USGS NY WSC: Baldigo 2008 Fish: Fish assemblage survey using three or more successive passes with a backpack shocker and three netters in a seine-blocked reach
|
Official Method Name
|
Fish assemblage by three or more successive passes, USGS New York Water Science Center |
|---|---|
|
Current Revision
| 2008 |
|
Media
|
Surface Water (Waterbody type - Wadeable stream) |
|
Instrumentation
|
Backpack Electrofishing Unit |
|
Method Subcategory
|
Population/Community |
|
Method Source
|
|
|
Citation
|
|
|
Brief Method Summary
|
Fish in all study sites were collected from seine-blocked, 87–120-m-long reaches during three or more successive passes using a battery-powered backpack electrofisher and three fish netters. A fourth pass was added when the decrease in salmonid numbers between the second and third passes was insufficient to derive variances (95% confidence intervals [CIs]) that were smaller than 10% of the estimated salmonid population sizes. Fish from each pass were maintained in separate batches; individuals from each pass were identified to species. The lengths and weights of all salmonids were recorded; for non-salmonid fish, length and weight data were collected only for individuals that were longer than 150 mm. Because condition and length frequency distributions of most nonsalmonids (less than 150 mm) were of less concern and because such fish were collected in the thousands at some study reaches, their total biomass was determined partly from pooled subsamples to curtail field processing time and effort. For subsamples, the lengths and weights from only 40–50 individuals/species were measured; thereafter, total weights and counts were recorded for batches of 10– 50 individuals/species. All fish were returned to the stream after measurements from all fish collected in all passes had been obtained. |
|
Scope and Application
|
Fish and habitat surveys were conducted at the reach scale in three streams where large NCD restoration projects (0.4–3.0 km long) were implemented over the course of the study (Figure 1). Fish and habitat surveys were done annually at four small (87–112 m long) treatment reaches and three reference reaches 1–2 years before restoration and 2–3 years after treatment reach restoration; sampling years differed among streams. Surveys were done at treatment reaches that were located entirely within the larger restoration project reaches and at stable references reaches that were located upstream from the restoration project reaches. Study reaches were about 20 mean stream widths (MSWs) long and covered one or two complete geomorphic channel sequences (Meador et al. 1993). The reaches were relatively short and therefore might not accurately represent habitat, community, and population conditions existing across larger stream segments (Simonson et al. 1993); however, that was not their main purpose. The permanent study reaches were selected to characterize prerestoration (baseline) conditions, provide a way to adjust indices for normal year-to-year variation, quantify index responses to restoration, and permit the completion of surveys within a single day. |
|
Applicable Concentration Range
|
|
|
Interferences
|
|
|
Quality Control Requirements
|
|
|
Sample Handling
|
|
|
Maximum Holding Time
|
|
|
Relative Cost
|
|
|
Sample Preparation Methods
|
