Description: An RMT 25 opening/closing net was used to sample the nekton comunity at 2 stations in the ice free zone (IFZ) of the Scotia Sea (Stn 1 approximately 10 nautical miles south of the Antarctic Polar Front, Stn 2 on the edge of the South Georgia Shelf Break to the northwest of the island) Oblique hauls sampled 200 m depth layers to 1000 m during both day and night. Total and individual volumes of each species in each 200 m layer were measured by displacement The data were used to generate biomass and numerical spectra for day and night at each station for the whole water column to 1000 m. At both stations the relationship between log10 biomass density (B/A) and log10 individual body mass (M) were strongly positive. Slopes of the biomass spectra were not significantly different among the day and night stations and an overall regression showed that biomass density scaled as M061. Analysis of biomass spectra revealed that although the species composition and biomass density vaned between the 2 stations, energy turnover in the nekton community in the 2 areas was similarly dominated by animals of larger size. Considering energy turnover in terms of taxonomic groups revealed that Stn 1 turnover was dominated by tunicates (salps) followed by fish and cnidarians and at Stn 2 turnover was dominated by crustaceans followed similarly by fish and cnidarians. Use of biomass spectra in this case study was shown to enhance insight into the comparative function of 2 pelaglc systems obtained using a conventional taxonomc approach The analysis of biomass spectra in the absence of taxonomic data would have had limited value as it would not have emphasised the major difference between the 2 stations: the domination by tunicates, an energetic dead end, at Stn 1 and crustaceans, which are available to predators, at Stn 2.

Description: In the Antarctic there are large unexploited stocks of cephalopods with high potential commercial value and there are two important fisheries for squid in the cool temperate waters of the Southern Ocean, adjacent to the Antarctic, in the Atlantic and Pacific sectors. Squid fisheries can develop very rapidly, and if this were to happen in the Antarctic before adequate management plans could be established, there would be serious consequences for the squid stocks, and also for the vertebrate predator populations which depend on them. It is especially important to increase our knowledge of the Antarctic cephalopod species, their distribution and role in the food chain, and to understand their life cycles

Description: The "Discovery" collections contain 51 specimens ot Alluroteuthis antarct,cus from the Southern Ocean 0'"-30°E, S of the Antarctic Polar Front. Of these, 45 specimens were caught during "Discovery" Cruise 100 with the open1ng-clos1ng "RMT 8" net. Capture rate of the species was highest in the 800-900 m depth layer. At night. Alluroteuthis appears to spread vertically and there is evidence of ontogenetic descent. When vertical distribution of A. antarcticus is plotted as a tunclion of mantle length and compared with the distribution of the cranchi1d Galiteuthis glac,alis apparently there is spacial separation between the two species in the water column. The degree of ecological separation cannot be determined in the absence of information on the trophic ecology of these squids.

Description: Juvenile cuttlefish Sepia offcinalis were hatched and reared in the laboratory at six ration levels and two temperatures. At 12.5 °C there was little growth whereas at 17.5 °C growth rate responded strongly to ration level. Nucleic acids were extracted into buffer containing 0.01% SDS and assayed by fluorescence using ethidium bromide and bis-benzimide and by absorbance at 260 nm. The sensitivity of nucleic acid assay using ethidium bromide was increased by shortening the excitation wavelength to 305 nm. RNA:DNA ratio was strongly correlated with growth rate in cuttlefish held at 17.5 °C; at 12.5 °C, the relationship was similar but not statistically significant. At low growth rates, RNA:DNA ratios were similar to those reported for larval fish; nucleic acid ratios at higher growth rates were higher than reported so far. This may be related to the very high growth rates achieved by many cephalopods.

Description: A scientific research fishing expedition targeting the oceanic/slope ommastrephid squid Martialia hyadesi was undertaken by a Korean-registered squid jigger in CCAMLR area 48.3, near South Georgia, in June 1996, providing the first opportunity to collect data on the fishery biology of this species during the austral winter. Fishing took place over a period of 8 days; a series of eight drifts was undertaken along an approximately east/west transect of about 200 nautical miles to the north and west of South Georgia, over depths ranging from 1,700 to 2,713 m. All fishing was to the south of the Antarctic Polar Front. Data were collected on sea surface temperature, catch per unit of effort, size, sex, maturity status and stomach contents of the catch and a sample of squid was aged by counting putative, daily microgrowth increments in the sectioned statolith. All squid were caught by jigs operating at depths from 80 to 100 m to the surface. Catch per unit of effort per drift varied between 1.0 and 21.9 kg min−1 and there was no by-catch. Greatest numbers of squid were caught at dusk and dawn. Mantle length fell in the range 220–350 mm (males) and 212–370 mm (females). Most males were sexually mature (Lipinski's stages IV–V) and most females were immature (stage II). The absence of mature females suggests that no spawning takes place in this area during the austral winter. The squid were up to 1␣year of age and had hatched during the previous winter. They were apparently from the same cohort as had been sampled at the Antarctic Polar Front in February 1996. Myctophids were the major prey in the stomach contents and the squid Gonatus antarcticus was also important; crustaceans were relatively unimportant. The results suggest that concentrations of Martialia hyadesi are present in the vicinity of South Georgia, south of the Antarctic Polar Front, during the austral winter. The squid are actively feeding during the austral winter and are susceptible to jigging gear.

