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At least 1,117 records · Page 62Linked to original sources
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↗
USGS1977

Verification of a model for predicting the effect of inconstant temperature on embryonic development of lake whitefish (Coregonus clupeaformis)

Eggs stripped from lake whitefish (Coregonus clupeaformis) spawning in Lake Michigan were incubated in the laboratory at temperatures similar to those on whitefish spawning grounds in Lake Michigan during December-April. Observed times from fertilization to attainment of each of 21 developmental stages were used to test a model that predicts the rate of development at daily fluctuating temperatures; the model relates rate of development for any given stage j, expressed as the reciprocal of time (Rj), to temperature (T). The generalized equation for a developmental stage is Rj = abTcT??. Observed times agreed well (5.5% mean difference for all stages) with times predicted by the model; the observed time of 135 days from fertilization to hatching (stage 21) was only 5 days (3.7%) less than the predicted time of 140 days. The model was further verified by applying it to unpublished data supplied by the Ontario Ministry of Natural Resources, for eggs from Lake Huron whitefish incubated in the laboratory in untempered Lake Huron water. The model was used to predict the effects of small temperature increases (caused by a hypothetical waste-heat discharge) on the rate of development and time of hatching of lake whitefish eggs. According to this simulation, continuous addition of waste heat sufficient to raise the temperature 1, 2, or 3 C above ambient on the spawning grounds during December-April would advance the time of hatching 8, 16, or 21 days, respectively. Possible effects of this advancement on the reproductive success of whitefish are discussed.

Technical Paper↗
USGS1977

Abundance, composition, and distribution of crustacean zooplankton in relation to hypolimnetic oxygen depletion in west-central Lake Erie

Samples of crustacean zooplankton were collected monthly in west-central Lake Erie in April and June to October 1968, and in July and August 1970, before and during periods of hypolimnetic dissolved oxygen (DO) depletion. The water column at offshore stations was thermally stratified from June through September 1968, and the hypolimnion contained no DO in mid-August of 1968 or 1970. Composition, abundance, and vertical distribution of crustacean zooplankton changed coincidentally with oxygen depletion. From July to early August, zooplankton abundance dropped 79% in 1968 and 50% in 1970. The declines were attributed largely to a sharp decrease in abundance of planktonic Cyclops bicuspidatus thomasi . Zooplankton composition shifted from mainly cyclopoid copepods in July to mainly cladocerans and copepod nauplii in middle to late August. We believe that mortality of adults and dormancy of copepodites in response to anoxia was the probable reason for the late summer decline in planktonic C. b. thomasi .

Technical Paper↗