Probabalistic Projections for Recovery of the Endangered Cui-ui

Abstract

The cui-ui Chatnistes cujus. a lake sucker found in only Pyramid Lake, Nevada, is listed as endangered under the U.S. Endangered Species Act, and a recovery plan has been formulated in an effort to save it. We used a population simulation model that incorporated environmental stochasticity in water availability to project the persistence of cui-ui over 200 years. Based on this approach, recovery of the species in terms of persistence was evaluated for the existing hydrological situation and for situations involving water supplementation in various amounts. Our calculations indicate that immediate (as of spring 1991) acquisition of 70,000 acre-feet per year of supplemental water to raise levels in Pyramid Lake would have assured recovery and persistence over 200 years with a probability of 0.95. Postponement of acquisition for 3 years followed by incremental increases of 3,000 or 10,000 acre-feet per year would require, respectively, 83,000 and 120,000 acre-feet of annual supplemental water to assure persistence. The approach is applicable to a wide range of species and conditions.

Cui-Ui Reproductive Success from Potential Egg Deposition to Larval Emigration

“…Comparable early lifestage data on population survival are rare because there is typically not the opportunity to sample larvae for most fish populations and systems (Houde 2002). These results may be helpful in understanding the population dynamics of other long-lived western North American lake suckers and may enhance information on conditions affecting cui-ui population dynamics (Emlen et al 1993). Our study suggests that increasing the amount of spawning habitat (currently restricted by inability of fish to move past dams) and increasing seasonal river flows would increase cui-ui survival from egg to emigrating larvae in this system.…”

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

“…This would more precisely quantify the effects of nonannual spawning on fecundity. Regardless, information from this study can be used to improve, revise, or replace parts of the existing cui-ui population viability model (Emlen et al 1993).…”

“…The newly discovered longevity of cui-ui Chasmistes cujus led to construction of a population viability model to gauge the species persistence under varying hydrologic regimes. Cui-ui has the distinction of being the only western North American catostomid with a published population dynamics model aimed at its management (Emlen et al 1993). The model is a population viability analysis and predicts cui-ui persistence during a 200-year period under different springtime flow regimes in the Truckee River.…”

A Life History Model for Peppered Chub, a Broadcast‐Spawning Cyprinid

“…The Leslie matrix model has a long history of use in natural resource management (Caswell 2001) and has been used extensively in fishery management and conservation (e.g., Jensen 1971;Heppell et al 1999;Brewster-Geisz and Miller 2000;Gross et al 2002;Mollet and Cailliet 2002). Because peppered chub is a broadcast spawner and because first-year survival rates of fishes are strongly, and often nonlinearly, related to stream discharge (Emlen et al 1993;Capra et al 2003;Lobón-Cervia 2004), we modified the basic Leslie matrix to relate first-year survival of peppered chub to stream discharge. Our model allowed us to assess the potential effects of altered flow regimes on abundance and persistence of the species and identify the life history stages that have the greatest effect on peppered chub population growth rate.…”