marlins

Billfish Conservation: Tag & Release Research

(Source: The Billfish Foundation)

  • What are Billfish?

The term Billfish refers to a group of pelagic, highly migratory, predatory fish that are characterized by prominent bills, or rostra, and by their large size.

Billfish include sailfish, marlins, and swordfish. They are apex predators and feeds on a wide variety of small fish, crustaceans and cephalopods.  They are found in all oceans, but mostly in tropical and subtropical waters. 

They use their long sword-like nostrum to slash at and stun prey during feeding.  Swordfish and billfish are built for speed with their long bills cutting through the water and their aerodynamic bodies allowing them to reach speeds of up to 120 kph! They are among the fastest fish in the ocean.

  • Why Are They Threatened?

According to a 2011 global assessment by the IUCN ( which is responsible for the Red List of Threatened Species), blue marlins, white marlins and striped marlins are threatened, and the key to recovery is reducing commercial fishing pressure.

Overfishing is the main threat to billfish. The most frequent method used to catch these fish is longline fishing. Longline fishing consists of a long line with baited hooks that are attached at intervals by means of shorter, branch lines (snoods). Longlines are placed in the water column. Hundreds or even thousands of baited hooks can hang from a single line. Longline fishing poses a significant threat not only to billfish but also to other endangered species such a marine turtles, sharks, and dolphins.

(Source: The AUM Blog)

A significant number of swordfish are also caught by illegal driftnet fisheries in the Mediterranean. Labelled “walls of death”, driftnets are also indiscriminate, catching any animal that crosses their path. Yet again, it is crucial that consumers find alternatives to billfish and promote sustainable fishing.

Additionally, billfish are among the most coveted of big gamefish for recreational fishermen. Nevertheless, billfish anglers are a small constituency compared with the other angler groups or anglers overall. 

  • Community-Driven Conservation: Why Tagging Billfish is Important

Very well aware of the threatened status of their favorite fish, the vast majority of sport fishermen now work along conservationists to gather biological and ecological information, and to  implement tag and release programs. The Billfish Foundation (TBF) is a leader in the tag-and-release research. Their program was established back in 1990, and it is now the largest private billfish tagging database in the world! With more than 200,000 tag and release reports, TBF receives over 15,000 tag and release records annually from across the globe.

Such success is due to the willingness of anglers and captains worldwide to voluntarily tag, release, and report their billfish catches. These tags give us crucial information on migratory patterns, habitat utilization, growth rates and post-release survival rates. 

(Striped marlin equipped with a satellite popup tag. Photo source: Marine CSI)

  • What About the Fish? Isn’t it Stressful for them?

Unfortunately, stress is unavoidable for any kind of tag-and-release program, and the process of catching billfish can leave them too traumatized to recover. To make sure catch-and-release fishing remains a viable conservation strategy, proper fish handling is crucial. It is highly discouraged to bring the fish out of the water, and to tag and release the animal as quickly and safely as possible.

(Sailfish in the open ocean. Photo by Tony Ludovico)

Furthermore, scientists are constantly working on finding less invasive and stressful methods. Studies have shown that circle fishing hooks do much less damage to billfish than the traditional J-hooks, yet they are just as effective for catching billfish, are easier to remove, and  they improve survival rates post-release. Additionally, the Billfish Foundation has published guides on how to tag an individual properly. 

It is also important to recognize that sport fishing around these animals is of great social and economic impact in many coastal states and countries around the Caribbean. Anglers contribute to $599 million annually in the country of Costa Rica, and up to  $1.125 billion annually for the small town of Los Cabos in Mexico, on top of creating thousands of jobs!! Such an economic impact for the smaller communities and countries is crucial and is not negligible.

(Photo by Tony Ludovico)

Since sports fishing is quite a popular activity around the globe, conservationists have taken the smart approach of partnering with fishermen to advance billfish research. Many anglers have great work ethics and comply with the safe fish handling and tagging methods. Due to such successful community participation, billfish research and conservation is advancing daily.

While I am personally not the biggest fan of sports fishing, I do appreciate the partnership between conservation organizations and sport fishermen, and recognize the value of the scientific data collected that can later be used to create adequate policies. We would not get even half of that data if it weren’t for such great participation from the anglers.

Here is a cool video on how tagging a billfish is done, and here is a fun little video featuring some members of The Billfish Foundation on a  tag-and-release trip in Guatemala.

(Photo by Tony Ludovico)