batch marking fish

[cpw]

I am wondering if a model in Mark can be used for the following scenario or if I am restricted to a Schnabel estimate for population estimate?

I am working with fish in a closed reservoir. I have multiple groups, each stocked at the same time a year+ ago, and each unique group (of same spp.) was given a unique complete fin clip. There are no other fish of this species in the reservoir other than the ones I stocked. I night electrofished about once every two weeks this past spring for roughly two months and again in the fall at the same regularity. In the spring I gave each fish that I captured a lower caudal fin clip and did a basic mark-recapture sampling throughout the spring giving lower caudal clips to any captures not already having the lower caudal.

In the fall I did the same procedure, this time with an upper caudal clip.

There are no indivudal clips in the study. Just batch clips identifiying treatment groups and then the clips given in sp or fall for the mark-recapture estimates.

Is there a model in MARK program that would give me better estimates and CIs than just using a Schnabel estimate? Can I get survival of each treatment group from spring period to fall period with CIs for the survival?

Thanks so much!

Sincerely
cpw

[bp]

CPW,

So does each fish have at most two marks (one unique for the batch and another mark common to all the recaps in that season)? If you have unique recapture marks, you can probably use CAPTURE (stand alone or within MARK) for closed population estimates using your batch marks for SOME of your dates. If you do this again, give each recapture occasion a unique fin clip as well instead of all recaptures receiving the same mark. A paper you probably have that uses batch marks and the closed models in capture is

Mitro, M. G., and A. V. Zale. 2002. Estimating abundances of age-0 rainbow trout by mark-recapture in a medium-sized river. North American Journal of Fisheries Management 22:188-203.

If you only have a unique release mark, and then a single recapture mark, take a look at the blue AFS monograph #5 by Burnham, Anderson, While, Brownie and Pollock. You could set your capture histories up so that when you recapture an individual in the spring (when you gave all of the recaps the same mark) that those individuals were "removed" as in scenario 1.3.3.4 on page 39 of the book. You might have to use program release (not sure if MARK does everything discussed in the blue book or not), but I'm pretty sure you could get the survival estimates you are after.

Good luck,
bp

I am wondering if a model in Mark can be used for the following scenario or if I am restricted to a Schnabel estimate for population estimate?

I am working with fish in a closed reservoir. I have multiple groups, each stocked at the same time a year+ ago, and each unique group (of same spp.) was given a unique complete fin clip. There are no other fish of this species in the reservoir other than the ones I stocked. I night electrofished about once every two weeks this past spring for roughly two months and again in the fall at the same regularity. In the spring I gave each fish that I captured a lower caudal fin clip and did a basic mark-recapture sampling throughout the spring giving lower caudal clips to any captures not already having the lower caudal.

In the fall I did the same procedure, this time with an upper caudal clip.

There are no indivudal clips in the study. Just batch clips identifiying treatment groups and then the clips given in sp or fall for the mark-recapture estimates.

Is there a model in MARK program that would give me better estimates and CIs than just using a Schnabel estimate? Can I get survival of each treatment group from spring period to fall period with CIs for the survival?

Thanks so much!

Sincerely
cpw