Silverside

Odontesthes regia is a bony fish of the family Atherinopsidae, in the order Atheriniformes ^[1]. In Peru it is called pejerrey ^[2]. It lives close to the coast, between 0 and 50 m deep, from Punta Aguja, in Peru, to Iquique, in Chile, and it is the second most important resource among the coastal species landed in the country, according to the average of the last 5 years ^[2]. Its global category on the IUCN Red List is Least Concern ^[3].

The Instituto del Mar del Perú places its range between Punta Aguja, in Peru, and Iquique, in Chile ^[2]. Another author, cited by a study in Arequipa, extends it to 46° S, in Aysén in Chilean territory ^[4]. In Chile it matters to artisanal fishers, above all in the tenth and eleventh regions, where 90 % of the country's catch is landed ^[5].

It is a neritic pelagic species that lives close to the coast, between 0 and 50 m deep, associated mainly with sandy bottoms with vegetation and with river mouths ^[2]. Juveniles are often found in open sea, tied to the cold coastal waters of the Humboldt system ^[2].

In 2024 IMARPE distinguished two fishing zones with different sizes. In the north and centre (Tumbes to Ica) it measured 37220 fish of 10 to 24 cm total length, with mean and modal size of 14 cm. In the south (Arequipa to Tacna) it measured 5256 fish of 12 to 23 cm, with mean and modal size of 17 cm ^[2]. In Arequipa, between 2016 and 2018, 47734 fish were measured, of 9 to 24 cm, a smaller range than the 12 to 34 cm published by another study in 1997, a difference the authors attribute to the negative effect of the fishery ^[4].

In the Pisco area 1590 ovaries were examined under the microscope. The mean length at maturity was estimated at 15 cm and the length at first maturity at 14 cm total length; in the periods of greatest reproductive activity, batch fecundity was 1174 oocytes and relative fecundity 56 oocytes per gram of weight ^[6]. Before the year 2000 the length at maturity had been calculated at 16.8 cm, so it has fallen over the years ^[4].

In Arequipa, between 2016 and 2018, the sex ratio of 3275 fish was close to 1 female for every male. The main spawning season was spring: reproductive activity exceeded 50 % from August to November, with August and October the most important months, and the gonadosomatic index reached 7.16 %. There was another, shorter and weaker spawning in January and February, with less than 40 % activity ^[4]. The authors suggest that the prolonged spawning could be related to the species' ability to spawn several times within one season ^[4].

In sea cages in southern Chile, at 42° S, juveniles that entered at a mean length of 13.88 cm grew 9.44 cm in 12 months and showed no signs of maturity. The growth rate peaked around day 130, when they measured 16.5 cm, and water temperature ranged from 7.7 to 20.1 °C ^[5].

Because the Humboldt system is highly variable, IMARPE notes that the biological state of the pejerrey, in both body condition and reproduction, can change with the environmental scenario and the region of Peru ^[2].

Between 2002 and 2014 the estimated parental biomass was above its reference point, about 12000 t, and since 2015 it has been below it. IMARPE links that break to the warm conditions that began in mid-2014 ^[2]. By contrast, landings in the south were not affected by the weak El Niño events of 2016 and 2017 ^[4].

Its global category on the IUCN Red List is Least Concern ^[3].

In Peru the minimum catch size is 14 cm total length (Ministerial Resolution 232-2003-PE), and since Ministerial Resolution 468-2016-PRODUCE there is a national reproductive closure between September and October, whose dates depend on the reproductive indices that IMARPE estimates ^[4],[2]. IMARPE explains that the rule aims to protect a resource whose exploitation is at the limit of maximum sustainable yield, with a risk to the stock ^[2].

Parental biomass has been below its reference point since 2015, but it is rising: in 2024 it increased by 35 %, about 1114 t more than in 2023. From January to August 2024, 31 % of the fish measured in the north and centre were below the minimum size, against 0.4 % in the south ^[2]. IMARPE's work plan for a research activity during the spawning period prohibits removing eggs and sets a cap of 120 t on the total catch ^[2].

Its flesh is well accepted in the domestic market for its pleasant flavour and good texture ^[4]. In northern and central Peru about 776 t were landed between January and August 2024, and in the south about 56 t, mostly with gillnets and, to a lesser extent, with purse seines ^[2].

In Arequipa, between 2016 and 2018, 671536 kg were landed: gillnets provided 71.92 % of the catch and the zapato, an informal vessel with no registration, 48.89 % ^[4]. In Chile its culture in sea cages has been tried, with results that its authors consider comparable to those of other cultured marine fishes ^[5].

In Peru the pejerrey is above all a fishery fish: it lives between 0 and 50 m deep near the coast, and juveniles are often in open sea ^[2]. Between January and August 2024 the largest landings were those of Lima, about 528 t, and Ica, about 203 t ^[2]. In Arequipa, between 2016 and 2018, 54.84 % of what was landed came ashore at Lomas and 32.90 % at Quilca ^[4].