Coastal cod and north-east-Arctic cod - do they mingle at the spawning grounds in Lofoten?

Cod (Gadus morhua L.) off northern Norway are divided into two main g roups. The north-east Arctic cod (NAC) migrate southwards from the B arents Se to the main spawning area near the Lofoten Islands on the c oast off northern Norway. Coastal cod (CC) are relatively stationary, live and spawn along the entire Norwegian coast, including near the Lofoten Islands. In order to test if the two groups physically inter mingle at the spawning grounds, cod were sampled by trawl and Danish seine at the traditionally important spawning grounds near the Lofote n Islands during the spawning season in 1995-97. Cod from 24 samples were examined for haemoglobin alleles, length, sex, and stage of sex ual maturity.The results indicate that: (1) NAC and CC did not mingle randomly. (2) However, speciemens from both groups may stay simultan eously at the same local spawning ground within an area of less than 0.012 km2. (3) Distribution of NAC and CC overlapped vertically, alth ough NAC was more abundant than CC in samples from deep waters. (4) T he sex ration was skewed towards males in a majority of the samples. (5) A larger percentage of males compared to females was ready to spa wn. (6) Cod shoals may be s