Estimation of tag reporting rates in agestructured multicomponent fisheries where one component has observers

1999 ◽  
Vol 56 (7) ◽  
pp. 1255-1265 ◽  
Author(s):  
William S Hearn ◽  
Thomas Polacheck ◽  
Kenneth H Pollock ◽  
Wade Whitelaw
Keyword(s):  
Maximum Likelihood ◽  
Maximum Likelihood Estimators ◽  
Bluefin Tuna ◽  
Mortality Rates ◽  
Reporting Rate ◽  
Natural Mortality ◽  
Integrated Likelihood ◽  
Age Dependent ◽  
Southern Bluefin Tuna ◽  
Reporting Rates

For many tagging experiments, it is vital that fishers find and report all tags to scientists. If not, the tag reporting rate needs to be estimated so that fishing and natural mortality rates can be estimated. One way to estimate this rate is to have one fishery component (e.g., with observers) report every tag found from all fish that it catches. If the numbers of fish caught by all fishery components are also known and the tagged fish are mixed with the population (or subpopulation) being harvested, then one can estimate the reporting rate of underreporting fishery components. This procedure can fail if data are pooled over ages. We obtain maximum likelihood estimators for the reporting rate for each age and (or) each fishery component. We show how to estimate reporting rates if mixing of tagged and untagged fish occurs with some delay. We also obtain overall age-dependent reporting rates, which combine reporting rates from all components of the fishery. Our likelihood is part of an integrated likelihood that allows estimation of age-dependent fishing and natural mortalities in addition to the reporting rates. Our procedures are illustrated with some southern bluefin tuna (Thunnus maccoyii) tagging data.

scholarly journals Simulation testing the robustness of a multiregion, tag-integrated assessment model that exhibits natal homing and estimates natural mortality and reporting rate

2017 ◽  
Vol 74 (11) ◽  
pp. 1930-1949 ◽  
Author(s):  
Matthew T. Vincent ◽  
Travis O. Brenden ◽  
James R. Bence
Keyword(s):  
Reporting Rate ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
Model Complexity ◽  
Natural Mortality ◽  
Movement Rates ◽  
Natal Homing ◽  
Accuracy And Precision ◽  
Simulation Testing ◽  
Reporting Rates

The influence of model complexity on integrated tagging and catch-at-age analysis (ITCAAN) parameter estimation is poorly understood for populations exhibiting natal homing. We investigated ITCAAN performance under varying levels of movement, degree of similarity in population productivities, data quality, spatial complexity in parameterization, and whether natural mortality and (or) reporting rates were fixed at actual values, estimated, or misspecified. Dynamics of four populations with natal homing that intermixed during periods of harvest were simulated based on Lake Erie walleye (Sander vitreus). Our results suggest, when high-quality tagging data are available, ITCAAN models are able to simultaneously estimate movement rates, natural mortality, and tag reporting rates, though accuracy and precision of model estimates will decrease with greater model complexity and fewer tags released. Additionally, ITCAAN models may have difficulty estimating individual population abundances under certain movement rates when population productivities are vastly different. ITCAAN models that estimate natural mortality and reporting rates may perform best with similar sized populations and when data are available to assist the estimation of reporting rates.

scholarly journals Analysis of an age-dependent SI epidemic model with disease-induced mortality and proportionate mixing assumption: the case of vertically transmitted diseases

2004 ◽  
Vol 2004 (3) ◽  
pp. 235-254 ◽  
Author(s):  
M. El-Doma
Keyword(s):  
Stability Analysis ◽  
Epidemic Model ◽  
Special Form ◽  
Transmitted Disease ◽  
Mortality Rates ◽  
Steady States ◽  
Natural Mortality ◽  
Force Of Infection ◽  
Threshold Conditions ◽  
Age Dependent

An SI epidemic model for a vertically as well as horizontally transmitted disease is investigated when the fertility, natural mortality, and disease-induced mortality rates depend on age and the force of infection corresponds to a special form of intercohort transmission called proportionate mixing. We determine the steady states and obtain explicitly computable threshold conditions, and then perform stability analysis.

