摘要:

Fish live and thrive in water with turbidities that range above 400 p.p.m. and average 200 p.p.m. The waters of the Great Lakes usually are clear except in Lake Erie where the turbidities of the inshore areas averaged 37 p.p.m.; the turbidities of the offshore waters averaged less. Lake Erie waters were no clearer 50 years ago than they are now. In fact, the turbidity values are less now than they were in the earlier years; the annual average of the inshore waters dropped from 44 p.p.m. before 1930 to 32 p.p.m. in 1930 and later, and the April-May values decreased from 72 p.p.m. to 46 p.p.m. Any general decline in the Lake Erie fishes cannot be attributed to increased turbidities. Furthermore, these turbidities averaged well below 100 p.p.m. and, therefore, were too low to affect fishes adversely.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1945)75[281:TAAFIT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1948

数据来源: Taylor

摘要:

In 1936, after a biological survey and a consultation of several fish-culturists, it was decided to attempt the introduction of rainbow trout (Salmo gairdnerii) into Clear Lake. This decision was influenced by the urgent need for a suitable game fish in this lake, the chief resort in Riding Mountain Park, and by the wish to check the feasibility of rainbow trout for stocking in lakes of this life zone. Planting, in the years 1937 to 1942 was carried on according to a plan which made use of rearing ponds to increase the size of the fish released. In 1942, when it was found that the rainbow trout were not surviving, it was recommended that planting be discontinued and an attempt made to establish lake trout (Cristivomer namaycush). After three years of planting with adult lake trout it was found that they were surviving in the lake but as yet no evidence of spawning has been obtained. In this report the physical and biological conditions in the lake are described and discussed in relation to the fish-culture experiments. It is concluded that great difficulty will be encountered in attempting to introduce rainbow trout into lakes in which a heavy population of competitor and predator fish is already present.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1945)75[323:TFORTA]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1948

数据来源: Taylor

摘要:

Successful spawning of the creek chub (Semotilus a. atromaculatus) was achieved in a specially designed raceway. An artificial stream, having a gravel bottom with pools and riffles, was constructed within the basin of a pond in which brood stock were introduced. Spawning activity commenced in late April and terminated in early May. A heavy mortality occurred among the brood stock when the ratio of males was equal to, or greater than that of the females. A better survival was attained by increasing the number of females. The breeding fish had a tendency to concentrate in certain zones of the spawning raceway, and as a result many redds were destroyed in the overworked areas. To offset this condition, thus increasing the efficiency of the raceway, deposited eggs were removed from the beds and successfully cultured in a hatchery by the use of Mechean jars and egg trays. The complete incubation period (fertilized egg to free-swimming fry) was about 25 days at a mean temperature of 55° F. Several rearing ponds were stocked with 8-day-old fry; others with 20-day-old fry. Though the 8-day-old fry were found to tolerate long-distance transporting, they did not survive in any appreciable numbers after introduction into rearing ponds. The stocking of ponds with 20-day-old fry was more successful, for more than 50 percent of the fry survived. Production in ponds where the fish had to rely on a natural food supply was light as compared to that achieved in a pond where artificial feeding was practiced.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1945)75[336:POTCCI]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1948

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1948.10493257

出版商:Taylor & Francis Group    

年代:1948

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1948.10493258

出版商:Taylor & Francis Group    

年代:1948

数据来源: Taylor