Two species of tarpons exist today, one in the Atlantic (Megalops atlanticus), the other (M. cyprinoides) in the Indo-West Pacific region. The name “tarpon,” or “tarpom,” is apparently of New World origin. The Englishman William Dampier encountered tarpons on his first voyage to the Bay of Campeche (which he called Campeachy), México, and his mention of the Atlantic tarpon is one of the earliest. Dampier wrote about the fish in his journals in 1675 and later included these entries in the account of his voyages around the world. The copies of Dampier’s Voyages cited here are early twentieth-century editions edited by the poet John Masefield, but earlier versions were published in the seventeenth and early eighteenth centuries. In Volume II, Dampier (1906: 117–118) stated: “The Tarpom is a large scaly Fish, shaped much like a Salmon, but somewhat flatter. ’Tis of a dull Silver Colour, with Scales as big as a Half Crown. A large Tarpom will weigh 25 or 30 Pound.” Because of their extensive distributions, both species have numerous other common names in many languages.¹ For simplicity, I refer to them as Atlantic and Pacific tarpons. The Pacific species is also called the Indo-Pacific tarpon and oxeye (or ox-eye), or sometimes oxeye (ox-eye) tarpon or herring.

Atlantic tarpons grow large, reaching 2.5 m and weighing 150 kg. The Pacific species is comparatively small, attaining only 0.6 m and 3 kg, although unsubstantiated reports exist of specimens three times this length (Seymour et al. 2008 and references). Despite the size disparity, their morphology, physiology, ecology, developmental biology, and other life-history features are so similar that I often found little justification for separate treatments, although I have separated them when possible for clarity. In some instances, such as discussion of distributions, I was handicapped by limited access to literature on the Pacific form.

Previous books have concentrated on just a few aspects of tarpon biology or restricted discussion to the Atlantic tarpon recreational fishery. My objective is to cover these and other topics without being too tiresome. The angling aspect presented (Chapter 8) is not about how to catch tarpons but how to conserve them and, if you must catch them, how best to do so with minimal stress to the fish and then release it in a manner offering the best chance of long-term survival.

My presentation of tarpon biology derives from a broad perspective, one in which I hope to assess the tarpon’s unique life-history in terms of fishes generally. Books like this are usually written by groups of specialists, the result being a series of chapters in which different aspects are partitioned, handed to separate authors, and subsequently treated in isolation. The result is often uneven, redundant, incompletely integrated, and fails to view the subjects themselves – tarpons in this case – as entities ruled by common natural forces for which data from more extensively studied species can sometimes apply just as well. Every biography is, in the end, a narrative of heritage and commonality.

My objective as a single author is to provide a cohesive picture of tarpon biology, ecology, and fisheries in which specialty aspects usually compartmentalized (e.g. physiology, larval development) blend at the edges and reinforce one another. I hope to accomplish this without loss of accuracy. For example, variations on the cube law used to practical advantage in fishery biology for predicting length and weight of individual fishes and assessing the condition of populations also apply theoretically to certain facets of water circulation in the buccal cavity (i.e. lamellar length scales isometrically with body weight). To receive full benefit of this integrative approach, chapters need to be read in sequence. This book, like my others, has been designed to be read, not consulted. Skipping through the text and examining sections out of sequence is guaranteed to be less satisfying. The reader has been duly advised, and I offer no apologies.

Symbols and abbreviations are generally defined at first use, but a roster of them is provided in the book’s front matter. Background information necessary to understand certain concepts is given either superficially in the text or, if more detail is necessary, in occasional footnotes. The presentation overall assumes a certain advanced level of knowledge.

An early anonymous reviewer made the reasonable suggestion that I include a section on tarpon evolution. However, not being an ichthyologist I felt uncomfortable doing so. I therefore left this subject and certain other avenues of specialization (e.g. detailed aspects of tarpon skeletal anatomy) to the experts. I take a systems approach instead, integrating functional biology with ecology, and discussing both disciplines in terms of effects caused by humans in the recreational and commercial fisheries at both the individual and population level. Only a few reports exist on tarpon physiology, although other species can safely be used as proxies at the system and even cellular level, at which point any differences are of degree, not kind.

