U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY
M/V QUILLBACK CRUISE Q-1-97-GB
PHYSICAL CHARACTERISTICS OF DUNGENESS CRAB AND HALIBUT HABITATS
IN GLACIER BAY, ALASKA
October 15 through October 30, 1997
Glacier Bay, Alaska
Guy R. Cochrane (1), Paul R. Carlson (1), Jane F. Denny (2), Michael E. Boyle (1),
S. James Taggart (3), and Philip N. Hooge (3)
Open-File Report 98-791
This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Use of trade, product, or firm names in this report is for descriptive purposes only and does not imply endorsement by the U.S. Government.
1. U.S. Geological Survey, MS 999, 345 Middlefield Road, Menlo
Park, CA 94025
2. U.S. Geological Survey, Woods Hole, MA 02543
3. U.S. Geological Survey, Alaska Biological Science Center, Glacier Bay Field Station, P.O. Box 140, Gustavus, AK.
Glacier Bay Park
Sidescan Surveying System
Data Acquisition and Processing|
Analysis of Side Scan Imagery
In Glacier Bay National Park, Alaska there are ongoing studies of Dungeness Crab (Cancer magister) and Pacific Halibut (Hippoglosus stenolepis). Scientists of the United States Geological Survey (USGS) are attempting to ascertain life history, distribution, and abundance, and to determine the effects of commercial fishing in the park (Carlson et al., 1998). Statistical sampling studies suggest that seafloor characteristics and bathymetry affect the distribution, abundance and behavior of benthic species. Examples include the distribution of Dungeness crab which varies from 78 to 2012 crabs/ha in nearshore areas to depths of 18 m (O'Clair et al., 1995), and changes in halibut foraging behavior according to bottom type (Chilton et al., 1995).
This report discusses geophysical data collected in six areas within the park in 1998. The geophysical surveying done in this and previous studies will be combined with existing population and sonic-tracking data sets as well as future sediment sampling, scuba, submersible, and bottom video camera observations to better understand Dungeness crab and Pacific halibut habitat relationships.
Glacier Bay Park
Glacier Bay National Park is a 3.3 million-acre park and preserve that extends from Icy Strait and Cross Sound in the south to the Canadian border in the northwest (Figure 1). In the last 200 years, the large glacier that filled Glacier Bay during late Neoglacial time (commonly referred to as the Little Ice Age, Goldthwait, 1963), has retreated, exposing about 100 km of a spectacular fjord system that has developed over possibly the past 100,000 years (Goldthwait, 1987). As the glacier has retreated, the newly exposed benthic habitat has undergone rapid physical and biological changes making it an ideal site to study glaciology, fjord sedimentation, and species succession (Milner and Woods, 1990; Engstrom, 1995).
Commercial fishing is one of the major sources of income in the adjacent communities. There is also an economically important recreational fishery in the area. But, significant questions have been raised in Congress as to whether fishing should be allowed in Glacier Bay Park. Mapping of the benthic habitat will result in improved management of the fisheries resources in the area,
Klein 2000 Sidescan Surveying System
A Klein 2000 sidescan system was used for geophysical surveying. The unit features 8 channels of processed data, 7 subsurface from the towfish (5 sonar and 2 instrumentation) and 1 surface (external analog input). Two sonar channels each were devoted to 100 KHz and 500 KHz sidescan data and a fifth sonar channel was used for 4KHz subbottom profiling.
The 1997 Glacier Bay survey was navigated with a Leica Differential Global Positioning System (DGPS) which provided a position with accuracy of 1-5 m in DGPS mode. At times during the cruise, differential signal was interrupted. In non-differential mode, the receiver provided a position with 30-50 m accuracy. A KVH Industries Inc. azimuth digital gyro-compass provided ship headings with 0.5 degree accuracy. Navigation data were recorded using Yo-Nav version 1.19 (Gann, 1992).
Data Acquisition and Processing
We used the M/V QUILLBACK, owned by the United States Minerals Management Service and operated by the National Park Service, for our geophysical surveying. Side-scan-sonar imaging (side-scan) and seismic reflection profiling (profiling) began on October 15 after two days of mobilization and ended October 30 with one day of demobilization. A Triton Elics Isis brand side-scan data recording system was used on the cruise, that simultaneously records 5 channels of data; port and starboard 100 KHz side-scan data, port and starboard 500 KHz side-scan data, and profiler data. Side-scan data shown in this report are 100 KHz data. Typically, 2048 samples were recorded per channel over a swath width of 200-400 m yielding a resolution of 0.1 - 0.5 m of seafloor area for the side-scan data. The resolution of the profiler data is 1-3 m of sub-bottom depth (with penetration of tens of meters in soft sediment and a few meters in harder sediment).
