The human race is generally a bit, dare it be said, ‘uneducated’ with regards to the ocean and all that she holds. Leisure Boating will look at different ocean species every month with the aim of giving our readers a closer look at the wide range of life forms that lurk below.
A member of the family Scombridae which includes bonito, mackerel and tuna; the Yellowfin tuna is one of the most popular game fish species in the world and probably the most sought-after and hunted big game species in South Africa. Anglers travel from all over the world to fish the waters off Cape Point in the hope of landing one of these beautiful fighters. Many anglers believe that large Yellowfin are, pound for pound, the fastest and strongest of all big game tunas. However, they are not only prized for their feisty and powerful antics when hooked, but also for their scrumptious flesh which is becoming more popular by the day in the culinary industry as they are replacing the majestic and endangered Bluefin on the plates of sashimi lovers.
What they look like
Smaller than the Bluefin and perhaps the Bigeye but larger than most other tuna species, the Yellowfin can reach weights of well over a 100 kg. The IGFA all tackle record for Yellowfin is a massive 193.68 kg monster caught by Guy Yocom about 100 miles off the coast of Cabo San Lucas, Mexico.
Like all tunas, Yellowfin are torpedo-shaped and built for speed – enabling them to hunt fast-moving baitfish. Probably the most colourful sibling in the tuna family, the Yellowfin’s back is blue-black and fades to silver on the flanks and belly. A golden yellow band runs from eye to tail and as many as 20 vertical silver lines can be seen across the body but aren’t always prominent.
Larger species have overextended second dorsal and anal fins that may reach more than halfway back to the tail. All fins and finlets are a bright golden colour and sometimes the dorsal and anal fins may be silver edged while the finlets are black tipped.
Unlike some of its bigger cousins, the Yellowfin’s liver is without striations on the ventral surface, and a swimbladder is present. They have small eyes and heads with about 26 to 35 gill rakers on the first gill arch and very small and fine teeth in the jaw.
Where to find them
Yellowfin can be found in deep, warm temperate oceanic waters – they are the most tropical species of tuna and are abundant in tropical waters throughout the world’s oceans. They are both pelagic and seasonally migratory, but have been known to venture quite close to shore as well. Juveniles are known to form large schools near the surface, while adults inhabit fairly deep water but may also frequent shallower columns near the surface to feed. The coast of Mexico is known to hold some of the largest Yellowfin in the world (also where the current IGFA record holder caught his prize Yellowfin) but South African Yellowfin aren’t to be sneezed at as huge specimens are caught every year in the Cape. Just last year I was fortunate enough to witness Frank Scholtz wrestle a 106.75 kg belter for close on seven hours on mere 10 kg line to land himself in the record books. The most abundant tuna grounds in SA (also where Frank boated his famous fish) can be found between 15 and 40 nm off Cape Point, depending on weather and ocean temperatures. Yellowfin are also highly prized in the sport fisheries of Australia and New Zealand.
Habits, prey and predators
Yellowfin Tuna grow relatively quickly and reach sexual maturity at a younger age (at around two or three years old) than most other tunas. They produce millions of eggs per spawning, and can live up to nine years.
The Yellowfin mostly travel in schools with similar-sized companions and prey on other fish, pelagic crustaceans and squid. But in some cases, as is often seen off Cape Point, they will school with other tuna species such as the smaller Skipjack and Longfin tuna and is known to sometimes even associate with dolphins!
Yellowfin tuna are extremely fast swimmers and are able to produce blindingly fast bursts reaching speeds of up to 80 kph. They are able to streamline their bodies for faster swimming by folding their fins into special indentations when hunting speedy prey such as flying fish.
Adult Yellowfins are threatened only by toothed whales, pelagic sharks, large Blue and Black marlin, and of course its biggest predator, industrial tuna fishermen (and recreational anglers to a lesser extent).
How to catch one
There are a number of methods with which to target Yellowfin and both bait and lures will work if you know how. You should adjust your tackle to the size of fish you’re targeting. When you’re in an area where small ‘schoolies’ are the target, five to 10 kg line should be sufficient and will give you a more exhilarating battle. However, when your goal is to land a trophy, heavier tackle is advised with at least 50 kg braided line.
When fishing with lures, top-water techniques can be used as they feed near the surface and anything from tuna feathers, cedar plugs to plastic skirted trolling lures, poppers or Rapala-type plugs will do the trick. It is recommended that you use single or double hooks as they are less likely to be thrown or bent.