Tarpons are distributed widely throughout subtropical and tropical waters around the world. Appendix A at the end of the book comprises a partial list of countries from which both species have been recorded in the literature. Pusey et al. (2004) provided an outstanding short summary of the Pacific tarpon’s natural history. Nothing I found on the Atlantic species in the recent literature matches it for brevity and completeness. Hildebrand’s (1963) treatment came closest, but his information is outdated.

The Atlantic tarpon ranges north to Nova Scotia and south to Brazil. Some authors extend its southern range to the coast of Argentina (e.g. Castro-Aguirre et al. 1999: 89; Gill 1907: 36; Hildebrand 1963: 119), although I was unable to find a published record of its presence in either Uruguay or Argentina (e.g. Bouyat 1911 did not mention it). The warm, south-flowing Brazil Current stops at the mouth of the Río de la Plata, and the sea beyond, including off Patagonia, is temperate. It seems that any Atlantic tarpons found there could only be stragglers from Brazil.

Reports about the tarpon in the eastern Atlantic are uncommon in the refereed literature, aside from its inclusion in species lists or as notes mentioning its appearance in regional ichthyofauna. Tarpons in the eastern Atlantic range north to the Formigas, a group of small islands in the eastern Azores (Costa Pereira and Saldanha 1977) and the inshore waters of continental Europe including the Tagus River estuary of Portugal (Costa Pereira and Saldanha 1977), the Lee River of Cork County, Ireland (Twomey and Byrne 1985; Wheeler 1992), and the French Basque coast (Quero et al. 1982: 1022–1025). I could not find specific mention of Atlantic tarpons entering the Mediterranean, but surely they have.

Minimum water temperatures probably influence the distributions of Atlantic tarpons (Killam (1992: ix). Costa Pereira and Saldanha (1977) pointed out that north of Sénégal and south of Angola sea temperatures begin to cool and salinity rises, conditions they believed restrict the tarpon’s latitudinal range in the eastern Atlantic. These regions are characterized by heightened rates of surface evaporation, lower seasonal rainfall, and weak fluvial flow into the Atlantic, factors that combine to keep coastal salinity values high and perhaps discourage inshore migration of metamorphosing tarpon larvae. Lower sea temperatures both to the north and south are the result of increasing latitude. The only elopiform listed by Penrith (1976) from Namibia and all of South Africa’s western coast was the bonefish (Albula vulpes). Evidently this region falls outside the Atlantic tarpon’s southern latitudinal range.

Costa Pereira and Saldanha (1977) did not mention that between Sénégal and Angola, where the “skull” of the African continent curves eastward, are sandwiched 13 countries with coastlines characterized by warm seas, high seasonal rainfall supporting tropical forests, mostly strong fluvial flow, an abundance of swamps and brackish lagoons, and other environments favorable for tarpons. The Atlantic tarpon’s range is likely to be extended to southeast Asia at some future time now that specimens have been imported into Thailand and released into recreational fishing reservoirs (Chapter 7.2). Some individuals will inevitably escape into coastal waters or be released there. Atlantic tarpons are already established on the Pacific coasts of Panamá and Costa Rica,² having traversed the Panamá canal after its opening in 1914 (Anonymous 1975; Hildebrand 1939).

The Atlantic tarpon is essentially a straggler outside the subtropics, but the Pacific tarpon’s normal range north and south seems broader, perhaps extending

How the length of a fish is determined requires comment, because the terms defined in this paragraph are used throughout the book. A fish can be measured and its length expressed in several ways: standard length, SL (tip of the snout to end of the last vertebra); fork length, FL (tip of the snout to where the center-most rays of the caudal fin terminate); total length, TL (tip of the snout to end of the caudal fin, sometimes with the lobes compressed so they extend to maximum length); and notochord length, NL in early larvae, equivalent to standard length before skeletal development. If enough specimens of a species have been measured using SL, FL, and TL, any of these measures can be converted to the others, as shown for the Atlantic tarpon (Table 0.1). To Breder (1944: 219), TL was measured with the caudal fin lobes spread, and overall length was the term he used when they were compressed. I consider this to be TL too. In either case, TL includes the length of the caudal fin, and the literature is seldom specific about which method was used.