EK80 Water Column Sonar Data Collected During PC2405_Leg3

Much greater uncertainty in estimating annual catch limits for multiple reef fish will occur if this survey is not conducted. Without this survey, there will be greater uncertainty and thus decreased stakeholder confidence in stock assessment results for myriad reef fish species. When uncertainty increases, there is a larger window of opportunity for industry to dispute management actions with lawsuits. For example, without continued collection of SEFIS data in the South Atlantic, it will be nearly impossible to reassess red snapper, meaning the fishery may be closed longer than needed, with significant lost revenue and
economic losses for the fishing community.


On legs 1 and 2, we will deploy baited traps with attached video cameras at a variety of stations in the U.S. South Atlantic. Traps have a single line connected to two surface buoys. Vessel operations will occur over a 24-hour workday. Trapping, video, hook-andline sampling, and CTD operations will occur from approximately 0700 to approximately 1900 each day, during which time at least three vessel crew members will be needed on deck. We will use the time between approximately1900 and 0700 each day for multibeam sonar mapping, transit to the next dayâs sampling stations, or for hook-andline
sampling. We will also be continuously running the calibrated EK-80 to collect acoustics data for fish during trap deployment and retrieval.
The FPC has already supplied the ship with GPS points of most trap/video sampling locations, and trap sampling will commence at approximately 0700 each morning.
We expect that six traps will be deployed off the stern of Pisces (down the stern ramp while the vessel is traveling at approximately 4.5 kt) over the course of approximately 20 min, one trap being deployed at a time and no closer than 200 m from another trap. After a group of six traps are deployed in an area, a single CTD cast will be conducted, and then traps will be retrieved after each trap has soaked for approximately 90 min (but no more than 150 min). Trap retrieval will take place at the side sampling station using the pot hauler (note the need to be careful to not let the trap and cameras hit the bottom of ship upon retrieval), and then the scientists will move traps to the back deck for subsequent deployments. On each day, we expect at least three trap âsetsâ (set = 6 simultaneously deployed traps) to be deployed and retrieved on leg 1 and four trap âsetsâ to occur on leg 2. The biggest key to successful sampling on Pisces is picking up traps as quickly as possible so trap samples soak for a similar amount of time. If not, trap samples will be excluded from analyses, considerably reducing efficiency.
After discussions with the Chief Survey Technician in March of 2024, it has been agreed that he will work either the noon to midnight or midnight to noon shift, while the Junior Survey Technician will work the opposite shift. This will allow one Survey Technician to be on shift each hour of the day over the entire 24-hour period. From 0700-1900 on legs 1 and 2, the Survey Technicians will assist with CTD casts, SCS operation, EK-80 data collection, and address any other technical issues encountered during trap-video sampling. From 1900-0700, the Survey Technicians may be asked to map the seafloor using the EM2040 multibeam sonar unit. During leg 3, no trap-video sampling will occur â multibeam sonar mapping will occur 24-hours per day.
(A) Fisheries Acoustic Surveys: Split-beam acoustic surveys using Pisces Simrad EK-80 scientific echosounder (18 kHz, 38 kHz, 120 kHz, 200 kHz) will be conducted during the day to help determine exact trap-video sampling locations and quantify fish abundance around sampling sites. The science party is familiar with EK80 operation and will be capable of self-operation following orientation to the vesselâs computer network and data storage procedures. It is imperative that the EK80 is calibrated before the SEFIS cruise.
EK80 calibration will be performed by a science party member if the wish is to update the calibration completed in June of 2024 in the Gulf of Mexico.

(B) Trap-camera arrays: Baited chevron traps mounted with two high-definition video cameras will be utilized for (1) hard bottom reef fish community assessments, (2) reef fish biological sample collection (i.e., otoliths and gonads), and (3) comparative gear sampling (e.g., cameras versus traps versus split-beam sonar). We plan to deploy and retrieve up to 24 traps per day (sunrise to sunset); six traps will be deployed and retrieved in a set, and three to four sets will be sampled in a day. Individual trap soak times are targeted to be 80-100 min. It is important that traps are hauled back in a
timely fashion, because traps soaking longer than 150 min are excluded from future analyses. A hydraulic pot hauler will be required for trap retrieval, and traps will be deployed off the stern, down the trawl ramp. The science party requests that the grate over the trawl ramp be removed for our cruise.

(C) Hook-and-line fishing gear for collection of reef fish for otoliths, gonad, and diet collection. Reels (N = 4) will be hand cranked with a single hooked line and will not require power, occurring on the back deck. Hook-and-line sampling will typically be conducted after trapping operations have finished for the day, usually around 1400- 2100. Dynamic positioning is useful to hover the vessel at specific locations.

(D) CTD Operations: CTD casts will typically be performed in conjunction with trap camera operations during daytime operations, generally one CTD cast for each deployment of six traps/one set (i.e., 3-4 CTD casts during the day). CTD casts may also occur for mapping purposes.

(E) Multibeam sonar (EM2040) mapping: On legs 1 and 3, we are planning to use the EM2040 to map seafloor habitats using a plan developed in collaboration between the FPC and Chief ST Walsh. On leg 1, multibeam sonar mapping will occur during overnight hours to find locations to sample the next day. On leg 3, multibeam sonar mapping will occur 24 hours per day to ultimately estimate the proportion of the seafloor that is hardbottom between FL and NC, which is critically important for numerous projects in the region. This will consist of zig-zag mapping lines between 20 and 200 m
deep across the region. About 40% of these zig-zag lines were mapped in 2023, so the goal for leg 3 in 2024 is to complete the remaining 60% of this mapping. The two survey technicians on Pisces will carry out all mapping.

Tags: acoustic scattering, acoustic sounders, aquatic ecosystems, aquatic sciences, bathymetry, bathymetry/seafloor topography, benthic, biosphere, doc/noaa/nesdis/ncei, doc/noaa/nesdis/ngdc, earth science, ecosystems, fisheries, in situ/laboratory instruments, marine ecosystems, national centers for environmental information, national geophysical data center, nesdis, noaa, ocean acoustics, oceans, pelagic, profilers/sounders, seafloor topography, south atlantic ocean, u.s. department of commerce, vertical location, water column, water column mapping system, wcms
Organization: National Oceanic and Atmospheric Administration, Department of Commerce