There are no subtidal benthic habitat maps of Kachemak Bay, Alaska, to support essential fish habitat and place-based management needs. In response, we are developing benthic habitat maps for the bay using multibeam sonar data to inform future coastal conservation, management, and planning activities.
Why We Care
Currently, there are no subtidal benthic habitat maps of Kachemak Bay to support essential fish habitat and place-based management needs. With the designation of Kachemak Bay as a Habitat Focus Area under the NOAA Habitat Blueprint, accurate benthic habitat maps will be a necessity for future coastal conservation, management, and planning activities.
Benthic habitat maps will provide crucial information to a number of ongoing coastal management issues. For example, maps will supply important data for efforts examining declines in shrimp and crab that have not recovered despite fisheries closures. The data will also be valuable to ongoing efforts within the bay to examine the associations of ground fish with particular benthic habitats.
What We Did
We are developing the maps for the bay using multibeam sonar data collected during hydrographic surveys conducted by the NOAA Ships Fairweather and Rainier. The area we are mapping is large and deep, approximately 71 kilometers long and 10 kilometers wide (229 square nautical miles), and approximately 170 meters at its deepest. To aid the development of the maps, we are using an extensive July 2016 field verification effort that visualized bottom habitats with underwater video. To date:
- We created a draft benthic map that was used to guide our first field data gathering mission in July 2016, and
- During the July 2016 field mission, we collected underwater video at 300 sites throughout the bay to aid in benthic habitat classification.
This is a collaborative effort with the University of Alaska and Alaska state entities, including the Alaska Department of Fish and Game and the Kachemak Bay National Estuarine Research Reserve.
We are using the underwater video to create a final map product. If funding is available, we will conduct another field mission in summer 2017 to collect additional underwater video in areas with discrepancies. We will also attempt underwater video in the deepest sections of the bay. In 2016, we were only able to visualize habitats up to 120 meters deep due to the limitations of our equipment.