摘要:

We analyzed the food habits of rainbow trout (Oncorhynchus mykiss) from Lake Oahe, South Dakota, from May through September, 1993–1994. Rainbow trout were captured in surface, suspended and bottom monofilament gill nets. Diets were analyzed using the relative importance index (RI). Composition of the diet differed among months and among size categories of rainbow trout. Greatest RI values for zooplankton prey occurred during May, July and August. Terrestrial invertebrates had the highest RI value during June and September. Overall, RI values for aquatic macroinvertebrates and rainbow smelt (Osmerus mordax) were lower than the other two prey categories. Zooplankton were the most important prey for rainbow trout < 330 mm and decreased in importance as rainbow trout increased in length. Rainbow trout between 330–459 mm fed predominantly on terrestrial invertebrates. Rainbow smelt were incorporated into the diet of rainbow trout between 201–330 mm and increased in importance as rainbow trout length increased. Rainbow smelt dominated the diet of rainbow trout > 460 mm.

ISSN:0270-5060    

DOI:10.1080/02705060.1995.9663463

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Complementary lines of evidence were used to understand distribution and effects of metal contaminants above and below Ridgway Reservoir on the Uncompahgre River in Colorado. Water chemistry identified sites that were contaminated by Zn, while analysis of bryophyte tissue identified sites which had statistically significant differences in metal uptakes, including metals which were not detected in water samples (i.e., Hg and Se). Macroinvertebrate metric values also detected environmental degradation at some sites and generally supported results of water and tissue analyses. In general, water quality improved longitudinally from upstream to downstream. The two stations above Ridgway Reservoir had relatively inferior water quality and higher metal concentrations compared to the station below the reservoir. The exception was in Se concentrations which were enriched in bryophyte tissue at the downstream station.

ISSN:0270-5060    

DOI:10.1080/02705060.1995.9663464

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

South Cross Creek Reservoir is a 192 hectare subimpoundment of the Cumberland River (Lake Barkley) within Cross Creeks National Wildlife Refuge, Tennessee. Between April 1989 and March 1991, 542 harvestable-sized (>75 cm) paddlefish,Polyodon spathula, were measured, tagged, and returned to the reservoir. Using the Fisher-Ford method, we estimated the population at 1,689 paddlefish with an annual survival rate of 91%. The reservoir contains a higher density of paddlefish, 8.8 per hectare, than Lake Barkley (Cumberland River). A low level of exchange occurs between paddlefish in South Cross Creek Reservoir and Lake Barkley, with immigration and emigration occuring during spring flooding when the Cumberland River overflows into the subimpoundment. Fish movement appears to be more dependent upon the water temperature at the time of flooding than the level of flooding. If the water temperature does not exceed 10°C, the paddlefish may not be stimulated to migrate to spawning areas outside of the subimpoundment.

ISSN:0270-5060    

DOI:10.1080/02705060.1995.9663465

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We studied diet of largemouth bass (Micropterus salmoides) from four small, nutrient limited, kettle lakes in Michigan's Upper Peninsula near Land of Lakes, WI, from 1980–1994. We collected stomach contents from 4,846 individual live bass. Although six different species of small mammals were recorded, small mammals were not common in the diet; frequency of occurrence (FO) in the diet was only 0.29% over the duration of the study.

ISSN:0270-5060    

DOI:10.1080/02705060.1995.9663466

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1995.9663467

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1995.9663468

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1995.9663452

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor