Laserfiche WebLink
28 <br />River often are low in zooplankton biomass, and tend to be oligo- or <br />resotrcphic in productivity (Paulson et al. 1980). Lake Mohave tends <br />to have variable but higher primary productivity as a response to <br />inflow of nutrient-rich hypolimnetic water from lake Mead (Priscu <br />1978; Pr'iscu et al. 1982). 2ooplankton in Lake Mohave nonetheless <br />tends to remain relatively low (1.5 to 45 organimms/L) (Paulson et al. <br />1980). <br />Reasons for consistent failure of razorback sucker year classes <br />are unknown, although to date, egg and larval predation by non-native <br />fishes has been considered the most likely explanation. Inadequate <br />nutrition and transport from the reservoir by subsurface currents have <br />been suggested as alte=rnative possibilities (Marsh and Ianghorst <br />1988)• I experimentally evaluated the role of food availability in <br />survival and growth of razorback sucker larvae. This paper reports <br />survival and biomass of larvae in artificial ponds at Dexter National <br />Fish Hatchery (NM . New Mexico, under quantified levels of food <br />availability induced by an array of fertilization regimes. Effects of <br />different food concentrations on gbh of individual larvae, and <br />foods and feeding of larval razorback suckers are also described. <br />Methods <br />Earthen ponds varied from 0.04 to 0.10 hectares in surface area <br />(mean, 0.06±0.01). Total water volumes, plus volumes of three <br />designated habitats, shallows, bottcans, and open waters (defined <br />x;