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étiquettes: bathymetry, oceanography, sonar survey, hydroacoustic survey, arctic cod

Objectif(s): To collect baseline data on fish distribution and abundance, particularly Arctic Cod (Boreogadus saida), during summer/fall in the southeastern Beaufort Sea and Amundsen Gulf using the SX90 fish finding sonar; and to assess the effectiveness of active acoustics in detecting and identifying marine mammals at a distance from the research platform.

Description du projet: As part of the ArcticNet marine-based research program, the Canadian Coast Guard Ship (CCGS) Amundsen will conduct standard oceanographic and bathymetric sampling operations in the Beaufort Sea/Amundsen Gulf/Mackenzie Shelf region. The Amundsen will conduct an active acoustics survey in a designated area of Amundsen Gulf and opportunistic surveys along the ship track in the southern Beaufort Sea and Amundsen Gulf. The project is focused on two main research components: 1) fisheries research; and 2) marine mammal detection. The general objectives of this project are: 1) To collect baseline data on fish distribution and abundance, particularly Arctic Cod (Boreogadus saida), during summer/fall in the southeastern Beaufort Sea and Amundsen Gulf using the SX90 fish finding sonar. 2) To assess the effectiveness of active acoustics in detecting and identifying marine mammals at a distance from the research platform. Survey Protocol SX90 Sonar The active acoustics project will use the Kongsberg-Simrad SX90 long range, low frequency (20-30 kHz) fish finding sonar. This sonar operates at a similar frequency to the existing EK60 echosounder on board the Amundsen, but with its omni-directional beam surmounts the narrow beam coverage and detection limitations of the EK60 in the upper surface layer (see section 7 for more details). Target detection and identification using the SX90 sonar can be influenced by the physico-chemical properties of the water column and type of bottom sediments. Hence, before conducting the surveys, a custom 50x50 cm tri-plane reflector will be used as a reference target to calibrate the SX90 sonar. This calibration will provide information on how the physical environment affects sonar observations and in turn, fish or whale detections. Fish Survey An SX90 survey will be carried out in a designated area in Amundsen Gulf. The survey area is roughly 10000 km2 with water depths ranging from 30m to 600m. A total of 48-h (non-consecutive) will be spent in the survey area where the ship will run between two and five transects with the SX90 sonar to collect baseline data on fish distribution and abundance, particularly Arctic Cod (Boreogadus saida). All transects will be located at least 10 nautical miles (18.5 km) from the nearest coast. The number of transects for the survey area was determined using a standard fisheries survey calculation, with additional transects added to improve the robustness of the study. The Amundsen will run transects along the length of the survey area at a vessel speed ranging between 8 and 12 knots (approx. 22km/h). Both the SX90 sonar and EK60 echosounder will be operational during the survey and if fish aggregations are detected, a rectangular mid-water trawl will be deployed to sample the fish and thus enable the validation of the observed echoes. Opportunistic and Adaptive Surveys In addition to conducting an active acoustics survey in a designated area in Amundsen Gulf, the ship will be operating the SX90 sonar on an opportunistic basis when in transit between sampling stations. If fish aggregations are detected while in transit and conditions allow, a rectangular mid-water trawl will be deployed to sample the fish. An adaptive survey approach may also be used while the ship is in transit to reduce the uncertainty associated with large-scale field surveys of populations with a highly skewed distribution (e.g. pelagic fish) or low numbers (e.g. cetaceans) (Harbitz et al. 2009). The omni-directional sonar beam of the SX90 allows for observation of the whole water volume up to 2km around the vessel. Hence, if fish aggregations or cetaceans are detected at some distance from the ship, the course may be changed to track the targets and increase the number of observations recorded by the sonar and therefore maximize the accuracy of survey results. However, it is important to note that during adaptive surveys for marine mammals (cetaceans or pinnipeds), the ship will always stay at a distance greater than 150 m from the target and the gathering of data with the sonar will last no longer than 10 minutes. ArcticNet is committed to executing the surveys as outlined within this document to the best of its ability in the context of environmental conditions and limitations. As in past years, research results will be communicated to Inuvialuit organizations and communities through progress reports submitted to the Aurora Research Institute as well as during community visits and regional scientific meetings conducted by ArcticNet researchers. The ArcticNet annual report is also sent out to Inuit partners and Northern organizations. To promote communication between researchers and community members and therefore more easily distribute results and information to and from the communities, ArcticNet co-funds a full time Inuit Research Advisor position in all 4 Inuit regions of Canada (see: http://www.arcticnet.ulaval.ca/research/advisors.php). All results from ArcticNet’s marine-based research program are made available as peer-reviewed articles in scientific journals. Once the intellectual property rights of the researchers and partners are satisfied for publication, relevant data sets will be incorporated into the central database of ArcticNet (http://www.polardata.ca/) and offered for inclusion in national and international data banks. The fieldwork for this study will be conducted from September 8, 2013 to October 1, 2013.