Nototodarus gouldi (McCoy 1888)

Nototodarus gouldi (McCoy, 1888)

The dominant ommastrephid in continental shelf waters off southeastern Australia and around the North Island of New Zealand is N. gouldi, and its abundance has resulted in the development of significant jig fisheries in these regions, especially during the summer months (Winstanley et al., 1983).

Nototodarus gouldi larvae were first described from eastern Australian shelf and upper slope waters by Allan (1945) from plankton samples taken between eastern Bass Strait (39°20′S) and southern Queensland (26°54′S). They also were caught off central and northern New South Wales in continental shelf and slope waters between 29°S and 36°45′S, between January and May 1983, where sea surface temperatures (where recorded) varied from 17° C to 23.7° C (Dunning, 1988c).

In eastern Australian waters, adult N. gouldi have been caught between 27°13′S and 43°40′S where sea surface temperatures varied from 11° C to over 25° C. Although it has been taken in demersal trawls on the upper continental slope to depths of 800 m, it has been most abundant in commercial jig catches where bottom depths range from 50 m to 200 m (Winstanley et al., 1983).

Nototodarus gouldi occurs in New Zealand waters southward to 44°S off the west coast (Smith et al., 1987). It has been trawled together with N. hawaiiensis (Berry, 1912) north of New Zealand on the South Norfolk Ridge at 29°40′S, 168°E (bottom depth 362–438 m), and off the eastern Australian coast at 27°15′S, 153°54′E (bottom depth 535 m).

Nototodarus gouldi (McCoy, 1888)

Ommastrephes gouldi McCoy, 1888:255, pl. 169.

Ommatostrephes sagittatus sloanei Pfeffer, 1900:179 [part].

Ommatostrephes sagittatus var. sloanei.—Hoyle, 1909:272 [part].

Ommatostrephes sloanei sloanei.—Pfeffer, 1912:458, pl. 34: figs. 1, 2, 7 [part].

Nototodarus gouldi.—Berry, 1918:228, figs. 10–23, 26, 27, pls. 63–66.

Nototodarus sloanii sloanii.—Dell, 1952:105, fig. 7, pls. 21–25 [part].

Nototodarus sloani gouldi.—Voss, 1963:132.

DIAGNOSIS.—Right arm I with 28–50 pairs of suckers, hectocotylized right arm IV distally with 1 dorsal row of slender, conical papillae and expanded ventral protective membrane with supports opposite entire distal row of dorsal papillae (Figure 1b).

ORIGINAL REFERENCE.—McCoy 1888:255, pls. 169, 170. Berry (1918) provided a further detailed morphological description of post-juvenile growth stages of this species from southern Australian waters.

DEPOSITION OF TYPES.—Holotype: Female, 10.4 inches ML (264 mm), Museum of Victoria, Melbourne, Australia, F5104, in alcohol, good condition, collected in Hobson's Bay, Port Phillip, Victoria.

Paratypes: None designated.

DISTRIBUTION.—Nototodarus gouldi is the dominant ommastrephid in continental shelf waters south of 27°S off the Australian coast and off the northern and central coasts of NewZealand. Its abundance has resulted in the development of significant jig fisheries in this region, especially during the summer months. Around New Zealand, it is partially sympatric with N. sloanii between 40°S and 44°S. In slope waters to the north of its range, N. gouldi is occasionally caught together with N. hawaiiensis (Dunning, 1988c).

Nototodarus gouldi has been caught where surface water temperatures vary from 11° C to over 25° C. The largest specimens from Australian waters were a 412 mm ML female and a 320 mm ML male, both were taken in a demersal trawl in the eastern Great Australian Bight in August 1981.

Previous studies of N. gouldi in Australasian waters have provided basic information on the population structure during the summer fishing season. Variation in mantle-length distributions during the 1977–1978 summer fishing season from a restricted area in western Bass Strait appeared to conform to a three-“brood” structure similar to that reported for Todarodes pacificus (Steenstrup) around Japan (Harrison, 1979). In this same area in the following two summers, however, polymodal mantle-length distributions in the jig catches and the presence throughout the fishing season of recent recruits suggested that the population consisted not of a few discrete broods but rather resulted from temporally and geographically extensive spawning of a number of subpopulations in this region (JAMARC, 1980b, 1987). A complex population structure has also been revealed for N. gouldi in the Taranaki Bight region off New Zealand (Sato, 1985).

