Evaluation of Trawls for Monitoring and Harvesting Fish Populations in Lake Oahe, South Dakota PDF Download
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Author: William Roland Nelson
Publisher:
ISBN:
Category : Fish populations
Languages : en
Pages : 16
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Book Description
Trawls of various designs and sizes were compared to evaluate their use for monitoring and harvesting fish populations in Lake Oahe. Catches of a 20.7-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 the fish caught in small-mesh trawls differed from thos caught in trap nets. Trawl cataches were too small to recommend or warrant their use as a commercial fishing gear, but the use of both small mess trawls and trap nets should improve accuracy in monitoring fish populations in this reservoir.
Author: William Roland Nelson
Publisher:
ISBN:
Category : Fish populations
Languages : en
Pages : 16
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Book Description
Trawls of various designs and sizes were compared to evaluate their use for monitoring and harvesting fish populations in Lake Oahe. Catches of a 20.7-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 the fish caught in small-mesh trawls differed from thos caught in trap nets. Trawl cataches were too small to recommend or warrant their use as a commercial fishing gear, but the use of both small mess trawls and trap nets should improve accuracy in monitoring fish populations in this reservoir.
Author: D. F. Woodward
Publisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 12
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Book Description
Two formulations of the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid) - the butyl ester (BE) and the propylene glycol butyl ether ester (PGBEE) -- had 96-h LC50's to cutthroat trout and lake trout ranging from 490 to 1,200 microgram/liter in static tests. A third formulation -- the isooctyl ester (IE) -- was not toxic to cutthroat trout or lake trout at concentrations below 60.000 microgram/liter. The butyl ester (2,4-D BE) was slightly more toxic than 2,4-D PGBEE, and the toxicity of both esters increased as water temperature decreased.
Author:
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ISBN:
Category : Fish culture
Languages : en
Pages : 494
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Author: James Walter Morton
Publisher:
ISBN:
Category : Dredging
Languages : en
Pages : 44
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Book Description
The goal of this study was to prepare a comprehensive review of the literature on the physical, chemical, and biological effects of dredging and spoil disposal in estuaries and to identify alternative spoil disposal methods. Specific objectives were to identify the most critical problems relating to dredging and spoil disposal and to summarize the progress made to date in solving these problems. Using literature search facilities, bibliographies, and communications with experts throughout the United States, about 520 scientific and technical articles on dredging and spoil disposal were screened. Information extracted from selected articles is included in this review.
Author: United States. Bureau of Sport Fisheries and Wildlife
Publisher:
ISBN:
Category : Fisheries
Languages : en
Pages : 40
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Author: Roy F. Heberger
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ISBN:
Category : Biochemical oxygen demand
Languages : en
Pages : 24
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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 coincidently with oxygen depletion. 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 of planktonic C. b. thomasi.
Author: William H. Berlin
Publisher:
ISBN:
Category : Fishes
Languages : en
Pages : 12
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Book Description
Eggs stripped from lake whitefish 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 attachment 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 = abt ct[squared]. 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.
Author: W. Waynon Johnson
Publisher:
ISBN:
Category : Acute toxicity testing
Languages : en
Pages : 16
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Toxicities of four chemical forest fire retardants, Fire-Trol 100 and 931 (ammonium sulfate, or polyphosphate with an attapulgit clay thickner) and Phos-Chek 202A and 259 (diammonium phosphate with guar gum derivative thickner) were determined by static and flow-through toxicity tests for fry and fingerling coho salmon and rainbow trout; fingerling fathead minnows, bluegills, and largemouth bass; and mature scuds. In static tests, Phos-Chek formulations were more toxic than either of the Fire-Trol formulations to scuds and all life stages of fish. In salmon and trout, fry were generally more susceptible than fingerlings to all formulations; yolk-sac fry were more susceptible than swim-up friy. Toxicities of all formulations to salmon and trout were similar at 6 to 11 degress centigrade. Un-ionized ammonia is believed to be the most toxic component of thes fire retardants.
Author: U.S. Fish and Wildlife Service
Publisher:
ISBN:
Category :
Languages : en
Pages : 42
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Book Description
Author:
Publisher:
ISBN:
Category : Fisheries
Languages : en
Pages : 324
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