USGS Science⌕ Search

SEARCH · USGS Science

Results for “Technical Report”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
USGS1973

Seasonal variation of nitrogen, phosphorus, and chlorophyll a in Lake Michigan and Green Bay, 1965

Total and dissolved phosphorus, nitrate, and chlorophyll a were measured at four stations in northern Lake Michigan (inshore Michigan, offshore Michigan, offshore Wisconsin, and inshore Wisconsin) and one station in southern Green Bay during 16 sampling periods in 1965. The nutrients were measured at depths of 2, 5, and 10 meters and chlorophyll a at 2 meters. In Green Bay total phosphorus (33.7 ppb) was about five times as high and dissolved phosphorus (7.0 ppb) more than twice as high as the averages for the four Lake Michigan stations, but nitrate nitrogen concentration (37.3 ppb) was only about onethird that in the lake. Total and dissolved phosphorus were about 50 percent higher in the inshore Michigan area than in the other three lake areas. Concentration and seasonal trends in nitrates differed relatively little among the four lake stations. Nitrate at all areas and depths sampled decreased to almost nondetectable levels during September. Chlorophyll a was 70 percent higher at the two inshore areas than at the two offshore areas in the lake and was more than four times higher in Green Bay than at any lake area.

Technical Paper↗
USGS1974

Physical and chemical characteristics of Lake Oahe, 1968-69

The physical and chemical characteristics presented provide a description of Lake Oahe and establish bases for certain characteristics which may alter as the reservoir ages. Water temperatures were strongly influenced by wind-driven currents and water depth. The duration of thermal stratification varied from about 3 wk in the upstream portion of the reservoir to about 15 wk near the dam in 1968 and from unstratified upstream to about 15 wk downstream in 1969. Dissolved oxygen was usually near saturation, although it fell to 30% in 1968 and 43% in 1969. Nitrate nitrogen and soluble phosphorous were present on all sampling dates in 1969. Silica levels may have become limiting for diatoms in late summer, 1969.

Technical Paper↗
USGS1974

Limnetic crustacean zooplankton of Lake Oahe, May-October 1969

The limnetic crustacean zooplankton of Lake Oahe was dominated by copepods. Cyclops bicuspidatus thomasi was the dominant crustacean throughout the lake. Mesocyclops edax, Diaptomus ashlandi and Daphnia pulex were major components of the zooplankton in the deep, downstream portion of the lake while Bosmina longirostris and Daphnia retrocurva were important constituents in the river-like, upstream section of the lake.

Technical Paper↗
USGS1974

Species and age composition of trap net catches in Lake Oahe, South Dakota, 1963-67

Twenty-seven fish species were captured in Lake Oahe with trap nets in 1963-67. The catch was dominated by eight species in order of abundance: black crappie (Pomoxis nigromaculatus), bigmouth buffalo (Ictiobus cyprinellus), white crappie (Pomoxis annularis), carp (Cyprinus carpio), river carpsucker (Carpiodes carpio), freshwater drum (Aplodinotus grunniens), smallmouth buffalo (Ictiobus bubalus), and goldeye (Hiodon alosoides). Catch per unit of effort did not reflect changes in abundance of some of the species because of variation in environmental conditions. Frequency and strength of postimpoundment year classes were considered the best indicators of the ability of a species to adapt to reservoir conditions. Northern pike (Esox lucius), carp, smallmouth buffalo, and bigmouth buffalo established strong year classes in the early years of impoundment (1952-62), when previously unflooded terrain was inundated as the reservoir filled. The infrequency of abundant postimpoundment year classes and the limitations caused by spawning habitat requirements indicated that the abundance of these species will decline. Goldeye, channel catfish (Ictalurus punctatus), white bass (Morone chrysops), white crappie, black crappie, sauger (Stizostedion canadense), yellow perch (Perca flavescens), and freshwater drum which do not require inundated vegetation for spawning had better reproductive success after 1962 than before.

Technical Paper↗
USGS1974

Evaluation of trawls for monitoring and harvesting fish populations in Lake Oahe, South Dakota

Trawls of various designs and sizes were compared to evaluate their use for monitoring and harvesting fish populations in Lake Oahe. Catches of a 10.7-m semiballoon trawl, selected to monitor changes in the fish populations from 1965 to 1970, showed a downward trend in the abundance of all species, except walleye; the decline was largest in the lower area of the reservoir with a slight increase in the upper area. Of two trawl designs tested, semiballoon trawls captured more fish per hour than high-rise trawls, and a 15.9-m semiballoon trawl with a 3.8-cm mesh cod end captured fish at the highest and most consistent rate. The size and species composition of fish caught in small-mesh trawls differed from those caught in trap nets. Trawl catches were too small to recommend or warrant their use as a commercial fishing gear, but the use of both small mesh trawls and trap nets should improve accuracy in monitoring fish populations in this reservoir.

