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We are currently analyzing data from nearly 10 years of mark-recapture research on spiny dogfish. Over 36,000 tags have been released by East Carolina University researchers or collaborators. Of those tags, nearly 350 were returned, giving us a 0.9% return rate. These data have been entered into software called GIS, or Geographic Information System (ESRI, www.esri.com). GIS allows us to plot geographic coordinates and environmental data together on a map. We can then relate the recapture locations to variables such as days at large (time from release to recapture), depth of recovery, and water temperature at recovery. We can also use the biological information that you provide to us to measure how much the sharks have grown since their release. Taken together, the recapture data plotted on the map can answer some very interesting biological questions; the timing of migration, the extent of migration (how far north and south?), and the extent that dogfish groups move together.
In the above graph, recaptures from commercial fishermen are indicated in red.
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