StrikeAhead

Almaco jack (Seriola rivoliana): the Mediterranean’s second amberjack — six records since 2000, and probably many more mix-ups

Anyone who lands a big amberjack in the Mediterranean assumes it is *Seriola dumerili*. Usually that’s right. But since 2000 a second, very similar species has been documented in the Mediterranean: *Seriola rivoliana* — in English almaco jack or longfin yellowtail, in Italian ricciola oceanica or ricciola falcata (Italian Wikipedia), in French sériole limon, in Spanish medregal limón among others, in Catalan círvia rivoliana, in Japanese ヒレナガカンパチ and in Russian Южноамериканская лакедра (GBIF, Wikidata, Wikipedia). We found no German name of its own — neither GBIF nor Wikidata lists one. The same goes for Danish, Swedish, Norwegian, Finnish, Turkish, Greek, Croatian, Slovenian, Albanian and Arabic; Portuguese has only írio, a name it shares with *S. dumerili* (see below). Here is how to recognise it, where in the Mediterranean it has already been caught, what it eats — and why the CIESM Atlas suspects it is more common than the numbers say.

A fish with ten old names

It was described in 1833 in the *Histoire naturelle des poissons* by Achille Valenciennes and Georges Cuvier — although, according to English Wikipedia, Cuvier had already died in 1832. That is why some sources give “Valenciennes, 1833” (FishBase, GBIF) and others “Cuvier, 1833” (CIESM Atlas). English Wikipedia lists ten synonyms, including *Seriola bonariensis*, *S. falcata*, *S. colburni* and *S. dubia* — the species was “discovered” again and again. It belongs to the jack family (Carangidae) and is closely related to the greater amberjack and the yellowtail (English Wikipedia).

How to recognise it — and tell it apart from the greater amberjack

  • The key feature: the fin lobe. The raised front lobe of the second dorsal fin is strikingly long in this species: 19–22 % of fork length (CIESM Atlas; FishBase: 18–22 %). In the greater amberjack (*S. dumerili*) and its relatives, according to the CIESM Atlas, this lobe fits 6 to 8.6 times into the fork length and is usually slightly shorter than the pectoral fin. Hence the names *longfin* and *falcata* (“sickle-shaped”).
  • The shape: less elongate and more compressed than most jacks (English Wikipedia). Italian Wikipedia describes it as noticeably deeper-bodied than the greater amberjack, especially in the dorsal profile.
  • The head: a dark oblique band runs from the eye to the start of the first dorsal fin and, according to Italian Wikipedia, usually remains visible in adults too. The upper jaw reaches to about the middle of the pupil (FishBase) or the middle of the eye (CIESM Atlas).
  • The colour: back brown, olive green or bluish green, sometimes with violet or bronze reflections, belly paler, often brassy or lavender (Italian and English Wikipedia). The flanks often carry a yellowish or amber lengthwise stripe (FishBase, CIESM Atlas). The pelvic fins are white underneath (English Wikipedia).
  • The fins: dorsal fin with 27–33 soft rays in its second part, anal fin with 18–22 (all sources). The tail fin is deeply forked, and the caudal peduncle has a groove above and below (FishBase).
  • The juveniles: up to about 18–20 cm they carry six to seven dark vertical bars on the body and a dark nape band (Italian Wikipedia, CIESM Atlas, FishBase).

How big it gets

FishBase gives a maximum length of 160 cm (fork length) and a maximum weight of 59.9 kg, with 90 cm as the common length — the same figures appear in the English, Italian, Catalan and Japanese Wikipedias. According to English Wikipedia, the Florida Fish and Wildlife Conservation Commission states that a typical catch weighs only about ten pounds (around 4.5 kg) — it lives in small groups spread over wide areas and is not a common catch. The CIESM Atlas puts the figures considerably lower — see below.

Where it lives — worldwide

It occurs in all tropical and warm-temperate seas (CIESM Atlas, FishBase): in the Indo-Pacific from Kenya and South Africa to the Mariana Islands, the Ryukyu Islands, New Caledonia and the Kermadec Islands, and in the Eastern Pacific from California to Peru including the Galápagos (FishBase, English Wikipedia). It is absent from the Red Sea and French Polynesia (FishBase, Spanish and Catalan Wikipedia). In the Northeast Atlantic its distribution is “not well known” according to FishBase; English Wikipedia names the Azores, Madeira and mainland Portugal, plus reports from southern England and the Bay of Biscay, while Italian Wikipedia considers it fairly common along the Portuguese coast.

