Fish Sense

Channel Catfish Brood Stock, Courtesy US FWS

Hi, I’m Holly Strand from Stokes Nature Center in beautiful Logan Canyon.

Have you ever wondered about how a fish perceives its environment? Well I never did. But then I was approached by Dr. Phaedra Budy an expert on fish ecology at the College of Natural Resources at Utah State University. She sent me some posters on the subject prepared by her fish diversity class.

Now I’d like to share with you some interesting facts that I learned from Phaedra and her students,
First of all, fish smell. I mean they have a sense of smell. But instead of a nose, fish have olfactory receptors located in pits on top of their heads. Water flows through these olfactory pit via cilia movement, muscular movement, swimming, or a combination of these. Odors in the flowing water are detected by receptors called olfactory rosettes. Fish use their sense of smell to distinguish other fish, communicate danger or find food. Some even use smell to find their way home. For instance, salmon species smell their way back to the stream where they were born in order to spawn.

Fish use taste buds to identify useful food vs. noxious substances. Interestingly, their taste buds don’t have to be located in the mouth. They can be located anywhere on skin, fins and barbels. Barbels are the fish equivalent of whiskers .

Imagine tasting a chocolate sundae with your whole body. If you were a catfish, you could. That’s because catfish have taste buds from head to tail. A six-inch catfish has over a million taste buds covering its whole body. Perhaps catfish are so dependent on their ability to taste because their murky environment makes it difficult to use their sight. Even a blind catfish will almost always be able to find food using its sense of taste.

The lateral line is a special sensory system found only in fishes. It runs along the length of the fish’s body and allows it to sense water displacement caused by the movement of other animals as well as the presence of stationary objects. Along this line, receptors called neuromasts sit in shallow pits or grooves between pores which are open to the environment. These neuromasts are sensitive to movement and send neural impulses to the brain regarding any type of external disturbance. The lateral line helps fish avoid collisions when schooling and to navigate successfully in lowlight conditions. Without the lateral line system, fish would constantly be swimming into the glass sides of aquariums.

If you want to find out more about fish perception or have other questions about fish biology, stop by the Nature Center on Saturday, November 22 from 2-4. Students of Dr. Budy’s fish diversity class will be hosting a poster display on how fish perceive their environment. And Dr. Budy herself will be on hand to answer any questions you might have about fish biology. For more information see www.logannature.org.

Thanks to the Rocky Mountain Power Foundation for supporting research and development of Wild About Utah topics.
For Wild About Utah and Stokes Nature Center, I’m Holly Strand.

Credits:

Photo Courtesy US Fish & Wildlife Service, La Cross Fish Health Center http://www.fws.gov/midwest/LaCrosseFishHealthCenter/

Text: Stokes Nature Center: Holly Strand

Additional Reading:

Moyle, Peter B., and Joseph J Cech, Jr. 2000. Fishes: An Introduction to Ichthyology (4th edition) NJ: Prentice Hall.

WATS 3100 poster assignment. 2008. Fish Diversity class. Dept. of Watershed Resources, College of Natural Resources, Utah State University.

Learn More:

The World According to Carp, Stokes Nature Center, November 22, 2:00 to 4:00 p.m. http://www.logannature.org/sat&community.htm#fish

Kokanee Salmon

Kokanee Salmon above Porcupine Reservoir
Kokanee Salmon above Porcupine Reservoir
Copyright 2008 Mary-Ann Muffoletto

A little over a week ago, I saw my first kokanee salmon run up Little Bear River just east of Porcupine Reservoir. This year, researchers counted over 10,000 fish within a mile of the reservoir. That’s a record number. My friends and I marveled at these wriggling flashes of color as they struggled upstream. It inspired me to spend the week reading about salmon. Here’s what I learned.

