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Going Out Again


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#21 Guest_NateTessler13_*

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Posted 02 January 2008 - 06:31 PM

What are you studying?


The study involves a few things. First off, it's a study being conducted by two of the ecology professors at Bowling Green State University, I'm just added help. The first part of the study involves getting water samples from all of the hatcheries that release steelhead into tributaries to Lake Erie. These water samples are analyzed to determine whether or not an identifiable element or trace of an element can be found in the water. For example, the water in Sandusky Bay and the nearby hatchery has high levels of Strontium. This is like looking for a signature element in the water. This signature shows up in the fishes otolith. The otolith (our ear bone) develops "rings" on it that develop every year. You can age a fish by its otolith. Also though, you can (using lasers and a very expensive machine) determine the chemical composition of the otolith. When fish live in a body of water for awhile, their body takes in elements in the water (i.e. mercury warnings for fish consumption). Well, their otolith maintains the chemicals. So then, fish from a hatchery in the Sandusky Bay area are going to have Strontium in their otoliths. A Steelhead that is taken that has Strontium in it's otolith then can be assumed to have come from that hatchery. Using that as an example, you can determine which rivers are getting which hatcheries fish returning to them to spawn. There are scenarios, like in the Ashtabula River, where there is no stocking program, however there are quite a few Steelhead in that river. With these signatures established, we can determine which hatcheries these fish are coming from.

If a fish's otolith composition does not match up with that from any hatchery, then it may be that the fish was derived from natural reproduction. This study can help determine how much natural reproduction there is in the Lake Erie tributaries. I know the DNR is going to help with electro-fishing surveys of the river. The more fish, the merrier though. There are many uses for this study on the lake, and I think it's a worthwhile cause to find out this information. So, if anyone gets any Steelhead out of Lake Erie tributaries (or the lake itself), feel free to send some fish heads my way. I'll be going to the Vermillion River this weekend with that intention.

-Nate

#22 Guest_fundulus_*

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Posted 02 January 2008 - 07:14 PM

I'm impressed. Otoliths are data recorders, and very powerful ones at that, if you have the gear to work with them. My graduate work involved reading the otoliths of young-of-the-year bluegills and pumpkinseeds to age them to the day they left the paternal nest as part of a study of the effects of acidic precipitation in several Massachusetts ponds. Tedious work, but it yielded strong results. I look forward to hearing what your PI's and you find.

#23 Guest_ashtonmj_*

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Posted 02 January 2008 - 08:13 PM

Wouldn't it be cheaper and faster to use a colored otolith marker like oxytetracycline or calcein for the various hatcheries? Or combinations of wire tags and clipping? Searching for trace elements in otoliths has to be alot more tedious and exspensive... Will it address whether or not the fish came from another state? You said all hatcheries, as in ALL, or just Ohio hatcheries? We already know fish stocked in PA have to go into OH to get to the Lake in at least one stream plus there seems to be a decent amount of straying salmonids in Lake Erie as there are naturally elsewhere.

If a goal is to determine natural reproduction this seems like a backwards way of getting the information. If the otolith doesn't match any hatchery I understand that with some certainty you can assume that it was not a hatchery fish. Wouldn't it again be easier to answer the question of natural reproduction by electrofishing post spawn? Trout smolt tend to stay pretty close to redds, which a simple redd count would be an easy step to identify potential/probably spawning. If there are YOY then it's pretty obvious you have natural reproduction and it can be quantified. Why look for older, returning steelhead rather than the direct evidence other than the fact you already have the fish for another purpose and you can extrapolate some further information that isn't necessarily as concrete as other ways of getting it?

Just trying to further a good discussion...

#24 Guest_NateTessler13_*

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Posted 02 January 2008 - 08:27 PM

Wouldn't it be cheaper and faster to use a colored otolith marker like oxytetracycline or calcein for the various hatcheries? Or combinations of wire tags and clipping? Searching for trace elements in otoliths has to be alot more tedious and exspensive... Will it address whether or not the fish came from another state? You said all hatcheries, as in ALL, or just Ohio hatcheries? We already know fish stocked in PA have to go into OH to get to the Lake in at least one stream plus there seems to be a decent amount of straying salmonids in Lake Erie as there are naturally elsewhere.

If a goal is to determine natural reproduction this seems like a backwards way of getting the information. If the otolith doesn't match any hatchery I understand that with some certainty you can assume that it was not a hatchery fish. Wouldn't it again be easier to answer the question of natural reproduction by electrofishing post spawn? Trout smolt tend to stay pretty close to redds, which a simple redd count would be an easy step to identify potential/probably spawning. If there are YOY then it's pretty obvious you have natural reproduction and it can be quantified. Why look for older, returning steelhead rather than the direct evidence other than the fact you already have the fish for another purpose and you can extrapolate some further information that isn't necessarily as concrete as other ways of getting it?

Just trying to further a good discussion...


Those are very valid points. I'm not the person spear-heading the operation, and perhaps some of these things have been considered already. All the hatcheries that release Steelhead into Lake Erie are being accounted for, as is my understanding. That includes those outside of Ohio.

I may have misspoke about it being one of the goals of the project. I believe he said that after the project we would be able to make implications about the natural reproduction. The primary goals are more set at tracking return rates of fish to the streams they were stocked in and how much "straying" is going on.



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