Cisco Sonar

Sculpin
By Bryce Neilson, The Cisco Sonar

Bear Lake is once again covering the rocks along the shore with water. This will provide much needed spawning habitat for one of the endemic species.

The Bear Lake sculpin (Cottus extensis) during most of the year are scattered throughout the lake on the bottom feeding on midge larvae, nematodes, stray eggs or anything else they can consume.  In early April, they begin to migrate towards shore.  They are poor swimmers and only move in short bursts.  They are the most highly evolved fish in the lake and most of their cousins are marine (ocean) species.  They do not have scales but have a large well developed head and pectoral (front) fins.  They are characterized by opercle (cheek) spines and brilliant blue eyes, the same color as Bear Lake.  The adults average three to four inches but rarely exceed six inches.

They also have another unique characteristic.  They are the chameleons of the lake.  Depending on what color the lake bottom is from white to dark, they will change color to blend in with it.  If it is all one color they will mimic it. If there are gravels, they will be splotchy.  This adaptive characteristic allows them to hide in depressions suckers make when they are feeding.

During spawning, they swim across the lake to find rocks to attach egg masses to.  The males stake out their territory under flat rocks and entice the females with the best spawning habitat.  Typically, the larger the male, the bigger the rock.  As the two fish invert, the female deposits a sticky patch of about 400 eggs on the bottom of the rock and the male fertilizes them.  The female then swims off leaving the male to protect the egg mass until they hatch.  He fans the eggs with his pectoral fins to keep the silt off and oxygenate them while protecting them from crayfish and other egg predators.

Our observations would indicate that the hatching of the eggs is keyed to agitation. The spawning areas(rock covered bottoms) are limited to the east and western shores. When the spring storms arrive, the crashing waves trigger hatch.  The larval fish are dispersed in the epilimnion (upper water column) and are spread throughout the lake.  After they absorb their yolk sack and need to feed they drop to the bottom and being their existence.  This evolutionary trait scatters out the newly hatched fish over a wide area and not just in the nursery area where competition for resources would be limited.   The adult sculpin then go back to their solitary ways in the depths.