摘要:

Within the 21,500 m2headwater, the standing population of juvenile rainbow trout reached a high of 7.05 g/m2in October. Production was maximum during August at 1.77 g/m2. Total annual production is calculated at 284.5 kg (13.2 g/m2). Spring emigrants (no less than 4830 fish weighing 69 kg) were age I (91%) and age II. Minimum calculated ratio of production to yield as emigrants was 4.1:1. Comparatively few age 0 fish emigrated during summer. Because of their demonstrated capability to produce juveniles, sensitive headwaters must be preserved from ecological disturbance to assure self-perpetuating rainbow trout populations in the Great Lakes.

ISSN:0706-652X    

DOI:10.1139/f74-021

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The mean lengths of adult males and females of the sea lamprey (Petromyzon marinus) migrating into the Humber River from Lake Ontario in each of the years 1968–1972 varied little, and were similar to those found by other workers in recently established populations in the upper lakes. In contrast, the ratio of males to females, which lay within the narrow range of 1:1 to 1.26:1, was similar to those reported for long-established populations.

ISSN:0706-652X    

DOI:10.1139/f74-022

出版商:NRC Research Press    

年代:1974

数据来源: NRC