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At least 91 records · Page 5Linked to original sources
USGS1973

Thermal characteristics of Lake Michigan, 1954-55

The thermal regime of Lake Michigan is described on the basis of the analysis of 1,671 bathythermograph casts made in 1954 and 1955. The beginning, duration, geographic extent, and ending of thermal stratification were determined from 51 thermal profiles from all areas of the open lake. The lake gained heat for about 5 months (mid-March to mid-August) and lost heat over the rest of the year. It was thermally stratified during much of the warming cycle and vertically isothermal during much of the cooling cycle. The annual warming period began by April and was well underway by mid-May. During the transitional period between the isothermal conditions of winter and the thermal stratification of summer, the rate of warming was relatively fast. Seasonal warming began in the shallow inshore waters, which were usually thermally stratified by mid to late May. Stratification persisted in the deeper offshore water into December. Maximum surface temperatures and highest average metalimnion temperatures were reached in early August. Local variations in water temperatures during stratification, however, were a common feature of the thermal characteristics of Lake Michigan. These sometimes sudden changes were caused by upwellings of cold bottom waters that in some instances affected areas of hundreds of square miles. During the warming period of 1954, the heat content of Lake Michigan increased an average of 425 gm-cal/cm??/day. The annual heat budget of the lake for 1954 was 51,700 calories which is similar to that reported for 1942 (50,000 calories) and 1943 (62,000 calories). Heat was lost from mid-August until March, at a rate of about 250 gm-cal/cm??/day. Seasonal thermal characteristics differed little between 1954 and 1955, and were similar to those observed during studies in 1941 and 1942.

Technical Paper↗
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

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

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↗
USGS1974

The commercial fishery in Lake Oahe, North and South Dakota, 1964-70

Ten species were commercially harvested in Lake Oahe, among which bigmouth buffalo (Ictiobus cyprinellus) predominated (63.8% of the total weight), smallmouth buffalo (Ictiobus bubalus) and goldeye (Hiodon alosoides) ranked second, and third. Variations in the seasonal and annual production of buffalo were governed by market conditions and availability. Production of minor species depended on the amount of fishing effort directed toward the harvest of buffalo. Gill and hoop nets were the principal fishing gears. The fishing season usually extended from April through December; most fishing was in May through August.

Technical Paper↗
USGS1974

An experimental trap net fishery, Lake Oahe, South Dakota, 1965

Large trap nets were evaluated as a commercial gear for capturing buffalo fish during July-September 1965. During the 72-day fishing period, 13,171 fish weighing 21,669 kg were taken. Bigmouth buffalo ( Ictiobus cyprinellus ) and smallmouth buffalo ( Ictiobus bubalus ) dominated the catch (78.2% by weight). Eight sport species accounted for 3.6% of the total catch. Both 7.0-cm and 12.7-cm mesh (extended measure) were used in the back of the bailing crib of the nets to determine the effect of the 12.7-cm mesh in reducing the catch of sport species and nonmarketable size groups of commercial species. The 12.7-cm mesh reduced the catch of nonmarketable bigmouth buffalo 29%, smallmouth buffalo 11%, river carpsucker ( Carpiodes carpio ) 18%, carp ( Cyprinus carpio ) 8%, freshwater drum ( Aplodinotus grunniens ) 35%, and sport species 68%.

Technical Paper↗
USGS1977

Clinical methods for the assessment of the effects of environmental stress on fish health

Clinical methods are presented for biological monitoring of hatchery and native fish populations to assess the effects of environmental stress on fish health. The choice of methods is based on the experience of the authors and the judgment of colleagues at fishery laboratories of the U.S. Fish and Wildlife Service. Detailed analysis methods, together with guidelines for sample collection and for the interpretation of results, are given for tests on blood (cell counts, chloride, cholesterol, clotting time, cortisol, glucose, hematocrit, hemoglobin, lactic acid, methemoglobin, osmolality, and total protein); water (ammonia and nitrite content); and liver and muscle (glycogen content).

Technical Paper↗