It is a fish of the open sea beyond the shelf and, according to Italian Wikipedia, only comes close to the coast where the water is very deep. Adults hold in small groups on outer reef slopes, seamounts and banks (FishBase, Japanese Wikipedia); according to English Wikipedia it visits wrecks more often than most other jacks. The CIESM Atlas considers it “probably more oceanic” than its congeners. Juveniles gather offshore beneath floating objects (FishBase, Italian Wikipedia, CIESM Atlas). Spanish Wikipedia gives preferred water temperatures of 18–24 °C.

In the Mediterranean: six documented fish

The first Mediterranean record dates from 2000, a single fish off the island of Lampedusa (Castriota and colleagues 2002, *Journal of Fish Biology*). A second followed from the same area (Castriota and colleagues 2004, *Cybium*). In 2011, three specimens off Mallorca were reported — the first record from the western Mediterranean (Valls and colleagues 2011, *Marine Biodiversity Records*) — and in the same year the first from northern Tunisia (Mansour and colleagues 2011). Libya followed in 2017 (Shakman and colleagues 2017, *BioInvasions Records*). The CIESM Atlas of Exotic Fishes in the Mediterranean counts a total of six caught specimens at different sites and in different years and gives the pathway as “via Gibraltar” — so it arrived from the Atlantic, not through the Suez Canal.

And then comes the sentence that matters to anglers: because it looks so much like the greater amberjack, it may have been confused with it and may therefore be more common than the records show (CIESM Atlas). Italian Wikipedia considers it possible that, with the tropicalisation of the Mediterranean, it will turn up elsewhere too. So if you catch an “amberjack” with a strikingly long dorsal-fin lobe, take a closer look.

What it eats

It is a predator that, according to English and Japanese Wikipedia, feeds by day and by night: smaller fish, plus small squid, octopus, crabs and shrimp. FishBase names mainly fish, alongside invertebrates, and places it at trophic level 4.5 — high up the food chain. Spanish Wikipedia describes how its diet changes with size: juveniles of around 4 cm feed mainly on copepods of the genus *Calanus*, fish of around 15 cm already on sardines, mackerel and squid. English and Japanese Wikipedia describe one peculiarity: it rubs against the rough skin of sharks to get rid of skin parasites — and sometimes against divers, whom it apparently mistakes for sharks.

Spawning and growth

Its eggs and larvae drift freely in the water (FishBase, CIESM Atlas); according to Spanish Wikipedia the eggs are transparent and about 1.2 mm in size, and the reproductive rate is high. According to English Wikipedia it spawns all year round, up to weekly; Italian Wikipedia describes spawning aggregations. FishBase makes an important point: its resilience is rated low — a population needs 4.5 to 14 years to double, and its vulnerability to fishing is rated high to very high (74 out of 100).

Angling, farming and a warning

According to English Wikipedia, its exceptional stamina makes it a sought-after target in deep-sea sport fishing; FishBase lists it as a game fish and a food fish in the “very high” price category. In the Mediterranean context, Italian Wikipedia mentions only lines, pelagic nets and trolling. Better known than the wild fish is the farmed one: off Hawaii it is raised in deep, anchored net pens as “Hawaiian Kampachi” or “Kona Kampachi”, in Mexico as “Baja Kampachi” (English Wikipedia); according to Spanish Wikipedia, Ecuador also planned to farm it. Its flesh is firm and dense like tuna and contains about 30 % fat (English and Japanese Wikipedia). Important: wild-caught fish can transmit ciguatera (FishBase, English and Japanese Wikipedia), especially from coral-reef areas; according to English Wikipedia, farmed fish on controlled feed do not. We found no ciguatera report from the Mediterranean in our sources.

