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mizer 2.5.0

This release introduces a change that requires you to upgrade your old MizerParams and MizerSim objects with upgradeParams() or upgradeSim().

External encounter rate

Now the model can include an external encounter rate that represents the rate at which a predator encounters food that is not explicitly modelled. This encounter rate is set with setExtEncounter() or ext_encounter<-() and can be read with getExtEncounter() or ext_encounter(). So this is similar to how external mortality is handled.

Given versus calculated species parameters

You can now use given_species_params() to see the species parameter values that you have explicitly specified and calculated_species_params() to see the species parameter values that mizer has calculated automatically or set to defaults. You can continue to use species_params() to get all species parameters, irrespective of whether they were given or calculated.

You can still set parameter values with species_params<-(), but you can also use the stronger given_species_params<-() which not only sets the values you give but also triggers a re-calculation of the calculated species parameters. Using given_species_params<-() is therefore usually the better option.

New mizer course

There is now a three-part mizer course at with each part consisting of several tutorials, including code and exercises:

  • Part 1: Understand
    You will gain an understanding of size spectra and their dynamics by exploring simple example systems hands-on with mizer.

  • Part 2: Build
    You will build your own multi-species mizer model for the Celtic sea, following our example. You can also create a model for your own area of interest.

  • Part 3: Use
    You will explore the effects of changes in fishing and changes in resource dynamics on the fish community and the fisheries yield. You will run your own model scenarios.

Other improvements

  • Warnings are given if user gives irrelevant species parameter values.
  • Some messages have been converted to warnings and some to signals that are not shown as frequently.
  • Frequent warnings are avoided when length-based and weight-based parameters are both given and are inconsistent. #277
  • Documentation of effort argument in project() is improved.
  • An error message is given if a predation kernel returns negative values or is everywhere zero. #283

Bug fixes

  • When the coefficient h of the maximum intake rate is not given, it is now again given a default value. #282
  • matchGrowth() no longer gives an error when there is no w_inf column. #279

mizer 2.4.1

CRAN release: 2023-04-26

This minor release was made necessary to keep mizer on CRAN after a unit test failed on macOS 13.3 with version 14.3 of the CLT toolchain.

mizer 2.4.0

CRAN release: 2022-12-23

This release introduces a change that requires you to upgrade your old MizerParams and MizerSim objects with upgradeParams() or upgradeSim().

See mizer 2.4.0 blog post

Avoid confusion between maximum size and von Bertalanffy asymptotic size

For an explanation see blog post at

The species parameter that specifies the size at which also the largest fish stop growing is renamed from w_inf to w_max. The parameter w_inf is now reserved for the von Bertalanffy asymptotic size parameter. If you upgrade your existing MizerParams object with upgradeParams() the w_inf column is copied over to the w_max column automatically, but you may want to change the values yourself if they do not currently reflect the maximum size of the species. Otherwise the size distributions predicted by mizer will not match observations.

Set resource abundance rather than carrying capacity

The resource parameters kappa and lambda are now used to set the abundance of the resource in the steady state rather than the carrying capacity, because the latter is not observable.

While tuning the steady state using the steady() function the resource abundance is now being kept fixed at the chosen value. Then the resource dynamics can be switched on later with setResource() without changing the steady state. At that stage you only choose either the resource intrinsic growth rate or the resource carrying capacity and the other is determined by setResource() in such a way that the resource replenishes at the same rate at which it is consumed. If you want to keep the old behaviour and switch off this automatic balancing you have to add the balance = FALSE argument when calling setResource().

You can also choose between semichemostat dynamics resource_semichemostat() or logistic dynamics resource_logistic() or you can write your own function implementing more sophisticated resource dynamics.

The setParams() function no longer includes the arguments for setting the resource parameters. Instead you set these separately with setResource().

Automatically match growth rates

As explained in the blog post at, the von Bertalanffy curves fitted to size-at-age data are not suitable for estimating the size-dependent growth rates in mizer. It is therefore now recommended that instead of von Bertalanffy parameters you supply the age at maturity in the age_mat column of the species parameter data frame. This is then used by mizer to calculate a default for the maximum intake rate parameter h if you do not supply this.

In the past, whenever you changed any model parameters, you needed to re-tune other parameters to keep the growth rates in line with observations. There is now a new function matchGrowth() that automatically scales the search volume, the maximum consumption rate and the metabolic rate all by the same factor in order to achieve a growth rate that allows individuals to reach their maturity size by their maturity age while keeping the feeding level and the critical feeding level unchanged. This function does not however preserve the steady state, so you will need to also call steady() after matching the growth rates.

