Cisco Sonar
Whitefish of Bear Lake
A little background on this
unique family of fish, Coregonus, “whitefish” is probably needed. There are many species of whitefish and
cisco. They are primarily found in the
northern latitudes including Alaska, Canada, Great Lakes, Scandinavia, Russia
and from the Arctic Ocean south to Bear Lake, the furthest south and highest
elevation of any population.
If you grew up in the western
U.S. and fished cold, clear streams in the mountains you may have heard of whitefish
or maybe you called them “herring”. They
had a tiny mouth and were hard to catch, except during spawning. If you did accidentally catch one on a fly,
you may have thrown it back in disgust because they had scales larger than
trout and they were “bony”. What you
were catching were mountain whitefish, a stream dwelling form that feed on
small, aquatic insects.
Three endemic species are found
in Bear Lake. The Bonneville cisco,
Bonneville whitefish and Bear Lake whitefish.
They all evolved from a common ancestor that probably rode the ice
sheets down during the ice ages and established in Bear Lake. After thousands
of years of isolation, three distinct species have evolved.
The Bonneville whitefish is the
largest of the three species. It feeds on bottom for invertebrates, oligochaetes
and Bear Lake sculpin. They begin spawning around the early part of December
and are being caught by fishermen now. They
are distributed throughout the lake near the bottom in the cold water. They are
popular sport fish that are harvested during spawning and when they are feeding
on cisco eggs during the winter through the ice.
The Bonneville cisco is a pelagic,
open water, schooling fish that feeds on small zooplankton. They usually spawn
the last half of January off the east shore of the lake but can be found in
various habitats lake wide. They can also be harvested with jigging off the
rock pile as they congregate out there to spawn. Dip netting has been the most
popular method to catch cisco, but it has been difficult in last few years due
to various factors. There is a lot of speculation but no answers for sure.
The Bear Lake whitefish is a dwarf form rarely getting over
10 inches long. They spend most of their time in water over 100 feet deep and
feed on ostracods, small crustaceans about the size of a grain rice. They move into shallower water, although it's
very cold, to spawn in February where they attach their eggs to rocks. They are rarely caught by anglers.
The fate of the millions of whitefish eggs spawned is
basically an unknown in Bear Lake. In other lakes they sink to the bottom substrate
where they spend up to 100 days before they hatch due to the cold water. During this time, they are eaten by all types
of fish, invertebrates, crustaceans and covered in silt. The few surviving
larval fish may be picked up by lake currents and distributed throughout the
lake. Probably less than 1% ever survive
to adulthood after this first year of life.
I wish I knew more about what happened to them because we never see any
small fish so where they go, how fast grow and many other factors are still a mystery.
Bonneville Cisco
