Story: Dr Julian Pepperell
Photos: Dr Julian Pepperell, David Granville & Nathan Ghosn

'Citius, Altius, Fortius'. This is the great and noble motto of the Olympic Games which translates from the Latin simply as 'Faster, Higher, Stronger'. Anglers could no doubt argue for days about the relative athletic merits and physical attributes of various species of gamefish, but if these species were put to the test, which fish would be waving its fins on the winners' podium?

Many anglers would agree that at least part of the great allure of gamefish lies in the athletic prowess of the fish themselves, the fighting qualities of the fish once hooked. But what qualities exactly are being referred to here? Thinking of all the factors which might be able to be measured; they might include aggressiveness in taking a bait or lure, speed of swimming, ability to swim at speed for extended times (what might be termed the duration of 'burst' speeds), predisposition to jump and head-shake, or alternatively, tendency not to jump, tendency to fight harder when near the boat, tendency to fight harder when on the trace or just sheer doggedness.

There is a natural tendency to anthropomorphise animals; that is, to bestow them with human qualities and attributes. Certainly plenty of that goes on when thinking and talking about gamefish, and in many ways, this is what makes gamefish so awe-inspiring. Gamefish appear to be imbued with super-piscine powers and abilities far beyond those of normal fish.

The ancient Greeks and Romans wrote about swordfish and giant bluefin tuna with great reverence, as do modern writers today. In Hemingway's The Old Man and the Sea, the huge marlin that Santiago finally subdues has an almost mythical stamina and strength. And on the very pages of this illustrious magazine, you won't have to read far to find prose describing many of the great gamefishes in glowing terms.

So let's now pose the questions. Which fish does swim the fastest? Which jumps the highest? Which
is the strongest? And for good measure, we will also ask which fish swims deepest? And which travels the greatest distance?

SPEED KILLS
Ideally, scientists like to be able to measure such things as how fast fish swim under controlled conditions. It is therefore not surprising that quite a number of experiments have measured swimming speeds of various fish species in captivity.

In one such experiment, fish were allowed to swim in circular tanks and then analysed for such factors as tailbeat amplitude, maximum and sustained speed, and so on. For comparative purposes, speeds were measured in terms of body lengths per second (L/sec), and maximum speeds measured in this way included the following: goldfish (3.5–9.3L/sec), rainbow trout (1.5–11.6L/sec), Atlantic cod (2.8–3.5L/sec), slimy mackerel (5.3–18.0L/sec) and bluefin tuna (9.3L/sec).

While the results seem to indicate that the maximum relative speeds of different species are pretty comparable, when the body lengths of the bluefin tuna (2.3m) and goldfish (7.0cm) are taken into account, the absolute maximum speeds measured were 77km/h for the tuna and 2.3km/h for the goldfish.

While it is relatively easy to measure the swimming speeds of fish in captivity, it is another matter entirely to try to obtain an accurate speed of fish in the wild. In fact, I know of only one published study which attempted to directly measure speeds of open ocean gamefish. This was done by hooking fish and measuring the speed of their first burst by clocking the rate at which line peeled off a reel. This was achieved with quite sophisticated equipment but only two species, yellowfin tuna and wahoo, were clocked. Nevertheless, the results were of great interest. Yellowfin burst speed was recorded at 74km/h while the wahoo was clocked at 77km/h.

These are certainly impressive speeds, however, scientifically measured as they were, they are not the fastest speeds of a fish you will find in the mainstream media. The fastest speed attributed to a fish in any of the usual encyclopaedias that you might care to consult (which all seem to be sourced from the Guinness Book of Records, by the way) is 110km/h for a sailfish. This incredibly oft-quoted figure seems to derive from an anecdotal observation of a hooked sailfish in Florida which peeled off 300ft of line in three seconds. These round numbers sound suspiciously like estimates to me, rather than the result of carefully timed events although one account insists this is an average of a series of "speed trials".

Other top speeds attributed to various fish species, which I have found on different websites include the following (speeds in km/h in brackets): blue shark (15.1), barracuda (16.9), flying fish (21.8), mahi mahi (23.0), bonito (25.0), albacore (25.0), unspecified marlin (31.3) and swordfish (37.5) and mako (50–74). But before you go off quoting those numbers, I should warn you that I cannot vouch for their sources. I suspect that some may be based on estimated heights of leaping fish, but in any case, they do seem well within the range of the few reliable measurements of speeds for some of the gamefish at least.

High-speed predatory fish such as tuna and billfish are certainly superb examples of evolution of body form towards sheer speed. It is no easy matter to swim through water quickly, simply because water is much denser than air: 750 times as dense, in fact. Because water offers so much resistance to movement, such predators (and some of their prey) have all evolved an extreme streamlined shape, together with other features which all reduce drag.