MIGRATION.—Preliminary tagging studies in Bass Strait and adjacent waters and more comprehensive studies off the west coast of New Zealand (Taranaki Bight) (Sato, 1985) provide no confirmation of large-scale migrations for N. gouldi of the magnitude reported for Todarodes pacificus around Japan (Okutani, 1977). Although some recaptures have been made off the west coast of New Zealand up to 193 km from the tagging site (after 46 days at liberty), recaptured squid had moved in all directions with no relationship between time at liberty and distance traveled. These data were not consistent with a fixed population migration path but supported a complex population structure consisting of many localized schools (Sato, 1985; Yamada and Kattoh, 1987). The few recaptures resulting from tagging in Bass Strait (Machida, 1983) revealed movements of less than 100 km during periods of up to 57 days, suggesting that summer N. gouldi populations in southern Australian waters, like the New Zealand populations, are not highly migratory and have relatively restricted distributions. This view of their population structure is further supported by the presence of all life stages of N. gouldi from small juveniles to mature and spent adults in Bass Strait during the summer months (Dunning et al., 1981).

Length-frequency data obtained from N. gouldi trawled in the eastern Great Australian Bight in late 1981 provided an indication of a general increase in mantle length of squid with increasing bottom depth that may be the result of an offshore movement, either with growth or for spawning, in this species. A similar distribution pattern was observed for N. sloanii off the southeast coast of New Zealand (Mattlin et al., 1985).

SIZE, MATURITY, AND SEX RATIO.—Size at maturity of N. gouldi shows variation with locality and season although the proportion of males to females in jig catches generally showed little difference from unity throughout the distribution range of this species. Catches from Bass Strait showed proportions of 0.94 in 1979–1980 and 0.96 in 1980–1981 (JAMARC, 1980b, 1987), whereas off southern Western Australia in late 1979 this proportion varied from 0.73 to 1.06 (Western Australian Department of Fisheries and Wildlife, pers. comm., 1980). In trawl samples taken in the eastern Great Australian Bight in November and December 1981, this proportion was 0.67 (235:351). In jig catches reported by Sato (1985) from Taranaki Bight and off the northwest coast of the South Island of New Zealand, the male to female proportion varied from 0.35 to 0.56.

In Bass Strait during the summer months, the majority of males of more than 230 mm ML and females of more than 300 mm ML were fully mature (JAMARC, 1980b, 1987). Among specimens collected during this study in the eastern Great Australian Bight in late winter to early spring, males matured at similar sizes to those in Bass Strait in summer, but the majority of females reached maturity at smaller sizes; most specimens of more than 250 mm ML carried eggs in their oviducts. Off the New South Wales coast near 34°S in spring to early summer, most males of more than 170 mm ML were mature, whereas near 37°S similar reproductive development was not evident until at least 190 mm ML. The smallest mature females at these latitudes were 190 mm ML and 220 mm ML, respectively (Gorman and Graham, 1983).

GROWTH.—In the absence of collections obtained throughout the year and given the polymodal mantle-length distributions typical of the major summer fishing ground, the growth rate and the longevity of N. gouldi in Australian waters has not previously been estimated with any confidence (Winstanley et al., 1983). Preliminary growth estimates of up to 4.0 cm/month and 3.0–4.5 cm/month were obtained from length-frequency data for this species jigged in Bass Strait and trawled in the Tasman Bay-Kaikoura region of central New Zealand, respectively (Harrison, 1979; Mattlin et al., 1985).

LARVAE.—Larvae of this species were described and illustrated by Allan (1945) and Nesis (1979a). They are characterized by the absence of photophores and the possession of eight approximately equal-sized suckers on the tip of the proboscis (the precursor to the tentacles). Morphological differences between the larvae of N. gouldi and N. sloanii have not been described (Förch, 1986), but N. gouldi can be separated from N. hawaiiensis on the basis of the two much larger suckers on the extremities of the proboscis tip and the concentrated chromatophore band around the middle of the mantle of the latter species (Harman and Young, 1986).

During summer surveys across the continental shelf and slope off central and northern New South Wales, larvae of N. gouldi were most abundant where bottom depth was between 50 m and 200 m rather than in slope waters (Dunning, 1986). When they had reached 9–10 mm ML, most larvae had completed the transition from rhynchoteuthion to the juvenile stage. Larvae close to the probable hatching size (0.8–1.0 mm ML) identified as this species were collected over a broad area of the southern Australian continental shelf from 28°S off southern Queensland to the western Great Australian Bight from late spring to summer. They were present in plankton samples taken off the central New South Wales coast from at least January to July (austral midsummer to midwinter).