The World's Three Toughest Fish

One of the questions I am most regularly asked by fellow anglers is “What is your favourite fish to catch?” There are so many variables in a question like this that I often give an answer like, “The one on the end of my line at the time.” Glib, I know, but there are many contenders, both freshwater and salt, in many different parts of the world. I rate our kingfish highly, and I have been impressed by Atlantic tarpon, roosterfish, halibut, king salmon, bonefish and black and striped marlin, to mention a few others. The size potential of the fish, the tackle and technique used to catch it, and the circumstances of the capture all make a big difference to how much a given capture is enjoyed. 

Choosing a favourite fish is a subjective thing and depends on your personal experiences and which fish species you have encountered. Much of the satisfaction of catching a particular fish depends a lot on the difficulty of catching it, which in turn depends on how hard the fish fights.

So, in no particular order, the following are my nominations for the worlds’ three toughest saltwater fish on a kilo-for-kilo basis. This is just my opinion of course. There are plenty of species I haven’t caught, so I will stick to those I have had a reasonable amount of experience with and can make a fair personal assessment of. Broadbill, for example, are highly rated as a tough proposition and will probably be on some people’s lists, but although I have bent a rod on a couple of them for periods of up to half an hour, it has always ended with a pulled hook, so I don’t feel qualified to add swordfish to my list.

Blue marlin
Internationally, blue marlin are probably the most sought-after marlin species, highly prized for their dynamic fighting ability and their potential for very large size. Blue marlin were only recognised as a Pacific species around 1950, and the first distinct NZ specimen was taken in the 1951-1952 season from the Bay of Islands. Only a very few per season were taken for many years, but with the advent of boats fishing further offshore, the increased popularity of lure trolling, and possibly the effect of ocean warming, more are being caught now – including a couple of world records and three ‘granders’ (fish over 1000 old-fashioned pounds).

These big fish are all females as males seldom grow to more than 135kg. As nearly all NZ blue marlin caught weigh more than this (averaging about 190kg), probably all our blues are female. Blues prefer higher water temperatures, 20-30 degrees C being their accepted range. The heaviest weighed specimen is reported from Hawaii at 850kg (1805lb).

Blue marlin, to a greater extent than other marlin species, are mostly found in deep water off and around the edge of the continental shelf (this is comparable to a depth of around 200m). Structures that may lead to concentrations of feed, such as canyons, banks or seamounts, are likely areas to fish for blues. Likewise, temperature break lines, schools of fish such as skipjack tuna, and floating objects such as logs are all worth investigating for these predatory fish.

February and March are usually the best months for blues in New Zealand as water temperatures are at their peak. The north-east coast and the Bay of Plenty produce the bulk of the catches, with occasional fish from the West Coast and Gisborne. Two main fishing techniques are particularly effective on blue marlin: trolling skirted lures and trolling bridle-rigged livebaits.

One of the main attractions of blue marlin, besides size, is the berserk approach they often take to their fight. On average, I reckon they out-shine stripies and blacks in this regard. Although not every blue marlin will perform in this fashion, these fish are capable of very high-speed runs, explosive aerobatics, mind-bending changes of direction, and shifting more water than a car dropped from 200 metres! 

As an angler, every time I look up from the reel they seem to be in a different part of the ocean, going in a different direction. As a deckie, with the angler in the chair, rod loaded, reel howling and several hundred metres of line running off rapidly astern, I have seen the fish explode from the water right under the outrigger, narrowly missing being entangled in the outhaul line! Most fishermen who have encountered a few blue marlin will have similar stories. 

Given their dynamic fight and high average size, standard tackle for these fish is 37kg or even 60kg. They are a real challenge on 24kg line, and the odds are against the angler on 15kg. The key to staying connected to these fish during the first dynamic minutes is keeping the drag light. When learning to fish 24kg tackle for blues I found that much more than four kilos of drag early in the fight often means a broken line. Because of the light drag, a lot of line can be lost initially and full line loads of 900-1000m are required. Full line loads also help keep the retrieve-rate high while chasing fish to try and get some line back. 

In New Zealand, it is sometimes easier to contain blues as they are often hooked up on the continental shelf (about 200m deep) and with good boat handling you are unlikely to be spooled. In the Pacific Islands you are often ‘over the edge’ in 3000m or more and there you can get taken to the spool knot by a fish that goes straight down! Aggressive chasing and taking the fight to the fish is generally considered to be the best tactic on a big blue. The real trick is to get the boat to the fish when the fireworks have finished, but before they can sound.