In most of the mackerels, tunas and billfishes, the fins fold beautifully into slots for high speed bursts. All of these fishes also have other drag-reducing features such as lateral keels on the tail wrist, and single or multiple finlets in front of the tail, these adaptations no doubt helping to reduce turbulence at the body surface.

Obviously, extreme speed is only used for hunting or fleeing, but when they do turn on the power, the oceanic gamefish leave everything else in their wake.

And the winner of the sprint event? With not all results in to the judges yet, the tentative gold medal goes to the wahoo, but with a strong protest coming from the sailfish camp.

THE HIGH FLYERS
Many fishes leap when hooked, but there are some which leap of their own accord - the so-called 'free jumpers'. Perhaps the best known examples of free-jumping fishes would be the marlins, the sailfish and the mako shark, but others would include yellowfin tuna, mahi mahi, Spanish mackerel and, yes, the aptly named Watson's leaping bonito.

Why do these fish jump? For species like makos and yellowfin tuna, the hunting strategy is often to attack prey fishes from below by rushing vertically upwards at high speed.

On the other hand, free-jumping sailfish will often make a series of crashing leaps, one after another, describing an arc as they go. In this case, the sailfish is actually rounding schools of baitfish into tight balls which are subsequently preyed upon by other members of the hunting pack of sailfish.

The heights that jumping fish might be able to attain have not, as far as I am aware, ever been reliably measured. However, that doesn't mean there aren't plenty of estimates around. For example, both mako sharks and manta rays have been attributed jumping heights of six metres. While I strongly doubt that figure for a manta ray, the few grainy photos in existence of free-jumping makos do indicate that these blue streaks might actually be capable of that sort of mighty leap. This seems even more feasible when noting that the speed required of a mako to reach such a height is apparently a modest 35km/h - certainly within the range of the top speeds for gamefish, including makos, mentioned above.

So, unless there are any challengers out there who might have some reliable estimates of maximum heights of other jumping species, the gold medal in this event goes to the shortfin mako shark.

TUG O' WAR
The relative strength of fish, pound for pound or kilo for kilo, is a topic that has no doubt generated more arguments than any of the other fishy attributes discussed in this article. I have lost count of the number of times that the topic of the strongest or toughest fish has come up in gamefishing circles.

Unfortunately, there is no simple answer to what constitutes a 'tough' fish from a scientific point of view. However, probably one factor with which most would agree in relation to the 'toughness' of fish would be their 'pulling power', especially over a sustained period. And pulling power all boils down to the internal biology of the fishes themselves.

Pulling power is related to the physiology and biochemistry of the muscle, and can, to some extent, be related to the proportions of red and white muscle that a fish has.

Red and white muscle I hear you ask? Well, if you cut a fish into steaks, you will notice distinct sections of red muscle usually running along the midline of the fish under the skin, sometimes penetrating to the backbone, and at the base of the fins.

Red muscle is the muscle which is used for sustained swimming, whereas white muscle is mostly used for burst speed swimming. The white muscle is not well supplied with blood vessels and tires out much more easily than red muscle. So one simple way of considering which fish might have the highest pulling power (rather than which are the speediest) is to look at those species which have the largest percentage of red muscle compared with white.

To cut to the chase, it turns out that the tunas tend to have most red muscle, and therefore, they are more likely than other fish to be able to pull harder for longer. The mackerel sharks (mako, porbeagle and white) also have a greater proportion of red muscle than most of the other sharks, so again, they can pull harder for longer, at least in theory.

However, it seems to me that this general rule doesn't always hold true. Broadbill swordfish and marlin don't appear to have a lot of red muscle compared with white muscle (compared with, say, tuna) but they can certainly pull for a long time, and like tuna, are also capable of very long distance migrations which require sustained muscle activity.

Because of this, I had thought that perhaps the whole subject needed a closer look. It may be that the white muscle of marlin and swordfish is better supplied with blood vessels than the white muscle of, say trout and freshwater pike - the sorts of northern hemisphere fishes on which early studies of this sort were made.

The pelagic fishes all have remarkable physiological adaptations to their own particular habitats, including the ability to rapidly swim down vertically into water with very low oxygen concentrations, but still maintain oxygen to their muscles, brain and eye.

Perhaps, as noted, other adaptations of species like swordfish were yet to be discovered, which will explain their 'pulling power'. Further research on the actual distribution of red muscle in the bodies of tunas does indicate that there is more to sheer power and sustained swimming speed than the simple ratio between red and white muscle, indicating that species such as marlin and swordfish may well be able to hold their own in this event.

This is all very well, but the question still remains: which fish would win the tug o' war event? To me, this is the most difficult of all to assess, so to avoid a sack full of mail by picking just one species, I am going to opt for a group of finalists, and let you the reader imagine the possible winner. My final group therefore in the tug o' war would include the broadbill swordfish, yellowfin and northern bluefin tunas, dusky whaler and for good measure, the giant trevally.

