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密西根湖鲟的修复策略
Michigan’s Lake Sturgeon Rehabilitation Strategy
Substantial population declines since the 1800s led the State of Michigan to list lake sturgeon as a threatened species. The primary causes of the decline of lake sturgeon are insufficient recruitment due to habitat loss and degradation, often caused by dams and poor spawning habitat quality, and excess mortality on adults through fishing. This document provides guidance for the management of lake sturgeon with the goal of eventually rehabilitating this species to the point of removal from the threatened species list and to levels that provide productive and unique fishery opportunities. The primary goals for lake sturgeon are to: (1) conserve populations that are currently self-sustaining; and (2) rehabilitate depressed populations to the point that they are self-sustaining at a higher level of abundance. Currently, there are 24 lake sturgeon populations as distinguished by major watersheds in Michigan waters: two in the Lake Superior drainage, 11 in the Lake Michigan drainage, nine in the Lake Huron drainage, and two in the Lake Erie/Lake St. Clair complex. Of these 24 populations, only five are large in size and three of these are considered to be abundant and stable enough to support harvest fisheries. Among the remaining 19 populations, 12 are below the minimum viable population size (80 adults) and are at high risk of extirpation due to random factors. Four populations are classified as small in size (80200 adults) and are at a high risk of declining to below the minimum viable population size. Three populations are classified as medium in size (200750 adults).