Pacific Albacore Tuna is a highly migratory species, traveling long distances throughout the ocean.
There are two stocks of Pacific Albacore Tuna:
the North Pacific stock and the South Pacific stock.
We have collaborated on and supported albacore research since 1978 that has helped define and change how we understand the behavior of this tuna.
North Pacific Albacore
North Pacific Albacore Tuna spawn between March and July in tropical and subtropical waters of the central and western Pacific Ocean. Females broadcast their eggs in surface waters where they are fertilized. Juveniles typically begin their trans-Pacific migrations in spring and early summer, moving from waters off Japan to the Canadian and US West Coast.
Archival (data logging) tags from studies supported by ARF identified five distinct movement patterns of juvenile North Pacific Albacore Tuna in the eastern Pacific (Childers et al. 2011 Figure 4). The fish move to offshore areas north and northwest of Hawaii, areas offshore from California and Baja Mexico and nearshore areas along the Baja peninsula during the winter season, returning to coastal fishing grounds in the spring and summer. The timing and distance of their migrations in a given year are highly dependent on oceanic conditions. Albacore Tuna are known to favor productive areas along oceanic fronts that concentrate forage.
As the fish mature at around 5 years of age they return to the western Pacific to spawn. Depending on their size, females may release between 800,000 to 2.6 million eggs per spawn and will spawn repeatedly throughout the season. Juvenile North Pacific Albacore Tuna are taken by troll and pole and line fisheries on both sides of the Pacific with adults harvested by longline gear mainly in the west.
This archival tag track and video show a multi-year movement track of a North Pacific Albacore Tuna that after additional analysis by researcher Stephanie Snyder revealed new information. ARF supported her to present the data to the 60th annual Tuna Conference in 2018. The location track shows the fish moving offshore in the fall to feed along the north Pacific transition zone to the central Pacific and return to the coast the following season.
In year two, the Albacore Tuna again moved out to the central Pacific but then moved south to the waters of Papua New Guinea and the Solomon Islands where the fish dipped below the equator, crossing the supposed stock boundary for a North Pacific Albacore Tuna before returning north of the equator where it was recaptured by a longline vessel.
This mixing of stocks has since been confirmed by a genetic study that was also supported by ARF biological sampling (O’Malley et al. 2020). The tag also recorded the depth and temperature of the fish at frequent intervals throughout the track and clearly showed a deeper diving behavior and wider temperature range as the fish grew and matured.
South Pacific Albacore
Less is known of the movements and spawning habits of Pacific Albacore Tuna in the South Pacific Ocean. South Pacific Albacore Tuna are believed to spawn in tropical and subtropical waters of the central and south western Pacific. Juveniles move south from the tropics when they are about a foot long and then populate the cooler surface waters from the Tasman Sea, around New Zealand and eastward to high seas areas south of French Polynesia. The fish return to tropical waters as they mature to spawn. Juvenile South Pacific Albacore Tuna are taken by troll fisheries from New Zealand as well as US trollers that make the long journey to the South Pacific grounds. However, most of the fishing effort on the stock comes from longline fleets from Taiwan, China and vessels flagged to Pacific Island nations.
ARF is helping to support a groundbreaking study on South Pacific Albacore Tuna by supplying samples in support of a Close-Kin Mark-Recapture (CKMR*) study. This novel genetic method can determine the overall stock size of the resource by the collection and analysis of small, non-invasive tissue samples. This information is critically needed to manage the resource sustainably. The project is ongoing in collaboration with scientists from the Pacific Community and the Commonwealth Scientific and Industrial Research Organization (CSIRO).
*Close-Kin Mark-Recapture is an alternative method for estimating stock abundance and other population parameters (e.g. population trend, survival rates, connectivity), using kinship relationships (parent-offspring pairs) determined from genetic samples.
ABOUT ALBACORE TUNA BIOLOGY AND NUTRITIONAL VALUE
-
Albacore Tuna are a highly migratory species. They can swim faster than 50 miles per hour and cover vast areas during annual migrations.
-
North Pacific juvenile Albacore Tuna have the highest levels of Omega- 3 fatty acids of all tunas.
-
Smaller, troll-caught Pacific Albacore Tuna from the West Coast of the U.S. contain significantly lower levels of mercury than adult fish harvested in other parts of the world.
ABOUT ALBACORE TUNA HABITAT
-
Albacore Tuna movements are dependent on local oceanographic conditions that influence currents, thermocline depth, upwelling and oceanic fronts. These factors enhance productivity and the amount and quality of food and feeding that affect surface catch rates. North Pacific Albacore Tuna feed heavily on small fishes, particularly northern anchovy, juvenile rockfish, Pacific saury and sardines in addition to squids, shrimp and other crustaceans.
-
Migration patterns. North Pacific Albacore Tuna spawn and recruit in the western Pacific ocean. Juveniles migrate to the U.S. and Canadian West Coast to feed and grow.
-
Albacore Tuna spend very little time at the ocean’s surface. These movement patterns are of interest to the North Pacific fleet which is a surface troll fishery working in the top 2 ft of the water column.