Table 1. Summary statistics of 2002-2004 abalone cruises 3
2. Introduction 5
2.1 ROV Project Management 5
3. Overview of the ROV System 6
3.1 The ROV 6
3.2 The ROV console and heads up display 7
3.2.1 Directional Hydrophone, Transponder and Trackpoint 7
3.2.2 DGPS 7
3.2.3 Pitch and Roll Sensor 8
3.2.4 Tracking and Data Processing Software- WinFrog & Ribbit 8
3.3 The Tether 9
3.4 Vessel and Cranes 9
3.5 Clump weight and cable counter 10
4. Habitat Mapping and Transects 10
4.1 Habitat Mapping and Transects 10
4.3 Data collection 10
5. Analysis strategies 11
5.1 Determining transect area 11
5.2 Population estimates 12
5.3 Refinements to the base model 14
6. Project Management 14
6.1 Timing and Logistics 14
6.2 Team structure 14
6.3 OH&S 15
6.4 NOAA Corps and Scientists on-board communications 15
7. Discussion 16
8. Acknowledgements 17
9. References 17
Davis, G.E., Richards, D.V., Haaker, P.L., Parker, D.O. 1992. Abalone population declines and fishery management in southern California. In: Sheperd S.A., M.J. Tegner, and S.A. Guzman del Proo (eds.), Abalone of the World: Biology, Fisheries, and Culture. Fishing News Books: 237-249. 18
Table 1 19
Appendix I- Overboard Equipment and ROV Configuration 24
Appendix II- Onboard Equipment and Software 25
Appendix III- Work Day Start Up Check list 26
Appendix IV- Pre-deployment Checks 27
Appendix V- Transect Checks 28
Appendix VI- ROV Deployment 29
Appendix VII- ROV Recovery 31
Appendix VIII- post dive checks 32
Appendix VIII- Setting up the WinFrog Program. 33
Appendix XII- Mobilization logistics checklist 36
List of Tables
Table 1.Summary statistics of 2002-2004 abalone cruises
List of Figures
Figure 1. Diagrammatic representation of the ROV console and placement of devices on the ROV.
Figure 2. Captured image of WinFrog screen as viewed during a dive.
Figure 3. Quantitative Measurement Software (QMS) video grab. Lasers are used as reference points to measure between particular points on the image (blue and red dots).
Figure 4. Bathymetry map of white abalone habitat with transect tracts (black lines), abalone sightings (yellow circles), and abalone shell sightings (red circles) at San Clemente Island.
1. Executive Summary To minimize negative impacts on organisms being studied it is important to use non-destructive sampling methods when possible. Depending on the life history characteristics and habitat type of the study organism this can be a large challenge. SCUBA diving surveys are a natural choice for non-destructive sampling, but animals that occur in relatively deep water (> 30 m) cannot be studied effectively by these means due to the time-consuming nature of SCUBA surveys. Manned submersibles have been used to study deep dwelling organisms, but are costly in general, especially when extensive and repeat surveying is necessary. The use of remotely operated vehicles (ROVs) is a relatively low cost, non-destructive method that is ideal for surveying many deep dwelling organisms.
The use of ROVs to survey invertebrates and fishes has moved from a design and development phase to a standard procedure at the NOAA Fisheries South West Fisheries Science Center (SWFSC). The aim of this manuscript is to document the scientific and technical knowledge of the SWFSC ROV program to assist others working with ROVs, and to compile the extensive knowledge acquired during the design phase of the ROV program. The study organisms to date have included the white abalone (Haliotis sorenseni) and various rockfish species. These case studies will provide examples of the ability of scientists to use ROV surveys to study organisms ranging from slow-moving invertebrates to highly active fish. Use of an ROV for stock assessment has proven to provide a large amount of information with a reasonable amount of effort and expense. Additionally, surveys are captured by video and still camera for permanent documentation. The ROV program design described in this manuscript has proven useful for many purposes and is worthy of emulation by others seeking similar survey methods.
