1. Looking for Fish of the Right Age: GIS, Salmon Genetics, and the Need for Better Bathymetry
JON KRIER | 44th Annual Meeting of the Alaska Anthropological Association| Department of Applied Anthropology | Oregon State University | February 2017
Results and Discussion
Introduction
Need For Better Bathymetry
Improved understanding of major Beringian drainages and the LGM environment
St. Matthew Island identified as a potential area of relatively intact submerged landforms
Isostatic adjustments vital for future analysis
New bathymetric data needed for future study
Limitations
INSTAAR dataset, while superior to anything else in region, still subject to artifacts and resolution issues
Other datasets inadequate for analysis purposes
Current sostatically adjusted datatsets too limited in scope and bathymetric resolution to provide more than sea level approximations for central Beringia
One of the primary challenges to continuing with this sort of analysis is the lack of adequate bathymetric data. St. Matthew Island was identified as an area of interest. However as the top image shows, there are too few sonar scans to build a detailed model. Incorporating those scans into NOAA’s base data only serves to enhance the inadequacy of current sounding data.
North of St. Lawrence Island there was a small sonar survey footprint. The third image shows the NGDC Autogrid output for that area, in contrast to the St. Matthew sonar data. The fourth image shows that sonar data with a simple IDW interpolation. The final image puts that small survey into context, and drives home the scale of the data problem
Geospatial analysis of Beringian bathymetric data provides powerful tools for formulating predictive modeling of submerged sites of Pleistocene age. With the acceptance of Pre-Clovis archaeological sites in the Americas (Jenkins et al., 2012), attention has shifted to alternative models of the peopling of the Americas. A Coastal Migration hypothesis has been proposed by Erlandson et al. (2013, 2015), however any evidence of such a route is now submerged. Ice free areas along the Pacific margin of North America would have provided refugia for early peoples. Inspired in part by Haida traditional histories, this analysis is attempting to identify streams that could have supported anadromous fish species, like salmon. In addition to being an attractive resource in their own right, anadromous species provide marine derived nutrients to a variety of terrestrial taxa. More broadly, incorporation of genetic data and contemporary population studies provides insight into the effects of climate change on economically important species. This study provides preliminary results of hydrologic analysis as well as recommendations for future inquiry.
Note on the Projection:
For all of the maps generated for this project the Berghaus Star AAG projection was used. This projection was selected for reduced distortion at polar latitudes, as well as relatively less distortion a middle latitudes than other polar oriented projection systems.
Slope and Curvature
One of the analysis goals of this project is to identify areas where it appears that landforms have been preserved. It is thought that visible landforms could represent relatively intact landscapes that were not too deeply buried beneath alluvial sediments during oceanic transgression.
The first approach employed in the search for intact landforms was a slope analysis. By limiting the analysis to the submerged areas contrasts were emphasized. However, this method did not reveal terrain complexity along the Yukon paleo-drainage.
Identifying Drainages and Streams
The next approach utilized contour lines at 10 meter intervals. This method revealed more terrain complexity, but once again did not indicate preserved landforms in the are of the Yukon paleo-drainage
Key to this analysis project was the identification of streams and drainages (to identify the areas that were appropriate for additional analysis). Using hydrologic analysis to understand the drainage of Beringia allowed for the generation of stream and drainage layers.
Alsek River (red) and Haida Gwaii (green)
Note on Salmon Genetics
Research for this project included a focus on the results of more than a decades worth of salmon microsatellite loci DNA analysis (Smith et al. 2001, Beacham et al. 2006a, 2006b, 2009, 2012). The inspiration to look for paleodrainages was the idea that salmon would be an attractive resource, but it was not immediately clear if there even were salmon in Beringia during the LGM. The genetic data indicates that there were indeed salmon populations that persisted in Northern refugia through the LGM. Beringia appears to have supported all salmon species, while two other refuges in SE Alaska and Haida Gwaii supported partial species assemblages.
The original goal was to also conduct similar analyses of South Central and Southeast Alaska, as well as the Haida Gwaii. Due to data limitations only minimal sea-level analysis was possible. The Alsek River had been identified as a center of genetic diversity, however the drainage was under a lobe of the ice sheet at the LGM.
The final approach employed in this analysis was to incorporate curvature analysis (slope of the slope). Using the profile curvature in conjunction with hillshade revealed apparent Yukon stream channels near St. Matthew Island (as well as data artifacts).
Analysis model shown is the steps taken to generate the stream layer.