Big ol' AFS Review: Part I

The 140th meeting of the American Fisheries Society in Pittsburgh PA is over and I am sure most people would say it was a huge success.  I met some interesting, and helpful people and reconnected with others who could potentially help me with my research along the way.  I was able to attend a number of talks that dealt with otolith chemistry and its application so I will briefly review some of the most interesting.

Monday
 
The first otolith talk I attended was “Isotopic signatures of otoliths in identification of Pacific hake stocks” was given by Yongwen Gao.  I find this topic pretty interesting because it utilizes otolith chemistry rather than genetic techniques, which have apparently been somewhat ineffective in stock discrimination of marine species.  Essentially the core of Pacific hake otoliths was analyzed for oxygen and carbon isotope ratios and significant differences were found between fish caught on the Washington Coast and fish caught in Georgia Strait, British Columbia, indicating that there are separate stocks of Pacific Hake.  I have read a couple papers on stock discrimination of marine fish using otolith chemistry and it appears to be pretty accurate especially when utilizing stable isotope ratios (this will be a running theme throughout this review).  

I then attended “Using a combination of genetic markers and otoliths chemistry to examine connectivity issues and management implications for spotted seatrout” presented by R. Deborah Overath.  This research wanted to address connectivity of seatrout between coastal and in shore habitats on an area of the Texas coast.  While most of the genetics data was over my head, the otolith data was interesting.  Stable oxygen and carbon isotopes were utilized to classify fish to habitat type.  If I am not mistaken the outer edge of the otolith was used for analysis because the research wanted to focus on classifying trout to their most recent habitat area.  

*Begin Tangent*

One of the interesting things about otoliths is that they accrete calcium carbonate sequentially throughout the entire lifetime of the fish and otolith material is not reabsorbed.  The easiest way to think of how an otolith is formed is to think of tree rings.  If you cut a tree you see growth rings, which allows you to make age estimates.  If you cut an otolith you see similar patterns, so much so that we can even count daily rings in some instances.  However, otoliths are more like rocks than trees, and a more accurate method of visualizing the structure of and otolith is to think of an onion.  Onions are made of layers of material in a spherical shape; this is pretty similar to the arrangement of otolith material.  It is this structural pattern that allows us to examine the life history of a fish from birth to death.   

*End Tangent* 

Using isotope ratios 64% of samples were assigned to their correct region.  This number seems a bit low but I believe the area they were working in was pretty small.  It also appeared that straying of fish occurred between habitats that were adjacent to each other.  Perhaps this research could be useful in examining ranges of fish?  I also think that had elemental ratios been incorporated rather than just stable isotopes, the classification success may have been greater (again this will come up later). 

One of the best talks I attended was by Renee Reilly called “Time series applications in otlith chemistry”.  For the life of me I cannot recall many of the details of this talk.  It dealt with the interpretation of elemental ratios across the entire scan of an otolith, and methods to properly interpret this data.  This research is useful when looking at migration patterns and habitat shifts of fish.  Essentially, it involves looking at a string of data and determining where the significant differences are if there are in fact any.  I really hope this research is published, because it would be very helpful in my own data interpretation.

Also of interest on Monday were talks by; Roger Rulifson on restoring river herring in North Carolina, Anthony Overton on growth and mortality rates of larval river herring in the Tar-Pamlico River, Sarah E. Friedl on mortality estimates of juvenile spot in North Carolina, Johnny E. Moore on site fidelity of sand tiger sharks, and Jordan R. Allison on Walleye reproduction in Lake Michigan.  

Tuesday

As far as I can tell there was really only one talk on Tuesday dealing with otolith chemistry (given by me), and I don’t really want to discuss that any further here.  However, Tuesday was the first day of the Shad and River Herring symposium so I attended many of those talks.  Included in the symposium was the work of Kenneth L. Riley and Samantha M. Binion who both presented on different aspects of river herring work on the Roanoke River.  Both of the talks dealt with early life history of river herring and American shad and were very well done. 

Many of the talks given on the first day of the shad and herring symposium dealt with the removal of dams and the effectiveness of this in restoring populations.  It seemed as though the results were mixed.  Even though spawning habitat was opened up if it was a river with multiple impoundments the amount of habitat opened could be insignificant.  It also seems as though these species may not immediately utilize new upstream habitat.  Many theories were bounced around as to why this may be, I found the most interesting to be “the lack of leader fish hypothesis” (not exactly sure who said this but I know I heard Karin Limburg mention this).  Essentially, while the dam has been in place fish that spawn successfully below the dam have been selected for, once the dam is removed there are no fish that are conditioned to make the longer upstream migration so this habitat is not utilized.  The theory is that younger fish will follow “leader” or older fish into the river to make spawning migrations.  If there are no older fish making these longer spawning runs younger fish will not make them either. 

