Fishing Smarter: - Fisheries and Marine Institute

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NOT FOR REPRODUCTIONhave a big influence on the response threshold andbehaviour toward fishing gear.The study of animal behaviour in relation to fishing gearbegan as a formal scientific discipline among developedcountries in about the 1960s. Since that time, anincreasing number of government laboratories anduniversities have developed research capacity in thisarea. It is usually centred around either 1) thefundamental need to understand and improve stockassessment, or 2) applied R&D for the fishing industry toimprove harvesting efficiency and selectivity. Together,this scientific body includes members from dozens ofcountries that meet annually to share new discoveriesand developments.Types of Technology UsedPrior to the industrial revolution,observational techniques forstudying animal behaviour inrelation to fishing gear wereundoubtedly limited to watchingfrom the riverbank, peering over theside of a boat, and snorkelling.While simple and effective eventoday, they are severelyhandicapped in their ability toobserve at greater depths, reducedlight, increased turbidity, and cold temperatures. It wasnot until the post-war years that significant technologicaladvancements occurred in underwater breathingapparatus, optical camera systems, and acoustictechnology. In many cases, it has been technologydeveloped for military and medical use that fishing geartechnologists and fish behaviourists soon found a way toadapt for the study of fish capture behaviour.Direct observations by scuba divers was one of the firsttechnological strides in the 1960s. With the advent ofSCUBA, humans could now stealthily descend onto thefishing grounds and observe interactions betweenanimals and fishing gear. At first it was static gears suchas baited traps and impounding gears such as weirs andcod pots. But it was not long before divers developed theskill to dive on mobile fishing gears such as bottomtrawls, scallop drags, and clam dredges. The techniqueis still in use today and has been perfected to include theuse of multiple support vessels, two-way communicationamong divers, manned vehicles, etc. The approach isused by research teams at the Fisheries ResearchServices (FRS) Marine Laboratory in Scotland as well asthe National Oceanic and Atmospheric Administration(NOAA) Southeast Fisheries Science Center Laboratory inPascagoula, Mississippi, USA. It is particularly usefulwhere investigations can be conducted in shallow wellilluminatedwaters.Underwater cameras are perhaps the most widely usedinstrument for observing animal behaviour in relation tofishing gear. They are small robust tools for the recordingof information in the field that can be later analyzed in thecomfort of the laboratory. Earlyversions were hand held butengineers soon developed watertight,self-contained recording unitsthat could be deployed onto fishinggear without the intrusion of adiver. Early versions were onlyGRAHAM SANGSTERFigure 1: SCUBA diver filming from the headline ofa bottom trawl.capable of still photography. Thetechnique has proven to beparticularly ideal under darkconditions as animals do notperceive the device until the flash is released and thephotograph taken. It is an unbiased means of recordinganimal behaviour without the worry that your recordingdevice may be altering the behaviour you are trying toobserve. But researchers soon yearned for motionpictures (video). Introduced in the 1960s, chargecoupleddevices known as CCD cameras and siliconintensifier tube (SIT) cameras became available. Not longafter, there were intensified CCD cameras (ICCD) andintensified SIT cameras (ISIT), helping propel scientificenquiry into deeper and darker waters where humanshad never before observed. Uptake of these devices infisheries research grew rapidly through the 1990s due totheir small size, relative robustness, and relatively lowcost. In the 21 st century, we are now seeing researchers16 THE JOURNAL OF OCEAN TECHNOLOGY • EssaysCopyright Journal of Ocean Technology 2008
NOT FOR REPRODUCTIONFISHERIES AND OCEANS CANADAFigure 2: Gear technologist preparing a camera system for deployment.employing multiple-camera systems throughout the fulllength of a bottom trawl, stereophotography for precisesize and swimming speed measurement, as well asinfrared lighting and laser scanning technology to pushthe limits of the depths and distances that opticalsystems can function.One of the common obstaclesof underwater video camerasis the storage of the images.In shallow applications, anumbilical to the surface isoften successful. It is realtimeand cost-effective. Butfor deeper applications this isnot always practical or costeffective.One approachpioneered in Norway was thewireless acoustic transmissionFigure 3: Deployment of video system with umbilical to the surface.of live underwater video to the surface. But poor imagequality and low frame rate transmission has prevented itswide-scale uptake. Another more popular approach hasbeen to store the video in a recording bottle underwaterand then retrieve it at a later time. Early versions werepurpose built customized devices. Today severalcompanies have now developed commercial off-the-shelfproducts. These recordingbottles have internal clocksthat are pre-set to turn on andoff at determined times,contain batteries that sendpower out to the camera andlights (if desired), a captureboard that digitizes thereturning video, and arecording device to store theMARINE INSTITUTEimages. In fact, some of therecent designs can operateCopyright Journal of Ocean Technology 2008All the Fishes that Swim, Vol. 3, No. 2, 2008 17
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