scholarly journals Estimating natural and fishing mortality and tag reporting rate of southern rock lobster (Jasus edwardsii) from a multiyear tagging model

2001 ◽  
Vol 58 (12) ◽  
pp. 2490-2501 ◽  
Author(s):  
S D Frusher ◽  
J M Hoenig
Keyword(s):  
Mortality Rates ◽  
Fishing Effort ◽  
Reporting Rate ◽  
Standard Errors ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Rock Lobster ◽  
Relative Standard ◽  
Jasus Edwardsii ◽  
Mortality Estimates

Fishing and natural mortality rates and tag reporting rate for rock lobsters (Jasus edwardsii) in northwest Tasmania, Australia, were estimated using multiyear tagging models. These estimates are necessary for assessment of the resource. Several models were examined that had either two or three tagging events each year, and either combined sexes or kept sexes separate. The model that best described the dynamics of the fishery utilized three tagging events within a year. The year was divided into discrete periods and, within each year, fishing effort and duration of period were used to apportion fishing and natural mortalities, respectively, to the periods. The separation of fishing mortalities by sex was not found to improve the models. Although high (1.0–1.2·year–1), the instantaneous fishing mortality estimates were comparable to estimates obtained from other methods and the relative standard errors were low. Reporting rate estimates were also precise and indicated a lack of participation by the fishing industry. Estimates of natural mortality were low (0.00–0.02·year–1) but imprecise.

Pre- and post-season tagging models: estimation of reporting rate and fishing and natural mortality rates

1998 ◽  
Vol 55 (1) ◽  
pp. 199-205 ◽  
Author(s):  
William S Hearn ◽  
Kenneth H Pollock ◽  
Elizabeth N Brooks
Keyword(s):  
Mortality Rates ◽  
Reporting Rate ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Special Cases ◽  
Simulation Results ◽  
Return Data

Brownie et al. (1985, U.S. Fish Wildl. Serv. Resour. Publ. 156, p. 159) presented models for tag returns from multiple taggings of animals when tagging is done twice per year. Here, we present a reformulation of their model suitable for pre- and post-season fishery tag return studies. Under this model, it is possible to estimate fishing mortality, natural mortality, and reporting rate from the tag return data alone. (Under once-a-year tagging models, the reporting rate usually has to be estimated externally.) We consider two special cases: (i) a pulse fishery and (ii) a continuous fishery over part of the year. An artificial example and simulation results are presented to illustrate the methodology and the properties of the various estimators. Unlike for catch-based methods, the correlation between estimates of fishing mortality and natural mortality is moderate. While pre- and post-season tagging studies are likely to be difficult to run in practice, other methods of estimating reporting rate are also difficult to implement, and therefore, this approach may prove quite useful, especially in fisheries that have heavy exploitation rates.

A combined telemetry – tag return approach to estimate fishing and natural mortality rates of an estuarine fish

2009 ◽  
Vol 66 (8) ◽  
pp. 1230-1244 ◽  
Author(s):  
Nathan M. Bacheler ◽  
Jeffrey A. Buckel ◽  
Joseph E. Hightower ◽  
Lee M. Paramore ◽  
Kenneth H. Pollock
Keyword(s):  
Mortality Rate ◽  
Seasonal Pattern ◽  
Mortality Rates ◽  
Sciaenops Ocellatus ◽  
State Agency ◽  
Estuarine Fish ◽  
Joint Analysis ◽  
Natural Mortality ◽  
Combined Model ◽  
Reporting Rates