Also of interest on Tuesday were talks by; Mike Bednarski on population trends of shortnose sturgeon in the Altmaha River (which he nailed!), Daniel W. Cullen on the influence of temperature on monkfish distribution, Elizabeth Fairchild on spawning movements of winter flounder (which was one of my favorite talks).

Keep reading part II for reviews of Wednesday, Thursday and some closing thoughts.

Dooms Day!

After staying up until 12:30 am last night (and then being woken up at 2:30 am) to put the finishing touches on my presentation for AFS, I woke up at 6:30 am to load my power point onto the computer.  I then milled around until 8:00 am and went to the room were the Marine Ecology section would be located.  There were two presenters before me that presented very well, one talk was on monkfish, and the other was on flounder.

The whole time I was waiting in the room for my presentation to start my heart was definitely pounding as I had never presented my research before and had never given any presentation in a setting such as a national meeting.  My talk started at 8:40 am, and overall went pretty well.  I feel like I stumbled around in some places and was maybe a little vague in others but for the most part I felt pretty comfortable talking about my research.  To be honest I was probably nervous for nothing.  At the present time I really do not have enough data to do any in depth analysis so most of what I presented on was fairly basic and uncomplicated.  I finished my talk two minutes early which left plenty of time for question but alas there were none, which was disappointing as I was really hoping for some comments and suggestions.

Most of the people I talked to afterward said I did really well although I did talk kind of fast, which I kind of expected to be the situation.  Now that I am through with my talk it really feels like a huge weight has been lifted off my shoulders and I look forward to attending more talks tomorrow particularly a few from the shad and river herring symposium that are very similar to my project and utilized otolith microchemistry.

I will probably have a more in depth post concerning some of the more interesting talks after the conference is finished but until that time if something interesting happens I will try and make a short post.

AFS Day 1

Well the trip from North Carolina to Pittsburgh was relatively uneventful.  I think we watched about four movies because it took us about 11 hours to make the drive.  Which incredibly is the same amount of time it takes me to drive from NC home to New York. 

After going to bed way to late last night and getting up way to early this morning I attended the continuing education class Basic Fisheries Population Modeling using Excel.  It was a very interesting and useful class and it was good to learn new techniques from a software program that I feel like I've used way to much.  It always helps to have someone walk you through complicated sequences step by step.

Presentations start tomorrow and I am really looking forward to seeing some of them.  And Mike will be here tonight!

Road Trip!

Today I leave for Pittsburgh PA for the the meeting of the American Fisheries Society.  Eight hours in a van driving through NC, VA and West Virginia will hopefully make for some interesting/hilarious red neck and hilbilly jokes.  While I enjoy going to conferences I have been somewhat dreading this one due to the fact that I will be giving a presentation on what little data I have thus far.  At the very least it should be a good learning experience and I always welcome constructive feedback on my project.  The conference should be a good time and I look forward to meeting up with people I haven't seen in a while.

I will try and post updates from the conference, especially Tuesday after I present, however I am not positive on internet availability so don't expect to much.

Why the Endolymph?

Who am I?

Well, my name is Dan.  I am currently a biology graduate student in eastern North Carolina.  I am studying nursery habitat and migration patterns of river herring (alewife and blueback herring) in tributaries of the Albemarle Sound.  If you are familiar with the area the tributaries I am focused on are the Chowan River, Scuppernong River, Perquimans River, Alligator River (which you may have driven over on your way to the Outer Banks), and the world famous Roanoke River.

However, more interesting than actually simply studying river herring is the method with which I am utilizing.  I am using a technique called otolith microchemistry.  I won't get into the nitty gritty details right now (just wait) but here is a quick overview.  Bony fish have structures in their heads, in what is essentially their ear, called otoliths.  There are three pairs of otoliths, that help the fish hear and stay balanced in the water.  Otoliths are made of calcium carbonate, however, trace elements, such as strontium, barium, manganese and magnesium, may substitute for calcium in the otolith.  Water bodies and habitats have different ratios of trace elements in the water, and these ratios are often reflected in the otoliths of fish.  This allows us to track habitat usage, natal origins, migratory patterns, and allows for stock discrimination.  It all seems very complicated, and it is, but I hope to break things down enough so that if anyone winds up reading this they don't start bleeding from the ears. 

Anyway, elements come together to form otoliths in the endolymph fluid, located in the endolymph sac, hence the name of the blog.  My goal is to bring many thoughts together into one tangible thingy (aka blog).  While I will try and focus on new and exciting happenings in the world of otoliths, namely my own otolith research, I will also probably post on interesting happenings (if such things exist) in my life, and yes I will probably write a little (probably a lot) about hockey.

Enjoy!