How to Tag Dolphinfish | Dolphinfish Research Program | Mahi-Mahi | Mahi | Dorado | Dolphin | Dolphinfish
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How to Tag Dolphinfish

Field Methods for Tagging Dolphinfish

How to Tag Dolphinfish

The value, integrity, and credibility of the Dolphinfish Research Program (DRP) depend on the proper tag and release of dolphinfish as well as the quality of field data recorded. The quality of the information that you provide will determine the value of the recovery of your tagged fish.  Below, we provide tagging tips based on notes taken while fishing with Captain Don Gates and the Killin’ Time II fishing team.  As of April 2020, the Killin’ Time II fishing team has tagged and released 3,382 dolphinfish since they started tagging for the DRP in 2002.  In August 2018, they tagged their 3000th fish, which was featured in a short film (click here to view that film).  A major part of their success in tagging lies in the use of an efficient tagging system that focuses effort at a custom tagging station integrated into the transom of Captain Gates’s 25′ Parker.  Once fish are hooked up, through a combination of trolling, sight-casting, or live baiting, anglers dipnet fish and gently handle, measure, tag, and release all fish from the tagging station.  The proximity of tagging tools and rod holders as well as an integrated ruler and data sheet table allow the Killin’ Time II fishing team to process the release of wild dolphinfish with incredible efficiency.  Their techniques, which can be modified to fit the layout of your vessel or fishing program, not only produce results (click here for recapture overview) but also highlight just how much fun tagging dolphinfish can be.  Check out their tagging station below as well as additional tips on how to properly handle, tag, measure, and record quality field data on dolphinfish for the DRP.

The Ultimate Dolphin Tagging Station

Whether you design an integrated tagging station on your vessel or have all of your tagging supplies stored in one location, being prepared to tag with some sort of plan for when the fish come onboard will make tagging more enjoyable and your contribution to our research more valuable.

1. Tagging Table: 

Retrofit a piece of starboard or similar material into your transom, on top of a cooler, or simply have a piece loose to use as a surface to conduct your tagging.

2.  Ruler or Measuring Tape:

One of the single most important data records to note when you tag and release fish is length.  If you construct a tag board, consider adhering a ruler along the edge of the board so you can quickly read a fork length (tip of snout to fork between the caudal tail).  You could also adhere a ruler to a cooler which could be useful when tagging.  In most tagging kits, the DRP provides a measuring tape.  If you need one contact us.

3.  Live Bait Tubes:

Live bait can be the x-factor while fishing for dolphin.  One of the most innovative features of Captain Don Gates’s tagging station is his modified tuna tubes for handling small live bait such as pinfish.

4.  Rod Holders:

One of the most difficult aspects of tagging is dealing with the fishing rod as well as the hook once the fish comes onboard.  By placing rod holders close to your tagging station you can greatly increase the ease of removing the hook efficiently as well as decrease the likelihood that the fish will suffer injuries while handled out of the water.

5.  Tag Tools Spot: 

Being efficient with tagging starts with having all of your tagging tools in one place.  If you are a boat owner, setting up a tool holder close to a tag board or fish cleaning station can help increase your tagging efficiency by providing a consistent location to keep your tag applicator, snips, pliers, scissors, or any other tool you use while fishing.  For mobile anglers, consider wearing a tool belt to keep your tagging tools close by when the action heats up.

6.  Data Sheet:

The quality of information that you provide will decide the value of the recovery of your tagged fish.  It is important to take some basic notes after tagging fish such as the tag number, location, and fork-length.  An easy way to collect this information is to retrofit a data sheet board onto your transom or onto the top of a 5-gallon bucket (See image below).  In addition, check out the next section below for more details on how to keep your data sheet close by to record accurate field data.


1. Field Log on PVC Pole:

If you enjoy tagging and collecting fisheries information incorporating a data sheet location into your tagging station will increase your ability to accurately record data in the field.  As mentioned in the previous section, you can also modify a 5-gallon bucket to hold a data sheet table on top of the lid and/or just keep a clipboard in your cockpit.  The key, however, is recording data immediately after a fish is tagged and released.  In doing so, you will provide better and more accurate information than if you record that information when you get back to the dock or the next time you visit your boat.