Other improvements

  • New function steadySingleSpecies() that only balances the size-spectrum dynamics while ignoring multi-species effects. In other words, it calculates the steady-state size spectrum of each species as it would be if the abundance of prey and predators could be kept constant at their current values.
  • plotGrowthCurves() can now superimpose a scatterplot of size-at-age data if you supply this via the new size_at_age argument.
  • New functions calibrateNumber() and matchNumbers() that are like calibrateBiomass() and matchBiomasses() but work with observed numbers instead of observed biomasses.
  • New function age_mat() to calculate the age at maturity from the growth rate and the size at maturity.
  • If an effort vector or effort array contains NA’s, these are now replaced by the default effort value. #230
  • The entries of the interaction matrix and of interaction_resource are no longer restricted to be less or equal to 1. #232
  • If user supplies no row names in the interaction matrix but gives column names then the column names are also used as row names. #247
  • project() now also works when called with a MizerSim object with additional components.
  • steady() now preserves the RDD function in the MizerParams object rather than always setting it to “BevertonHoltRDD”.
  • When averaging abundances over time in plotSpectra() or setInitialValues() the user can now choose geometric averaging with geometric_mean = TRUE.
  • The w_mat25 species parameter is no longer filled in automatically if it is not supplied. This makes it easier to change w_mat without having to change w_mat25 at the same time.
  • compareParams() now also checks the validity of its second argument.
  • Hide the printing of messages about chosen defaults in newTraitParams().
  • Higher values for the info_level argument in newMultispeciesParams() now leads to more messages.
  • Giving more helpful messages in validSpeciesParams(). #136
  • New helper functions l2w() and w2l() for converting between length-based and weight-based species parameters. #258
  • Check that assessor functions for MizerSim slots are called with a MizerSim object.
  • Add style argument to plotDataFrame() to facilitate producing area plots.
  • Add wrap_scale argument to plotDataFrame() to control scaling of axes in faceted plots.
  • plotDiet() can now show diets of several predator species in a faceted plot. #267
  • Change from size to linewidth aesthetic to avoid warnings in new version of ggplot2.
  • Better error message when functions are called with no valid species selected. #251
  • If there are no differences then compareParams() says so clearly.
  • getReproductionLevel() works as long as R_max is set. #252
  • Converted several unit tests to edition 3 of testthat package.
  • Improved documentation for gear_params().
  • Improved defaults can now be implemented while keeping backwards compatibility via defaults_edition(). #186
  • New defaults edition 2: catchability = 0.3 instead of 1, initial effort = 1 instead of 0. #243
  • In defaults edition 2, get_gamma_default() ensures a feeding level of f0 for larvae also if interaction_resource is not equal to 1. #238
  • Set default linecolour and linetype for external mortality.

Bug fixes

mizer 2.3.1

CRAN release: 2022-07-06

  • Resolved conflict in mizerPredRate() between the argument t and the function base::t().
  • Assert that upgradeParams() must be called with a MizerParams object and upgradeSim() with a MizerSim object.
  • Errors changed to warnings in getRequiredRDD()
  • renameSpecies() no longer fails when linecolour and linetype are of different lengths.
  • matchYields() now also works for a model with only a single species.
  • setInitialValues() can now average over a time_range.
  • getSSB(), getBiomass(), getN(), getYieldGear() and getYield() can now be called with a MizerParams object as well as with a MizerSim object. (#200)
  • Updated the shiny app in inst/shiny/selectivity_effects to current mizer version.

mizer 2.3.0

CRAN release: 2021-09-11

New features

  • New plots plotBiomassObservedVsModel() and plotYieldObservedVsModel() contributed by @SamikDatta., together with their plotly counterparts.
  • New calibrateBiomass(), calibrateYield() to set the model scale to agree with total observed biomass or total observed yield. Uses the new scaleModel().
  • New matchBiomasses() and matchYields() will try to adjust the abundances of the species to produce the observed biomasses or yields. See blog post at .
  • There are now accessor and replacement functions for rates. So for example instead of params <- setReproduction(params, maturity = my_maturity) one can simply use maturity(params) <- my_maturity. These are documented together with the setter functions. #213
  • New setMetadata() to add information to a MizerParams object describing the model, for example a title, a description, the author or list of authors, a url and a doi. This will be particularly useful for sharing your models with others
  • New saveParams() for saving a MizerParams object to a file and readParams() for reading it back in. The resulting files can be shared with others who want to run your model.
  • A MizerParams object now registers the mizer version under which the model was last saved. Should the model not be working as expected in the current version of mizer, you can go back to the older version under which presumably it was working. This helps with the reproducibility of your research.
  • A MizerParams object registers the time when it was created and the time it was last modified. See getMetadata(). This helps you keep track of different versions of your model.
  • steady() now has a preserve argument with possible values erepro, R_max or reproduction_level to specify which quantity to preserve. This means that one can continue to use steady() also once one has started to tune the density dependence in reproduction. #208
  • Our website is now using the nice new mizer logo designed by Kira Askaroff (
  • There is a new mizer extension package mizerMR allowing you to include multiple resource spectra in your model.

