Yellowfin Tuna

The Science

No other fish can swim as fast or far as tuna; its fins help reduce turbulence and drag as it swims through the water.

The Fishery

Yellowfin tuna, like other tuna species, is highly migratory. It can travel across entire ocean basins and therefore requires cooperative international management to ensure its abundance and sustainability.

The Seafood

Yellowfin is sold as “light tuna” when canned, is called “ahi” when sold fresh or frozen, and called “maguro” when in sushi.

The Science

yellowfin tuna
anglersjournal.com

Taxonomic description

  • It has a sleek torpedo-shaped body for fast movement. 
  • It is dark blue on the back, which changes from yellow to silver down to the belly.
  • The dorsal and anal fins are bright yellow giving the fish its name.
  • It is difficult to distinguish from other tuna species except for the elongated, sickle-shaped dorsal and anal fins found on large adults. [1]
  • It can grow to be 1.8 m (6 feet) long and over 180 kg (400 lbs). [1]

Distribution

  • As a highly migratory fish, yellowfin tuna is found in warm seas all over the world except the Mediterranean. [1]
  • It can travel across the entire ocean basin. [1]

Life history

  • It is a fast growing fish with a somewhat short life span of 6 to 7 years. [1]
  • Most yellowfin tunas are mature enough to reproduce around age 2 or 3. [1]
  • This fish spawns at sea throughout the year in tropical waters, and from the spring–summer in cooler waters. [1]
  • 24° C (75° F) is thought to be the lowest temperature limit for spawning. [1]
  • It can produce two to seven million eggs per spawn. [1]

Habitat

  • Yellowfin tuna travels in schools of similarly sized fish.
  • It is mostly found in the surface layer (≤100 m or 330 ft) of the open ocean above the thermocline, but is capable of diving over 1000 m (3300 ft). [1]
  • This fish is typically found in water temperatures between 15° – 31° C (59° - 88° F). [2]
  • It is known to make migratory trips to higher latitudes as the temperature of the water increases. [1] 
  • It likes to gather in areas with high productivity where smaller prey is available.
  • Yellowfin tuna feeds opportunistically in open ocean on small fish, squid and invertebrates such as pelagic crabs. [1,2]
  • Predators of yellowfin tuna include sharks, billfish and large marine mammals. 

The Fishery

Recreational fishermen posing with catch of yellowfin tuna
Point Loma Sport fishing

Seasonal availability

  • The fishery is open year-round, and is mostly recreational off San Diego in August & September.

Regulatory and managing authority

  • It is managed federally under the Highly Migratory Species Fisheries Management Plan where NOAA & the Pacific Fishery Management Council establish permit & operational requirements, gear restrictions, & mandatory workshops for fishers. [1]
  • As a member of the Inter-American Tropical Tuna Commission (IATTC), the U.S. has implemented purse seine fishery closure & catch retainment requirements to limit illegal discarding of undersized tuna. [1]
  • The International Dolphin Conservation Program sets guidelines to reduce bycatch of dolphins & undersized tuna. [1]

Gear type

  • Yellowfin tuna is mostly caught by purse seines, but troll, hook-and-line, & pelagic longlines are also used. Hook and line is used recreationally.

Status of the fishery

  • NOAA defines the population as “abundant” and fishing rate as “sustainable”. [1]
  • Monterey Bay Aquarium’s “Fish Watch” lists hook-and-line tuna as “Best Choice”. [3]
  • Most regulations focus on reducing the catch and mortality of non-target species.
  • U.S. fishermen responsibly harvest tuna by following strict international and domestic regulations aimed at reducing fishery impacts on other species (e.g., longliners use special hooks and bait that reduce bycatch; fishers train in the safe release of non-target species; vessels are regularly monitored by scientists & managers who reassess management actions as needed). [1]

Potential ecosystem impacts

  • This species is fairly resistant to fishing pressure given early maturing, high fecundity, moderate life span, & wide distribution. [4]
  • Troll & hook-and-line methods have relatively low bycatch [5] whereas purse seines and long lines potentially result in moderate to high bycatch of species associated with yellowfin schools if actions are not taken to reduce bycatch and mortality rates. [1]
  • Purse seiners using fish aggregating devices (FADs, manmade floating objects) to attract yellowfin must take precautions to avoid bycatch of juvenile yellowfin & non-target pelagic species. 

