What is yellowfin tuna used for

As foraging opportunities decline in shallow waters in the colder months, YFT may need to target prey at other, potentially less optimal or physiologically taxing depths including the deep scattering layer, resulting in behaviour dominated by DVM in these months. Previous studies show similar diel patterns which have been linked to YFT tracking the behaviour of prey inhabiting the deep scattering layer Weng et al.

The increasing role of crustaceans in the cold season Laptikhovsky et al. The fishery targets tropical tuna by using a combination of cut bait, live bait and trolling in surface waters which means that fishing operations are limited to relatively shallow fishing grounds surface m. Noting that trends in CPUE can be influenced by a number of factors in addition to stock abundance Goodyear et al.

CPUE needs standardisation as a means to remove or minimise the impact of other factors unrelated to stock abundance. Therefore, the behaviour of the YFT and catchability by different gears needs to be accounted for. For example, in the months where there is reduced catchability for surface targeting fleets like bait boats, there should be an increase in catchability for deep set gears like long lines.

Remote volcanic islands and seamounts are known to produce local upwellings and this has been linked to aggregations of pelagic prey and predators Pitcher et al.

Previous studies have shown that YFT have extended fidelity to St Helena waters, with St Helena considered to be a feeding ground for tuna Wright et al. Results from the present study provides evidence of diurnal and seasonal variability in the behaviour and catchability of YFT in the South Atlantic around the island of St Helena. This study shows the potential for electronic tags recording acceleration to be used to predict the depth and time when feeding behaviours occur. Future studies could explore the use of electronic tags to create models of catchability in space and time which can be used to help validate and standardise CPUE at a regional level, including assessing the drivers of spatial changes in catchability.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation. All authors contributed to the article and approved the submitted version. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Blank, J. Google Scholar. Block, B. Environmental preferences of yellowfin tuna Thunnus albacares at the northern extent of its range.

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Horizontal movements and depth distribution of large adult yellowfin tuna Thunnus albacares near the Hawaiian Islands, recorded using ultrasonic telemetry: implications for the physiological ecology of pelagic fishes.

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Yellowfin tuna are torpedo-shaped. They are metallic dark blue on the back and upper sides and change from yellow to silver on the belly. True to their name, their dorsal and anal fins and finlets are bright yellow.

An adult yellowfin tuna can be distinguished from other tunas by its long, bright-yellow dorsal fin and a yellow stripe down its side. Yellowfin tuna grow fast, up to 6 feet long and pounds, and have a somewhat short life span of 6 to 7 years. Most yellowfin tuna are able to reproduce when they reach age 2. They spawn throughout the year in tropical waters and seasonally at higher latitudes.

Their peak spawning periods are in spring and fall. Yellowfin are very productive. Females can spawn almost daily and release millions of eggs each time they spawn. Adult yellowfin tuna feed near the top of the food chain on fish, squid, and crustaceans. Fish, seabirds, dolphins, and other animals prey on larval and juvenile tuna. Marine mammals, billfish, and sharks feed on adult tuna. Yellowfin tuna are found in tropical and subtropical oceans around the world, including the waters around the U.

Pacific Islands and off southern California. Managed under the Fishery Management Plan for U. West Coast Fisheries for Highly Migratory Species : Fishermen are required to have permits and to record their catch in logbooks. Gear restrictions and operational requirements are in place to minimize bycatch.

Younger specimens usually form large banks near the surface, while adults prefer depths. They usually reach sexual maturity when they reach a length of approximately 40 cm and can reach cm. As a curiosity, this type of fish lacks mechanisms to maintain the flow of water through the gills, so it must remain in continuous movement, if it stops swimming it dies from anoxia. It has a robust body with a bluish color, a very consistent meat and an intense, very penetrating flavour, with a colour that tends towards red.

In Spain, it approaches the waters of the Cantabrian Sea during the summer, where it reaches a size that ranges between 20 and 50 Kg,. Yellowfin tuna has flesh coloration that ranges from pink in small fish to deep red in large fish.

Large fish have greater potential to have a higher fat content than smaller fish, a desirable attribute for raw fish products, as well as for searing and broiling.

Fish landed in Hawaii range from 3 to well over pounds. Smaller fish are usually caught around fish aggregation buoys and over seamounts. The large fish over pounds are usually caught in deep open ocean waters.