Life History of a Fish: Giant Trevally

By Scotty Kyle

I am the monarch of one of the largest, most aggressive and impressive families of marine fish anywhere in the world. My prowess, fighting abilities, boldness and size have made me one of the top challenges and targets of human recreational sport anglers. Human scientists have named me Caranx ignobilis, the “royal” trevally, as I am king where I am found. All in the water fear me while I can bring an adrenaline rush, second to none, to any human who hooks onto one of my species. 

My family, the Carangidae, contain many amazing species such as the bluefin, brassy, bigeye and golden trevally, but I reign supreme in simple dominance, as well as mass. None of my relatives can challenge the size to which I can grow and then there’s my attitude. I am Napoleon Bonaparte and Adolf Hitler rolled into one! I cruise my kingdom with arrogance and aggression looking for food or trouble. 

Many of my family are impressive fish, but none can compete with my size – which can be up to at least 170 cm. (67 in.) and 80 kg. (176 lbs). I have a typical trevally appearance, being laterally compressed with long pectoral fins and an unimpressive looking tail fin. This is my secret weapon. It is this weak-looking fin that powers me when cruising round reefs, wrecks and in the open ocean and then allows me to surge powerfully into action to smash into shoals or fish or to grasp a lure or fly. I am silvery grey on my upper body and slightly darker on top. Old males of my species can be very dark and even black. I have large eyes on the front of my head and a big mouth with fearsome teeth, to gulp in and hold whatever I can suck into my mouth.

When I was young, I ate a mixture of invertebrates and fish and then graduated to mostly fish, but now, fully adult, I choose what I am going to kill and eat. Most of my food is still fish, including smaller members of my family or species, but I will also take or attempt to take anything that looks edible. I can eat baby turtles, sea snakes or swimming birds. I have even heard that there are videos of my species barrelling out of the ocean to snatch flying birds out of the air. In areas where there are sea turtles hatching, my species will congregate and feast on the little turtles as they enter the water. I am not always angry or a bully but, when my species is cruising a reef, it looks as though I am. I am simply “top dog”, the “apex predator” and I patrol my region looking for injured or unwary fish or anything else that looks edible. I am not actually aggressive, I simply have a good appetite and feed by charging at prey and gulping it in. 

giant trevally at the rocks

There are still large gaps in human knowledge of my breeding and growth, but it is known that at times I congregate in huge numbers at specific places each summer. People assume that almost all the adults of my species in an area will migrate to these areas which are usually a little offshore in fairly deep water. Our females produce large numbers of eggs that are fertilised externally by us males and the eggs hatch in the water column. Larval giant trevally can drift great distances in ocean currents before heading for the shallows and many of us spend our first few years close inshore and often in estuaries or lagoons. Here, the feeding is usually much better and easier than in the offshore waters and, cover from predators such as barracuda, is readily available. In short, many of the young giant trevally that do not find the abundant food and good cover close inshore are predated in the ocean. These inshore areas, including places such as mangrove swamps, are important for our recruitment to the ocean. 

For much of the time and most of our lives, we are solitary, or move in small groups of similar sized individuals. Humans are trying hard to discover our life cycles and breeding secrets using techniques such as fish tagging and they are making progress. What they have found out is that every giant trevally is an individual and, while one tagged fish may do a particular thing, others may do something completely different, particularly individuals in other areas. Giant kingfish have been tagged on a rocky outcrop and recovered, one or several years later, at the exact same locality. This is interesting, but does not mean that the fish did not travel distances between tagging and recapture. Newer, more sophisticated, tagging using satellites and constant surveillance have shown that some individuals are resident for years at limited localities while others move vast distances and often repeat migrations annually. Some large specimens stay for years in estuaries, even small estuaries, then will suddenly head out to the ocean and then, often for no apparent rhyme or reason, return again. Unlike northern hemisphere salmon, none of my family spawn in freshwater. 

All members of my family live in warm marine waters and, while some of my cousins have limited or localised distributions, my species is more cosmopolitan and I can be found around the world in suitable areas with the exception of the Atlantic Ocean. We rarely stray far from land but can be particularly abundant round islands, particularly fairly isolated archipelagos. Humans love my species and, sadly, we are caught by them commercially in many areas resulting in our numbers and average size being greatly diminished in these places. Where there is no commercial fishing, however, I am often still abundant and, if allowed to survive, I can grow very large. 

In places where I grow very big, humans have developed almost a “cult” around my species. We are simply bigger, stronger and more assertive than almost all other bony fish species. Around Hawaii, Mauritius, the Maldives, the Philippines, along northern Australia and eastern South Africa, well organised and resourced sport fisheries with excellent charter operators and guides have developed. These are often successful and ethical operators who offer amazing fishing opportunities in magnificent areas and, usually, they are “catch and release” practitioners. 

