tailieunhanh - Lake Trout Ecosystems in a Changing Environment - Chapter 11

Việc kiểm soát thu hoạch trong hồ cá hồi thể dục thể thao thủy sản trên tiền Cambri lá chắn hồ Mặc dù pháp luật ngày càng toàn diện và phức tạp nhằm mục đích điều chỉnh khai thác, nó là sự căng thẳng quan trọng nhất ảnh hưởng đến hồ cá hồi Salvelinus namaycush qua Tiền Cambri khiên. Hai yếu tố chính góp phần dễ bị tổn thương bẩm sinh của cá hồi hồ khai thác và tăng trưởng nhanh chóng của câu cá giải trí sau khi kết thúc Chiến tranh thế giới thứ II. . | section III Biological effects and management reactions 2004 by CRC Press LLC chapter eleven The control of harvest in lake trout sport fisheries on Precambrian Shield lakes Charles H. Olver Ontario Ministry of Natural Resources retired Daniel J. Nadeau Société et de la faune et des parcs du Québec Henri Fournier Société et de la faune et des parcs du Québec Contents Introduction Angling seasons Winter fishing Access control Size limits Catch limits Quotas Gear Population models Conclusions Recommendations Acknowledgments References Introduction Despite increasingly comprehensive and complex legislation intended to regulate exploitation it is the most critical stress affecting the lake trout Salvelinus namaycush across the Precambrian Shield. The two main contributing factors are the lake trout s innate vulnerability to exploitation and the rapid growth of recreational fishing following the end of World War II. For instance angling almost quadrupled in Ontario between 1950 and the 2004 by CRC Press LLC early 1970s Ontario Ministry of Natural Resources and Environment Canada 1976 . With the development and expansion of highways and forest access roads the advent of the snow machine and the all-terrain vehicle and the ready availability of aircraft few lake trout lakes are inaccessible to anglers. The sensitivity of lake trout to exploitation has been described by several authors see for example Fry 1949 Daley et al. 1965 Martin and Olver 1980 . Lake trout are easily caught by angling so stocks can be depleted with only a moderate amount of fishing pressure MacKay 1956 Eschmeyer 1964 . Certain biological characteristics of the species slow growth late maturity and low reproductive potential and the unproductive nature of the waters it inhabits low nutrient levels cold temperatures also contribute to the vulnerability of lake trout to exploitation. As a result of these limiting factors lake trout occur in a small number of Precambrian Shield lakes where they form .