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

  • Sleek torpedo-shaped body for fast movement. 
  • Coloration: dark blue on the back, changes from yellow to silver down to the belly.
  • Dorsal and anal fins are bright yellow giving the fish its name.
  • Difficult to distinguish from other tuna species except for the elongated, sickle-shaped dorsal and anal fins found on large adults [2]
  • Can grow to be 1.8 m (6 feet) long and over 180 kg (400 lbs) [1]

Distribution

  • Highly migratory fish and are found in warm seas all over the world except the Mediterranean [2]
  • Can travel across the entire ocean basin. [1]

Life history

  • Fast growing fish with a somewhat short life span of 6 to 7 years. [1]
  • Live 8 yrs, but most are mature enough to reproduce around age 2 or 3 [2].
  • Spawn at sea throughout the year in tropical waters, and in spring –summer in cooler waters. [1,2]
  • 24° C (75° F) is thought to be the lowest temperature limit for spawning. [2]
  • Can produce two to seven million eggs per spawn. [2]

Habitat

  • Travel in schools of similarly sized fish.
  • Mostly found in the surface layer (≤100 m or 330 ft) of the open ocean above the thermocline, but capable of diving over 1000 m (3300 ft) [1]
  • Typically found in water temperatures between 15° – 31° C (59° - 88° F). [3]
  • Known to make migratory trips to higher latitudes as the temperature of the water increases. [1] 
  • Gather in areas with high productivity where smaller prey is available.
  • Feed opportunistically in open ocean on small fish, squid and invertebrates such as pelagic crabs [2,3]
  • Predators include sharks, billfish and large marine mammals. 

The Fishery

Point Loma Sport fishing

Seasonal availability

  • Fishery open year-round, mostly recreational off San Diego in August & September

Managing authority

  • 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 [5].
  • 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 [5]
  • International Dolphin Conservation Program sets guidelines to reduce bycatch of dolphins & undersized tuna [5]

Gear type

  • Mostly purse seines, but troll, hook-and-line, & pelagic longlines are also used. Hook and line is used recreationally.

Status of the fishery

  • NOAA defines population as “abundant” and fishing rate as “sustainable” [5]
  • Monterey Bay Aquarium’s “Fish Watch” lists hook-and-line tuna as “Best Choice” [6]
  • 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 [5]

Potential ecosystem impacts

  • Species is fairly resistant to fishing pressure given early maturing, high fecundity, moderate life span, & wide distribution [7]
  • Troll & hook-and-line 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 [5]
  • 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, norecipes.com

Edible portions

  • Usually sold as rounds, loins, or steaks  

Description of meat

  • Mild, meaty flavor; firm texture
  • The flesh has a deep red color when raw

Culinary uses

  • Eaten raw or cooked, but this fish loses its flavor & dries out when well-done [13].
  • May be frozen, but tightly wrap in plastic & keep it 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 [14]
  • 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) [9]

Toxicity report

  • No consumption advisories are listed for troll or pole-caught yellowfin as these methods catch younger tuna with lower mercury levels [11]
  • 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 [12]

Seasonal availability

  • Fresh in San Diego August–September [10]

References

1. FishWatch. 2013. Yellowfin Tuna. National Oceanic and Atmospheric Administration (NOAA) Fish Watch & Seafood Profiles. www.fishwatch.gov/seafood_profiles/species/tuna/species_pages/pacific_ye...

2. South Atlantic Fishery Management Council. 2013. Yellowfin Tuna. www.safmc.net/fishidandregs/fishgallery/yellowfintuna/tabid/257/default....

3. Froese, R., Pauly, D., eds. 2008."Thunnus albacares" in FishBase.  www.fishbase.org/summary/SpeciesSummary.php?genusname=Thunnus&speciesnam...

4. Horst, J. 2013. Yellowfin! Louisiana Fisheries. www.seagrantfish.lsu.edu/resources/factsheets/yellowfin.htm

5. FishWatch: 2013. Pacific Yellowfin Tuna. NOAA. www.fishwatch.gov/seafood_profiles/species/tuna/species_pages/pacific_ye....

6. Seafood Watch: 2013. Yellowfin Tuna. Monterey Bay Aquarium. www.montereybayaquarium.org/cr/seafoodwatch/web/sfw_factsheet.aspx?fid=219.

7. Roberts, S. 2010. Seafood Watch Yellowfin Tuna Report. Monterey Bay Aquarium. Monterey Bay Aquarium. www.montereybayaquarium.org/cr/cr_seafoodwatch/content/media/mba_seafood....

8. "Highly Migratory Species: Background." Pacific Fishery Management Council. Pacific Fishery Management Council, 20 Nov. 2012. Web. 10 Aug. 2013. www.pcouncil.org/highly-migratory-species/background/

9. SELF Nutrition Data: Know What You Eat. 2013. Fish, tuna, fresh, yellowfin, raw.. http://nutritiondata.self.com/facts/finfish-and-shellfish-products/4150/2.

10. California Dept. of Fish & Wildlife. 2013. Marine Sportfish Identification: Tunas & Mackerels.. www.dfg.ca.gov/marine/mspcont1.asp.

11. Monterey Bay Aquarium. 2013. “Yellowfin tuna.” Seafood Watch. www.montereybayaquarium.org//cr/SeafoodWatch/web/sfw_factsheet.aspx?fid=...

12. EDF Seafood Selector. 2013. Tuna. Environmental Defense Fund. http://seafood.edf.org/tuna.

13. 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

14.  Bauer, E.. 2006. Seared Ahi Tuna. Simply Recipes. http://www.simplyrecipes.com/recipes/seared_ahi_tuna/