Integrating Charting and Acoustic Habitat Research

Sea Technology, Aug 2008 by Lomnicky, Jay, McConnaughey, Robert

Bristol Bay was chosen as the study area because this region supports important commercial fisheries for species including red king crab, Pacific salmon and Pacific halibut, and the Bristol Bay side scan sonar pilot study demonstrated a high degree of spatial variability in the acoustic seafloor return. The relatively flat, featureless seafloor is also an important criterion, since it allows for relatively safe deployment of towed survey equipment. Charted sounding data are sparse in Bristol Bay, and acoustic data are almost nonexistent over much of its central waters. Notwithstanding, the hydrographic priority of these waters is very low. Considered together, highaccuracy acoustic data from the area would contribute significantly to both the fisheries and the hydrographic missions.

A successful FISHPAC cruise in 2006 proved that interoffice cooperation on multi-mission surveys is feasible, mutually beneficial and highly productive. Without the aid of technically experienced sonar operators and hydrographers, large-scale acquisition and processing of high-quality acoustic data would be impractical for fishery scientists, or at best, unnecessarily expensive.

Conversely, without an exigent need for the bathymetry, many navigable areas such as Bristol Bay would remain unsurveyed well into the future.

Some specialized equipment acquired by NMFS for FISHPAC (e.g., the MVP, C&C Technologies' [Lafayette, Louisiana] C-NAV) is finding good use in the ship's regular hydrographie mission.

In addition to valuable information and technological enhancements benefiting both groups, this inaugural venture provided important experience and insight for improving future projects of this nature, including a follow-up EBS cruise this year.

Lessons Learned

Besides supplying sonar data useful for fisheries management and navigation safety, a number of valuable lessons were learned from the 2006 FISHPAC project effort. Taken together, they provide guidance for planning and executing similar multi-mission collaborative efforts.

A research team will usually bring aboard large quantities of specialized project gear during cruise mobilization. Advance planning for loading and storing these items is important, especially in cases involving otherwise dedicated (hydrographic) vessels.

Complex integrations between project equipment and standard vessel systems should be worked out well beforehand.

Because multi-mission efforts will usually involve unfamiliar activities, time must also be allocated to develop safe and effective operations procedures. In both cases, detailed documentation is a useful starting point for subsequent cruise planning and compensates for ship's crew rotations.

Some procedural changes may be necessary when conflicting data needs exist. For example, gain and rangescale settings chosen to optimize backscatter may increase noise in the bathymetry data. Such compromises are inevitable in a multi-mission setting; they must be carefully considered in advance and any deviations from standard protocols clearly communicated to all operators.