THE DEEP DIVERS
Water is a dense medium to move through but has other features which also present real challenges to fish which live near the surface: the deeper you go, the more pressure is exerted, the darker it gets, the colder it gets and the less oxygen there is.

Sonic tracking and pop-up satellite tags have revolutionized our knowledge about the depths to which pelagic fishes dive. Electronic tagging has shown that some species (yellowfin tuna, marlins, sailfish) tend to be very surface oriented, while others (swordfish, bigeye tuna, albacore) often dive to deeper depths.

Before the advent of high-tech tags, the deep sea diving bell, the Alvin, was attacked by a swordfish at a depth of 610m, while another submersible, the Deepstar 4000, photographed a broadbill resting on the bottom in 642m of water. More recently, a Japanese study of a 120kg swordfish showed that it regularly descended to at least 900m as part of its normal daily vertical movements.

But as deep as swordfish might dive, electronic tagging has shown that the champions in this event are bigeye tuna. Early tagging showed that this species could make extremely rapid vertical dives. For example, one fish tagged off Hawaii dived to a depth of 250m in just one minute! Subsequent tagging with pop-up tags showed that bigeye routinely swim down to, and remain at depths of 400–600m. At those sorts of depths, temperatures, even in the tropics, drop to seven to nine degrees Celcius, and oxygen levels in the water are very low for an animal which has such a high metabolic rate.

But bigeye tuna are not ordinary fish. Their blood (like an athlete, or a human which has adapted to high altitude) can carry a lot more oxygen than the more surface-oriented tunas, allowing them to take advantage of prey species to be found at greater depths. The latest research has shown that bigeye often make protracted deep dives to 800m, almost certainly for foraging for food, and more importantly, that the maximum depth so far recorded for this species is between 1400 and 1500m. (The lack of precision in the depth measurements is due to the electronic tags being rated to only 1000m, so the depths of dives deeper than this are estimated based on the temperature of the surrounding water. It is interesting to note that the temperature at a depth of 1500m in the above study was a mere three degrees Celcius.)

And so ladies and gentlemen, I give you the indisputable winner in the deep diving event: the bigeye tuna.

THE MARATHON SWIMMERS
Fittingly, the last event in our fishy Olympics is the marathon. And while a normal marathon is held over a set distance, in this case, we will consider which fish swim the furthest distances, given that the marathon course is potentially all of the world's oceans.

Having mentioned above the extraordinary speeds that some pelagic fish are capable of attaining over short bursts, it might come as a surprise to learn that the average sustained swimming speeds of most are very leisurely. Tracking tagged fish indicates normal cruising speeds of the order of one to two knots; consistent across the board for tunas, billfish and sharks. At those speeds, without assistance from currents, a fish would easily cover 20 to 40 nautical miles per day. So for how long and for how far can an individual fish maintain a steady, directional cruising speed?

The longest distances travelled by fish have been recorded via conventional tagging programs. Before such tagging programs were instigated, we had little information on the movements oceanic gamefish.

Because in the past, pelagic fishes were observed to appear seasonally, it had been assumed that they must travel. As long ago as 1757, Fray Martin Sarmiento wrote: "Tuna have no native country, nor lasting domicile. All the sea is their native country. They are wandering fish."

It was not until tagging commenced however, usually with the help of recreational anglers, that it was actually proven that many of the tuna, billfish and shark species do indeed undertake extensive movements. Tagging in the 1950s and 1960s showed that bluefin tuna and blue sharks regularly crossed the Atlantic, and that in the Pacific, species such as albacore and bluefin tuna were capable of moving between Japan and California.

Conventional tagging also showed that some species move much less than others. For example, on average, yellowfin and bigeye tuna tend to move less than skipjack tuna, while sailfish, striped and white marlin cover less distance overall than blue or black marlin.

But which species have moved the furthest distances? Since the early 1960s, over 300,000 billfish and more than a million tuna of various species have been tagged. And of the thousands of recaptures, the two record holders which have emerged are first cousins, the blue and black marlin. The record distance so far recorded for black marlin is 14,556km, while the blue marlin's record currently stands at just 327km more, a total distance from points of release and recapture of 14,893km.

While our black marlin's epic journey took it all the way across the Pacific Ocean, from Cairns in Australia to Costa Rica in Central America, the blue marlin pipped it by not only moving several hundred kilometres further (as measured along the shortest possible route) but by moving from one major ocean to another - from the Atlantic seaboard of the US to Mauritius in the Indian Ocean. And as a matter of interest, the only other inter-oceanic movement for any fish so far recorded was for another blue marlin. This world traveller moved from the east coast of Australia in the Pacific to the central Indian Ocean off Sri Lanka.

So as is the tradition, the last gold medal of the fish Olympics for the oceanic marathon goes to the blue marlin... just.

In closing, I would hope that we all keep in mind that other noble Olympic ideal. It is not whether you win or lose, but how you play the game... or should that be gamefish?