply of males is generally not limiting (i.e., several males attend a single female) and males spend more time at spawning areas, participation in the act of spawning by a female is probably more important to the spawning success of the subpopulation than it is for an individual male.…”

Effect of Brook Trout Removal from a Spawning Stream on an Adfluvial Population of Lahontan Cutthroat Trout

“…We converted Lea's standard length measurements to fork length (FL) using the conversion developed by Sigler et al (1978) for LCT in Pyramid Lake, Nevada. Because Lea had access only to smaller (263-429-mm FL) and presumably younger females, use of his data may give erroneous results when projecting fecundity for older and larger fish (Scoppettone et al 2000). We therefore used the formula generated by Sigler et al (1983) for LCT 365-705-mm FL taken from Pyramid and used a regression to fit it to Lea's fecundity data.…”