ODFW Aquatic Inventories Project

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Data
Fish Survey Data - From Map
Fish Survey Data - Tabular

 Fish Inventories 

Fisheries managers require information on the fish species present in each basin and the extent of their distribution.  This information is critical to determine protection standards, assess potential effects of management activities, develop fish management plans, and design restoration strategies.  While this information is basic to most fish management activities, it can be lacking or poorly documented.

The distribution of a fish species is defined by the presence or absence of a species at a series of sites throughout a stream, watershed, or basin.  A survey may be designed to assess (1) the distribution of a species in a stream or watershed, (2) the distribution of a particular life history stage of a species, (3) the distribution of an assemblage or group of fish in a stream or watershed, (4) the presence of a rare species, or, (5) the upstream limits of fish distribution.  The objectives of each survey may differ, but each is designed to establish the presence or absence of fish at some spatial and temporal scale.

A variety of sampling techniques can be used to observe or collect fish in a stream for presence/absence surveys.  Each method has strengths and weaknesses for a particular environment and for a particular species.  A combination of methods may be used for determining distribution of fish throughout a watershed.

Electrofishing with a backpack electroshocker is the most common method for small streams.  It is not as appropriate for streams that contain large fish or rare species that may be injured by electric fields.  Snorkeling may be a very effective method to observe fish in deep pools or in medium sized streams.  Snorkeling surveys require trained surveyors who can correctly view and identify fish.  Also, the surveys may be negatively impacted by turbidity or low light conditions.  Seining is used effectively in large pools or slow water habitats.  It is less effective when the habitat has large substrate or wood that allow fish to escape the net.  Minnow traps are useful to capture small fish in slow water habitats.  In some cases, minnow traps may be the only way to capture some species.

For more information about fish inventories contact Charlie Stein (541) 757-4263 x258.

      
                                Redband Trout  (photos above)