@article{jiang_pollock_brownie_hightower_hoenig_hearn_2007, title={Age-dependent tag return models for estimating fishing mortality, natural mortality, and selectivity}, volume={12}, ISSN={["1537-2693"]}, DOI={10.1198/108571107x197382}, abstractNote={Tag return studies play an important role in providing estimates of mortality rates needed for management of many fisheries, but current methods of estimation do not allow age dependence of instantaneous mortality rates. We present models that allow age-dependent fishing and natural mortality rates, an important advance, because there is often substantial variation in age (and size) of fish at tagging. Age dependence of fishing mortality is modeled by assuming that availability to the fishery, that is, selectivity, depends on age but is constant over years. We assume that all age classes are tagged each year, and allow for incomplete mixing of newly tagged fish and for fisheries that are year-long or limited to a fishing season. We investigate parameter redundancy and estimator performance using analytic and simulation methods, and show that estimator properties are poor if the tag reporting rate is estimated (without auxiliary data such as planted tags). We analyzed multiple age class tag return data from a 13-year study on striped bass (Morone saxatilis) and saw clear evidence that selectivity increases with age. Assuming that the tag reporting rate is constant and known, results also demonstrate age dependence of natural mortality rates, and an increase in natural mortality rates from about 1999 coinciding with observation of a bacterial disease in the fish.}, number={2}, journal={JOURNAL OF AGRICULTURAL BIOLOGICAL AND ENVIRONMENTAL STATISTICS}, author={Jiang, Honghua and Pollock, Kenneth H. and Brownie, Cavell and Hightower, Joseph E. and Hoenig, John M. and Hearn, William S.}, year={2007}, month={Jun}, pages={177–194} }
 @article{jiang_pollock_brownie_hoenig_latour_wells_hightower_2007, title={Tag return models allowing for harvest and catch and release: Evidence of environmental and management impacts on striped bass fishing and natural mortality rates}, volume={27}, ISSN={["0275-5947"]}, DOI={10.1577/M06-089.1}, abstractNote={Abstract Catch‐and‐release fisheries have become very important in the management of overexploited recreational fish stocks. Tag return studies, where the tag is removed regardless of fish disposition, have been used to assess the effectiveness of restoration efforts for these fisheries. We extend the instantaneous rate formulation of tag return models to allow for catch and release as well as harvest. The key point of our methods is that, given an estimate of the tag reporting rate, the fishing mortality rate ( F ) is separated into two components: the mortality on harvested fish and the “mortality” on tags (because the tags are removed) of fish released alive. The total fishing mortality rate for untagged fish is the sum of the F s due to harvest and hooking mortality suffered by fish released alive. Natural mortality rates can also be estimated. Both age‐independent models and age‐dependent models are constructed, and the age‐dependent models are illustrated by application to data from a study of striped bass Morone saxatilis in Chesapeake Bay from 1991 to 2003 by the Maryland Department of Natural Resources. By fitting models of the natural mortality rate with limited age and year dependence, we demonstrate an overall decrease in natural mortality rates as fish age and provide evidence of an increase in natural mortality beginning in the late 1990s, when an outbreak of the disease mycobacteriosis is thought to have begun. Our results indicate that fishing mortality is age dependent; selectivity increases up to age 6, when fish appear to be fully recruited to the fishery. There is also evidence of an increase in fishing mortality since 1995, when regulations were relaxed.}, number={2}, journal={NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT}, author={Jiang, Honghua and Pollock, Kenneth H. and Brownie, Cavell and Hoenig, John M. and Latour, Robert J. and Wells, Brian K. and Hightower, Joseph E.}, year={2007}, month={May}, pages={387–396} }