Before we get to the Fairweather logs, we need to update the last post, NOAA Ship Fairweather zigzags her way to accurate and precised depth soundings. Cmdr. Crocker reports that the “normal” zigzagging won’t start until they head further north, starting near Point Hope. It was not planned for the trip to Kotzebue, and he would have run a straight course if he could have. This log by Ensign Hadley Owen explains why they zigzagged earlier than planned, as well as what they are doing for their first scientific project. We apologize for the error in the last post. -DF
Fairweather Log Entries, August 2 and August 5
by Ensign Hadley Owen, NOAA, Junior Officer, NOAA Ship Fairweather (S-220)
2400 hours, Thursday, August 02, 2012: 57°04.9’N 167°05.5’W, underway, Dutch Harbor to Kotzebue Sound
We left Dutch Harbor on the NOAA Ship Fairweather on August 1, to begin our 30-day reconnaissance trip bound for the Arctic. Our departure had been delayed until 1800 on Wednesday in order to let pass a 988 MB low-pressure system moving northeast through the Aleutians. Our initial plan was a straight line running generally west by north, on which we would acquire seafloor data using the ship’s hull-mounted multibeam echo sounder and a towed Klein 7180 long-range side scan sonar (a one-of-a-kind device designed to maximize the effectiveness of broad-scale fish habitat studies using acoustic “backscatter”). However, a persistent 8’ swell on the ship’s beam resulted in a more than 20-degree roll that kept many crewmembers in their beds and made useful data acquisition nearly impossible. Cmdr. James Crocker, commanding officer of the Fairweather, made the call to alter course in order to pass over the acquisition stations in a tacking motion – zigzagging our way north in order to minimize the effects of the swell on our ship’s data collection activities.
The first leg of our Arctic cruise is focusing on work conducted for NOAA’s National Marine Fisheries Service, and led on the Fairweather by Dr. Bob McConnaughey. He and his team of NOAA scientists and Navy technicians have been studying and mapping benthic regions in the eastern Bering Sea since 1996, addressing a congressional mandate to understand the habitat requirements of the nation’s managed fish and crab populations. Their recent work has focused on using a variety of sonars to identify seafloor properties that affect the distribution and abundance of fish, including the Fairweather’s multibeam echosounders (traditionally used for hydrographic surveying) and side scan sonars that can continuously survey a swath of seafloor up to a kilometer-wide, at a maximum speed of 12 knots. The project goal is to measure backscatter from the ocean’s bottom, rather than to simply produce images of it, and to use this information in combination with other environmental data and estimates of fish abundance from annual bottom trawl surveys to improve the team’s mathematical models that identify the habitat requirements of individual species. At the same time, we are taking care to produce hydrographic-quality bathymetric data for updating nautical charts in areas with outdated or non-existent information – a great example of NOAA’s integrated ocean and coastal mapping strategy.
The NMFS team’s broader interest in the Fairweather’s reconnaissance mission is to be at the forefront of activity documenting the areas that are opening up as the region’s ice-cover retreats. By this work, NOAA’s intention is to be well prepared to support fishery management decisions related to emerging uses: commercial fishing, large-scale shipping and navigation, and oil exploration interests. The team aims to document similarities and differences in the seafloor habitats found along the more than 1,000 km reconnaissance line extending from Dutch Harbor in the Aleutian Islands to the Kotzebue Sound area above the Arctic Circle. The data collected from the eastern Bering Sea, the northern Bering Sea and the Chukchi Sea will provide insights about possible outcomes if fish populations redistribute northward due to environmental change. It will also help us to understand the susceptibility of these areas to new forms of human disturbances.
As of the end of Thursday, August 2, the seas have settled down and allowed the Fairweather to deploy the long-range side scan sonar and begin acquiring data. Depending on conditions, the sonar’s towfish will remain in the water until the northern end of the survey line near Kotzebue. In addition to backscatter data, the side scan sonar is also acquiring data about water column properties such as chlorophyll.
We are keeping a close eye on ice conditions for the latter part of our route. The current ice edge runs to Barrow, and will at present prevent us from completing the last leg of our track in the Beaufort Sea – along the north coast of Alaska and east to the Canadian border. However, any data obtained during this reconnaissance mission will initiate a new large-scale systematic study of the region’s benthic habitats, will provide new bathymetric data for nautical charts, and will ultimately create a foundation for appropriate management and safe navigation in the region’s future.
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1800 hours, Sunday, August 5, 2012: 67°00.8’N 165°35.5’W, heading east, Kotzebue Sound, north of the Arctic Circle
We have been transiting increasingly shallow water since we passed Nunivak Island. As the Klein 7180 operates best in depths greater than 20 fathoms, we were able to take advantage of improved weather and relatively calmer seas to bring the towfish on board yesterday morning. However, data acquisition continues with the ship’s multibeam echo sounder.
At 1400 hours we crossed the Arctic Circle (66°33’N), heading northeast towards the town of Kotzebue. Dr. Bob and his crew will disembark the Fairweather early Monday morning and we will shift focus with a new team of scientists as we continue north. As we transit to our anchorage near the head of the Sound this evening, we will navigate using the newest chart (16161) of the area. NOAA produced Chart #16161 in May, using survey work conducted on the Fairweather last summer; it will be an inspiration for the work to come.