Small improvements

  • The rownames of gear_params are now set to “species, gear”, so that one can access individual entries with for example gear_params(NS_params)["Cod, Otter", "catchability"]. #212
  • The z0 argument of setExtMort() has been deprecated in favour of ext_mort in order to avoid confusion with the species parameter z0.
  • setColours() and setLinetypes() now issue warnings when invalid values are given and ignores NAs.
  • The experimental comment arguments to the setter functions have been removed. #214
  • The setter functions have a new reset argument which, when set to TRUE will recalculate the rates from the species_, gear_ and resource_params even when custom values had been set. #214
  • The species argument to various functions, which is checked with valid_species_arg(), now does not throw an error even when there is no valid species included. Only a warning is issued. That means that for example plotSpectra(NS_params, species = list(), total = TRUE) is now allowed.
  • getComponent() from the mizer extension mechanism now returns NULL when asked for a non-existent component instead of giving an error. This gives an easy way to check for the existence of a component.
  • The example interaction matrix inter for the North Sea model now has the alternative name NS_interaction, with the old name deprecated.
  • Species added with addSpecies() are now by default given a reproduction level of 1/4 instead of 0, because at the low densities at which they are introduced there would otherwise not be enough density dependence to stabilise them.
  • The size range arguments min_w, max_w, min_l and max_l used in some summary functions and processed by get_size_range_array() accept vector values setting different limits for different species.
  • The resource dynamics function is now also passed the resource_rate and the resource_capacity as arguments, which makes it easier to use them in extension packages.
  • Species names are now always coerced to strings, even if the user gives them as numbers. #202
  • There is a new system for informing the user about how defaults were set by newMultispeciesParams(), #199
  • Many improvements in the documentation.
  • Many small improvements to code quality and testing.
  • Better social media cards, especially for twitter.
  • mizer can be run on binder,

Bug fixes

  • Changing linecolour or linetype in the species parameters now actually changes the linecolours and linetypes as intended.
  • Growth curves calculated with getGrowthCurves() and plotted with plotGrowthCurves() are now correct, and no longer extend above the asymptotic size.
  • plotGrowthCurves() with species_panel = TRUE now respects the species argument to only show growth curves for selected species, it works with a MizerParams object as well as a MizerSim object, and it shows the panels in the correct order. #201
  • Reinstated the example .csv files that were missing from the package because the vignettes are no longer included.

mizer 2.2.1

CRAN release: 2021-08-03

New functionality

  • The setBevertonHolt() function has been expanded with more arguments. It allows you to change the density dependence in reproduction without changing the steady state of your model.
  • The new getReproductionLevel() function tells you at what proportion of their maximum reproduction rate the species are operating in your model.
  • The package now comes with an example MizerSim object NS_sim which holds a simulation of the North Sea model.
  • New function plotDataFrame() allows easier creation of plots.

Bug fixes

  • setInitialValues() correctly preserves the gear names on the initial effort. Thanks to Axel Rossberg.
  • getFMort() correctly passes the t argument on to any custom fishing mortality function you may have written.
  • The legends in the plots now only show the species that are actually included in the plot.

