Obstacle Avoidance Fish Stock
Fishery-dependent data (e.g. CPUE from hook-and-line or trawl fisheries) have been the
cornerstone of stock assessment. However, many of these methods have limited ability to sample demersal stocks and hence, the data produced by these methods is often biased and, in some cases, of limited value. Extraction-based methods are not allowed in many marine protected areas or when the sampled stock has already reached its maximum allowable quota. Trawl surveys are unable to sample in the highly complex habitats favored by many fish species. Baited methods, whether fishery-dependent or independent serve to increase precision at the cost of accuracy. To address some of these challenges, the Northwest Fisheries Science Center (NWFSC) and Pacific Islands Fisheries Science Center (PIFSC) jointly own and operate a SeaBED Autonomous Underwater Vehicle (AUV), in collaboration with the Woods Hole Oceanographic Institution. This partnership is currently in the process of transitioning the SeaBED from a research-and-development platform to a fully operational tool for the routine assessment of bottomfish in the Pacific Islands Region and groundfish stocks along the U.S. west coast. A recent (Sept. 2011) PIFSC-funded cruise in the Hawaiian Islands was designed as a pairwise comparison among several different fishery-independent methods for assessing bottomfish stocks. These methods included the SeaBED AUV, stationary baited remote underwater stereo video camera systems, and active acoustics. Although data from the cruise are still being analyzed, stock assessment personnel participating in the cruise were able to provide several recommendations to improve the survey design and enhance the SeaBED’s ability to sample bottomfish stocks. While the SeaBED was programmed to operate in close proximity to steep rocky slopes, at present it cannot navigate safely directly along the face of these slopes that are the preferred habitat for bottomfish. The most critical recommendation was to engineer changes in the AUV’s behavior to enable it to operate directly on steep slopes and ledges and in complex habitats where bottomfish densities are greatest. This proposal requests support to develop and test changes in the AUV’s sensor package and operating software to enable basic obstacle avoidance, allowing the SeaBED to conduct surveys along an isobath while remaining within close proximity to steep slopes. Developing this capability will overcome a significant obstacle to the effective use of the SeaBED as an operational fishery-independent assessment tool for bottomfish stocks in the Pacific Islands Region. This capability will also enhance the SeaBED’s ability to survey complex and untrawlable seafloor habitats preferentially utilized by rockfish on the west coast, as well as deep coral and sponge reefs in that region.