Doryteuthis (Amerigo) gahi (D'Orbigny 1835)

Introduction

Characteristics

1. Mantle
   1. Mantle moderately elongate.
2. Fins
   1. Fins rhomboidal, short, their length about 40 to 45% of mantle length.
3. Arms
   1. Arms elongate, especially ventral and ventrolateral.
   2. Arm sucker rings with 6 or 7 broad, flat teeth in distal half, proximal half smooth.
   3. Left ventral arm hectocotylized in dista1 1/3: suckers on dorsal row greatly reduced in size and set on elongated, triangular, swollen pedicles that grade smaller distally; ventral row unmodified.
4. Tentacles
   1. Tentacles long, slender.
   2. Clubs narrow, unexpanded, with relatively small suckers on manus.
   3. Median suckers about 2 times the diameter of the marginal suckers
   4. Teeth on club sucker rings pointed, very numerous: 25 to 35 (possibly 45).

Habitat and Biology

Occurs from the surface to 350 m depth but usually only to 285 m. The greatest numbers of juveniles were consistently caught in waters of <100 m to the south and east of East Falkland. Most D. gahi juveniles aggregate close to the sea floor.

Inshore spawning sites of D. gahi were found in the waters of East Falkland (Southwest Atlantic), where there is a major fishery based on this species. Egg masses occurred in algal beds, often at the outer (seaward) edge, with ambient water temperatures of 6.5-9 C. Egg strands were attached to the kelp algae Lessonia spp. and Macrocystis pyrifera from 0.5 m to 2.5 m off the bottom at 8-20 m depths. The capsules are mainly 50-60 mm in length and contain an average of 70 fertilized eggs. Eggs laid in winter are significantly larger than those laid in summer. 

Doryteuthis gahi increase in size and maturity with depth. Immature and fully mature squid were found at depths less than or equal to 100 m. The data support the hypothesis that this species spawns in shallow water and migrates down the continental shelf and continental slope after hatching. It then returns to shallow water to spawn. Highest concentrations of squid appeared to occur at depths and in areas where the commercial fishery operates.

Geographic Distribution

Eastern Pacific Ocean from southern Peru to southern Chile; reported in the South Atlantic from the Gulf of San Matias, Argentina to Tierra del Fuego. The northern limits on both coasts are unknown.

Other Names for Doryteuthis (Amerigo) gahi (D'Orbigny 1835)

• Synonymy: Loligo patagonica.
• Vernacular Names: En: Patagonian squid, Fr: Calmar patagon, Sp: Calamar patagónico, Local species names: Argentina, Chile, Peru: Calamar