Other improvements

  • Speed improvement in mizerPredMort() suggested by Axel Rossberg.
  • plotSpectra() now only shows those species in the legend that are actually contained in the plot.
  • Updated tests of plots to use new version of vdiffr package.
  • Some improvements to the examples on the help pages.
  • Some functions do more thorough tests of their arguments to give more useful error messages.
  • initialNOther() also works with MizerSim object.
  • When projectToSteady() is called with effort, this effort is now also stored in the initial_effort slot.
  • Improvement to summary() which is now using sprintf() for better formatting and also gives the initial_effort.
  • Improved documentation of size grid and bins.
  • The arguments to project_simple() have been given convenient defaults.
  • The tooltips in the plotly plots have been cleaned up a bit.
  • Species names are now always coerced to strings, even if the user supplies numeric names.
  • Update to the “A Multi-Species Model of the North Sea” tutorial to use projectToSteady().

mizer 2.2.0

CRAN release: 2021-06-24

New functionality

  • New function newSingleSpeciesParams() for creating a single species in a power-law background.
  • New function animateSpectra() creating an animated plot of a simulation.
  • New functions addSpecies(), removeSpecies() and renameSpecies().
  • The parameters for an ecosystem component added with setComponent() can now take any form, they no longer have to be a named list.
  • New argument return_data in the plot’s functions allows to return the data frame used for the ggplot instead of the plot.

Breaking changes

  • steady() no longer switches off the Beverton-Holt density dependence. You can do this manually with setBevertonHolt() with R_factor = Inf.

Bug fixes

  • getYield() now also works with density-dependent fishing mortality. Thanks to James Roger for discovering the problem.
  • The gamma argument now is no longer ignored in newTraitParams() but correctly overrides the f0 argument. #188
  • getFMort() again works correctly when called with a MizerSim object.
  • resource_semichemostat() no longer fail when at some sizes both the resource growth rate and the resource mortality rate are both zero.
  • The default for no_w in newTraitParams() is now always an integer.
  • Problems with different machine precision no longer prompts the error “The w_min_idx should point to the start of the size bin containing the egg size w_min”.
  • `addSpecies() no longer extends grid due to rounding errors.
  • If valid_species_arg() is called with species = NULL and there are no background species then it returns NULL.


  • New tutorial about single-species sizes-spectrum dynamics.
  • Improved documentation of getDiet() and plotDiet().
  • More info on units added to documentation of summary functions.

mizer 2.1.0

CRAN release: 2021-03-21

New functionality

  • New function projectToSteady() to run the full dynamics to steady state.
  • New functions distanceSSLogN() and distanceMaxRelRDI() to measure distance between two states.
  • New function compareParams() to compare two MizerParams objects.
  • Added constantEggRDI() to allow keeping egg densities fixed.
  • When setting custom parameter arrays with the setter functions, it is now easy for the user to document that via “comment” arguments. #177
  • New function customFunction() to allow users to overwrite mizer functions.
  • Now if the effort is specified as a named vector giving values only for some gears, the effort for the remaining gears is assumed to be zero.
  • Added the possibility to see the output of plotGrowthCurves as a panel of species with their respective Von Bertalanffy curves

Breaking changes

  • By default, the functions plotPredMort() and plotFMort will stop displaying mortality values past the species’ asymptotic size. The argument
    all.sizes allows you to continue to show these values.

Bug fixes

  • getFMort() now passes time argument correctly. #181
  • validEffortArray() now sets the dimnames correctly. #173

Code improvements

  • Using lifecycle package to indicate status of some functions and arguments as ‘experimental’ or ‘deprecated’.
  • Improved error handling in setFishing(). #172
  • Made use of vdiffr conditional, as required by § of ‘Writing R Extensions’.
  • Consistent handling of species argument in mizer functions, via the new valid_species_arg() function. #170
  • More tests. Test coverage now at 94.71%
  • Improved argument checking in setInitialValues()
  • Throwing error if min_w_pp is larger than min_w
  • Improved documentation of functions for getting fishing mortality.

mizer 2.0.4

CRAN release: 2020-08-30

Bug fixes

  • The value of t passed to dynamics functions has been corrected.
  • setReproduction() now correctly sets the the total proportion psi when the maturity proportion is changed.


  • The way times are set in project() has been simplified. They are now either set by the arguments t_start, t_max and t_save or by the dimension names of the effort array.
  • Renamed setRmax() to setBevertonHolt() and allow it to work on an arbitrary MizerParams object. The old name setRmax() is still available as alias.
  • mizerFMort() now can also use the abundances and the rates e_growth and pred_mort. This is useful for example for implementing balanced harvesting.
  • A calculation in the numeric scheme has been simplified.
  • gear_params is allowed to have zero rows.
  • In validGearParams() the species name is used as gear name in case gear_name is NA.
  • validGearParams() ensures that all required arguments of the selectivity function are supplied and checks validity of species names.
  • species_params()<- suppresses warnings.
  • When steady() fails because RDI is zero it gives a meaningful error message.
  • newCommunityParams() now protects its zero investment in reproduction with a comment.
  • The default maturity ogive is truncated at proportions smaller than 1e-8.
  • A new helper function valid_species_arg() checks validity of species selection arguments.
  • upgradeParams() can now also upgrade old MizerParams objects that do not have a consistent initial_effort.
  • A new helper function validParams() validates a MizerParams object and automatically upgrades it with upgradeParams() if necessary.
  • Old MizerParams objects are updated automatically when used in plot functions, rate functions, summary functions or in project() or steady(), #163.
  • New function getRates() to calculates all rates and collects them in a list.
  • steady() with return_sim = TRUE now creates the MizerSim object the same way as project(), namely with the original values in the first time slot.
  • Added documentation for species_params(), gear_params() and resource_params().
  • Numerous small improvements to documentation.