2.  Clipboard Fitted to Starboard:

Mounting a metal clipboard with stainless steel clips will ensure your data sheet stays secure forever.

3.  Tag Holders:

On the side of Captain Don Gates’s data sheet table are small holes (1/8″ drill bit) that hold 25 tags.  Tags are loaded in the holes prior to departing to tag for the day so that when they get into a school of fish they are ready to tag as many individuals as they can without having to go look around for the tags.  As mentioned previously, a modified 5-gallon bucket can include 1/8″ holes along the side to hold tags, too.

4.  Field Log with Additional Clips: 

If you have a field log table by your tagging station you can complete all the data fields efficiently.  If not, take note of the tag number, fork-length, and location the fish was caught and record that information when you get to your field log.  Below, is an image of the DRP’s current field log.

Tag Placement Methods

Volunteers should never try to tag a small dolphinfish while the fish is in the water or dangling from the hook. This is not good practice. Attempting to implant the nylon dart tag into small fish not fully under control could result in poor tag placement or injury to the angler. Tags are easily lost out of the applicator when using the hand applicator on fish in the water.

  • The first step toward correctly tagging dolphin is to have the tag in the applicator, a wet towel, and a measuring device ready before the fish is brought into the boat. Place the wet towel over the fish’s eyes while it is still hooked. Lay the fish on a wet, smooth, flat surface with the measuring device under it or immediately adjacent. Such a surface reduces slime loss while the measuring device allows for a quick, accurate length assessment before the fish is returned gently to the water.


  • Proper insertion of the tag into the fish’s back muscle requires the fish to be against a solid surface and immobilized.


  • Place the tag in the back musculature from 1/4 to 1/2 the fish’s body length behind its head. The applicator should be inserted at a 45 degree angle toward the head of the fish with the plastic tag bard facing down toward the fish and its trailing tip pointing toward the fish’s tail. Insert the applicator point deep enough to allow the barb to pass between the spines that radiate off the top of the backbone at the midline of the back. This permits the barb to lock around one of the spines ensuring that the tag will not be shed. Try not to hit the fish’s spine, which will cause paralysis.


  • Typically, 3/4 to 1 1/2 inches of the tag head should be buried in the fish. As a final step give a light tug on the tag to make sure that it is securely implanted.
Figure 1 The ideal tagging location is in the upper dorsal musculature as shown in this image. Do not over constrain your fish during the handling and tagging process as this could cause internal injuries. Wrap a wet towel around the fish or use it to cover its eyes to help prevent injuries and calm it down.
Data Reporting Methods

The value, integrity, and credibility of this study depend on the recording of quality field data. The quality of the information that you provide will decide the value of the recovery of your tagged fish.

The final step in tagging a dolphin is to complete the pertinent information requested on the field data card or field log:


o Date, latitude and longitude

o Fish’s fork length and sex

o Distance from shore at tagging site

o Whether sargassum, birds, or a FAD were present where the fish was caught

o The name of the angler and captain

o Outing catch composition (the number of individual species caught)

o Whether the fish was hooked in the Jaw, Gut, Gill, Eye, or Other

o Bleeding when released? Indicate yes or no.

o Did the fish swim off fast, slow, or it died. Please choose one.


We are also interested in collecting your catch composition from your outing. To do this, just list the individual species you caught and the number on the data card or field log. For example, if you tagged and released 1 dolphinfish and caught 2 wahoo put “2” next to wahoo on the data card and on the field log put “wahoo, 2” in the designated column. If you catch some dolphinfish that you keep make note of this in the notes section on the data card or put
“dolphinfish, 2” on the field log.

Data Field Card
The Dolphinfish Research Program data card contains data fields to record information on the length and sex of the fish as well as release condition. Other necessary fields include the date of release, location, water temperature, habitat information, and angler/captain details. These postcard sized field cards are pre-postmarked. Simply fill in the necessary information and drop your card in the mail.
Data Field Log
The Dolphinfish Research Program field log is a 8.5" x 11" data sheet provided to anglers that tag more than 10 fish per year. Anglers that tag a lot for the DRP prefer this form of data submission. This field log contains the same data fields as the data cards but data submission is usually electronic. The easiest way to transmit the data is to simply take a photo of your log and email it to

How to Tag Dolphinfish

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