The smelts are small salmons in all essential respects, except that their stomach has few pyloric caecae, or none, whereas there are large numbers of such caecae in their larger relatives of the salmon family. However, it is not necessary to look so deeply to learn whether a fish be smelt or very young salmon, for the former all have pointed noses and are very slender, whereas the young of our four salt-water salmons—humpback, silver Atlantic, and sea trout—are much stouter, with blunt noses. In most cases, too, the shape of the tail would suffice of itself to separate smelt from salmon smolt, for it is never as deeply forked in the latter as in the smelts.
Two smelt fishes occur in the Gulf of Maine: the smelt (very common), and the capelin (a sporadic visitor from the north). The argentine (p. 139) is so closely related to the smelts that it is included in the following key.
|KEY TO GULF OF MAINE SMELTS AND ARGENTINES|
|1.||The dorsal fin originates over the tips of the pectorals; the mouth is very small||—||Argentine, p. 139|
|The dorsal fin situated far behind the pectorals; the mouth is large||2|
|2.||Upper jaw almost as long as lower; teeth large; there is a group of strong fangs on the tongue; the pectoral fins have 12 rays or fewer||—||Smelt, p. 135|
|Lower jaw much longer than upper; teeth so small as hardly to be visible; no fangs on tongue; the pectoral fins have 15 to 20 rays||—||Capelin, p. 134|