mizer 2.0.3

CRAN release: 2020-07-28

Bug fixes

  • Correct handling of shiny progress bar in project().


  • Consistently passing the time argument to the rate functions. This will allow extensions to implement time-dependent rates.
  • Passing growth and mortality rate to RDI function.
  • Simplified the getRates() functions by removing the arguments that passed in other rates. Instead the required rates are now always calculated within these functions.
  • Improved documentation of rate functions and of how to register your own rate functions.
  • In validGearParams() handle NAs more gracefully and check that there are no duplicates.
  • Updated hake-mullet selectivity demonstration shiny app.
  • Improved user documentation in several places.

mizer 2.0.2

CRAN release: 2020-06-08

Bug fixes

  • Time passed to rate functions is now the actual simulation time, not the time elapsed since start of simulation.
  • upgradeParams() works also on params objects that were created with a development version of mizer.
  • When upgrading an older params object, upgradeParams() does a better job at guessing the value for w_pp_cutoff.
  • getFeedingLevel(), getPredMort(), setInitialValues() and steady() now work also when model has extra components.
  • The critical feeding level lines are now mentioned in the legend of plotFeedinglevel() when called with include_critical = TRUE, see #162.
  • Avoid annoying warnings from dplyr package when species_params is a tibble.

Name changes

Minor enhancements

  • Some improvements to documentation.
  • More unit tests.
  • Uses less memory when time step is very small by not creating array with effort values at each time step.
  • getDiet() also takes into account possible contributions by user-defined other components.
  • In extension mechanism, now the name of a component is also passed to the functions implementing dynamics, encounter and mortality.
  • If project() is called with t_max < t_save then t_save is automatically reduced so that the result at t_max will get saved.
  • Start showing progress bar earlier during project().
  • New helper function project_simple() that projects a given number of time steps. This might be useful to extension writers.
  • The ... argument to project() is passed on to the dynamics and rate functions.
  • steady() runs faster by using project_simple().
  • Documentation on mizer website now has a search bar.

mizer 2.0.1

CRAN release: 2020-05-05

Bug fixes

Name changes

Some inconsistencies in the choice of names for parameters was removed by renaming

  • interaction_p -> interaction_resource
  • r_resource -> resource_rate
  • K_resource -> resource_capacity

Minor enhancements

  • New functions other_params()<- and other_params() for setting and getting other parameters, for example to be used in user-defined rate functions.
  • setInitialValues() also sets initial_effort. #157

mizer 2.0.0

CRAN release: 2020-04-04

This is a major new release with many new features, an internal refactoring of the code and a new extension mechanism.

Backwards compatibility

Nevertheless this version of mizer is almost fully backwards compatible with version 1.0 with the exception of bug fixes and the following breaking changes:

  • The previous version of mizer inconsistently truncated the lognormal predation kernel when calculating predation but not when calculating encounter. The new version never truncates. That leads to very small differences in simulation results.
  • Removed the print_it argument from plot functions.
  • plotFeedingLevel() now only plots the values within the size range of each species. If for some reason you want the old plots that show a feeding level also for sizes that the fish can never have, you need to supply an argument all.sizes = TRUE.
  • The way the density-dependence in the reproduction rate is set has changed, see RDD argument in setReproduction().
  • The sex_ratio argument has been removed from getRDI() and getRDD().
  • The set_scaling_model() function has been removed because such models can now be set up with newTraitParams() with the options perfect_scaling = TRUE and egg_size_scaling = TRUE.
  • The functions display_frames(), addSpecies(), setBackground() and retuneAbundance() have been removed to the “mizerExperimental” package (
  • During runs of project() a progress bar is displayed by default. You can turn this off with the option `progress_bar = FALSE.
  • Throughout mizer the term “plankton” has been replaced by “resource”, which affects the labelling of the resource spectrum in plots.

