Assessing sources and ages of organic matter supporting river and estuarine bacterial production: A multiple-isotope (Delta C-14, delta C-13, and delta N-15) approach

AZ Horodysky
JE Graves


Short-duration (5- or 10-day) deployments of pop-up satellite archival tags were used to estimate survival of white marlin (Tetrapturus albidus) released from the western North Atlantic recreational fishery. Forty-one tags, each recording temperature, pressure, and light level readings approximately every two minutes for 5-day tags (n=5) or four minutes for 10-day tags (n=36), were attached to white marlin caught with dead baits rigged on straight-shank ("J") hooks (n=21) or circle hooks (n = 20) in offshore waters of the U.S. Mid-Atlantic region, the Dominican Republic, Mexico, and Venezuela. Forty tags (97.8%) transmitted data to the satellites of the Argos system, and 33 tags (82.5%) transmitted data consistent with survival of tagged animals over the deployment duration. Approximately 61% (range: 19-95%) of all archived data were successfully recovered from each tag. Survival was significantly (P<0.01) higher for white marlin caught on circle hooks (100%) than for those caught on straightshank ("J") hooks (65%). Time-todeath ranged from 10 minutes to 64 hours following release for the seven documented mortalities, and five animals died within the first six hours after release. These results indicate that a simple change in hook type can significantly increase the survival of white marlin released from recreational fishing gear.