Ecology of Sthenoteuthis oualaniensis
 
Main Ref. Jereb, P. and C.F.E. Roper, 2010
Remarks Widely distributed, abundant and highly productive, epipelagic to mesopelagic and upper bathypelagic species that inhabits open waters over great depths of more than 200 to 400 m, at sea surface temperatures from 16° to 32°C, but usually above 20° to 22°C. Reproductive area located in the Indian Ocean northward of 18°S to 22°S, in the North Pacific Ocean between 20°N to 25°N, and in the South Pacific Ocean from 16°S to 25°S. The more high-latitude areas of the species range is used by migrant squid as foraging zones, mainly by the females of the middle-sized form. Squid migrate to high latitudes with seasonal warming during summer in their appropriate hemisphere along the shift of surface isotherms of 20° to 22°C; then return to lower latitudes with the seasonal autumn. Truly pelagic and not associated with the bottom. An active predator with a very wide spectrum of food organisms. Planktonic paralarvae and juveniles usually live in the homogenous surface layer above and near the gradient layer (0 to 75 m and 100 m). Diurnal vertical migrations by paralarvae and juveniles are absent or very short in distance. During daytime the main bulk of juveniles occurs near the surface from 0 to 30 m, while at night they descend deeper, between 25 and 75 m, moving out of the zone of maximum numbers of conspecific predatory adult squids. Subadult and adult squids are interzonal animals. At night they inhabit surface and subsurface layers from 0 to 150 m to feed, with maximum numbers between the surface and about 25 m. In the morning they descend to depths of 200 to 1,100 m and remain there during the day. Very fast growing: by the age of 300 days specimens can reach 550 to 600 mm mantle length and 8 to 9 kg body weight. Typical monocyclic r-strategist. Cruising speed of adult squid is about 3 to 10 km per hour, but the burst speed reaches greater than 25 to 35 km per hour. Nearly non-active during the day and observed either "hanging" in the water or moving slowly at 1 to 1.5 km per hour, propelled by undulating fins. Its helminth fauna consists of 12 species of larvae of trematodes, cestodes, nematodes and acanthocephalans, among which are 2 representatives of nematodes that have significant negative impact on the commercial importance of the species. Larvae of Anisakis sp., a threat to human health, are localized in the ovaries and encysted in the coelomic membranes. Larvae of Porrocaecum sp. Are encysted on the internal mantle wall and may significantly degrade the quality of the marketable components of the infested squid (Ref. 97142).

Aquatic zones / Water bodies

Marine - Neritic Marine - Oceanic Brackishwater Freshwater
Marine zones / Brackish and freshwater bodies
  • supra-littoral zone
  • littoral zone
  • sublittoral zone
  • epipelagic
  • mesopelagic
  • epipelagic
  • abyssopelagic
  • hadopelagic
  • estuaries/lagoons/brackish seas
  • mangroves
  • marshes/swamps
  • rivers/streams
  • lakes/ponds
  • caves
  • exclusively in caves
Highighted items on the list are where Sthenoteuthis oualaniensis may be found.

Habitat

Substrate Pelagic;
Substrate Ref. Roper, C.F.E., M.J. Sweeney and C.E. Nauen, 1984
Special habitats
Special habitats Ref.

Associations

Ref. Jereb, P. and C.F.E. Roper, 2010
Associations schooling; shoaling;
Associated with Dosidicus gigas; Ommastrephes bartramii.
Association remarks An obligate shoaling (schooling) squid throughout ontogenesis. Shoals usually consist of squid of uniform size. Shoal size is highly variable and depends on the productivity of the area and the density of the squid population; varying from 2 to about 800 individuals, sometimes more. At the periphery of its geographical range, may form joint schools with same-sized Dosidicus gigas and Ommastrephes bartramii (Ref. 97142).
Parasitism

feeding

Feeding type mainly animals (troph. 2.8 and up)
Feeding type Ref. Jereb, P. and C.F.E. Roper, 2010
Feeding habit hunting macrofauna (predator)
Feeding habit Ref. Jereb, P. and C.F.E. Roper, 2010

Trophic Level(s)

Estimation method original sample unfished population Remark
Troph s.e. Troph s.e.
From diet composition 4.56 0.62 Troph of juv./adults.
From individual food items 4.19 0.82 Trophic level estimated from a number of food items using a randomized resampling routine.
Ref. Xinjun, C., L. Bilin, T. Siquan, Q. Weiguo and Z. Xiaohu, 2007
(e.g. 9948)
(e.g. cnidaria)
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