The sidescan-sonar data were processed following the methodology of Danforth et al. (1991, 1997), through use of USGS software packages Xsonar and Showimage. The slant-range, destripe, and beam pattern-processing routines, executed within Xsonar and Showimage, correct geometric and radiometric distortions inherent in the sonar data. The slant-range algorithm removes the water column artifact from the sonograph and corrects slant-range distance to true ground distance; the destripe routine corrects fluctuations in adjacent ping values within the sonar record; the beam pattern routine corrects variations in beam intensity with range. The processed data files were mosaiced to form a composite image using PCI Remote Sensing Software. A linear stretch was applied to the final mosaics to enhance the contrast between low and high backscatter areas. The final mosaics were exported from PCI in TIFF format. The TIFF images were imported into an arc/info database (Geiselman et al., 1997) that contained coastline, geology, and bathymetry coverages.
Sidescan Sonar Mosaic Imagery
The 1997 sidescan images are displayed here. Interpretive efforts are ongoing for each of these areas.
Analysis of Side Scan Imagery (An Example)
In a future report, we will characterize the benthic habitat using a combination of the side-scan data, the profiling data, onshore geologic mapping by Brew et al. (1978), and previous marine geology work (e.g. Carlson et al., 1977; Cai et al., 1997). Final interpretations will be in the form of georeferenced habitat polygons which will be combined with the existing Geographic Information System (GIS) database (Geiselman et al., 1997). Our interpretation of the geophysical data will be based on the experience garnered in studying similar acoustic data from Glacier Bay and the Gulf of Alaska (e.g. Carlson et al., 1992, Carlson et al., 1980). We are using a variety of techniques (scuba, delta submersible, rebreathers, drop camera) to visually confirm our interpretation of the geophysical data. We plan to test the predictive value of the interpretation by conducting fish population studies in the areas where the geophysical data interpretations exist.
In this report we present an analysis of the sidescan image collected to the west of Strawberry Island (see above). Based on geologic mapping on Strawberry Island, we know that the surficial sediments are Quaternary age (Brew et al., 1978). Possible interpretations of the sidescan image include layered or structurally deformed bedrock, lateral moraines, or sediments grooved by the passage of large icebergs. A bedrock seafloor habitat will support a much different benthos than that supported by other adjacent bottom types including lateral moraines, or sediments grooved by the passage of large icebergs. Examination of the sub-seafloor seismic data (150 Kbytes) shows a prominent sub-seafloor reflection which rules out exposed bedrock as a possible interpretation, except at two locations where the reflector may intersect the sea floor at distances of 7 m and 68 m. Samples of the rock are needed to define what geologic units underlie the onshore sediment. Sampling, planned next year, with closed-circuit diving equipment (i.e. rebreathers) may provide bedrock samples from the area.
The criss-crossing pattern of grooves seen in the sidescan image east of Strawberry Island rules out lateral moraines as an interpretation of the seafloor habitat. Our preferred interpretation of the data is that the seafloor is composed of coarse sediment grooved by the passage of large icebergs. The earliest period when large icebergs would have calved up stream of this area is when the glacier terminus was in the Strawberry Island area between 1794 and 1845 (American Geographical Society, 1966). Sediment grooving could have occurred in more recent times as icebergs calving further up stream passed Strawberry Island on their way south. Using the habitat characterization scheme of Greene et al. (1995), this habitat would be described as Intermediate shelf, grooved gravel and boulder, flat bottom, with probable winnowing by tidal and riparian currents.
American Geographical Society. 1966. Glacier Bay, Alaska, map showing former positions of termini 1760-1966. American Geographical Society, New York, NY.
Brew, D.A., B.R. Johnson, D. Grybeck, A. Griscom, D.F. Barnes, A.L. Kimbal, J.C. Still, and J.L. Rataj. 1978. Mineral resources of the Glacier Bay national Monument wilderness study area, Alaska: U.S. Geological Survey, Open File Report 78-494: 670 p.