2.1 ROV Project Management
The sampling techniques used for stock assessment in fisheries biology could be described as trying to count trees, which you can’t see, that keep moving around. While the use of SCUBA diving has allowed biologists to study a number of marine species, excursions are limited to shallow depths. When scientists want to conduct research on living creatures at depths greater than 20 or 30 meters below the surface, they often need to resort to increasingly complicated and expensive machines. In recent years the use of remotely operated vehicles (ROVs) has increased in popularity as a research tool for studies of deeper living organisms.
At the NOAA SWFSC a ROV program based around a Phantom DS4 ROV has been in place since 1999. Since the inception of the program, 22 ROV cruises have been completed, with studies focused on squid fecundity, rock fish population assessment, and abalone conservation.
Although ROVs are now commonly used by researchers, they are typically not “off the shelf” items. Rather, they are complicated systems comprised of mechanics, electronics, and computers, where, in most cases, each component has been designed for a broad range of applications and must be adapted for specific use on the ROV. When combined with the extreme operational conditions in which ROVs operate, this adaptive engineering means that there is a high potential for multiple equipment failures during cruises. In addition to these technical difficulties, ROVs are often tasked to multiple programs, and at least for research, must be used within the rigorous demands of scientific design.
All of these facts make project management of ROV operations a demanding task. In such a complex working environment, the in-house knowledge of protocols that resides in the cumulative experience of staff is vital to the smooth operation of ROV programs. The problem with in-house knowledge, especially in small teams, is that it can be easily lost when staff members leave the organization. To combat this project management dilemma this document attempts to consolidate the technical knowledge developed since the inception of the ROV program in 1999.
2.2 Examples of ROV research objectives NOAA research on the endangered white abalone (Haliotissorenseni) is focused on stock assessment at various locations in its geographical range. As the species has been over-exploited and lives beyond SCUBA-safe depths, ROV surveys are used to locate, count, estimate size and photograph abalone. A secondary aim is to map the locations of individual white abalone so at a later date brood stock can be collected for a captive breeding program. The majority of suitable habitat in California is currently being sampled which will increase the confidence of the population estimate.
NOAA rockfish research has used ROV sampling techniques to assess southern California rockfish populations and to provide ground-truthing for sonar surveys aimed to identify rockfish assemblages. Additionally, the ROV is used to ground-truth sonar classification of rockfish habitat. The target rockfish species are found well below diver-accessible depths (~200 m), so the use of the ROV for video transects is very valuable. The ROV is used to survey fish schools, photograph fish for identification, and provide a view of the bottom for bottom-typing. Key species, such as cowcod and vermillion rockfish, are identified, counted, and measured.
The specifications of the Phantom DS4 ROV were chosen based on the physical and biological requirements of the sampling design. The Phantom is powered laterally by four ½ horsepower motors, vertically by two ¼ horsepower motors, and can dive to a maximum operating depth of 600 meters. The optical infrastructure consists of both streaming video and digital still cameras. While the base ROV unit is fairly simple, the system can be modified to fit the needs of a specific project (a list of overboard ROV equipment and specifications is provided in Appendix I). For example, in the case of the white abalone project, precise positioning data for the ROVs location on the bottom is necessary so brood stock can be collected by SCUBA divers. Obtaining this data requires implementing a vehicle tracking system that consists of a multi-beacon mounted on the ROV and a directional hydrophone mounted on the support vessel. The ROV also sends bearing, speed, depth, altimeter, temperature, and pitch and roll data back up the tether cable. These data are combined with a Differential Global Positioning System (DGPS) and Pitch and Roll sensor on the support vessel and then fed into a computer program called WinFrog. The program combines all of these data (and data from any other instrument that is added to the system) to be plotted on a computer screen displaying the ROVs position in real time. This allows for accurate estimates of transect distance to be obtained for each ROV dive.
Two sets of lasers are included on the ROV: one is spaced 10 cm apart for measuring abalone, and the second set is comprised of three horizontally aligned lasers with two fixed and one that is angled and therefore wanders. This second set of lasers provides a metric: when the wandering laser and outer fixed laser cross, the vehicle is ~ 2 m from this point. This allows for an accurate estimate of transect width.