Setting up models

The new functions

replace the old functions set_community_model(), set_trait_model() and MizerParams(), which are now deprecated. The new functions choose better default values, in particular for metabolic rate and maximum intake rate.

Setting model parameters

After setting up a mizer model, it is possible to change specific model parameters with the new functions

The new function setParams() is a wrapper for all of the above functions and is also used when setting up a new model with newMultispeciesParams(). (#51)

The documentation for these functions serves to explain the details of the mizer model.

Along with these setter functions there are accessor functions for getting the parameter arrays: getPredKernel(), getSearchVolume(), getInteraction(), getMaxIntakeRate(), getMetabolicRate(), getExtMort(), getMaturityProportion(), getReproductionProportion(), getCatchability(), getSelectivity(), getResourceRate(), getResourceCapacity(), getResourceParams(), getResourceDynamics(),

  • Setting of the maximum reproduction rate has been separated out into new function setRmax().

Initial Values and steady state

The MizerParams object now also contains the initial values for the size spectra. This is particularly useful if the model has been tuned to produce the observed steady state. The new function steady() finds a steady state for a model and sets it as the initial value. The initial values can be accessed and changed via functions initialN() and initialNResource(). The initial values can be set to the final values of a previous simulation with setInitialValues().

The MizerParams object now has a slot initial_effort that specifies the initial fishing effort to which the steady state has been calibrated.

Extension mechanisms

Mizer now has an extension mechanism that allows other R packages to be written to generalise the mizer model. See setRateFunction() and setComponent(). This mechanism is still experimental and may change as we gain experience in writing extensions for mizer.


  • Every plot function now has a plotly version that makes the plot interactive using the plotly package. So for example there is plotlyBiomass() as the plotly version of plotBiomass(), and so on.
  • New plotGrowthCurves() plots growth curves and compares them to the von Bertalanffy growth curve.
  • New plotDiet() plots the diet composition as a function of predator size.
  • New highlight argument to all plot functions that display curves for multiple species. Displays highlighted species with wider lines.
  • In the legends of all plots the species are now consistently ordered in the same way as in the species parameter data frame.
  • All plot functions that are not time-resolved now accept also a MizerParams object as an alternative to the MizerSim object to plot the initial state.
  • New plot() method for MizerParams object to plot the initial state.
  • Avoiding duplicate graphs in R Markdown documents.
  • New argument include_critical in plotFeedingLevel() allows to show also the critical feeding level.
  • New wlim argument to plotSpectra() in analogy to the existing ylim argument to limit the w range in the plot.
  • The colours used in plot functions can be set with setColours().
  • The default line type is solid but this can be changed via the setLinetypes() function.
  • Use colour and linetype for plots irrespective of the number of species.

General predation kernel

  • Users can now replace the lognormal function in the predation kernel by a function of their choice, allowing a differently shaped kernel for each species.
  • New box_pred_kernel() implements a box-shaped kernel as an alternative to the default lognormal_pred_kernel().
  • New power_law_pred_kernel() implements a power-law kernel with sigmoidal cutoffs at both ends. This is suitable for filter feeders.
  • Users can sets a predation kernel that has a predator-size-dependent predator/prey mass ration (via setPredKernel()). Mizer automatically falls back on the old non-FFT code to handle this. (#41)
  • New getPredKernel() returns the full 3-dimensional predation kernel array, even when this is not stored in MizerParams object.

New gear setup

Now it is finally possible to have several gears (or fleets) targeting the same species. The information is set up via a new gear_params() data frame. See setFishing() for details.

Other new functions

  • There are now accessor functions for all slots in the MizerParams and MizerSim objects. For example to get at the size grid and its spacing you would now use w(), w_full(), dw(), dw_full().
  • New upgradeParams() and upgradeSim() can upgrade objects from previous versions of mizer so they work with the new version.
  • New getDiet() calculates the diet of predators. (#43)
  • Alternative functions RickerRDD() and SheperdRDD() for density-dependence in reproduction, as well as noRDD() and constantRDD().
  • New gear selectivity function double_sigmoid_length() allows modelling of escape of large individuals.
  • New gear selectivity function sigmoidal_weight() is weight-based trawl selectivity function. (Ken H Andersen)
  • New getGrowthCurves() calculates the growth curves (size at age).
  • New mizerRates() calculates all the rates needed in the model and collects them in a list.
  • A convenience function times() to extract the times at which simulation results are saved in a MizerSim object.
  • Convenience functions finalN(), finalNResource() and finalNOther() as well as idxFinalT() to access the values at the final time of a simulation.
  • New function getCriticalFeedingLevel() returns the critical feeding level for each species at each size.
  • Mizer reexports the melt() function from the reshape2 package which allows users to convert the arrays returned by mizer functions into data frames that can be used for example in ggplot2 and plotly.
  • validSpeciesParams() checks validity of species parameter data frame and sets defaults for missing but required parameters.

