Large Pelagics Tag Recapture Reporting

Large pelagic fish often spend much of their lives in deep, offshore waters and some highly migratory pelagics travel great distances to feed and reproduce. Such factors make studying these species difficult, however tagging and recapture studies have allowed researchers to better understand their movement, distribution, abundance, and biology. The researchers in the Large Pelagics Lab at the Southwest Fisheries Science Center conduct fishery-dependent and fishery-independent research on billfish, sharks, and tuna found off the U.S. West Coast and in the greater Pacific Ocean.

Billfish Tagging

Since 1969, the Southwest Fisheries Science Center has provided conventional billfish tags to individual anglers, charter boats, and tournaments across the Pacific. Participating anglers also receive the International Billfish Angler Survey, which compiles information on recreational billfish catch and fishing effort by location. Trends in catch-per-unit-effort tracked over a 46-year time period serves as an indicator of change in the health of billfish stocks and can provide a measure of relative abundance.

Long-term trends in angler catch rates by specific area are also important in understanding the impact of fisheries on billfish resources. Species of interest are the Pacific blue marlin (Makaira nigricans), black marlin (Makaira indica), striped marlin (Kajikia audax), Pacific sailfish (Istiophorus platypterus), shortbill spearfish (Tetrapturus angustirostrus), and swordfish (Xiphias gladius). The results of the Cooperative Billfish Tagging Program can be found in our annual SWFSC Billfish Newsletter and on our billfish research site.

Shark Tagging

The Southern California Bight is an important habitat and pupping ground for various pelagic shark species. The researchers at the Southwest Fisheries Science Center conducts annual research cruises in which thresher sharks (Alopias spp.), shortfin mako sharks (Isurus oxyrinchus), and blue sharks (Prionace glauca) are tagged with satellite tags and conventional spaghetti tags to observe their abundance, distribution, movement, and growth. The vertebrae of the tagged sharks are injected with oxytetracycline, a fluorescent marker that provides a reference point in age and growth studies.

Tetracycline deposits where new calcification is occurring at the time of injection and makes a fluorescent time mark in the vertebrae that can be examined in relation to new vertebral growth when a fish is recaptured a year or more after injection and release. Our age and growth research is dependent on the reported recapture of these tagged sharks. If you captured a tagged shark, a reward is offered in exchange for recapture information and shark vertebrae.

Tuna Tagging

Since the 1970s, the Southwest Fisheries Science Center has collaborated with the American Fishermen's Research Foundation in tagging studies of north Pacific albacore (Thunnus alalunga). Through these studies we have learned that juvenile albacore (2 to years of age) make trans-Pacific migrations in their younger years between Japan and the West coast of North America.

To date over 24,000 albacore have been tagged with conventional dart tags and 1,245 of these have been recovered. A $500 reward is offered for the return of an albacore tagged with an archival tags to the Southwest Fisheries Science Center. An anchor worm parasite is often mistaken for these tags, so view a comparison of the tags and parasite to see the differences.

Reporting Recaptured Tagged Sharks, Billfish, or Tuna

If you capture a billfish, shark, or tuna tagged with a Southwest Fisheries Science Center tag, an reward (see below) is offered in exchange for the recapture information and retrieved tag:

Tag number and angler name (The tag number is indicated by "A0######", i.e. "A089287")
Recapture date, country, and longitude and latitude
Species and capture gear type
Fish length (centimeters or inches), length type (fork length, lower-jaw-to-fork-length, eye-to-tail, etc.), and weight (kilograms or pounds)
Fish sex