Pacific Goliath Grouper

Epinephelus quinquefasciatus is a grouper of the family Epinephelidae, described by Bocourt in 1868 under the name Serranus quinquefasciatus ^[1]. For a long time it was treated as part of a single giant grouper species found on both sides of the Americas, until a genetic study in 2009 showed that the eastern Pacific populations are a separate species and gave this name back to them ^[2]. In Peru it is called «mero ojo chiquito»; the management plan of the Reserva Nacional Mar Tropical de Grau presents it as a fish that can exceed 2 m and weigh 300 kg, once common on the Punta Sal reefs and now extremely rare ^[3]. The IUCN Red List classifies it as Data Deficient ^[4], and in the Arrecifes de Punta Sal and Cabo Blanco – El Ñuro sectors of that reserve it may not be taken ^[3],[3].

It is a massive, elongate grouper with a very broad head and a flat space between the eyes; at its widest the body is more than half as wide as it is deep, and that depth goes 2.7 to 3.4 times into the standard length ^[5]. The dorsal fin has 11 spines and 15 or 16 soft rays, and the anal fin 3 spines and 8 rays ^[5]. Its colour runs from yellowish brown to grey or greenish, with small black dots on the head, back and fins that get smaller as the fish grows; it lacks canine teeth at the front of the jaws ^[5].

No external feature is known that tells it apart from the Atlantic giant grouper: what separates the two species is a set of fixed differences in their mitochondrial and nuclear DNA, and the Isthmus of Panama, which closed about 3.2 million years ago and keeps them from interbreeding ^[2].

Similar species

• Epinephelus itajara: It cannot be told apart by appearance; it lives in the Atlantic, whereas the giant groupers of the eastern Pacific are Epinephelus quinquefasciatus ^[2].

It lives in the tropical eastern Pacific, from the Gulf of California to Peru, and is found down to about 100 m ^[5]. Peru's tropical north is the southern end of its range ^[6].

According to fishers on Colombia's Pacific coast, juveniles favour shallow estuarine water with plenty of structure, such as mangrove roots or fallen logs, while adults live offshore on complex rocky reefs, caves or wrecks shallower than 30 m ^[7]. Of those interviewed, 85 % agreed that the fish moves from the estuary to these offshore grounds as it grows ^[7].

In Peru it is a fish of caves in shallow water; it used to be common on the Punta Sal reefs, with records as far as El Ñuro ^[3].

No other reef fish in the tropical eastern Pacific grows as large ^[7], with a maximum recorded total length of 250 cm ^[5]. At the Buenaventura market in Colombia, 1981 fish were measured between July 2012 and December 2015: they ranged from 11.3 to 190.5 cm in total length and from 0.3 to 110 kg gutted, and only 6 % exceeded 110 cm, the size at which its Atlantic relative matures ^[7].

Otoliths from 210 fish bought at the main markets of Panama and Colombia gave ages from under 1 year to 13 years, most of them between 1 and 4 years ^[8]. The fitted growth model gives an asymptotic length of 207 cm, and the instantaneous mortality rate was estimated at 36 % in Colombia and 26 % in Panama ^[8].

Among the Colombian fishers interviewed, 46 % had never seen a mature female, and the authors conclude that the breeding season and size at maturity remain unclear ^[7]. Some 76 % knew that it makes loud, abrupt, low-pitched sounds, and the most experienced fishers use them to find it ^[7].

It is a predator. Colombian handline fishers name Euthynnus lineatus as its favourite prey, and that fish is also the bait most often used to catch it (52 %) ^[7]. Catches rise in August and in May; the good fishing in May coincides with the migration of Cetengraulis mysticetus, on which it feeds, and 63 % of fishers agree that the best time to catch it is the 3 days around the peak of spring tides, because, they say, only then does it feed ^[7].

Of those interviewed, 61 % described it as a passive fish, although spearfishers say that after a missed shot it may charge the diver; one of them told of being swallowed halfway, head first, and then released ^[7]. Some spearfishers have seen groups of more than 20 adults near Cabo Corrientes and Cabo Marzo, on the rocky northern stretch of Colombia's Pacific coast ^[7].

Its global category on the IUCN Red List is Data Deficient ^[4]. Behind that category lie the lack of data on its populations and the risk that fishing poses to it ^[9].

In Peru, 40 interviews with spearfishers carried out in 2020 showed that in the 1980s it was habitually caught along 284 km of coast and in 5 northern fishing grounds, and that by the 2010s it appeared in none: it vanished completely from the habitual catch, a 100 % reduction ^[6]. Today it is only mentioned anecdotally in turbid grounds next to the mouths of northern rivers, where it might still be present without being catchable, and the authors call for strict measures, such as fishing closures, to restore this and other species ^[6].

The management plan of the Reserva Nacional Mar Tropical de Grau regards it as highly threatened by poor spearfishing practices and other fishing gear ^[3], and notes that because it lives in shallow caves it is easy prey for the speargun ^[3]. The recovery zones of the Arrecifes de Punta Sal sector were placed on the reefs that once held healthy populations of this and other species now seriously threatened ^[3]. Taking it is forbidden in that sector ^[3] and in the Cabo Blanco – El Ñuro sector ^[3].

On the Pacific coast of Panama, the memory of handline and speargun fishers records a significant fall in the average weight of the fish landed between 1958 and 2018, put down mainly to market demand and environmental degradation ^[9]. In Colombia the fishery concentrates on small, immature fish, most of them taken from the southern mangroves, and 89 % of fishers believe the species has declined, mostly because of greater fishing effort and the arrival of spearfishing ^[7].

Colombia's Pacific coast is one of the few places where it is still fished regularly: landings there averaged 34.5 tonnes a year between 1995 and 2015, and in 2009 and 2010 they overtook those of Hyporthodus acanthistius, historically the most landed grouper on that coast ^[7]. Near the main market, small fish of 2.5 to 25 kg fetch more (about US$3.7 per kilo) than those over 25 kg (US$1.8), because fishers link large size with tougher flesh ^[7].

In Peru it was fished too: among the historical photographs gathered by a local ecological knowledge study is one of fish of this species caught at Punta Mero in 1964 ^[6].

According to the 2026 management plan, it is now extremely rare in Peru, although it was once common on the Punta Sal reefs and was recorded as far as El Ñuro, always in shallow-water caves ^[3]. In the 2020 interviews it no longer featured in the habitual catch of any fishing ground in the country ^[6]. In the Reserva Nacional Mar Tropical de Grau it may not be taken in the Arrecifes de Punta Sal sector ^[3] or in the Cabo Blanco – El Ñuro sector ^[3].