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Last modified
7/14/2009 5:02:34 PM
Creation date
5/17/2009 11:52:58 PM
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UCREFRP
UCREFRP Catalog Number
9314
Author
Wick, E. J. and J. A. Hawkins.
Title
Colorado Squawfish Winter Habitat Study.
USFW Year
1989.
USFW - Doc Type
Fort Collins.
Copyright Material
NO
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It is especially important to limit experimental stocking of captive-reared <br />fishes in order to evaluate the benefits, and to avoid potential adverse <br />affects on genetic diversity of wild stocks (Kapuscinski et al. 1993: <br />Philipp et al. 1993: Riggs 1990). O chatowich and Watson (1993) emphasized <br />that stocking of captive-reared fishes may be a useful management tool, but <br />should not be used as a substitute for the protection and restoration of <br />habitat. Management must emphasis protection, preservation, and enhancement <br />of natural habitats needed by all life stages. <br />B. Declining Stocks. Species in decline will be managed utilizing the same <br />systems approach as stable stocks IV.A (see Box 3). It is important to <br />identify factors that may be limiting the numbers of fish and actions needed <br />to remove or significantly reduce those factors responsible for population <br />declines. Emphasis will be placed on natural propagation of wild stocks so <br />that they can become self-sustaining. The relationship of captive <br />propagation and stocking to natural propagation is outlined in Figure 1. <br />All captive-reared fish for experimental, augmentation, or restoration <br />stocking will be propagated using procedures outlined in Section V "Genetics <br />Management of Captive Stocks" to maintain genetic diversity that is similar <br />to the wild stock used as founders of broodstocks. <br />C. <br />Stocking of larval or juvenile wild fish into protected habitats has been <br />suggested as a strategy to increase natural recruitment. Naturally spawned <br />larvae which have been collected in the wild are a form of extensive <br />aquaculture (i.e., captive propagation) since humans have intervened. The <br />genetic risks associated with this type of activity are uncertain. Before <br />this method is used, the management objectives, opportunities, and <br />alternative strategies should be carefully considered to reduce potential <br />genetic risks. For example, stocking equal numbers from all family lots of <br />captive-reared fish into protected habitats is a strategy with more control. <br />Sections IV.C.2. and IV.C.3.. provide guidance for stocking larval fishes <br />into protected habitats and comparing the genetic characterization of these <br />fish with wild stocks prior to release. <br />Background. A major limiting factor regarding endangered and candidate <br />fishes is often low survival during the early life stages that results <br />in little or no recruitment. When recruitment does not replace adult <br />mortality, wild stocks decline in numbers. Colorado squawfish and <br />humpback chub stocks are considered to be low but stable in the upper <br />basin. To protect these stocks and increase their numbers, fishways <br />will be constructed to mitigate the loss of passage over dams, providing <br />access into unoccupied historic habitats. In addition, stream flows <br />needed to maintain vital habitats for both species will be defined. <br />Recruitment of wild razorback suckers, however, is low or non-existent, <br />although spawning has been documented. Therefore, attempts will be made <br />to enhance flooded bottomland habitats with the goal of increasing <br />survival of razorback suckers during the early life stages to aid <br />12
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