Sailfish Tagging in Costa Rica
Information on a Billfish Tagging Program
Capullo Sportfishing, at the request of long time friend Dr. Frank Paladino (Indiana Purdue University Fort Wayne) is helping to initiate a unique tagging program designed to study movements of the Pacific sailfish and hopefully, marlin, off the northwest Pacific coast of Costa Rica. Capullo Sportfishing has played an integral role in the tagging program since its inception in May 2008. The program is sponsored by Dr. Paladino (IPFW) and Dr. Stephen Morreale (Cornell University) and other affiliated universities with participation by graduate students, such as Master's of Science candidate Sam Friederichs (IPFW).
Our relationship with Dr. Paladino and his research goes back to the 1980's, when we helped out with a program he and Dr. James Spotila (Drexel) developed under a grant from the National Geographic Society to tag Costa Rica's critically endangered leatherback sea turtles. These ancient mariners were tagged with various transmitters (i.e. radio, satellite and National Geographic’s Crittercam) while they nested on Playa Grande in nearby Las Baulas National Park. The tagged turtles would then return to the water after they finished nesting, at which point we would track them by boat and retrieve the tags and the valuable data they recorded.
Drs. Paladino and Spotila continue to this day their mission to study and protect the giant leatherback sea turtles from the Goldring Marine Biology Station, on Playa Grande, just a stone's throw north of our base in Tamarindo. For more information on the leatherback sea turtle and participating in hands-on sea turtle conservation visit earthwatch.org. Our new collaboration with Dr. Paladino and his team moves them off the beach and on to the water in their quest for Eastern Pacific billfish.
This new billfish tagging effort was designed to increase the knowledge of important marine species in Northwestern Costa Rica, namely billfish and other recreationally-sought gamefish. The current study employs multiple types of tags to monitor Pacific billfish off Costa Rica in order to better understand how these fish use the Eastern Pacific Ocean.
The first type of tag used is called a PIT tag or Passive Integrated Transponder. This tag is about the size of a grain of rice and is commonly implanted in pets in the United States. Each tag has a specific coded number that is read by a special scanner.
The tags are implanted in the muscle of the fish via syringe at the side of the boat during the release of the fish, while the fish is being revived in the water.
A hand held scanner is used to record the unique identifier of the tag, then the fish is released and we record the date and location of the release.
Each time a sailfish is caught and released, a scanner is passed over the fish and, if it has a tag, the identifier is displayed on the scanner. This identifier as well as the date and location of the release are recorded in a journal. PIT tags remain viable for decades; the transmitter is passive and needs no power source, as data is transmitted only when the scanner signals the tag. Since the tags are injected subcutaneously, the fish does not shed the tag. Data can be accumulated over the long term, to help identify fish that are caught more than once, and record where they were caught.
The second type of tag used is a PAT, or pop-up archival transmitter (satellite tag). These are the same tags commonly depicted in sportfishing magazines and have been deployed on most large sportfish species (i.e. billfish, sharks, tarpon, etc.). Typically these tags are programmed to record environmental conditions, such as depth and temperature, and then after a specified time period separate from the fish. The tag then floats to the surface and uploads its information to orbiting satellites and the data is retrieved via the internet.
Despite their name, most satellite tags deployed on fish only link with the satellite once they have detached from the fish. The tracks of where the fish traveled are then estimated based on the light levels the tag records. It is a complicated process involving computer algorithms but, this is where our satellite tagging differs.
The tags deployed from the Capullo are programmed to take advantage of a billfish’s tendency to bask on the surface, and can connect to the satellites when the fish come up to bask. This allows for near-real time locations of the fish during their travels as well as behavioral information. These fish sometimes spend long periods of time at depth; nevertheless this programming allows for increasingly accurate tracking and real-time behavioral analysis.
Satellite tags are applied to the fish externally, in much the same manner as conventional billfish tags. The satellite tag will store depth, dive duration, time-at-depth temperature, and light data. This data is then uploaded to a tracking satellite when the fish swims near the surface and the tag's antenna breaks the surface of the water. The amount of data uploaded is dependent on how long the fish stays up but could include a combination of GPS location, dive depth, time-at-depth and water temperature.
The satellite tag is a shorter term deployment and after a period of time, usually weeks or months, the tag will release or the fish will shed the tag. Nevertheless, these tags provide a wealth of valuable information about the fish’s movements throughout the ocean. Data show where the fish has traveled in addition to how movements correlate to environmental features, such as currents, sea surface temperature and chlorophyll-a blooms (basically, how much algae is in the water column).
Once thought to be a local, resident population of sailfish that migrated up and down the coast with the seasons, preliminary data of the first several sat tagged fish reveal the opposite. Stunningly, the satellite tags have shown that these fish are highly migratory! One fish traveled 900 miles in just 20 days, averaging 35 miles a day! Sailfish tagged ten miles offshore in front of Tamarindo have been shown to travel as far north as Guatemala and southern Mexico, and as far south as Colombia, as well as travel hundreds of miles offshore. This is very important data that illustrates the multi-national nature of Costa Rican sailfish. This population uses the waters of multiple countries and therefore requires collective management and conservation.