While we are present in some estuaries and lagoons, most of us larger fish prefer the more open coastal marine areas. We love coral and other reefs, as well as any structures such as wrecks and rocky pinnacles. Many of us stay all year round in fairly localised areas, but some are much more mobile and constantly patrol along reefs or shorelines or aggregate annually or opportunistically when mass feeding opportunities occur. Many of us follow annual migrations of smaller fish on which we feed voraciously. Smaller giant trevally are usually found in shallow water, or near the shore, but at any time or in any place, a massive member of our species can suddenly appear, cause chaos and an adrenaline rush, and then smash tackle and disappear.

trevally a group of

Within our range we generally migrate into cooler regions in summer and withdraw in winter. Wherever we are, we feed much more readily and enthusiastically in the warmer months and yet, carefully presented baits, lures, or flies can sometimes succeed even in mid-winter. We also feed 24/7, but, possibly due to our amazing fighting ability, most fishing for us is carried out in daylight with mornings and evenings being best.

People fish for using almost all methods available to them. Smaller individuals are often caught “opportunistically”, but really big specimens are usually specially targeted. Many people spend countless hours, and much money, travelling to destinations preparing for attempts to capture my species. We can be caught on bait, lure or fly depending on circumstances and the preferences of the sport angler. Whatever they are, the angler needs to use strong and reliable equipment and listen to much advice to find a good locality (at the right time) and know how best to attract, hook, play and land a good-sized giant trevally. He or she must know that the strike may be completely unexpected, brutal and ridiculously strong and rapid. It may also not be repeated and so a small mistake may be fatal!

Large giant trevally are found in coastal waters and close inshore and so, depending on circumstances and preferences, boat and kayak or shore and pier fishing might be best. Bait fishing can succeed with my species, but we are cautious about what we eat and shortcuts, like old or substandard baits, are folly. Live or freshly killed baits are our favourite and they can be free swimming, floating or anchored on the ground. 

Circle hooks are probably best as we often “crunch” a fish first and then swim off with it. If an angler strikes while we are “crunching”, he or she will probably pull the fish right out of our mouths. If a circle hook is used, let the fish bite and then, as it swims off, simply raise the rod and tighten the line and the fish will often be hooked on the side of the mouth. Spinning can fool us, but we more often prefer surface “splashing” plugs, lures or plastics that are recovered rapidly and strongly. 

We are not scared of a little splashing, in fact it often attracts us. Our preference is to locate prey, for example by spotting a disturbance in the water, and then race in at speed and smash into it, often knocking it out of the water, and then we grab it and run.  Not only that, but our approach is to immediately head powerfully and at great speed for any close structure, such as a rock, and swim around it. This often works for us, but not the human. 

a fishing boat seen from above

Our first “run” can be exceptionally swift, strong and determined and extremely difficult to arrest. Letting us run, but maintaining pressure is the best approach and lots of line in good condition is essential. If we reach cover the “game” is often over and the line parts but if, from the initial bite, every effort is made to guide the fish away from any cover, success is more likely. 

Fly fishers love and hate us. We often take a fly explosively, when least expected, and then head for the nearest cover resulting in many “takes”, but few fish. Apart from excellent strong equipment, a level of skill in casting and an ability to read, the water, landing a good giant trevally on the fly requires a substantial quantity of luck. 

Usually, as soon as one of us is hooked, the angler realises that it is a giant trevally – our fight is so vigorous and typical. Even small giant trevally have the species’s characteristics. To locate, target, hook, play and successfully land a good-sized giant trevally is no mean achievement and will be a treasured memory. Most anglers will, however, regard the time, effort, expense and stress as well worthwhile and he or she will want to try and repeat the experience.

While the capture of giant trevally isn’t always  easy or cheap, there are many ways to improve your chances of landing one. The internet can assist with destinations, charter operators, advice and equipment and it is also full of anecdotes about the capture of my species. It is probably best to first find the most appropriate locality and then establish the best time of year. Shore fishing can be fairly straightforward and you can use your own equipment and ask advice locally. The best, however, is probably to look through the listed local charters to find the most suitable and then use his means, knowledge, and resources to access the best areas and possibly also use his equipment. 

When targeting my species, humans need every advantage they can find, invest adequate time and cash and then hope for good fortune. Success, however, is well worth everything as, apparently, outwitting and landing a large giant trevally is one of the most rewarding experiences a sport fisherman can ever have. 

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