Other new features

  • The allometric exponents n, p and q as well as the feeding level f0 can now be set at the species level via columns in species_params.
  • The critical feeding level fc can now be specified as a species parameter and will be used to calculate the metabolic rate parameter ks if it is not supplied.
  • project() now shows a progress bar while a simulation is running. Can be turned off with progress_bar = FALSE argument.
  • Satiation can be switched off by setting the maximum intake rate to Inf.
  • Users can now set their own resource dynamics instead of the default resource_semichemostat().
  • Different species can interact with resource with different strengths, or not feed on resource at all, controlled by an interaction_resource column in the species parameter data frame.
  • The steepness of the maturity ogive can now be controlled via a w_mat25 column in the species parameter dataframe, which gives the size at which 25% of the individuals of a species are mature.
  • The scaling exponent for the allocation of energy into reproduction can now be set via the m column in the species parameter data frame.
  • project() can now continue projection from last time step of a previous simulation if the first argument is a MizerSim object. The new append argument then controls whether the new results are appended to the old.
  • Values for minimum resource size, and minimum and maximum consumer sizes are set automatically if not provided in newMultispeciesParams().
  • Default values for species parameters are used for missing values within a column in the species parameter data frame, not only if the column is missing entirely.
  • Rate functions take defaults for their n, n_pp and n_other arguments from the initial values in the params argument.
  • New perfect_scaling argument allows newTraitParams() to produce a perfectly scale-invariant model.
  • A new ext_mort_prop argument in newTraitParams() allows the inclusion of external mortality.
  • Added a data fileNS_params with the North Sea model MizerParams object.
  • Comments can be added to MizerParams objects and any of their slots. Slots that have comments are protected from being overwritten with allometric defaults.
  • Gear selectivity functions now can use the species parameters.


  • Mizer now has a documentation website at for the latest released version and at for the development version. (#48)
  • The help pages of mizer functions has been extended massively, see for example the help for newMultispeciesParams().
  • The vignette chapters are shown as pages on the website.
  • The html help pages for plotting functions now show example plots.
  • Clarified that mizer uses grams and years as size and time units and is agnostic about whether abundances are per area, per volume or per study area. (#42)
  • Added a tutorial on using ggplot2 and plotly with mizer.
  • Added a tutorial on working with git and GitHub for mizer development.
  • Added a FAQ page for developers.
  • Added a unit test to automatically run a spell check on documentation.
  • Renamed some functions for consistency and to make them easier to understand, but kept old names as aliases for backwards compatibility:
  • Renamed maximum reproductive rate from r_max to R_max.
  • Updated list of publications (@Kenhasteandersen)
  • Using R Markdown in all roxygen comments.

Bug fixes

  • In getSSB(), the calculation of the spawning stock biomass is done correctly using the maturity ogive instead of the proportion of energy allocated to reproduction. (#47)
  • The fast FFT method and the old method for calculating integrals now give the same numerical results. (#39)
  • getEncounter() and getPredRate() now set names on the returned arrays.
  • Resource carrying capacity for scale-invariant model is calculated in a way that reduces rounding errors.
  • Avoids potential problems with negative numbers due to numerical errors.
  • Consistently cutting off predation kernel at 0 and beta + 3 sigma.
  • The ylim argument is not handled correctly in plots.
  • display_frame() is now exported.
  • plotGrowthCurves() and getGrowthCurves() also works when there is only a single species
  • t_start argument in project() is used correctly
  • times are not truncated at 3 significant figures, because that would not allow something like 2019.
  • get_initial_n() gets values for n and q from params object
  • summary() of MizerParams object reflects the number of non-empty resource bins. (@patricksykes)