The Seafood

tuna poke with seaweed and sesame seeds
Tuna Poke/norecipes.com

Edible portions

  • It is usually sold as rounds, loins, or steaks.  

Description of meat

  • This fish has a mild, meaty flavor; firm texture.
  • The flesh has a deep red color when raw.

Culinary uses

  • It can be eaten raw or cooked, but this fish loses its flavor & dries out when well-done. [8]
  • It may be frozen, but should be tightly wrapped in plastic & kept out of direct contact with ice or water to ensure a longer shelf-life. 
  • Common preparations are to grill or sear the outside, leaving the center rare. [9] 
  • Before cooking, season the steaks (this can be as simple as salt & pepper).
  • Searing is easy-heat oil in pan over medium-heat, then place & cook the seasoned steak to desired temperature.
  • Common recipes include seared ahi, ahi burgers, ahi tacos, ahi salads, sesame crusted tuna, ahi tuna steak.

Nutritional information  

  • Raw (3 oz, 85 g). [5]

Toxicity report

  • No consumption advisories are listed for troll or pole-caught yellowfin as these methods catch younger tuna with lower mercury levels. [3]
  • Potential for mercury accumulation in larger tuna only (caught by seine or longline). Recommended servings that can safely be eaten per month are 4 or more for adults, 3 for kids 6-12 yr old, 3 for kids 0-5 yr old. [7]

Seasonal availability

  • Yellowfin tuna is available fresh in San Diego from August–September. [6]

References

[1] FishWatch. 2013. Yellowfin Tuna. National Oceanic and Atmospheric Administration (NOAA) Fish Watch & Seafood Profiles. https://www.fishwatch.gov/profiles/pacific-yellowfin-tuna. Accessed 16 Sept 2020. 

[2] Froese, R., Pauly, D., eds. 2008."Thunnus albacares" in FishBase. www.fishbase.org/summary/SpeciesSummary.php?genusname=Thunnus&speciesname=albacares. Accessed 16 Sept 2020. 

[3] Seafood Watch: 2013. Yellowfin Tuna. Monterey Bay Aquarium. https://www.seafoodwatch.org/seafood-recommendations/groups/tuna?q=yellowfin&t=yellowfin&type=yellowfin. Accessed 16 Sept 2020.

[4] Morgan, A. 2014. Seafood Watch Bigeye, Skipjack, and Yellowfin Tuna Report. Monterey Bay Aquarium. https://www.seafoodwatch.org/-/m/sfw/pdf/reports/t/mba_seafoodwatch_tuna_epo_purseseine_report.pdf. Accessed 16 Sept 2020.

[5] SELF Nutrition Data: Know What You Eat. 2013. Fish, tuna, fresh, yellowfin, raw. http://nutritiondata.self.com/facts/finfish-and-shellfish-products/4150/2. Acessed 16 Sept 2020.

[6] California Dept. of Fish & Wildlife. 2013. Marine Sportfish Identification: Tunas & Mackerels. www.dfg.ca.gov/marine/mspcont1.asp. Accessed 16 Sept 2020.

[7] EDF Seafood Selector. 2013. Tuna. Environmental Defense Fund. http://seafood.edf.org/tuna. Accessed 16 Sept 2020. 

[8] Riches, D.. 2013. Grilling Tuna: Rare or well you need to know the best method for grilling tuna. About.com. http://bbq.about.com/od/fishandseafood/a/aa103004a.htm. Accessed 16 Sept 2020.

[9] Bauer, E.. 2006. Seared Ahi Tuna. Simply Recipes. http://www.simplyrecipes.com/recipes/seared_ahi_tuna/. Accessed 16 Sept 2020.