Description: The seven star flying squid, Martialia hyadesi, is a Southern Ocean ommastrephid with an oceanic distribution that extends to the edge of the shelves and slopes of continents and islands. Its range is circumpolar and it is generally associated with the Antarctic Polar Frontal Zone. It has been caught in commercial quantities in the Atlantic sector but is only recorded in smaller numbers from the Indian Ocean and Pacific sectors in scientific samples, the gut contents of predators and in mass strandings on island shores. It has only occasionally been found in commercial catches outside the Atlantic sector. In the northern part of its range in the South Atlantic, commercial catches are highly variable and apparently linked to large-scale oceanographic variability. Martialia hyadesi appears to concentrate in frontal areas where characteristics of the bathymetry generate meso-scale oceanographic features. Such concentrations have been observed at shelf breaks and in the deep ocean near a submarine ridge. Predator data confirm the circumpolar distribution of the species and its relationship with the APFZ. Grey-headed albatrosses appear to forage for M. hyadesi in the region of meso-scale oceanographic features associated with the bathymetry of submarine ridges and the shelves of oceanic islands. In the medium future, improved understanding of oceanographic variability of the Southern Ocean may provide the basis for long term forcecasting in a fishery for the species. In the nearer future, improved knowledge of the behaviour of the species in relation to meso-scale oceanography may provide the basis for short-term forecasting of the location of shoals based on remotely sensed images of surface oceanography. The life cycle of M. hyadesi is poorly understood and, in view of increased commercial interest in the species in recent years, and its conservation value in the CCAMLR area, there is a need for more information on the location of spawning and feeding grounds and seasonal migrations.

Description: Mastigophora brevipinnis Owen, 1856, is a ‘fossil teuthid’ presently considered to be a member of the coleoid cephalopod Suborder Loligosepiina Jeletzky, which in turn has been placed by various authors in or near the Vampyromorpha Grimpe. Recent morphological and biochemical analyses indicate that vampyromorphs are more closely related to the Octopoda than to the Decapodiformes. Fossils of Mastigophora from the Oxford Clay (Jurassic: Callovian) show soft-tissue preservation and evidence of arm crown specialization. Some of these fossils have up to eight short, thick arms with circular sucker-like structures and filiform distal extensions, plus what appear to be the bases of two thinner ventrolateral arms. The latter lack proximal suckers and curve medially to insert into the arm crown, similar to the tentacles that are the modified ventrolateral arms of living squids and cuttlefishes. This suggests that the thinner structures were decapod-like tentacles. If Mastigophora had tentacles homologous with those of modern decapods, then it was a decapod, because this synapomorphy defines the Decapodiformes. This indication of decapod affinities for Mastigophora brings into question the relationships of the other ‘fossil teuthids’. The inferred relationship of the Loligosepiina, including Mastigophora, with the Vampyromorpha, based largely on similarities of gladius morphology with that of living Vampyroteuthis, may reflect shared plesiomorphic characters.

Description: Some 290 species of squids comprise the order Teuthida that belongs to the molluscan Class Cephalopoda. Of these, about 30-40 squid species have substantial commercial importance around the world. Squid fisheries make a rather small contribution to world landings from capture fisheries relative to that of fish, but the proportion has increased steadily over the last decade, with some signs of recent leveling off. The present overview describes all substantial squid fisheries around the globe. The main ecological and biological features of exploited stocks, and key aspects of fisheries management are presented for each commercial species of squid worldwide. The history and fishing methods used in squid fisheries are also described. Special attention has been paid to interactions between squid fisheries and marine ecosystems including the effects of fishing gear, the role of squid in ecosystem change induced by overfishing on groundfish, and ecosystem-based fishery management.

