Bignose anchovy

Anchoa nasus is a pelagic fish of the family Engraulidae, order Clupeiformes ^[1]. In Peru it is known as samasa, marqueta or anchoveta blanca ^[2],[3]. It is small, up to 17 cm in total length, and forms schools in coastal waters of the eastern Pacific ^[4]. In Peru it is fished for fishmeal, alongside the anchoveta ^[3]. Its global IUCN Red List category is Least Concern ^[5].

It is a fairly elongate anchovy with an oval cross-section and no spines in the dorsal or anal fin ^[4]. The anal fin has 20 to 25 soft rays and starts under the base of the last dorsal ray or just behind it ^[4]. The snout is at least about three quarters of the eye diameter, and the maxilla is long and pointed, reaching almost to the gill opening ^[4]. The pseudobranch is longer than the eye diameter and carries 30 or more filaments; the flank has a silvery stripe roughly one eye diameter wide ^[4].

Its maximum published length is 17 cm total length and its common length is 8 cm ^[4]. In Peru, the minimum catch size set by the Ministry of Production in 2001 is 9.5 cm ^[2].

It lives in the eastern Pacific, from San Juanico Bay in Mexico to Chimbote in Peru, and occasionally reaches Callao and Pisco ^[2]. Other authors cite it as far as the Chincha Islands and probably farther south ^[2]. FishBase places it between 31° N and 14° S ^[4]. During the 1997-1998 El Niño it spread over the whole Peruvian coast and, when the event ended, went back to its usual areas ^[2].

It is a coastal and estuarine pelagic species ^[2] that forms schools near shore, enters bays and tolerates some drop in salinity; it is recorded from 0 to 142 m depth ^[4]. In the Pisco fishing area, between 2011 and 2017, its highest catches per unit of effort occurred at surface temperatures near 20 °C ^[2].

According to FishBase, it spawns all year, more intensely in the warm months, spawns in schools, and has oval eggs ^[4]. For Peru, a study citing Whitehead et al. (1988), an FAO catalogue, reports spawning from January to March ^[2]. FishBase gives a length at first maturity of 6.0 cm ^[4].

An IMARPE team studied 442 individuals in histological sections, 250 ovaries and 192 testes, collected on IMARPE cruises between 2008 and 2013, and described 6 maturity stages for each sex: virgin, resting, maturing, mature, spawning or expelling, and recovery or post-expelling ^[3]. In females, hydrated oocytes or post-ovulatory follicles define the spawning stage, and in the recovery stage at least half of the oocytes are atretic ^[3]. In males, at the start of the expelling stage semen comes out under gentle pressure ^[3].

The authors note that the gonads resemble those of the anchoveta Engraulis ringens and that, like it and other engraulids, the species is probably an indeterminate partial spawner, although they say its reproductive biology is little studied ^[3].

It is a zooplankton feeder whose diet includes euphausiids and copepods, according to a work cited in a study of its niche ^[2]. FishBase assigns it a trophic level of 3.4 ^[4].

Its relation with the anchoveta is inverse: their catches vary in opposite directions and the joint presence of both is low (0.62 %) ^[2].

In Pisco Bay, between 2011 and 2017, its niche lay between 18.15 and 21.56 °C of surface temperature and between 34.915 and 35.070 of salinity, with surface oxygen above 8.02 mg per litre and chlorophyll a above 8.59 mg per cubic metre ^[2]. Oxygen was the factor most often outside the niche (85 % of cases), followed by chlorophyll (68 %), salinity (62 %) and temperature (46 %) ^[2]. Seasonal variation weighed more than variation from one year to the next ^[2].

Its global IUCN Red List category is Least Concern ^[5].

In Peru, the samasa and the anchoveta share fisheries management rules, including reproductive closures ^[3]. The minimum catch size is 9.5 cm ^[2].

On 19 October 2026 the Ministry of Production authorised IMARPE to carry out exploratory fishing for samasa beyond 5 nautical miles, with larger purse-seine vessels, for up to 15 calendar days and with a tolerance of 20 % undersized individuals per trip ^[6]. The rule cites an acoustic biomass of 242,602 t measured from 15 September to 7 October 2026, and states that the species' presence depends on the intensity of the 2026-2027 El Niño ^[6].

In Peru the fishery gained importance from 1995, when landings by the industrial fleet rose, and its main use is fishmeal ^[3]. Between 1993 and 1997 the average catch was about 30,000 t, mostly at Paita; in 1996 it was 31,000 t, and in July 1998, during El Niño, it reached a record 178,000 t ^[2].

It is also a bycatch of the anchoveta fishery, where it made up 3 % of the catch ^[2]. FishBase lists it as bait, and in Manta, Ecuador, as the most important tuna baitfish ^[4].

In Peru it is recorded as far as Chimbote and occasionally to Callao and Pisco ^[2]. There are studies in the artisanal fishing area of Pisco, between Ovillos Island and Tambo de Mora, within 2 nautical miles, using data from 2011 to 2017 ^[2]. The samples used to describe its maturity come from cruises of the research vessel J. Olaya, not from the shore ^[3].

Its abundance along the coast changes with El Niño, and IMARPE treats it as an opportunity resource in the 2026-2027 event ^[6].