Haddock otolith lengths decline from over 5% of the total length of the fish at 14 to 17 cm. to almost 3% at 74 to 77 cm. The otolith lengths of slow-growing haddock decline less rapidly than those of fast-growing haddock. Little difference was found between otolith lengths in male and female haddock of the same length.Slow-growing haddock both from the Grand Bank and from St. Pierre Bank have heavier otoliths than fast-growing haddock at the same fish lengths. This is true not only for fish of different year-classes in the same year but also for fish of the same year-class in different years.The otoliths of male haddock of the Grand Bank exceed progressively in weight the otoliths of females of the same length after the males become sexually mature. The relative increase in otolith weight of the male fish is attributed to a probably slower growth rate after sexual maturity, which occurs earlier than in females. Similarly, the heavier otoliths of mature fish in sizes overlapping with immature fish are due to a greater age of the mature fish at these sizes. Otolith weight relative to fish weight decreased considerably with increase in fish size, and no distinct differences were apparent between otolith weights as a percentage of fish weights in slow-growing and fast-growing fish of the same length.

Data from incidental trawl catches of squid by the research vessel, Investigator II, showed that distribution of Illex in the Newfoundland area was marked by a seasonal migration over the Grand Banks in early May, and northward and westward as far as Hamilton Inlet, Labrador, and inshore Newfoundland by August. Earliest occurrence inshore was in late June, earlier in recent years than heretofore. Comparative numbers taken on the Grand Bank in May and June in different years appear to indicate the abundance to arrive inshore later in each year. Annual abundance inshore varies, but years of scarcity do not appear to be cyclical nor need they indicate year-class failure. A correlation between abundance inshore and weather conditions may exist. Measurements during the inshore migration showed a regular and large increment of length and weight monthly until October. Female squid reached a greater size than males in the late season but weighed less than males at the same mantle length. Fin length was 35 to 40% of mantle length in Illex, compared with 53 to 63% in Loligo pealii. Many males taken in the late season had reached sexual maturity, but only two females captured on the Grand Bank in May, 1953, had reached equivalent maturity: these females had greatly enlarged nidamental glands.Small squid taken offshore in 1946 to 1952 had been feeding mostly on euphausids, but larger squid taken inshore had been feeding mostly on fish. In females 44% of the stomachs were empty, and in males, 50%.Parasites found were tapeworm plerocercoids of Phyllobothrium sp. and Dinobothrium (sensu lato) sp., and occasionally a small larval nematode.

A sample of about 1000 snow crabs (Chionoecetes opilio) from NAFO (Northwest Atlantic Fisheries Organization) Division 3K (Northeast Newfoundland Shelf), taken by bottom trawl for studies of their stomach contents, indicated that about 12 benthic or demersal prey types occurred in their diet from that area. The most frequently occurring prey types were sabellid polychaetes, crustaceans (shrimp, crabs and smaller crustaceans) and infaunal clams (Macoma calcarea). Shrimps (especially pink shrimp, Pandalus borealis) and fishes (especially capelin, Mallotus villosus) were the most important prey types with respect to their percentage contribution to the total food mass. Brittle stars (Ophiuroidea) were regularly preyed upon by males but were virtually absent from the stomach contents of mature females. Males preyed more heavily upon fish and infaunal prey types (polychaetes and clams) whereas females preyed more heavily on shrimp and readily-accessible epibenthic prey types (gastropods, crabs and sea urchins). Males appeared to be more capable predators than were mature females. Predation on fish was related to predator size for both sexes but was most commonly practiced by males that were larger than the maximum size of mature females. However predation on fish was also more commonly practiced by males than by mature females at comparable sizes. There were no other effects of predator size in the predation by males whereas predation by mature females on clams, shrimp, gastropods, sea urchins, and possibly polychaetes increased with predator size. Cannibalism was most frequently practiced by intermediate-sized crabs and more frequently by females than males. Cannibalism was more common in our study than in others reported to date and may represent an important densitydependent source of mortality that could affect recruitment levels and patterns.

Inspection of the fillets of cod and other fish species for nematodes was carried out mainly in the years 1947 to 1953. Fillets were examined on a candling table. Two varieties of nematodes were found: one, 94% in cod and 86% of the total in American plaice, witch flounder, haddock and redfish, was Porrocaecum, ranging between 15–16 and 57–58 mm. in length; the other, 6% in cod and 14% of the total for the other 4 fish species mentioned above, did not possess a caecum and had a longer pharynx than Porrocaecum relative to the total length and to the ventriculus length. The latter nematode was 17–18 to 33–34 mm. in length and resembled Anisakis but may possibly have been Eustoma.The infection level per 100 lb. (45 kg.) of cod fillets was lowest, 1 to 6 nematodes in ascending order, on Flemish Cap, the Grand Bank, the east coast of Newfoundland, off Labrador and southern St. Pierre Bank. It was highest, 223 nematodes, in the southern part of the Gulf of St. Lawrence. Intermediate values, 10 to 65 nematodes, were present in other areas. The nematode infection level in the larger American plaice was similar to that in cod, and infection per 100 lb. of fillets was especially heavy at the smaller sizes of plaice. Witch flounder, redfish and haddock showed low infection levels. Smelts living in the immediate neighbourhood of seal colonies were sometimes highly infected in terms of nematodes per 100 lb. of fillets. Nematodes were found in the fillets of the angler, Greenland cod, Greenland halibut, pollock, yellowtail flounder, longhorn sculpin and tomcod. It was concluded that the site of original infection of the fish was close to the site of deposition of nematode eggs by the seal host, and that the first intermediate hosts, invertebrates or small fish, were not very migratory.In the fillet, nematodes were most numerous in the thicker parts dorsal and posterior to the body cavity and less numerous in the thinner tail portion. The distribution fits the idea that nematodes emerging from the stomach of the fish enter the neighbouring body muscles.Of the seals which are the final hosts for Porrocaecum, harbour seals are common in Newfoundland areas where nematode infection of cod is high, as on the west coast of the island, but they are also especially numerous in southern Labrador where nematode infection of cod is low. The usual intermediate invertebrate or fish hosts may be scarce or lacking in Labrador and on the northeast coast of Newfoundland.It is concluded that the larger, browner, and more numerous Porrocaecum presents the problem of commercial importance, rather than the smaller, whiter Anisakis. The only practical biological attack in view at the moment is the reduction in numbers of harbour and grey seals, in the hope that the more numerous harp seal is not so important a final host as it at first sight appears to be in the Gulf of St. Lawrence. In many areas where harp seals are not present, or, where present, do not carry Porrocaecum, the harbour and grey seals appear to be the only final hosts of Porrocaecum. St. Mary's Bay, Newfoundland has many advantages as a site for a practical long-term experiment on reduction of nematode levels in cod flesh.

Length measurements of a migrant ommastrephid squid Illex illecebrosus illecebrosus (Le-Sueur), in Newfoundland east coast waters indicated that only one modal class was present except in November of some years. Average lengths and weights of random samples taken monthly from May to November indicated also that growth was very rapid during this period. The majority of the population, averaging 140 mm in mantle length (54 g whole weight) in both sexes in May, reached maximum mantle lengths of 260 mm in males and 300 mm in females by October (weights of 360 and 550 g in males and females respectively). By fitting growth curves to these data, and by observations on sexual maturity, the approximate times of birth and mortality were extrapolated. Spawning and probable subsequent mortality of this squid was estimated to be at not more than 2 years and most probably at only 1 year of age.