Fig 1.
A: Lake Sakakawea with blue dot showing site of study. B. The study site from (A) is shown enlarged, including the Garrison Dam and the fish hatchery at which the fish were raised and held. C. Lake Sakakawea State park showing the study site (S) and boat anchorages (L—boat launch site; P—Pontoon boat launch site). Images from NationalMap.Gov of the U.S. Department of Geological Survey.
Table 1.
Number of Fish Exposed or Used as Controls.
Fig 2.
Fish exposure cages.
Table 2.
Fish Exposure Information.
Fig 3.
Airgun barge and fish exposure cage locations in Lake Sakakawea.
Top: Photograph of the experimental setup. The seismic barge is to the left. Red floats indicate cage and autonomous multichannel acoustic recorder (AMAR) locations. Yellow floats are surface floats used for AMAR retrieval (they do not indicate the location of the AMARs). Airguns were hung from davits near the corners of the barge. The control cage is not shown in this figure, but it would be to the left (south) of the airgun barge. Bottom: Schematic of the locations of the five exposure cages relative to the airgun barge (upper left) and the airgun array (just below the barge). Distances in meters. Figure shows exposure cages at a depth of 6 m for pallid sturgeon. For paddlefish, the exposure cages were at a depth of 2 m (Table 2).
Table 3.
Average Sound Pressure Levels Measured at the Different Cages.
Fig 4.
A representative sound recorded at cage 3.
Top shows the time domain of the signal and the bottom shows the spectrogram. See Table 3 for details about the sounds at cage 3.
Table 4.
Summarized Injuries for Both Species.
Fig 5.
Examples of necropsied tissue.
Figure shows a ventral dissection of a pallid sturgeon 4A5B2E2D02after exposure at a of 0.61m and a depth of 6.09 m. All tissues are healthy and no different from controls.
Table 5.
Counts of Observed Mortal Injury by Treatment Group (proportion in parentheses) for Pallid Sturgeon.
Fig 6.
Scatterplots of observed rates of mortal injury after correction for control rates.
Data plotted against: a) peak negative sound pressure level (Peak- SPL) and b) sound exposure level (SEL) for pallid sturgeon and c) peak negative sound pressure level (Peak- SPL) and d) sound exposure level (SELss) for paddlefish. Data were pooled over replicates and exposure levels averaged. Treatments 1 to 5 are in order of increasing distance from sound source. (Peak- SPL in units of dB re 1 μPa; SELss in units of dB re 1 μPa2·s.).
Table 6.
Counts of Observed Mortal Injury by Treatment Group (proportion in parentheses) for Paddlefish.