I JUST finished writing this one page abstract of my current research goals for a scholarship I'm applying for. My reason for starting this blog was to have me think, and write about something other than work. But since I've already got this all typed up, I decided to share with people that are interested in what I am doing (although most of you already know). I had a hard time condensing it to the required length, but am reasonably happy with the final product.
Research Abstract
Salmon are iconic in the Pacific Northwest because of their anadromous behavior. This life history behavior heavily influences the culture and economy of the area. Fish returning from the ocean to spawn create runs of salmon with timing that is generally known and anticipated. Less obvious is the timing and conditions behind the seaward migration of juvenile salmon. Coho salmon usually spend a year rearing in freshwater before becoming smolts and migrating to the ocean. This juvenile life history timing has been generally accepted to apply to coho in all stream systems. However, in many watersheds, coho salmon fry have been observed migrating downstream in the spring shortly after they emerge from the gravel. For many years people thought that early downstream migrants were fish displaced from upstream habitats. It was assumed that these coho did not survive to contribute to returning runs of adult salmon. During the last decade there has been a renewed interest in studying the survival of these fish, and determining to what extent they contribute to spawning runs.
My research is addressing the contribution of early migrating coho to spawning runs. I am specifically interested in juvenile fish that migrated into the estuary before they are a year old. I am also investigating the possible genetic difference between early migrating coho and those moving downstream after a year. I have two main goals. My first goal is to identify the juvenile life history of returning coho salmon spawners. To complete this goal I will describe juvenile life histories of returning spawning coho, determine variances in proportions of juvenile life history types in coho that returned to spawn in 2008-2011, and determine survival rates for these different life history strategies.
My second goal is to determine if there is genetic differentiation between life history groups of coho. To do this I will determine if runs from two geographically close streams differ in microsatellite markers, determine if coho that move early differ at microsatellite markers from fish that migrate as smolts, and determine if coho that move early differ in clock genes from fish that migrate as smolts.
My research is conducted in two coastal lowland tributaries that flow into the Coos River estuary. I use two methods to determine the life history compositions of returning adult runs. The first method uses uniquely numbered tags to track fish throughout their life. Every spring and summer since 2007 juvenile coho in each tributary were tagged with passive integrated transponder tags; these fish began returning as adults in 2010. Tag detections from in-stream antennas allow the tracking of a single fish’s behavior over it’s lifetime. From this data I am determining the juvenile movements of adults that return, and can calculate the percentages of tagged adults returning that migrated early as juveniles.
The second method for determining an adult fish’s juvenile life history is to use a small bone collected from the head of spawned-out carcases. These bones, called otoliths, grow throughout the fish’s life, capturing in sequential layers the chemical make-up of the water surrounding the fish. Otoliths from all carcases encountered on spawning surveys since 2009 will provide microchemical data, allowing me to determine the size of the fish when it entered salt water. I will be determine if there is evidence that fish entering salt water at a small size survive to contribute to spawning runs in these creeks.
My second goal will use genetic markers to determine the structure of these populations. I am using nine neutral loci to determine if the runs in each tributary are genetically distinct and if there is a genetic difference between juvenile fish that migrate early or fish that stay for a year. I am also using three candidate loci to determine if the early migrating behavior is linked to genes which have been shown to influence circadian rhythm and migration timing.
Diversity in life histories is thought to increase salmon’s ability to adapt to changing environments. This adaptive ability could become critical with the progression of climate change. It is important to know how different salmon life histories influence survival and contribute to future runs so this information can be used to inform management, preservation, and restoration decisions in the future.
