|
Fisheries oceanographer Molly Lutcavage and lead author BenjaminGaluardi say the work shows that scientists now have tools todirectly observe bluefin tuna annual migration patterns andvertical habitat use (depth) in the Atlantic and Mediterraneanoceans in detail not possible in earlier studies. This newinformation should lead to better understanding of bluefin tunaecology, catch patterns and management of wild stocks that providea multi-million dollar sport fishery from Maine to North Carolina. Lutcavage, director of UMass Amherst's Marine Research Station andthe Large Pelagics Research Center (LPRC) in Gloucester, says,"Our tagging data are important because for the first timewe've got direct measurements of bluefin tuna movements and habitatassociations. In other words, their travel routes, depth andtemperature patterns, and where they intersect with recreationalfisheries." Galuardi, an LPRC scientist and doctoral candidate in the GraduateSchool of Marine Science at UMass Dartmouth, led the analysis ofdata returned from pop-up satellite tags used in this study, aswell as oceanographic conditions across bluefin migration paths.Details are reported in A recent issue of the Public Library of Science One ( PLoS One ) journal. "Knowing the dispersal patterns of these young fish after theyleave their nursery grounds and learning their year-round habitatneeds are important goals for the commercial fishery of adultbluefin tuna, as well," she adds. For example, these tunas'winter and spring movements and behavior of juveniles have largelybeen unknown until now. For this study, Lutcavage, Galuardi and fishermen partners deployed58 miniature pop-up satellite archival tags (PSAT) and 132implanted archival tags on juvenile Atlantic bluefin tuna between2005 and 2009. Because only one archival tag was retrieved, datareported are mainly from 26 PSATs. To deploy the PSATs, fish were caught by hook and line and broughtaboard the boat to attach a miniaturized PSAT to the fish's fin bya tether and dart anchored at the base of the fin. These wereprogrammed to record external temperature, depth and daily positionbased on light sensor readings every 15 minutes and to releaseafter 12 months. Later models also recorded light level. Once atthe surface, the PSAT tags transmitted the collected data toreceivers on earth-orbiting satellites. The data were thentransmitted to the researchers, allowing scientists to trace thefish's journeys and habitat over the previous year. The authors report that all tagged bluefin tuna remained in thenorthwest Atlantic for the duration observed, and, in summer monthsthey stayed in coastal waters from Maryland to Cape Cod out to thecontinental shelf. In the winter, they wandered more widely,exiting the Gulf of Maine and ranging south to the South AtlanticBight (North Carolina to Florida), the northern Bahamas and theGulf Stream edge. Lutcavage and Galuardi found that vertical habitat patterns showedjuvenile bluefin primarily occupied shallow depths, averaging about16 to 40 feet (5 to 12 meters) and relatively warm water, averaging64 to 70 degrees F (about 18 to 21 degrees C). In winter, theyfrequented deeper water and showed more variable depth patterns. "These findings are the first long-term view into a year inthe life of a juvenile bluefin tuna in the western Atlantic,"Lutcavage notes. "The geographic and vertical concentration ofsummer habitat had been suspected due to patterns in therecreational fishery, but was not confirmed until this study. Inaddition, little information existed on what these fish did inwinter months when the fishery does not operate. This informationprovides a window into what areas and conditions are important forgrowth and survival of juvenile bluefin tuna." The authors add, "Our tagging results reveal annual dispersalpatterns, behavior and oceanographic associations of juvenileAtlantic bluefin tuna that were only surmised in earlier studies.Fishery independent profiling from electronic tagging also providesspatially and temporally explicit information for evaluatingdispersal rates, population structure and fisheries catch patternsand supports development of direct assessments.". I am an expert from swimmingpool-cleaner.com, while we provides the quality product, such as Pool Vacuum Hose Manufacturer , Floor Cleaning Mops Manufacturer, Automatic Swimming Pool Cleaner,and more.
Related Articles -
Pool Vacuum Hose Manufacturer, Floor Cleaning Mops Manufacturer,
|
