摘要:

Hexagenia naiads were readily handled in bioassay, but Hydropsyche larvae showed high mortality until handling was reduced by providing small screens on which they built cases. The screens could then be transferred readily. Hydropsyche larvae were much more sensitive to Co-ral and to Dylox than were bluegills, but the ratio of the 24-hour TLmvalues of Malathion to Hydropsyche to bluegills was only about 1 to 10. Malathion was less toxic to Hexagenia naiads than to bluegills, and Co-ral and Dylox gave only about a 1 to 10 margin for Hexagenia compared with bluegills.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[1:EOTOIO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Published indirect evidence indicating that the toxicity of solutions of complex metal cyanides to fish is a function of the concentration of molecular (not ionized) HCN is reviewed. The striking influence of pH on the toxicity of the nickelocyanide complex could be explained only by assuming that HCN is the toxic factor. Recent re-evaluation of the dissociation constant of the tetracyanonickelate (II) ion, which showed previously accepted values to be grossly inaccurate and the true value to be in close agreement with an estimate based on toxicological data and theory, has confirmed the above interpretation of toxicity test results.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[6:ATTFOS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

A total of 489 bass were examined and 21 species of parasites were recovered, as follows: nine species of trematodes representing six families; one cestode; two acanthocephalans representing two families; four nematodes representing three families; two leeches representing one family; and three copepods representing three families. From 410 fish specimens taken from 25 collection sites along the White River drainage, 18 species of parasites were recovered; of these specimens all but one was parasitized by at least one species of parasite. Seventy-nine Micropterus salmoides were examined from three state fish hatcheries presently stocking Beaver Reservoir to determine if the preventative measures used were effective in eliminating ectoparasites. Of these, all but four were parasitized by one or more species of parasite for an overall infection rate of 95%. Eleven species of parasites were recovered from the hatchery fish, three of which were not present in the White River drainage. Posthodiplostomum minimum and Neoechinorhynchus cylindratus, respectively, were the most prevalent parasite species in all three of the hosts studied. Twenty-one selected surveys were compared with the present pre-impoundment survey to determine the frequency and geographical distribution of the parasite species recovered. A comparison made between the 1962 and 1963 collections revealed pronounced fluctuations in the percentage of infection of many parasite species. The distribution, prevalency, and host specificity of parasites, and the control of fish parasites with relationship to this study are discussed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[23:APSOTH]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Clinostomum marginatum (Trematoda: Clinostomatidae), the yellow grub parasite, was recorded in epizootic proportions from Lynch Lake, King County, Washington, in 1961 and 1962. The parasite larvae occurred principally in steelhead trout (Salmo gairdneri); cutthroat trout (S. clarki) were infected to a relatively minor degree. Fish and snail host populations were destroyed by rotenone and copper sulfate treatments.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[35:CMISTS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

