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The feeding ecology of Greenland halibut (Reinhardtius hippoglossoides) on the deep slope of the northeast Newfoundland continental shelf was investigated based on stomach analysis. Stomach samples were collected from the spring 1992 Canadian bottom trawl fishery at depths of 1000–1250 m. The squid, Gonatus spp., predominated in the diet, representing the first known instance of reliance of Greenland halibut upon this bathypelagic squid as prey in Canadian waters. A change from predation primarily upon pelagic prey, reported in earlier studies, may be related to annual variability in abundance and distribution of both Greenland halibut and its principal pelagic fish prey species, capelin (Mallotus villosus). Seasonal effects may account for the absence of epipelagic, juvenile Gonatus spp. from the diet. There was a linear size relationship in observed predation which may reflect a common size-related depth distribution pattern between predator and prey or, more likely, prey selectivity. At larger sizes, Greenland halibut switched from Gonatus spp. to groundfish as its principal prey. The importance of Gonatus spp. in the deep continental slope trophic web is reviewed.

We describe size at age, growth, and population structure of short-finned squid (Illex illecebrosus) from Newfoundland waters during 1990. Ages were estimated from statolith increment counts and used to back-calculate hatching dates. Hatching ranged between December and June with the hatching months of March to May predominating. Constant interchange of individuals in the inshore population was evident in that the modal month of hatching progressed from March within the earliest (July) sample to May within the latest (November) sample. Within the mantle length range available, growth was adequately expressed by a linear model. Females grew faster than males, and during the March to May months of hatching, length at age and growth rate increased with hatching month. This positive effect of late time of hatching was also seen in growth in mass and in gonad development and sexual maturation.

The potential use of growth increments deposited on the gladius of the short-finned squid (Illex illecebrosus) for age determination and growth studies was investigated. The gladius lies along the dorsal midline of the mantle and grows from the fins towards the head by the addition of layers of chitin. Growth increments were observed on the dorsal surface of the gladius and could be consistently enumerated. The frequency of deposition approximated statolith incremental deposition rates and the daily nature of gladius growth increments during the adult phase was supported. Total age could not be obtained by gladius growth increment counts on the dorsal surface because, as the gladius grows, the posterior zone becomes progressively vague and the early growth increments are masked. However, gladius increments were highly correlated with mantle growth and provided accurate estimates of size-specific growth. Both group and individual growth trajectories were reconstructed. The latter seemed to be sensitive to feeding events, temperature fluctuations, and maturation processes in captive squids. The potential for reconstruction of individual growth histories and for the study of growth patterns in wild populations is discussed.

A major extension of the geographic range of Loligo pealei, in quantitative as well as spatial aspects, is described. The species' range is extended northward and eastward to approximately 47°30′N: 53°06′W, based on its occurrence in Newfoundland inshore trap samples in the autumn of 1986. Biological data from these samples, as well as from collections from Nova Scotian inshore traps from 1974 to 1986, indicate that L. pealei becomes sexually mature and spawns in Nova Scotian waters but not at Newfoundland. Loligo pealei appears to be prevalent in Canadian waters at times when its sympatric competitor, the short-finned squid Illex illecehrosus, is not abundant. The reported catch of L. pealei in Atlantic Canada for 1986 was 67 t, which suggests that this species could possibly support a small Canadian fishery in some years.

During a plankton survey along the edge of the continental shelf south of New Jersey in February 1969. Illex sp. larvae were caught in the vicinity of the Florida Current between Cape Hatteras and central Florida (28°30'N 80° 00'W). The larva from the latter area represents the most southwesterly capture that has been reported to date. Illex sp. larvae were also caught during surveys in February-March of 1981 and 1982 south of Newfoundland in the northern partof the Gulf Stream, the most easterly capture being at 40°09'N 53°00'W and northerly capture at 41°00'N 56°00'W. The larvae taken off Florida were 1.1-6.2 mm mantle length (ML) and those from the region south of Newfoundland were 2.4-6.6 mm. From the observed distribution and sizes of larvae in relation to water masses associated with the Gulf Stream System and in the light of recent observations on Illex illecebrosus spawning in captivity and temperatures required for embryonic development, it is considered that spawning probably occurs pelagically a in the winter months within the Gulf Stream or in the Gulf Stream-Slope Water frontal zone south of Cape Hatteras.