Author: Cocco, 1829
Electrona rissoi Cocco, 1829
Status in World Register of Marine Species:
Accepted name: Electrona risso (Cocco, 1829) (updated 2009-06-25)
Diagnosis: North Atlantic population: dorsal finrays 13-14; anal finrays 19 (18-20); pectoral finrays 16 (15-17). Gillrakers 8 (9) + 1 + 19 (18-20), total 28 (27-30). AO 12 (11, rarely 10 or 13). Central Atlantic population: dorsal finrays 14 (13, rarely 15); anal finrays 19 (18, rarely 20); pectoral finrays 15 (14-16). Gillrakers 9 (8-10) + 1 + 19 (18-20, rarely 17 or 21), total 29 (27-30, rarely 26 or 32). AO 11 (12, rarely 10 or 13). South Atlantic population: dorsal finrays 14 (13-15); anal finrays 19 (18-20); pectoral finrays 16 (15, rarely 14 or 17). Gillrakers 8 (7) + 1 + 18 (16-19, rarely 23 or 24). AO 11-12 (10). Males with supra-caudal or infra-caudal gland or both; females typically with one supra-caudal and one infra-caudal gland (sometimes double) or occasionally with supra- or infra-caudal gland only. Size: to 82 mm.
Habitat: high-oceanic, mesopelagic. Mediterranean: day at 700-750 m; night at 150-200 m (specimens 9-31 mm) and at 400-700 m. Generally: day at 225-750 m; night at 90-375 m and at 450-550 m (maximum abundance at 200 and 500 m). Size stratification with depth at night, with post-larvae (8-10 mm) and adults (> 50 mm) below 500 m. Food: no data. Reproduction: caudal glands develop in both sexes from about 40 mm; sexually mature from about 59 mm. Spawning peak in summer-autumn (Mediterranean).
Distribution: widespread distribution in all three oceans, limited by 10° and 15 °C isotherms at 200 m and by a productivity greater than 50 gC m-2 y-l In the Clofnam area: east of 34° W, between 55° and 33° N and in eastern and western Mediterranean basins.
Eggs, larvae and young stages. Tåning, 1918: 28-31, fig. 9-10 | Sanzo, 1918: 14-21 | Tåning, 1931: pl. 109 (fig. 2) | Tortonese, 1956d: 923-926, fig. 804-806 | Moser and Ahlström, 1970: 35-40, fig. 8-9.
Otoliths (sagitta). Kotthaus, 1972b: 13, pl. 1 (fig. 1).