var SortedIDs = "";
$(".gvSortPorts").find("tbody > tr").each(function () {
    SortedIDs += $(this).attr("id") + "1";
});

<script src="scripts/jquery-1.4.3.min.js" type="text/javascript"></script>
<script src="scripts/jquery.tablesorter.min.js" type="text/javascript"></script>

<script type="text/javascript">
   $(document).ready(function() {

      $("#GridView1").tablesorter();

   });
</script>