First of all it surprised me that salmon and trout are so close genetically. Along with whitefish and grayling, they form the family Salmonidae, but salmon and trout are the most similar. The main difference between them is that salmon generally migrate from their freshwater birthplace to the sea to get more and better food. And then they return to spawn in freshwater rivers and streams where there are fewer predators. And generally – although it’s not true for all – salmon spawn once and die while trout go through a number of spawning cycles.

The Pacific Sockeye salmon resembles a silvery rainbow trout during most of its life. But when it spawns, the male especially undergoes a miraculous transformation. His head turns green, his body turns a bright red, and his back grows a bump. And his jaw begins to hook until he’s got a pronounced overbite. There’s a lot of jostling over females during breeding, and the humpback and hooked jaw helps him intimidate other male fish so he can fertilize more female eggs. And the red color is considered highly attractive to the opposite sex.

White-talied Kokanee Salmon Copyright 2008 Mary-Ann Muffoletto
White-talied Kokanee Salmon
Copyright 2008 Mary-Ann Muffoletto
The kokanee is an evolutionary branch of the sockeye. Both of them spawn in freshwater nurseries and then move to a nursery lake to grow for awhile. Then the sockeye salmon migrates to the ocean while the kokanee remain in the lake. After a few years they both return to the freshwater streams to spawn and die. The funny thing is, that if you take a sockeye and keep him in a lake, he doesn’t turn red when it’s time to spawn. That’s because red color derives from carotenoid pigments in the salmon’s diet and these pigments are much more prevalent in ocean food. So why does the kokanee turn the same red as the sockeye? It’s because the sexual preference for red was so strong that the kokanee actually evolved the ability to process carotenoid pigments with 3 times the efficiency of sockeyes.

White-talied Kokanee Salmon
Copyright 2008 Mary-Ann Muffoletto

Because it flexibly defines a lake as its ocean, the kokanee has become a popular fish for reintroduction into western lakes and reservoirs. In 1922, the kokanee was first introduced for sport fishing into Utah’s Bear Lake. Nowadays you can see them spawn in the Little Bear River out of Porcupine Reservoir, Sheep Creek near Flaming Gorge Reservoir, and tributary streams of Strawberry Reservoir.

If you hurry, you can still catch the last of the spawning kokanees, their bright red bodies an aquatic response to the flaming Utah maple on the surrounding hillsides.

Special thanks to Charles Hawkins (Watershed Sciences, College of Natural Resources, Utah State University) , Phaedra Budy (USGS Utah Cooperative Fish and Wildlife Research Unit, College of Natural Resources, Utah State University) and Bret Roper (US Forest Service, Fish & Aquatic Ecology Unit, Logan, UT) for their comments on this piece.

Credits:

Photo: Courtesy of and Copyright 2008 Mary-Ann Muffoletto
Text: Stokes Nature Center: Holly Strand

Sources & Additional Reading
Aggies Help State with Fall Salmon Count 2008. Utah State Today. Sept 25, 2008. http://www.usu.edu/ust/index.cfm?article=30698

Coates, P. 2006. Salmon. London: Reaktion Books

Craig, J.K., and Foote, C.J. 2001. COUNTERGRADIENT VARIATION AND SECONDARY SEXUAL COLOR: PHENOTYPIC CONVERGENCE PROMOTES GENETIC DIVERGENCE IN CAROTENOID USE BETWEEN SYMPATRIC ANADROMOUS AND NONANADROMOUS MORPHS OF SOCKEYE SALMON (ONCORHYNCHUS NERKA), Evolution 55(2), 2001, pp. 380-391.

Utah Division of Wildlife Resources. Kokanee (Oncorhynchus nerka). Wildlife notebook Series No. 10.http://wildlife.utah.gov/publications/pdf/newkokan.pdf (accessed Oct 3, 2008)

See also:

Kokanee Salmon in Strawberry Reservoir http://www.redrockadventure.com/fishing/Strawberry/strawberry_kokanee.htm

See bright red kokanee salmon at Sheep Creek, near Flaming Gorge http://wildlife.utah.gov/news/05-09/sheep_creek.html