A joint analysis of tag return and telemetry data should improve estimates of mortality rates for exploited fishes; however, the combined approach has thus far only been tested in terrestrial systems. We tagged subadult red drum ( Sciaenops ocellatus ) with conventional tags and ultrasonic transmitters over 3 years in coastal North Carolina, USA, to test the efficacy of the combined telemetry – tag return approach. There was a strong seasonal pattern to monthly fishing mortality rate (F) estimates from both conventional and telemetry tags; highest F values occurred in fall months and lowest levels occurred during winter. Although monthly F values were similar in pattern and magnitude between conventional tagging and telemetry, information on F in the combined model came primarily from conventional tags. The estimated natural mortality rate (M) in the combined model was low (estimated annual rate ± standard error: 0.04 ± 0.04) and was based primarily upon the telemetry approach. Using high-reward tagging, we estimated different tag reporting rates for state agency and university tagging programs. The combined telemetry – tag return approach can be an effective approach for estimating F and M as long as several key assumptions of the model are met.

scholarly journals A novel tag-recovery model with two size classes for estimating fishing and natural mortality, with implications for the southern rock lobster (Jasus edwardsii) in Tasmania, Australia

2003 ◽  
Vol 60 (5) ◽  
pp. 1075-1085 ◽  
Author(s):  
Robert J. Latour ◽  
John M. Hoenig ◽  
Daniel A. Hepworth ◽  
Stewart D. Frusher
Keyword(s):  
A Priori ◽  
Survival Rates ◽  
Mortality Rates ◽  
Reporting Rate ◽  
Natural Mortality ◽  
Rock Lobster ◽  
Jasus Edwardsii ◽  
Size Groups ◽  
Lobster Fishery ◽  
Recovery Models

Abstract Multi-year tag-recovery models can be used to derive estimates of age- and year-specific annual survival rates and year-specific instantaneous fishing and natural mortality rates. The latter, which are often of interest to fisheries managers, usually can only be estimated when the tag-reporting rate (λ) and the short-term tag-induced mortality and tag-shedding rate (φ) are known a priori. We present a new multi-year tagging model that permits estimation of instantaneous mortality rates independently of φλ, provided tagged animals from two adjacent size groups are released simultaneously. If the two size groups comprise animals just above and below the minimum harvestable size limit, then it is possible to estimate year-specific instantaneous fishing and natural mortality rates after 2 yr of tagging and tag-recovery. In addition to the standard assumptions of multi-year tag-recovery models, it is necessary to assume that recruited animals have equal selectivity, pre-recruited animals become fully recruited in 1 or 2 yr, and the size groups experience the same natural mortality rate. Applicability of the model to the Tasmania southern rock lobster (Jasus edwardsii) fishery is evaluated using a simulation model and parameters based on data from the lobster fishery; assumptions are likely to be met and precision should be adequate if at least 1000 animals are tagged per year in each size group.

Estimating exploitation rates of migrating yellowtail flounder (Limanda ferruginea) using multistate mark–recapture methods incorporating tag loss and variable reporting rates

2009 ◽  
Vol 66 (8) ◽  
pp. 1245-1255 ◽  
Author(s):  
Laura Cowen ◽  
Stephen John Walsh ◽  
Carl James Schwarz ◽  
Noel Cadigan ◽  
Joanne Morgan
Keyword(s):  
Mortality Rates ◽  
Assessment Model ◽  
Natural Mortality ◽  
Mark Recapture ◽  
Yellowtail Flounder ◽  
Limanda Ferruginea ◽  
Tag Loss ◽  
Model Migration ◽  
Reporting Rates ◽  
Mortality Estimates

Multistate mark–recapture models can be used to model migration through stratification of the study area into states (location). However, the incorporation of both tag loss and reporting rates is new to the multistate paradigm. We develop a migration model for fish that incorporates tag loss and reporting rates but has as its primary purpose the modelling of exploitation and natural mortality rates. This model is applied to a 2000–2004 yellowtail flounder ( Limanda ferruginea ) tagging study on the Grand Bank of Newfoundland, Canada. We found that exploitation rates varied over both location and years, ranging from 0.000 to 0.047. Migration into the centre of the Grand Bank (state 2) was three times higher than migration out. The estimate of the instantaneous annual natural mortality rate was 0.256, which is equivalent to an annual survival rate of 0.880. We describe how these mortality estimates will be quite valuable in specifying an assessment model for this stock.

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