A “rational” scheme of pink salmon exploitation in the Northwestern North Pacific was described recently by T. Doi. The scheme includes a 4-month term of offshore exploitation and inshore harvests of one-half of the resulting return; additionally, an offshore wastage coefficient equal to 0.5 F was assumed and a monomolecular pattern of weight growth during the last 4 months at sea. In this paper, yields are compared under various sets of natural conditions, and conditions of fishing. Yield relations are examined by means of Doi's index of rationality of offshore fishing and an alternative measure (the highest admissible inshore yield under protection of a specified target escapement). Fishery-connected variables include duration of offshore fishing, wastage, and inshore-offshore distribution of effort, given spawner requirements ranging from 17 to 50% of the return when offshore fishing is absent. In terms of effort distribution, unique solutions were obtained which are optimal with respect to total yield and target escapement.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[39:EOGPAE]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The virtual population estimation provides a useful minimal estimation of population size where a creel census is operated to provide estimates of total annual harvest and age structure. The creel census was operated from August 1957 through June 1960 indicating an average annual harvest of 1,067 bass from the 525-acre reservoir. An average virtual population of 3,325 bass was estimated following the method of Ricker (1958). Estimated maximal utilization rate was 0.32 and average postrecruitment annual mortality was 0.38.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[52:VPEOLB]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The annual rate r of tag loss may be estimated from observations on the proportion of tag retentions among recoveries of fish which were both tagged and permanently marked at the time of release. In samples recovered t years after release, the proportion of marked fish still bearing tags is assumed to be an estimate of rt. Homogeneity of these t-year loss rates for different year classes may be tested by Chi-square, and the information from all samples may then be combined in the form of a maximum-likelihood estimator of r. Finally, a goodness-of-fit Chi-square may be calculated to test the assumption of a constant annual rate of tag loss. When applied to recapture data on lake whitefish in Georgian Bay, these tests failed to detect any errors in this simple model.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[56:EOTLFR]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Walleye fingerlings (Stizostedion v. vitreum) were held in 0, 50, 100, and 150 ppm conifer-groundwood fiber at 65 F and 100% oxygen saturation for up to 190 days. Fish were contained in recirculating water-flow systems and fed daily; water and fiber suspensions were changed daily. At the end of the experiment, fish in fiber were 2 to 3% shorter in length and 6 to 11% lighter in weight than controls. Relative condition factor was unchanged. Routine metabolic rate of walleyes in 150 ppm fiber was 18% higher than controls and active metabolic rate was 15% lower. Number of mucous cells on gills of fish from 150 ppm fiber treatments was 38% lower than controls and hematocrit of fish held in fiber averaged 6% lower than controls.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[60:LEOCPF]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Sublethal levels of suspended conifer groundwood impaired oxygen uptake and swimming ability of fathead minnows (Pimephales promelas). In fiber-free water active metabolism at 15, 18, and 21 C was 11.7, 13.0, and 14.9 mg O2/kg of fish per min, respectively, when oxygen was not limiting. Fiber suspensions of 100 to 800 ppm were tested, and at 21 C for each doubling in fiber concentration, active metabolism was reduced by about 1.3 mg/kg per min and the decrease was about the same at all dissolved oxygen (D. O.) levels. At 15 C, for each doubling in fiber concentration, active metabolism was reduced by 1.0 mg/kg per min at low D. O. levels (2.5 ppm) and by 0.2 mg/kg per min at high D. O. levels (9.0 ppm). Swimming endurance was reduced by suspended fiber with the effect being greatest at low D. O. levels. Hematocrit rose by approximately 2 for each doubling in concentration of suspended fiber and rose by 1.4 for each 1 ppm decrease in D. O. Gill-cleaning reflexes increased markedly with increase in fiber concentration and this activity was considered to raise the energy requirements for maintenance. Lowered active metabolism and lessened swimming endurance are considered to indicate stress conditions and to decrease survival and production of fish in natural habitats.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[71:EOPFOO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Angling and trout population data are compared from two stream sections of the North Branch of the Au Sable River which were fished for alternate 3-year periods of normal regulations (7-inch size limit, 10-trout creel limit, any lure) and special regulations (9-inch size limit, 5-trout creel limit, artificial flies only). Results were: (1) Fishing pressure was reduced by 50% in special regulation sections. (2) Total catch of fish in the creel was reduced by elimination of fish between 7 and 9 inches. (3) Total catch of fish larger than 9 inches was not increased. (4) The catch per hour of fish larger than 9 inches was increased significantly in one special-regulation section, but fewer anglers were involved. (5) Postseason populations of adult trout were greater under special regulations, but nonangling mortality between seasons lowered these gains to normal levels; higher postseason adult populations did not increase reproduction significantly. (6) Trout larger than 16 inches were observed in the catch from normal waters as often as from the special waters. (7) Stream sections fished under normal rules provided the greatest total harvest in the creel and the greatest angler use.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1966)95[85:AATPOT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor