White mullet

Mugil curema is a fish of the family Mugilidae, order Mugiliformes ^[1]. Molecular analyses treat it as a complex of cryptic species, and the lineage of the American Pacific still has no formal name ^[2]. Its global IUCN Red List category is Least Concern ^[3].

It is described as a thick-bodied mullet, round in section, with a wide head, a level interorbital space and an adipose eyelid, well developed, that hides much of the pupil ^[4].

The external characters of mullets are highly conserved, and molecular analyses have shown they do not suffice to separate every species ^[2]. In the Gulf of Mexico, the shape of the ctenii on the scales was used to tell Mugil hospes from Mugil curema ^[5].

Using recent specimens from Ecuador and Peru, Britzke and colleagues redescribed Mugil setosus and discussed whether Mugil curema truly occurs in the Pacific Ocean ^[6].

Similar species

• Mugil setosus: By its redescription, the tip of the pelvic fin reaches beyond the vertical of the base of the third dorsal spine, the pectoral fin has ii+13–14 rays and the anterodorsal tip of the second dorsal fin is uniformly dark ^[6].

FishBase gives the eastern Pacific range as the Gulf of California to Chile, and for the species as a whole marine, brackish and fresh water, usually between 0 and 20 m depth ^[4]. That figure lumps the whole complex, and whether the name Mugil curema truly occurs in the Pacific is under discussion ^[6].

The Pacific lineage, called Mugil sp. O, was identified molecularly in specimens collected in Ecuador ^[2].

The Pacific lineage has 46 chromosomes, 2 of them metacentric and 44 subtelocentric or acrocentric, a karyotype unlike that of Mugil incilis, which has 48, of Mugil curema in the strict sense, with 28, and of Mugil margaritae, with 24 ^[2].

Reproductive data exist only for Atlantic populations. In the Paciência River estuary, in Maranhão (Brazil), 942 fish were measured during 2021, with a mean total length of 20.44 cm; size at first maturity was 19.04 cm and reproductive activity peaked in May and July ^[7]. That population belongs to the Atlantic, where the name keeps its original sense, so its figures cannot simply be carried over to Peru ^[2].

Otoliths of 163 fish from Mexico, Venezuela and Brazil, analysed through their strontium-calcium ratio, indicated that 87.1 % moved from the estuary towards the sea or hypersaline environments, and that 11.1 % showed marine-water signals from early ages ^[8].

Those results fit a fish that uses estuaries, lagoons and rivers together with the open coast, and in which juveniles predominate in estuarine areas that serve as nurseries ^[7]. For the authors of the otolith study, its sustainable use depends on conserving the estuaries and the corridors that join them with lagoons, rivers, mangroves and the sea ^[8].

The IUCN Red List places Mugil curema in Least Concern at the global scale ^[3]. According to the otolith study, its sustainable use depends on conserving estuaries and the corridors between environments ^[8].