|SCOR Working Group 118: New Technologies for Observing Marine Life|
Terms of Reference
Working Group Members
Funding provided by
the SLOAN Foundation's
Census of Marine Life
2001 Working Group Meeting
(27 October 2001, Mar del Plata, Argentina)
Census of Marine Life in the Gulf of Maine
Staying on the theme of mass production, Ken Foote made a strong plea for the provision of a calibrated output signal on mass-produced fisheries echo sounders, in place of the existing video signal. Artisanal fisheries in developing countries offered the potential for wide-scale synoptic surveys that could not be achieved with research vessels, provided standard sounders had a calibrated output. Water column mapping using sonar with a midwater signal was another area in which research could benefit from mass produced instruments. Mass-produced ADCPs, too, offered the potential of four scientific sounders looking simultaneously in different directions. A quantitative signal with a good dynamic range was, however, an essential prerequisite.
Turning to the specific problems of the Gulf of Maine census, Ken Foote provided a list of species for which it would be appropriate to use acoustic surveys and identified four challenges in the development and application of this technology. The first and second challenges were to make good acoustic measurements and quantitative biological measurements. The third entailed target classification, for which better acoustic bandwidths were required. The WG could help by supporting the case and stimulating manufacturers to provide solutions. The fourth challenge involved integrating optical and acoustic technology and using acoustics to extend the range of observation of optical instruments. Echo sounders or multi-beam sonars, for example, could be used in conjunction with video to provide both long- and short-range observations.
A major component of the Gulf of Maine project was a census of intertidal and sub-tidal benthos. Distribution and abundance would be surveyed from 0 to 20 m in specified areas, using transects and standard protocols. Soft sediments would be sampled using cores, or a cheap sediment profile-imaging camera. Epifauna would be recorded with a digital still camera prior to physical sampling and the bottom would be surveyed in 10-m wide swathes, using an ROV or AUV (e.g. REMUS) with the ability to navigate precisely in shallow water. Bathymetry and backscatter data would be obtained with interferometric sidescan sonar. Oceanographic data would be obtained from nearshore GoMoos moorings and data acquisition would be designed to complement parallel offshore benthic studies. The results of the pilot inshore and offshore studies would be fully integrated.
Data would be analysed, as follows:
In response to questions from David Welch, Fred Grassle and Dan Costa about the key research questions to be addressed by the project, Jesse Ausubel stressed that one of the key issues for the CoML programme was the distribution of biomass by taxon and habitat. This question, which had been highlighted by Van Holliday at the inception of the CoML programme, had not been addressed at all in some environments. Subsequent discussion concerned sampling from ships of opportunity, species identification by acoustic means and how to merge complex data into an ecosystem database.
Ships of opportunity offered great opportunities in both developed and undeveloped countries, provided various problems could be overcome. François Gerlotto pointed out that developing countries could afford neither expensive equipment, nor expert observers. Sorting and cleaning up data was therefore a major issue, especially as ships of opportunity afforded the only way of carrying out large-scale synoptic surveys in such countries. Experience in Japan (Yoshihisa Shirayama) and Canada (David Welch) had, however, demonstrated the wide-spread need for simple, reliable, automated ‘black box’ instruments, which could be readily used by fishermen or other mariners, and easily serviced and calibrated by scientists after each voyage. Fishing vessels, which could also provide ‘ground-truthing’, would provide ideal platforms in the Gulf of Maine and also in the Humboldt Current (Mariano Gutiérrez - see ISPPA below). Julie Hall pointed out that yachts could provide a useful alternative in some areas and Jesse Ausubel said that CoML had been approached by a group of ocean-going yacht owners, who were interested in marine conservation. The members of this association (Seakeepers) wanted to make observations at sea, but had no idea what to do; specific proposals were therefore needed if their interest and enthusiasm were to be usefully harnessed.
It was agreed that the question of equipping ships of opportunity was an important one to resolve, given the potentially large benefits in many parts of the world, especially developing countries. An ensuing discussion of ways and means of equipping fishing vessels concluded that, because fishermen replaced their instruments frequently (David Welch), and in Chile would even pay for scientific equipment (Mariano Gutierrez), it would appropriate to plan to install calibrated echo sounders. This would probably be more cost-effective than attempting to fit ‘black boxes’ in conjunction with existing sounders, although this might initially appear to be a cheaper alternative because it avoided dry-docking costs (Adrian Madirolas). Experience with the PICES programme in Canada (David Welch) indicated that, where other instrumentation was concerned, it was essential not only to provide an unobtrusive ‘sea chest’ but also to convince fishermen of its ease of use.
Olav Rune Godø asked how the complex acoustic data obtained by the Gulf of Maine project were to be merged into an ecosystem database. He also drew attention to the problem of species identification and the need to determine the probability of correctly identifying the composition of the targets giving rise to an individual echo sounder record. Neural networks might offer one approach to this problem, a solution to which would have world-wide application; a link to OBIS might be useful. In reply Ken Foote said that, given that species identification was the long-term goal, he was in discussion with interested manufacturers and trying to encourage the development of multi-frequency, broad band acoustic devices to be used in conjunction with neutral networks, as appropriate. Dan Costa pointed out that location per se might be a simple, effective way of differentiating between acoustic targets that would otherwise be indistinguishable by their echoes. Summarising the discussion, David Farmer said that, whilst recognising that there were formidable problems (e.g. swimbladder form and function), the WG concluded that acoustic assessment and identification was a key area for scientific advancement and that increasing the bandwidth of instruments was a key technical issue. François Gerlotto drew the WG’s attention to the ICES Symposium "Acoustics in Fisheries & Aquatic Ecology" (Montpellier, France, June 2002), at which bandwidth and multi-frequency would figure prominently.