The easiest way to differentiate between New Zealand’s large striped marlin and blue marlin is their dorsal fin; a blue has one which is half to two-thirds the length of its body depth, where the striped marlin has a dorsal fin height about the same as its body depth.
In addition, the under jaw of a blue marlin is not as long as that of a stripy. Blue marlins have a wide tail almost identical to black marlin, and their pectorals fold in alongside the body unlike the blacks’ which are rigid. Blue marlins are a brilliant deep metallic blue above, changing abruptly on the sides to bright silver.
Experts believe New Zealand to be the extreme limit of the blue marlin’s range and blue marlin are primarily caught around the north eastern New Zealand coasts in high summer (February-March). These fish average around 200kg, with the largest rod-and-reel capture listed at 461.3kg. Captures of these powerful and dynamic fish have increased in recent seasons, with more boats working further offshore in the blue marlin’s favoured deep water habitat.
Blue Marlin Feeding & Breeding
The diet of a blue marlin is the same as its cousins, and it is particularly keen on large striped bonito. The breeding season of blue marlin has not been firmly fixed and there is evidence of males spending much of the year segregated from females.
Blue Marlin Fishing
Trolling large skirted lures is the usual fishing technique.
The striped marlin is the most prevalent and the most common of the largest game fish. Striped marlin are brilliantly coloured with vertical pale blue stripes across the body, dark metallic blue on the back fading to silvery white underneath. The high dorsal fin is marked with blue spots. Its slender bill, high dorsal lobe and straight rear edge of the pectoral fin distinguish the striped marlin from its bulkier relatives.
New Zealand striped marlins are the largest in the world and most world records are held in this country, with the Bay of Islands boasting many of them. The weight range of these fish is between 70 and 220 kg and they can grow to a length of four metres. The heaviest striped marlin caught to date is 224.1 kg – the current New Zealand and world record.
Striped Marlin Feeding & Breeding
Striped marlin’s food source is mostly other fishes, large and small, and includes bottom as well as surface fishes. It is thought that the striped marlin of New Zealand spawns in the central South Pacific between Tonga and the Taumotu Archipelago.
Adults arrive in New Zealand waters in summer when the sea temperatures are 19 to 20 degrees Celsius (December to early January for the Northland coast); the prime season for striped marlin begins in January and ends in May when waters have cooled to about 17 to 18 Celsius.
Current fronts can generate a fair bit of action for striped marlin, particularly if the water temperature is to their liking on one side of the current. These current fronts create the right food chain reaction which in turn attracts the bigger predators.
Striped Marlin Fishing
Because striped marlins are smaller than their blue and black cousins, some fishermen may be fooled into thinking they’re an easy catch. Fast and spectacular, they can be the most difficult of opponents.
Since the introduction of a moratorium on the commercial catch and sale of marlin, numbers have dramatically increased. Over the last five years, recreational captures are the highest on record, although at least seventy-five percent of marlin are tagged and released.
As with all sports, there are various techniques that bring success, which when marlin fishing will vary according to the skipper and his boat. Blue water anglers generally troll. Switch baiting is one method used, where skirted lures are run as teasers on the outriggers and a large attractor can be run close to the boat in the wake. This may be complimented by additional lines of plastic squid on outriggers which also act as teasers. When a striped marlin comes up, it is common practice for live bait such as small tuna to be slipped back and the lures pulled from the water. Hopefully, the marlin then takes the bait.
An obvious reason for marlin being such a popular game fish, is the spectacular way in which it fights. Even the strike is impressive. Once focused on its target the marlin chases, lifts its bill and shoulder out of the water and swings down overpowering its prey. Realizing the restraint, the fish soars vertically out of the water shaking its head in an effort to toss the bait. Its physical prowess and stamina enables it to repeat this distinguishing manoeuvre, often followed by an escape to the deep.
The black marlin is a heavy, thick set marlin species found mainly in the warm Indian and Pacific Oceans, reaching New Zealand’s northern coasts in summer months, before wandering south to the East Cape. The black marlin has always been regarded as a most prized game fish because of its great fighting qualities and its bulky build.
The short, thick spear, low dorsal lobe and fixed pectoral fin are features which immediately distinguish this species from the more abundant striped marlin and the humped shoulder from the blue marlin. The black marlin has limited colour bands on the body, is blue-black above, greyish-white below – an overall bronze flush is sometimes present.
Black Marlin Feeding & Breeding
Black marlins are most regularly encountered around shallow reef structures. Catches of this species have dwindled in recent years, largely because of the swing towards lure fishing. Specialists targeting black marlin with large live-baits continue to have success as they are carnivorous, feeding on whatever fish are available, favouring large tuna and squid. The warmer summer months are the spawning season for black marlin.
Black Marlin Fishing
Usually fighting down deep, black marlins do not often jump when hooked, or at least not for some time afterwards. Some do not jump at all, but may come to the surface and thrash about at the trace with their bill.