Hello all,

I am working on a 5-year walleye project. Beginning in 2017, fish were tagged and released each spring (April-June) and returned via angler reports. We are using a Seber dead recovery analysis to estimate annual survival and explore survival patterns in relation to a number of variables.

We set up monthly capture histories to incorporate a time-varying environmental covariate in our models. To obtain annual estimates with the monthly capture histories, I specified that each monthly interval was equal to 1/12 of a period and binned time intervals to correspond to year in RMark.

We are considering removing the time-varying covariate from our models. I was curious if our annual estimates of survival would be the same with annual capture histories, so I collapsed the monthly capture histories into annual intervals and reran our models. I found that I had significant issues with estimating annual survival for some years. I think that this is related to minimal tagging that occurred in 2020 due to the pandemic. My question is – would it be acceptable to use the annual estimates from the monthly capture histories even if they are no longer necessary to incorporate our time-varying covariate? I am also wondering about the validity of annual survival probabilities estimated from the monthly capture histories given the discrepancy between the results.

I tried to be concise in my explanation, but please let me know if I have left out any important details that would be helpful in answering my questions.

Thank you in advance for any assistance!

Laurel