Technical Paper↗
USGS1974

Age, growth, and maturity of thirteen species of fish from Lake Oahe during the early years of impoundment, 1963-68

The body-scale relation, calculated length, length-weight relation, age at maturity, and sex ratio of 13 major species collected in Lake Oahe from 1963 to 1968 with trap nets and bottom trawls are described. Eight species grew at a faster rate than has been recorded in other Missouri River reservoirs: goldeye ( Hiodon alosoides ), bigmouth buffalo ( Ictiobus cyprinellus ), smallmouth buffalo ( Ictiobus bubalus ), white bass ( Morone chrysops ), black crappie ( Pomoxis nigromaculatus ), white crappie ( Pomoxis annularis ), walleye ( Stizostedion vitreum vitreum ), and freshwater drum ( Aplodinotus grunniens ). Four species grew at rates similar to those recorded from other Missouri River reservoirs: carp ( Cyprinus carpio ), yellow perch ( Perca flavescens ), northern pike ( Esox lucius ), and sauger ( Stizostedion canadense ). One species -- river carpsucker ( Carpiodes carpio ) -- grew slower than in other waters. Growth generally was excellent for all major species in the early years of impoundment (1959-62) but then declined. Species showing the greatest decline in growth from 1962 to 1967 were goldeye, bigmouth buffalo, sauger, walleye, northern pike, and freshwater drum. As growth rate decreased, age at sexual maturity increased for northern pike, carp, river carpsucker, bigmouth buffalo, and freshwater drum. Although inundation of new lands was associated with rapid growth of fishes in the early years of impoundment, water level fluctuations during the growing season had no discernible effect on growth rate. Increased average reservoir depth, which decreased the amount of littoral area, was associated with decreased fish growth.

Technical Paper↗
USGS1974

Population trends, growth, and movement of bigmouth buffalo, Ictiobus cyprinellus, in Lake Oahe, 1963-70

The bigmouth buffalo, Ictiobus cyprinellus, is the most important commercial species in Lake Oahe, a reservoir in the upper Missouri River. The population was dominated by three strong year classes (1959, 1960, and 1962). Estimated population in the fall of 1964 was 540,000 fish of the combined 1959-60 year classes and 5 million of the 1962 year class (equivalent to 81 kg per hectare). Abundance declined irregularly during 1964-70. Annual landings of these two dominant groups during 1965-70 ranged from 149 to 271 metric tons. The total landings during the period amounted to about 151,800 fish of the 1959-60 year classes and 313,000 fish of the 1962 year class. Growth rate was high during the first few years of impoundment and then declined. Males and females grew at about the same rate for the first 4 yr of life, but females were longer and heavier than males at ages V-VIII. At these ages, fish of the 1962 year class were about 10% shorter and 36% lighter than those of the 1959 year class. Growth of tagged and untagged fish was similar. The number of females per male increased with age. Age at maturity increased slightly as growth rate declined. Movement of marked fish was extensive and the recapture of marked fish was directly related to size of fish, location of release, and subsequent fishing pressure; 44% were recaptured downstream from the point of release, and 38% upstream. Females showed a stronger tendency to move downstream than males. Maximum distance traveled was 380 km and maximum rate of travel was 6.4 km per day. Successful reproduction appeared to be associated with flooding of shoreline vegetation during spring and early summer. Inasmuch as little such flooding is expected in the future, annual landings of bigmouth buffalo will probably continue to decline sharply.

Technical Paper↗
USGS1974

Goldeye, Hiodon alosoides, in Lake Oahe: abundance, age, growth, maturity, food, and the fishery, 1963-69

Reproductive success was relatively consistent, and adequate to maintain species abundance at a nearly constant level, during 1963-69. Both abundance and growth in length increased from the lower to the upper portion of the reservoir. In most characteristics -- growth in length, length-weight relation, age at maturity, and food -- goldeye in Lake Oahe were similar to those from other Missouri River impoundments. Experimental gill nets samples all lengths (range 80-460 mm; median, 320 mm) of goldeye, bottom trawls sampled mostly small fish, (median, 215 mm) and trap nets large ones (median, 345 mm). Commercial gill nets were highly size selective (median, 375 mm); fish of ages IV-VII made up 90% of the catch. Survival rates were 57 to 52% for ages II-X. Estimated survival rates for ages V-IX declined from 44 to 35% after the inception of the commercial fishery in 1966. The peak commercial catch was 151,432 kg (1.2 kg/hectare) in 1969. Unless recruitment declines, the population can support a fishery of that magnitude.

Technical Paper↗