A fish story from MIT

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    A fish story from MIT

    In a sad but typical example of its sleepy news medium, the Globe reported an innovation from MIT recently as though it were a done deal, lacking only a political champion--in the tiresome, garrulous Sen. Kerry. [ Jay Lindsay, Associated Press, New sonar technology could boost fish counts, Boston Globe, November 20, 2011, at www.boston.com/news/local/massachusetts/articles/2011/11/19/new_sonar_technology_could_boost_fish_counts/ ]

    Prof. Nicholas C. Makris of MIT and colleagues propose a sonar system, with which they have been working for several years, to improve the error-prone NOAA estimations of ocean groundfish from trawl samples. The Globe's story, unfortunately, was a hacked-down AP article, available in full only from other sources. [ WHDH, at http://www1.whdh.com/news/articles/local/boston/12005943421660/new-sonar-technology-could-boost-fish-counts/ ]

     
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    An emerging technology

    Ocean acoustic waveguide remote sensing (OAWRS) has become an enthusiasm of Profs. Nicholas C. Makris of MIT and Purnima Ratilal of Northeastern University, first reported by them to track schools of ocean fish in 2006. It is a derivative of an old technology, first applied in the 1930s, using sound echos in ocean, multiply reflected between sea surfaces and bottoms. As with accoustical imaging in geology, modern computational resources have improved the capabilities. However, it remains unreliable, plagued by several sources of spurious signals and by weak differentiation of signals among targeted sources.

    The accoustic system employed by Profs. Makris and Ratilal appears primitive, as compared to those used in geologic prospecting, with only 64 receiver elements. [Makris, et al., 2006, online supplement] Otherwise, its characteristics have apparently not been described in a peer-reviewed, technical journal.

    For mapping and tracking fish schools, it was found most effective at mid-range sonic frequencies of a few hundred Hz. The useful area resolution of images shown in 2006 was tens of acres over imaging areas of tens of square miles, enough only to spot large schools of fish. Frequency patterns of signals have proven far too diffuse to identify kinds of fish in multiple schools. Fish were identified only from trawl samples.

    So far, the only notable success of the technology has been mapping and tracking schools of Atlantic herring at mid-water depths, with time intervals of around one minute. It has yet to be shown that the MIT system can reliably map and track cod, haddock or other groundfish. It has yet to be shown that any system of the type can reliably distiguish between different kinds of fish found in nearby schools.

    [ Nicholas Makris, et al., Fish population and behavior, Science 311(5761):660-663, 2006, at http://www.sciencemag.org/content/311/5761/660.full.pdf ]

    [ Nicholas Makris, et al., Critical population density, Science 323(5922):1734-1737, 2009, at http://www.sciencemag.org/content/311/5761/660.full.pdf ]

    [ Srinivasan Jagannathan, et al., Ocean acoustic waveguide remote sensing, Marine Ecology Progress Series 395:137–160, 2009, at http://www.int-res.com/articles/theme/m395p137.pdf ]

    [ Zheng Gong, et al., Low-frequency target strength and abundance, Journal of the Acoustical Society of America 127(1):104-123, 2010, at http://asadl.org/jasa/resource/1/jasman/v127/i1/p104_s1 ]

     
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    Re: A fish story from MIT

    Since NOAA only looks at fish caught and has a large statistical bank of data over decades, this possible but not yet conclusive tech has to wait until a valid sample of the technique proves a good tool.
    Hey my grandma used to buy the latest gadgets all the time for this or that. But when you actually tried to use the great invention it either broke or cut your fingers or both. The point being that I am in research, what needs to be said to get more money and what needs to be done to get things that work well, are a whole different world.
    Any point source as a sample is useless in ocean populations. You either track or take a statistically important number of point sources. The fishing fleet does a hundred plus on a given day over a large region. So any tech like this would need to deploy over a hundred sensors on a day over a year or five to prove that actual catch and numbers in the ocean have a statistical match for the long term 50+ years of catch data.
    Plus you still need to prove that the acoustics of the scan do not affect the schools causeing them to gather or disperse or even just disrupting their breeding behavior, thus causeing more damage to the population.
     
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    Half a loaf

    Well, reader "topaz978" does have several good points here. A former MIT researcher for about 15 years has heard many a "fish story" over those times and so would not be surprised when the latest "MIT miracle" is slow to arrive.

    The "tried and true" NOAA system catches fish with trawls, just like the commercial fishing industry. To the extent of workers' abilities, probably substantial, fish caught will be accurately identified and sized. The limitations are in trying to probe the oceans with a virtual toothpick: a scattering of surveys, divorced from day-to-day fishing experience.

    The MIT system from Prof. Makris and colleagues goes to the opposite extreme--unidentified fish, yet a vivid, real-time picture of fish schools--at least at mid-ocean depths--capable of being mounted at most times of the year, not just on the rigid schedules of NOAA fish counts. Woe, we cannot yet combine those advantages!

    Just recently, federal "regulators could end fishing Gulf of Maine cod," based on sparse trawl surveys. A new England commercial fisherman says, to the contrary, that "cod isn't crashing but is so plentiful fishermen are taking steps to avoid it so they don't exceed tough catch limits."

    [ Jay Lindsay, Associated Press, New cod data shaking New England fishing industry, Boston Globe, November 26, 2011, at http://www.boston.com/news/local/massachusetts/articles/2011/11/25/new_cod_data_shaking_new_england_fishing_industry/ ]

    NOAA recently sank its available funds into a new research vessel and is unlikely to change course for years, so initiative is with Makris and colleagues. They need to develop means to identify schools of commercially valuable groundfish, near ocean bottoms, as well as their favored species, herring, at mid-depth. They need real-time sampling that unmistakably identifies fish in the large schools they can see and measure.

     
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