Status — and what you can do

On the IUCN Red List it is classed as “Least Concern”. English Wikipedia writes that wild stocks are abundant and have never been fished commercially on a large scale. Even so: with low resilience and high vulnerability to fishing (FishBase), it is one of the species where releasing a big fish makes a difference. Whether a minimum size, closed season or bag limit applies to it is set by national and regional regulations — we deliberately give no figure. Check what currently applies locally, especially in marine protected areas. And because there are only a handful of records in the entire Mediterranean: a photo of the dorsal fin with place and date is valuable for research.

Seven contradictions in the sources

  • Where in the Mediterranean? FishBase and the Italian, Spanish and Catalan Wikipedias name only Lampedusa. The CIESM Atlas additionally names northern Tunisia, the Balearic Islands and Libya. English Wikipedia writes of scattered reports from the Balearics to the Gulf of Gabès — we found no record from the Gulf of Gabès in the scientific literature cited by the CIESM Atlas.
  • Does it live in the Western Atlantic? FishBase, English and Catalan Wikipedia: yes, from Cape Cod to northern Argentina. Spanish Wikipedia: it is absent from the Western Atlantic.
  • How big does it get? FishBase and four Wikipedias: commonly 90 cm, at most 160 cm. CIESM Atlas: commonly 50–80 cm, at most 120 cm.
  • Which sex grows large? Spanish Wikipedia: males only about 50 cm, females up to 1.5 m. FishBase and Catalan Wikipedia explicitly give the 160 cm for males or “male/unsexed”.
  • How deep? English and Japanese Wikipedia: 5–160 m, mostly 5–35 m. FishBase and Italian Wikipedia: 5–245 m, mostly 30–35 m (FishBase). Spanish Wikipedia: typically around 50 m, recorded deeper than 300 m.
  • What does it mainly eat? FishBase and Italian Wikipedia: fish, with cephalopods only in second place. Spanish Wikipedia: adults eat molluscs, crustaceans, echinoderms and small fish — fish in last place.
  • When was it assessed? FishBase: IUCN assessment of 21 August 2012. English Wikipedia: assessed in 2015.

Not a contradiction, even though it looks like one: Italian Wikipedia counts 7 spines in the first dorsal fin and 1 in the anal fin, FishBase and Japanese Wikipedia 8 and 3. The CIESM Atlas resolves this: VII + I and II + I — depending on whether you count the spine in front of the second dorsal fin and the two detached anal-fin spines.

Five naming traps

  • “Kampachi” isn’t always kampachi. In Japan, カンパチ (*kanpachi*) is the greater amberjack *S. dumerili* (Wikidata, GBIF); *S. rivoliana* is ヒレナガカンパチ, the “long-fin kanpachi”. On Hawaiian and Mexican menus, by contrast, “Kampachi” means farmed *S. rivoliana* (English Wikipedia).
  • “Greater amberjack” is the other fish. For *S. rivoliana*, GBIF also lists the English names greater amberjack, European amberjack and even bonito — but “greater amberjack” is the standard name of *S. dumerili*, and “bonito” otherwise means the Atlantic bonito.
  • “Barnsteenmakreel” and “írio” are shared by two species. GBIF lists the Dutch name barnsteenmakreel and the Portuguese írio for both *S. rivoliana* and *S. dumerili*.
  • “Medregal”, “coronado”, “huayaipe” are umbrella names. GBIF lists medregal and coronado for both species; only medregal limón did we find exclusively for *S. rivoliana*. In Ecuador, according to Spanish Wikipedia, several Seriola species are called “huayaipe”. And GBIF even lists boquerón — in Spain the name of the anchovy.
  • “South American” is misleading. The Russian name in GBIF, Южноамериканская лакедра (“South American lakedra”), fits poorly for a fish that lives in all warm seas.

Which leaves the question every article in this series starts with: when. For a predator that holds in small groups on deep slopes, banks and wrecks and feeds by day and by night, the right day matters more than any rig. Habitat, prey and features are listed above, and they are fixed. What changes every day are the conditions on your water — StrikeAhead calculates them and tells you when the trip is worth it. And because you don’t know the edges and rules of unfamiliar water from day one, StrikeAhead Pathfinder tells you with whom to head out: curated guides and skippers, personally vetted before listing — licence and insurance —, with verified catches instead of advertising photos, no paid ranking and, for you as an angler, no booking fee. The app says when, Pathfinder with whom.