Also, if an Iceland Gull is 55cm long then these fish seem to be 1-1.5m long, too big for the average atlantic salmon.
Wikipedia says this about cod:
"Atlantic cod are a shoaling species and move in large, size-structured aggregations. Larger fish act as scouts and lead the shoal's...
In Tasermiut Fjord, southern Greenland a couple of weeks ago I kept seeing these groups of dark shapes swimming up the fjord followed by gulls. I presume they must be salmon heading to a river to spawn. But why do the gulls follow them?
Very poor photo attached.