fish report header

Casual Spawning

While many people have observed salmon swirling about in West Coast rivers during the spawning season, it's not always apparent what is actually happening beneath the surface. Like many other mating animals, salmon exhibit spawning behaviors. Females travel up river to find an appropriate location to create their redds or nests. Once a female finds substrate of suitable size with adequate flow to provide oxygen for her eggs, she will begin creating her redd. Female salmon will turn on their sides and flick their tails several times to move the substrate downstream, piling it upon itself. This digging also dislodges and clears any fine sediment from the substrate, which can smother eggs. The female will guard this redd position within the stream until a suitable male approaches her and she will often fight off other females for this position.


Females frequently show size selectivity (Berejikian et al. 1997) in their male partners, selecting larger, more fit, dominant males over the smaller males. While this one-on-one pairing does happen, multiple males often attempt to spawn with a single female. Dominance is determined by the competing males (either through female selection or fighting between males), but the dominant male may not be the single contributor of milt (male gametes) to the unfertilized eggs. The non-dominant males are referred to as 'satellite males', and usually do not occupy a position within the redd, but move around in close proximity (Esteve 2005). While smaller males are less likely to compete for the dominant male position, they do fight other smaller males to ensure they are as close as possible to the redd (Berejikian et al. 2010).


In this video, the dominant, larger male positions himself close to the female Chinook salmon. He attempts to maintain close proximity to her, especially when she is releasing her eggs. By staying as close as possible to her, he is trying to prevent other males from fertilizing the eggs. However, this video documents how these satellite males "sneak" in close to the female to release milt just as she is depositing her eggs. Males that perform this action are referred to as "sneaker males". These non-dominant, smaller males position themselves close to her vent, thereby increasing their chance to fertilize her eggs and pass on their genes. The dominant male can't fight off all the competing males, thus offspring from a single redd can be fathered by more than one male. The sneaker male strategy is not particularly successful, according to research conducted by Berejikian et al. 2010. The researchers found that jacks (smaller males) were the last male to enter into a mating and only sired about 20% of the offspring, based on the genetic make up of the sampled offspring. The order in which males join the spawning event may affect their success, with the first adult male typically having better success in passing on his genes. But then again, 20% is better than nothing. 


Follow Us!  Like us on Facebook  View our photos on flickr  View our videos on YouTube

email list
Recent Blog Post
A river undammed...   

On a recent trip to the Pacific Northwest one of our fisheries biologists visited the Elwha River on Washington's Olympic  Peninsula. The Elwha is the site of one of the most ambitious dam removal projects undertaken in North America to date. Two dams, Glines Canyon (constructed in 1927) and Elwha (constructed in 1913), have been removed in less than a year. The removal project allows for passage of five Pacific salmon species (Chinook, chum, coho, pink, and sockeye) that once inhabited the Elwha. The project, which began in 1992, has been a significant undertaking by the National Park Service, United States Geological Survey, National Oceanic & Atmospheric Administration, Washington Department of Fish and Wildlife, and the Lower Elwha Tribe. After nearly 100 years of sediment buildup and large woody debris accumulation in the upstream ends of each reservoir, the Elwha is finally moving those materials out. In the process, the river is depositing new logjams and point bars that will increase the habitat diversity in the river channel. Read more > 

Salmon spawning and sneaky jacks
IN THE NEWS: Recent stories you might have missed...
California salmon fall short

Daily News

An environmental organization that was part of the lawsuit that spurred the permanent raising of the Red Bluff Diversion Dam gates is saying federal agencies are still failing to meet salmon repopulation goals. The Natural Resources Defense Council released a new salmon index Tuesday showing the Sacramento- San Joaquin Basin Chinook salmon natural population is only at 13 percent of a required federal goal... Read more> 

Chinook are back in California's upper San Joaquin

Trout Unlimited

Yesterday, under a warm fall sun, I participated in the release of adult fall-run Chinook (king) salmon into the upper San Joaquin River below Friant Dam.  This release marked a historic milestone not only for the San Joaquin Restoration Program but for conservation in CA: this group of salmon will be the first to spawn in the upper San Joaquin River in half a century! This fall's translocation and release of adult fall-run salmon is the latest step in the revitalization of California's second longest river... Read more>
Study links climate change to warmer Oregon streams

A new study by Oregon researchers claims climate change is causing double trouble for our salmon. The snow that blankets Mount Hood is much more than just a pretty sight. It feeds the streams and rivers below it, giving fish the habitat they need to survive. But now some researchers say that habitat is at risk. "The fish and other aquatic organisms are under a higher stress," said Ivan Arismendi, a research professor in Oregon State University's department of Fisheries and Wildlife... Read more > 

Cormorants Who Eat Protected Salmon Subject Of Fed Meeting
Daily Astorian

The federal Army Corps of Engineers is holding public meetings this week in Portland and Astoria to discuss what to do about double-crested cormorants eating protected salmon in the Columbia River estuary. The largest cormorant colony in Western North America lies near the mouth of the Columbia River on East Sand Island. As their numbers grow, the birds are eating more and more of the young salmon and steelhead headed to the ocean... Read more > 

Columbia River northern pikeminnow reward program angler earns $77,238

Seattle Times 

This past season's northern pikeminnow reward catch figures dipped a little compared to 2011, but it still took out enough of the predatory fish that are known to gorge on young salmon and steelhead. A total of 906 anglers participated this season, catching 152,631 northern pikeminnows compared to 930 with 155,000 in 2011. This season the grand total paid out to anglers was $1,087,900 of that the top-20 anglers were paid out $496,477... Read more >