Daniel Wasilick
Dr. Palestis
Sockeye Salmon
12 December 2010
Sockeye Salmon
Despite all of the teachings in the bible, Darwin knew there was scientific reasoning behind the creation of life. Darwin’s view of life split the country in half when it came to this debate. Darwin states in is his book Origin of Species, “that natural selection is daily and hourly scrutinizing, throughout the world, the slightest variations; rejecting those that are bad, preserving and adding up all that are good… We see nothing of these slow changes in progress, until the hand of time has marked the lapse of ages.” (Darwin). But when it comes to Sockeye Salmon, Darwin’s idea of not being able to witness evolution in a lifetime is a false statement.
Sockeye Salmon are a form of salmon that formed when the glaciers of the last ice age melted and retreated. As a result, this created thousands of new lakes. Salmon swam into the lakes and stayed. The salmon that swan into the lakes began to mate with the other salmon in the lakes and the salmon that live in the streams (Sockeye Salmon) would mate with the other salmon in the streams. The reason that the Salmon would tend to change over the years is due to natural selection because both salmon live in two different habitats. This causes the salmon to develop different types of niches so they can both survive in their separate habitats. The two types of salmon have a couple things that differ from one another, one being the shape of the body. The salmon that would breed in the Cedar River, Sockeye Salmon, would have a more slender, thinner body type. The reason for a more slender body is due to the competition in mating and passing on genes, the salmon in the river would have to turn sideways in a stronger current and they would swim around the fish with a more round body. The salmon with the more round body would benefit more in calm waters. The reason being in more calm waters, like beaches, salmon with deeper bodies have a better chance of finding mates and passing on their genes. So females can dig their eggs into the sand. However, females in the river tend to have bigger bodies then the males. Rivers currents are always changing so that means females have to dig their nests deeper than most other salmon. So in order to get deeper the females must have bigger bodies to get deeper in the waters so their nests would be safe in the water. Body types can not only help the salmon maneuver around the waters or help the salmon lay eggs, but it can also determine whether the salmon can stay alive or not. Low lake levels can cause larger salmon to get stranded and die out before they get to the breeding grounds. Being smaller in lakes makes it harder to get down deeper for females to lay their eggs but with a low lake level the salmon must be smaller to even get to the breeding grounds. “Salmon breeding in Hansen Creek tend to be smaller, younger, and more streamlined than conspecifics from neighboring populations, suggesting that selection against large individuals could be driving these patterns.” (Carlson, Quinn 2620) Lake levels can ultimately affect the way the salmon breed and how they reproduce. Lake levels play a strong factor in the size of the different salmon in different lakes. With the size of the sockeye salmon constantly shifting it can cause problems for fisheries especially for The Skeena River System. The Skeena River System is one of the largest fisheries in the world producing the third largest amount of sockeye salmon in the entire world. The Skeena River Shed is made up of twenty one different lakes; the Babine Lake is by far the most important one. Although it produces the most sockeyes, so many sockeyes escape from the fishery. Scientists believe that it is due to the fact of sockeyes decreasing in size due to all of the changes in lake levels and sockeyes trying to adapt to their habitats. Whenever the name Charles Darwin comes up in topic you immediately think of evolution. Darwin claimed that watching evolution would be virtually impossible. Darwin said in his book Origin of Species “that natural selection is daily and hourly scrutinizing throughout the world, the slightest variations; rejecting those that are bad, preserving and adding up all that are good; silently and insensibly working, whenever and wherever opportunity offers. . . We see nothing of these slow changes in progress, until the hand of time has marked the lapse of ages.” (Darwin 47) Darwin also noted that watching evolution would be more boring than watching paint dry. But biologist Andrew Hendry proved Darwin’s theory of not being able to watch evolution wrong when it came to Salmon evolving into Sockeye Salmon. Darwin estimated that it would take approximately ten thousand to fourteen thousand generations for a new species to arise. But now biologists all over are watching Sockeye Salmon develop into its own species. Scientists like Andrew Hendry can now easily tell the difference between a Sockeye Salmon and a regular Salmon just by looking at their Otolith rings or by looking at their ear stones. Hendry could tell if the salmon had been born in the river or on a beach. Ololith rings can reflect the variations in water temperature while a fish embryo is developing. Water temperatures at the beaches are usually constant, while the temperature of the river is constantly changing. “Hendry and his colleagues checked the otoliths and collected DNA samples from the fish- and found that more than a third of the sockeye breeding at Pleasure Point Lake had grown up in a river. They were immigrants.” (Weiner 49) The sockeye salmon migrate over and live in the lake with the other salmon. Till this day at Pleasure Point Lake the sockeye salmon are two thirds the population in the lake. At this point the salmon should have blended back together but that’s not the case. So during breeding period the sockeye’s from the river were unsuccessful passing on their genes. Due to the fact they wouldn’t mate with regular salmon. Sockeye salmon feed off of zooplankton. The most common thought would be that organisms tend to migrate where there is most food. But that is not the case for sockeye salmon. Scientists ran studies on sockeye salmon and instead of them migrating to where there was food they would migrate to an environment that was filled with light. “This light environment allowed the sockeye to exploit an antipredation window whereby they could forage on zooplankton while reducing the odds of visual detection by their predators.”(Scheurel, Schindler 1713) Sockeyes main concern is not about their food supply, which helps survive better in their environment. It benefits the whole species when they do not have to worry about a food supply and can mainly focus on staying safe from predators such as bears. Sockeye salmon is a species that is quite extraordinary, from the way they turned into sockeye to the way the try to survive in their own environment. The way they adapt to stay safe from predators instead of worrying about food. Also the way sockeyes can vary all across the world due to different habitats.

--------------------------------------------
[ 1 ]. Weiner
[ 2 ]. Weiner
[ 3 ]. Larkin & McDonald
[ 4 ]. Weiner
[ 5 ]. Weiner
[ 6 ]. Weiner