Normanichthys crockeri

Normanichthys crockeri is a small, short-lived, schooling pelagic fish endemic to the southeast Pacific: it lives in coastal waters from Chimbote, in Peru, to about 44° S in southern Chile, and reaches about 11 cm in total length ^[1]. In Peru it is recorded under the names «mote» and «camotillo» ^[2]. It belongs to the family Normanichthyidae ^[3]. Its eggs and larvae gather in the top 50 m near the coast, and in Independencia Bay (Pisco) it is prey for seabirds ^[1],[4].

The species was described by H. W. Clark in 1937 in the journal Copeia, from fishes collected on the Templeton Crocker expedition of 1934 and 1935 ^[3]. The genus name honours the British ichthyologist John Roxburgh Norman (1898–1944), and the epithet crockeri honours Charles Templeton Crocker (1885–1948), a member of a Californian family ^[2].

It is a small fish: according to studies from central Chile it does not exceed about 11 cm in total length, and its larvae are slender with very large pectoral fins ^[1].

The most complete developmental series from Peru comes from Independencia Bay, in Pisco: 66 larvae of 1.9 to 20.5 mm, arranged by morphology and pigmentation from 3124 plankton specimens collected in 2000 ^[5]. Hatching occurs at about 1.8 mm; notochord flexion takes place between 6.2 and 9.0 mm and transformation into a juvenile at around 20.0 mm ^[5]. They have 36 to 37 myomeres, and the pelvic fins carry one spine and 5 rays; the large, lightly pigmented pectoral fins appear early, and the pelvic fins are the last to appear ^[5].

The eggs are spherical, 0.75 to 0.83 mm in diameter, with a single oil globule of 0.21 to 0.26 mm; the globule takes up 19 to 28 % of the egg diameter, a proportion that helps tell them from the eggs of other fishes in the area ^[1]. Preflexion larvae hatched from eggs found at sea were recognised by pigment dots along the ventral side of the trunk and tail, star-shaped cells on the dorsal part of the tail and pigment on the isthmus ^[1].

It is endemic to the southeast Pacific. A study from central Chile places its range from Chimbote (Peru) to 44° S in southern Chile ^[1]. FishBase places it between Chimbote and Isla Mocha (around 38° S) and describes it as demersal, usually at 37 to 200 m depth ^[2].

The early life stages live in the surface layer. In central Chile, between 33° S and 37° S, eggs were found less than 12 km from the coast and associated with headlands and the inside of gulfs, and eggs and larvae were mostly in the upper 50 m, in the mixed layer ^[1].

In Peru, the larvae have been studied in Independencia Bay, at Pisco ^[5]. García-Godos and Goya, of the Peruvian Sea Institute, cite an earlier study in which the main ichthyoplankton of that bay was anchoveta and the mote sculpin ^[4]. In November 2000, off Punta Carreta, an echo sounder showed a concentration of fish at 8 to 40 m depth that the authors thought were probably mote sculpins near the surface ^[4].

In central Chile, adults spawn all year round in surface waters near headlands and inside bays ^[1]. In March 2002 the mean density was 788 eggs per 10 m2, with a maximum of 9693 south of Cape Carranza ^[1]. In a 2-year coastal series off Talcahuano, eggs were most abundant in January, March and April, and larvae between August and November ^[1].

At 12 °C, development from the morula stage to hatching took up to 48 hours, and the larvae lived on their yolk sac for 6 days; at hatching they measured about 2.7 mm ^[1]. Afterwards, the larvae eat copepod eggs, copepodites and adult copepods ^[1].

Larval growth, measured from the otolith rings of 90 larvae, was linear, 0.15 to 0.20 mm per day in the first 3 months; the pooled value was 0.16 mm per day ^[1]. This is slower than the 0.40 to 0.79 mm per day cited in various studies for anchoveta larvae Engraulis ringens ^[1]. It is a short-lived species ^[1].

Adults feed on zooplankton, mostly copepods, and are preyed on by coastal fishes, seabirds and marine mammals ^[1]. FishBase gives it a trophic level of 2.8 ^[2].

In Peru, the mote sculpin is prey for the Peruvian diving petrel Pelecanoides garnotii, a seabird endemic to the Humboldt Current. On La Vieja Island, in Independencia Bay, 118 stomach contents were analysed between 1997 and 2000: the mote sculpin appeared in 16.1 % of the samples and made up 8.0 % of the mass, an important prey but smaller than the anchoveta (33.9 %) ^[4]. In 1997 it was, together with fish larvae, the main prey, which the authors possibly link to cold waters in the area, and its occurrence followed a pattern linked to El Niño years ^[4].

In central Chile it reproduces, like the anchoveta and the common sardine Strangomera bentincki, in bays and gulfs, although its larvae grow more slowly ^[1]. The larvae stay in the mixed layer, from the surface to about 50 m, and no daily vertical migration was detected in spring or summer ^[1].

FishBase indicates that the species has not been evaluated by the IUCN, so there is no global threat category ^[2]. The same source rates its resilience as high, with a minimum population doubling time of less than 15 months ^[2].

In Chile, the mote sculpin is part of the bycatch of small pelagic fisheries and is caught in the austral summer (February to May) and early spring (September and October) ^[1]. Its landings rose from 9300 t in 2003 to about 67000 t in 2008 ^[1]. FishBase assigns it a low price category ^[2].

Its ecological importance is greater than its commercial one: it feeds seabirds such as the Peruvian diving petrel, whose distribution is restricted to islands from Lobos de Tierra (6° S) to Corral (37° S) ^[4].