Under the hood

  • Now using vdiffr package to test plots.
  • Converted all S4 methods to functions to decrease the learning curve for new developers.
  • The calculation of defaults is now handled by new get_gamma_default(), get_h_default() and get_ks_default(), making it easier to change or extend these in the future.
  • Helper function set_species_param_default() makes it easier to set default values for species parameters.
  • Simplified FFT calculations are more readable.
  • Using @inherit functionality of roxygen2 to reduce duplication in roxygen documentation.
  • Using `@family’ to group function documentation pages.
  • The helper functions are now documented and exported.
  • getPhiPrey() is replaced by getEncounter() which now returns the full encounter rate, including the contribution from other components. Even in the absence of other components, getEncounter() differs from the old getPhiPrey() because it includes the search volume factor.
  • Changed naming convention: user-facing function names are now in camelCase.
  • Consistently use params to refer to an argument of class MizerParams, sim to refer to an argument of class MizerSim, and object to an argument that can be either.
  • Updated the calls to setClass() to follow the new guidelines, replacing representation by class and removing prototype and validity.
  • Added numerical tests.
  • Using assert_that to check arguments to functions more often.
  • Argument shiny_progress renamed to progress_bar because they control any type of progress bar.
  • In documentation renamed “background” and “plankton” consistently to “resource”.
  • Using outer() instead of tapply() where possible to improve readability.
  • Avoiding use of hasArg() and anyNA() because they were not available in R 3.1
  • A more robust code for setting up the size grids.
  • Improved consistency of when to issue warnings and when to issue messages.
  • Split large code files into smaller files.
  • Changes to MizerParams class:
    • Merged @std_metab and @activity slots into a single @metab slot.
    • Moved @w_min_idx out of @species_params into its own slot.
    • Added slot @maturity to hold the maturity ogive.
    • Added slot @pred_kernel to hold predation kernel if it has variable predator/prey ratio.
    • Added slot @resource_dynamics to allow user to specify alternative resource dynamics.
    • Added slot @gear_dynamics to species to be targeted by multiple gears.
    • Added slot @ft_mask that is used when calculating predation rates using the Fourier transform method.
    • Added slot @rates_funcs to allow mizer extensions to replace mizer rate functions with their own rate functions.
    • Instead of the function in the slot @srr we now have the name of the function in @rate_funcs$RDD, see #91.
    • Added slots @other_dynamics, @other_params, @other_encounter, @other_mort and @initial_n_other to allow mizer extensions to add more ecosystem components.

mizer 1.0.1

CRAN release: 2019-01-27

  • Now compatible with older versions of R > 3.1.0.
  • Skipping a test on CRAN that fails on some machines with different precision.
  • Fixing minor typos in documentation.

mizer 1.0

CRAN release: 2018-05-01

  • Fixed bugs in how the start time of a simulation was handled. This leads to small corrections, so that the output of this version is slightly different from previous versions.
  • Introduced a scale-invariant trait-based model, set up with set_scaling_model(), see section 12 in the vignette.
  • Added a function that adds news species to a scale-invariant background, and computes an approximately steady state close to the power law, see section 13 in the vignette.
  • Created an example shiny app to allow people to use mizer through a web browser without having to install mizer. The app explores the effect of more selective fishing gear in a case study.
  • Improvements to plots:
    • Added units to axes
    • Added function for plotting growth curves
    • PlotYield() no longer fails when species names are numbers or when a species abundance is zero
    • Added a total parameter to several plot functions to add the curve for the total community (sum over all species and resource)
    • Added a species parameter to all plot functions to allow for only a selection of species to be plotted
    • Allow the number of ticks on y-axis in biomass plot to be controlled
  • Allow for size- and species-dependent background death.
  • Add @initial_n and @initial_n_pp slots to MizerParams class.
  • Now checking that effort times are increasing.
  • Corrections in the documentation.
  • Improvements to the vignette.
  • Add a test of the numeric solution against an analytic solution.

mizer 0.4

CRAN release: 2017-12-14

  • Improvements made to the speed by evaluating convolution sums via fft, removing the bottlenecks in getPhiPrey() and getPredRate().
  • Using C++ for the inner loop in the project method for extra speed.
  • Minor corrections to vignette and documentation to bring them into alignment and to document the new home on GitHub and new maintainers.

mizer 0.3

  • Improvements made to the speed of the simulations. Remaining bottle necks are the sweep statements in getPhiPrey() and getPredRate().
  • Moved tests to new suggested folder.
  • Minor changes to documentation to pass new check requirements.

mizer 0.2

CRAN release: 2014-04-16

  • Release to coincide with the submission of the MEE paper. No major changes. Just minor bug fixes.

mizer 0.1

CRAN release: 2013-10-08

  • Beta release - just about works but still some gremlins to sort out. There are a number of features I’d like to add in the coming releases.