Download Free Genetic Effects Of River Fragmentation On The Federally Endangered Rio Grande Silvery Minnow Hybognathus Amarus Book in PDF and EPUB Free Download. You can read online Genetic Effects Of River Fragmentation On The Federally Endangered Rio Grande Silvery Minnow Hybognathus Amarus and write the review.

The endangered Rio Grande silvery minnow Hybognathus amarus was cultured in 2.44-m-diameter outdoor tanks in a 131-day yield trial to assess growth, survival, and percentage of taggable-sized fish ( total length) when stocked at 500/tank (1.07 million/ha), 1,000/tank (2.14 million/ha), and 1,500/tank (3.21 million/ha). At harvest, fish averaged 45.6 mm and 0.94 g in the 500/tank treatment, 42.6 mm and 0.74 g in the 1,000/tank treatment, and 38.4 mm and 0.55 g in the 1,500/tank treatment; the differences were significant (P = 0.05). Survival in the three treatments was 70%, 64%, and 52%, respectively, but the differences were not significant. Percent taggable-sized fish was 86%, 89%, and 65%, respectively, but the differences were not significant. Yield was 672.5 kg/ha, 1,026.6 kg/ha, and 887.8 kg/ha, respectively; yield in the 1,000/tank treatment was significantly greater than that in the 500/tank treatment, but was not significantly greater than that of the 1,500/tank treatment. This facility is a conservation facility and a major goal is to raise fish without formulated feed. Fertilization produced good growth for the first month, but little growth occurred during the second month so supplemental feed had to be used for the final 60 d of the yield trial.
Geomorphic changes resulting from the construction of dams, irrigation diversion structures, and flood control levees has separated the Rio Grande from its floodplain contributing to the decline of native fish species including the endangered Rio Grande silvery minnow (Hybognathus amarus). The species is currently restricted to 280‐km of the river in New Mexico. Since 2006, the New Mexico Interstate Stream Commission has constructed 121 ha of floodplain habitat between the river levees to improve habitat. To determine if constructed habitats were being utilized by the Rio Grande silvery minnow and the fish community, a presence/absence study was conducted on eight constructed floodplains during 2008 and 2009, and one natural floodplain in 2008. A total of 14 481 fish were captured in fyke nets during both years: 3528 fish were captured from constructed floodplains and 8410 were captured from the natural floodplain in 2008: 2543 fish were captured from the constructed floodplains in 2009. Of this total, 11 602 of the fish were Rio Grande silvery minnow: 2180 Rio Grande silvery minnow were collected from constructed floodplains and 7356 from the natural floodplain in 2008; 2057 Rio Grande silvery minnow were collected from constructed floodplains in 2009. Gravid female and male expressing milt were collected both years. A total of 1173 unidentified larval fish and 363 Rio Grande silvery minnow eggs were also collected during the surveys. The results show that the Rio Grande silvery minnow and the fish community utilized the constructed and natural floodplains during the spring spawning season.
This article describes the initial season‐long yield trial of raising the endangered Rio Grande silvery minnow, Hybognathus amarus, in the conservation rearing facility at the Los Lunas Silvery Minnow Refugium. Ten thousand fish (90,900/ha) were stocked on June 22, 2010. Production was based on a total of 653 mL (5.936 L/ha) of 11‐37‐0 N‐P‐K and 5.5 kg (50 kg/ha) of alfalfa pellets. Fish were harvested in October; almost all were harvested 18–27 October. At stocking, fish averaged 21.7 mm total length and mean weight was 0.10 g. At harvest, fish averaged 48.98 mm and 1.12 g. Fish were sampled monthly, and increased lengths and weights through the study were significant (P = 0.05). Five thousand eight hundred ninety‐two fish were harvested (58.92% survival). Yield was 59.99 kg/ha. Temperature, dissolved oxygen (DO), pH, un‐ionized ammonia, nitrite, turbidity, alkalinity, and chloride were measured at seven sites throughout the outdoor refugium. Secchi disc visibility was measured in the stream and in the ponds. Only two variables (DO and pH) went outside permitted values, but were easily corrected. Harvest was difficult due to the many different naturalized areas consisting of varying depths, channel widths, and substrates.