Cai, J., R.D. Powell, E.C. Cowan, and P.R. Carlson. 1997. Litthofacies and seismic-reflection interpretation of temperate glacimarine sedimentation in Tarr Inlet, Glacier Bay, Alaska. Marine Geology, v. 143, p. 5-37.
Carlson, P.R., B.F. Molnia, S.C. Kittelson, and J.C. Hampson, Jr. 1977. Distribution of bottom sediments on the continental shelf, northern Gulf of Alaska. U.S. Geological Survey Miscellaneous Field Studies maps and text, MF 876, 2 map sheets and 13 p. pamphlet.
Carlson, P.R., B.F. Molnia, and W.P. Levy. 1980. Continuous acoustic profiles and sedimentologic data from R/V Sea Sounder cruise (S-1-76), Eastern Gulf of Alaska. U.S. Geological Survey Open-File Report No. 80-65, 40 p. and 3 map sheets.
Carlson, P.R., R.D. Powell, and A.C. Phillips. 1992. Submarine sedimentary processes on a fjord delta front, Queen Inlet, Glacier Bay, AK. Canadian Journal of Earth Science, v. 29, p. 565-573.
Carlson, P.R., T.R. Bruns, K.R. Evans, J.T. Gann, D.J. Hogg, S.J. Taggart, and P.N. Hooge. 1998. Cruise report of M/V Quillback in Glacier Bay, Alaska: Physical Characteristics of Dungeness Crab and Halibut habitats. U.S. Geological Survey Open File Report 98-134: 50 pp.
Chilton, L., P.N. Hooge, and S.J. Taggart. 1995. Prey preference of Pacific halibut (Hippoglossus stenolepis) in Glacier Bay National Part. In: Engstrom, D.R. (ed.). Proceedings of the Third Glacier Bay Science Symposium, 1993. National Park Service. Regional Office Anchorage, AK. p. 209-214.
Danforth,W.W, O'Brien, T.F., and Schwab, W.C., 1991. Near real-time mosaics from high-resolution sidescan sonar - an image processing technique to produce hard-copy mosaics 'on site' proved successful during USGS survey, Sea Technology, V.32, no.1, pp. 54-59.
Danforth, W.W, 1997. Xsonar/ShowImage: A complete system for rapid sidescan sonar processing and display, USGS Open-FIle Report 97-686, 77 pp.
Engstrom, D.R. (ed.). 1995. Proceedings of the Third Glacier Bay Science Symposium, National Park Service, 1993. Alaska Regional Office, Anchorage, AK. 310 p.
Gann, J.T. 1992. YoNav: Your own integrated navigation system for DOS platforms. U.S. Geological Survey, Open File Report 92-565, 48 p.
Geiselman, J., J. Dunlap, P. Hooge, and D. Albert (eds.). 1997. Glacier Bay ecosystem GIS CD-Rom set. U.S. Geological Sruvey and Interrain Pacific. Anchorage and Juneau, AK.
Goldthwait, R.P. 1963. Dating the Little Ice Age in Glacier Bay, Alaska.. International Geological Congress, XXI Session, Norden, 1960, Part XXVII, Copenhagen, Denmark, p. 37-46.
Goldthwait, R.P. 1987. The glacial history of Glacier Bay Park area. In: Anderson, P.J., R.P. Goldthwait, and G.D. McKenzie, (eds.). Observed Processes of Glacial Depostion in Glacier Bay, Alaska. Guidebook for INQUA commission II Field Conference, June 1986. Byrd Polar Research Center Mscl. Pub. No. 236, p. 5-16.
Greene, H.G., M.M. Yoklavich, D. Sullivan, and G. Cailliet. 1995. A geophysical approach to classifying marine benthic habitats: Monterey Bay as a model. Alaska Department of Fish and Game Special Publication 9:15-30.
Milner, A.M., and J.D. Woods (eds.), 1990. Proceedings of the Second Glacier Bay Science Symposium, 1988. National Park Service, Alaska Regional Office, Anchorage, AK., 165 pp.
O'Clair, C.E., J.L. Freese, R.P. Stone, T.C. Shirley, E.H. Leder, S.J. Taggart, and G.H.Kruse. 1995. Nearshore distribution and abundance of Dungeness crabs in Glacier Bay National Park, Alaska. In: Engstrom, D.R. (ed.). Proceedings of the Third Glacier Bay Science Symposium, 1993. National Park Servbice, Alaska Regional Office, Anchorage, AK. p. 196-202.
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