Cisco Sonar

Sculpin

by Bryce Nielson, "The Character"

For eons there has been a sure indication of spring at Bear Lake.  You might think it is the budding of plants, a lack of snowstorms or hard freezes, or maybe the number of boats in the marina.  To me, however, it is the arrival of common loons and mergansers swimming close to shore along off the marina and Cisco Beach.  They are there because of an event going on under the water.  Cottus extensus, commonly known as Bear Lake sculpin, which is endemic, are starting their migration towards the rocks.

Few locals, other than fishermen, even know they exist because they are rarely seen.  The species Cottus is highly evolved.  Sculpin average two to three inches but I have seen them up to six inches in length.  They don’t have scales but more of a prickly skin.  Sculpin have a large head, fan like pectorals, stiff pelvic fins to keep them from laying on the substrate and tapered body with no swim bladder.  This means they cannot suspend themselves in the water column and are destined to a life on the bottom, only swimming in short bursts.  They are like chameleons and can change their color to match the material they are on.  The color that never changes is their “Bear Lake Blue” eyes prominent on top of their head.  They feed on all types of worms, insect larvae, minute clams and other detritus on the bottom.  They appear to be evenly distributed throughout the lake at all depths.

In late March and early April they begin their annual migration to the few rocky areas around the lake including the east shore, Gus’s Point, and marinas.  These little fish travel miles over sand, mud and marl to get to the rocks.  No research has been done to determine whether they return to where they were hatched (more research I didn’t have time to do before I retired).  During this journey they are exposed to predators, both fish and birds along the way and especially the loons and mergansers hanging around the rocks.  Once there, the males immediately start staking out large flat rocks and wait for ripe females.  The larger the rock, the larger the male.  Females swim under the rock, invert, and attach about 400 eggs while the male fertilizes them.  Then she packs it up and leaves.  Sculpins are “guarders”, which means the males take care of their eggs, fanning them to keep the slit off and scaring away other egg eaters.  Although I never had time to research it, through cursory observations, I believe the egg masses hatch in association with spring storm wave action.  The larval fry float while absorbing their yolk sacs and developing mouth parts. The wind and currents distribute the larval fish across the lake and when their yolk sacs are absorbed they sink to the bottom.  They frequently get inside shells like hermit crabs, to avoid predation and the cycle starts over.