Description: The nekton community was sampled by a Rectangular Midwater Trawl (RMT 25) over the upper 1000 m of the Scotia Sea dunng January 1991. A total of 81 nekton and micronekton species were collected from 2 sites, one in the oceanlc western Scotia Sea (Stn 1) and the other on the northwestern slope of the South Georgia shelf (Stn 2). Species composition, abundance, biomass and day/night vertical distribution were investigated. Crustaceans were the most important group in terms of species numbers (28 species) followed by mesopelagic fish (24), molluscs (15) and coelenterates (11). Species diversity increased with depth and was higher at Stn 2 (76 species) than at Stn 1 (62 specles). Biomass in the upper 1000 m was considerably higher at Stn 1 (94.6 g wet wt m-2 during daytime, 87 g wet wt m-2 during night) than at Stn 2 (10.2 and 23.7 g wet wt m-2, respectively), mostly due to dense concentrations of the tunicate Salpa thompsoni (41.6 g wet wt m-2 during night). The other main contributors to the high biomass at Stn 1 were coelenterates (28.3 g wet wt m-2 during night) and mesopelagic fish (4.9 g wet wt m-2 during night). Euphausiids (Euphausia triacantha and E. superba) accounted for 1.5 g wet wt m-2 at Stn 2 during night, with E. triacantha the more important of the two (1.4 g wet wt m-2). Except for Bathylagus antarcticus all common mesopelagic fishes showed a marked diurnal vertical migration (i.e. Electrona antarctica, Gymnoscopelus brauen, Krefftichthys anderssoni, Protomyctophum bolini). During daylight they stayed in the core of the Circumpolar Deep Water (CDW, 400 to 800 m) and at night they were mainly distnbuted in the Antarctic Surface Water (ASW, 0 to 400 m). Other species with pronounced vertical migration were the hydromedusa Calycopsis borchgrevinki, the squid Brachioteuthis ?picta, and the euphausiid Euphausia triacantha. The scyphomedusae Atolla wyvillei and Periphylla periphylla and the crustaceans Cyphocaris richardi, Gigantocypris mulleri and Pasiphaea scotiae did not appear to migrate and remained concentrated in the CDW. Spatial variability was analysed by multivariate data analyses (clustering techniques) and related to hydrography. Four main groups, characterised by different nekton communities, were derived: (1) a lower mesopelagic nekton community from the deeper layers of the CDW, apparent at both stations, (2) an upper mesopelagic nekton community from the core of the CDW, apparent at both stations, (3) an epipelagic nekton community from the ASW over the South Georgia slope (Stn 2) and finally (4) an epipelagic nekton community from the ASW of the oceanic Scotia Sea (Stn 1). The performance of the midwater trawl is discussed as it has a substantial impact on the catchability of the nekton. The presented data provide new information on the structure and spatial variability of Antarchc nekton communities and emphasise the geographical and vertical discontinuities between communities.

Description: In the Atlantic sector of the Southern Ocean, data from vertebrate predators and commercial fisheries suggests that the distribution of the ommast rephid squid Martialia hyadesi is related to the Antarctic Polar Frontal Zone, but it spreads further to the north in some years (Rodhouse, in press). A mass stranding of M. hyadesi occurred on Macquarie Island in 1971 (O'Sullivan et al. 1983) suggesting that its distribution is c ircumpolar (Rodhouse and Yeatman 1990). However, apart from a single beak collected from the s tomach of a wandering albatross at Mar ion Island (Imber and Berruti 1981) its presence has not, until now, been confirmed in the Indian Ocean sector and in particular it is not included in the list of cephalopods from the Kerguelenian Province (Lu and Mangold 1978). M. hyadesi is a major prey item of the grey-headed albatross, Diomedea chrysostoma, and the southern elephant seal, Mirounoa leonina, at South Georgia (Rodhouse et al. 1990; Rodhouse et al., unpublished data) and is present in the diet o f several other predators in the Scotia Sea area including the wandering albatross, Diomedea exulans (Rodhouse et al. 1987) and the giant petrels, Macronectes halli and M. gioanteus (Hunter 1983). It occasionally occurs as a significant by-catch in the lllex argentinus fishery on the Pa tagonian Shelf and has been taken during commercial squid jigging trials in the Scotia Sea at the Antarctic Polar Frontal Zone (Rodhouse, in press). It appears to have potential for commercial exploitation in the sub-Antarctic waters of the Atlantic sector of the Southern Ocean (Rodhouse 1990). In view of the ecological importance of M. hyadesi to Antarctic predators, and the likelihood that it will be commercially exploited in the future, it is important to thoroughly establish its geographical range, and in particular to confirm its circumpolar distribution.