An Analysis of Some Meristic Characters of the Staghorn Sculpin Leptocottus armatus Girard

Over a 4-year period, juvenile specimens of Leptocottus armatus were collected annually at nine stations along the Pacific coast from approximately 37 to 47° N latitude. Collecting was repeated at intervals at two stations (43°24' N and 44°36' N) during the seasons in which young fish were arriving from the plankton. Meristic character counts are similar over the northern part of the range studied, but there is a well-defined cline in conditions south of 43° N. The number of spines on the dorsal fin appears to be influenced very little by natural developmental conditions, if at all. At the two stations sampled at approximately monthly intervals, well-defined seasonal trends in meristic character counts appear to be related to thermal history. Freedom of independent expression of meristic characters in response to the natural developmental environment is restricted by timing of phenocritical periods and a factor of a more fundamental nature, presumably genetic