Stromateus stellatus

Stromateus stellatus is a pelagic fish of the family Stromateidae, known in Peru as chilindrina or pampanito ^[1]. It lives over the continental shelf, near the coast, and forms small shoals ^[1]. It is the only member of its family along the coasts of Peru and Chile ^[2]. Its flesh is rich in a lipid that causes diarrhoea, so it is hardly eaten and is usually discarded as bycatch ^[2].

The body is deep and laterally compressed, greyish, with dark spots above the lateral line and a rounded head profile ^[2]. According to FishBase, the back is bluish green, the belly silvery white, the fin margins darker, and it reaches about 25 cm standard length ^[3]. It has no spines in the dorsal and anal fins; the dorsal carries 47 to 50 soft rays, the anal 41 to 44, and there are 42 to 43 vertebrae ^[3],[4].

Juveniles have pelvic fins beneath the thorax, which are missing in adults ^[2]. It is the only stromateid species in the southeastern Pacific off Peru and Chile ^[2].

The species ranges across the South Pacific from the southern tip of Chile to Ecuador, Peru included ^[1]. FishBase places it between 12°S and 47°S, at 0 to 200 m depth, with benthopelagic habits ^[3].

In Peru it lives over the continental shelf near the coast, in small shoals associated with jack mackerel, sardine or anchoveta ^[1]. Early juveniles associate with macroalgae such as Macrocystis pyrifera and are part of the epipelagic ichthyoplankton ^[1].

It is a serial spawner and reaches first maturity at about 21 cm total length, according to a Chilean study cited by Herrera and colleagues ^[4]. The eggs have not yet been described ^[4]. Off central Chile its main spawning period is spring-summer, according to the same paper ^[4].

Larvae in the described material measure between 2.7 and 10 mm; notochord flexion occurs between 5.6 and 7.7 mm ^[4]. During development the body becomes deeper, from less than 5 % to more than 30 % of body length, and the preanal distance exceeds 50 % ^[4]. Larvae bear 3 melanophores on the dorsal contour that disappear during flexion ^[4].

In a 50-night sampling programme between 2015 and 2017 off Valparaíso and El Quisco, with 300 samples, larvae appeared in October and from late December to mid-January, always at fewer than 6 individuals per 100 m3 ^[4].

Two of the three parasites found in 80 specimens from Lima, the trematode and the nematode, are acquired by eating invertebrates; the trematode's cycle passes through calanoid copepods, ctenophores of the genus Pleurobrachia and chaetognaths of the genus Sagitta, which suggests that the chilindrina feeds on planktonic invertebrates ^[1]. Those 80 fish measured between 12 and 22.5 cm total length, with a mean of 16.5 cm ^[1].

The parasites were the trematode Lecithocladium cristatum in the intestine (prevalence 28.75 %), larvae of the nematode Hysterothylacium in the intestine (6.25 %) and the isopod Ceratothoa gaudichaudii at the base of the ventral interopercle (6.25 %); 54 fish had no parasite at all ^[1].

The chilindrina is part of the diet of the South American sea lion Otaria flavescens and the blue-footed booby Sula nebouxii ^[1]. It is part of the fauna that comes up alongside the Peruvian anchoveta Engraulis ringens in catches ^[2]. It has been considered an El Niño indicator species because of its wide distribution and abundance ^[1].

The IUCN lists Stromateus stellatus as Least Concern (LC) globally, based on the 2008 assessment ^[5],[3].

In the South Pacific catches are made mostly with purse seines, in artisanal and industrial fisheries ^[1]. Because it is not used commercially, the species is usually discarded as bycatch, and its biology and ecology are therefore poorly studied ^[2].

Not medical advice. For a sting, a poisoning or an allergy, seek medical care.

The muscle contains diacylglyceryl ether (DAGE) as its main lipid; eating it can cause diarrhoea or intestinal bleeding, which is why it is regarded as inedible ^[2].

Among 80 fish from Chorrillos, 5 harboured larvae of the nematode Hysterothylacium, a group with zoonotic potential through the eating of raw or undercooked fish ^[1].

The species is caught mostly with purse seines ^[1]. It forms part of what comes up with anchoveta and the Araucanian herring Strangomera bentincki, but it has little value and is usually discarded ^[2]. It still reaches landing sites: the 80 specimens of the Peruvian study were bought at the Chorrillos fishing terminal in Lima between December 2008 and September 2009 ^[1].

Because of its abundance and wide distribution, it has been considered an indicator of the El Niño events of 1982-83, 1991-93 and 1997-98 ^[1].

In Peru, the available source places it in coastal waters over the continental shelf, in small shoals, and in 2008-2009 specimens were obtained at the Chorrillos fishing terminal (12°30′S) in Lima ^[1].