Feeding Habits and Density Patterns of Greenland Cod, Gadus ogac (Richardson 1836), at West Greenland Compared to Those of the Coexisting Cod, Gadus morhua L.

J. R. Nielsen and M. Andersen. 2001. Feeding Habits and Density Patterns of Greenland Cod, Gadus ogac (Richardson 1836), at West Greenland Compared to Those of the Coexisting Cod, Gadus morhua L. J. Northw. Atl. Fish. Sci. 29: 1-22. https://doi.org/10.2960/J.v29.a1

The diet of Greenland cod (Gadus ogac) was found to be very similar to that of the coexisting Atlantic cod (Gadus morhua) based on stomach analyses of length groups larger than 30 cm sampled by longline in West Greenland waters. Estimation of relative frequency and relative weight of each food group in relation to predator length as well as mean partial stomach fullness index (PFI) and mean total fullness index (TFI) were performed. Mean TFI was found to be higher in the inshore areas compared to that of the coastal areas for both species. However, greatest variation in TFI was also observed in the inshore areas for both species. Gadus ogac feed on a broad variety of prey species, although fish (especially capelin, Mallotus villosus) and larger invertebrate prey groups (especially larger Malacostraca) were found to be the main diet in the autumn period. The importance of fish in the diet increased with length, in particular fish species other than capelin. Among the invertebrates the shrimps and crabs (large Malacostraca) were the most important food groups. Shrimps were most important prey for small predators ( <50 cm) of both species. However, while fish became dominant prey for larger G. ogac , large Crustacea (crabs, Brachyura) were primary food for larger G. morhua. In general, small (planktonic) Crustacea were not important in the diet of any of the settled size groups investigated of both species. The stomach content analyses of the two species were made in combination with comparative studies of their occurrence at West Greenland to investigate the degree of coexistence and overlap in distribution, in order to get an impression of potential interspecific competition for food and space or of interspecific predation. Comparative ANOVA analyses of G. ogac and G. morhua density patterns based on catch rate data from the same longline research fishery (1987-89), showed statistically significant coexistence and overlap in their distribution. Both species occurred with highest densities in the central part of West Greenland, and with highest overlap in occurrence in coastal and shallow waters. The broad overlap in distribution and diet in the autumn in West Greenland waters indicate the potential for interspecific competition for food and space.

PDF

Language - English
Publisher - Northwest Atlantic Fisheries Oragnization (NAFO), Dartmouth, N.S., Canada
Publication Date - 2001
Publication Type - Journal Article

Download Citation Data

 

Citation to clipboard

Reference management software (Endnote, Mendeley, RefWords, Zotero & most other reference management software)

LaTex, BibDesk & other specific software