Adding size structure in the model is unfortunately a little more complicated than just fitting the model to the data over an additional dimension. Because of survey size selectivity, small fish are very rare, so the data makes it look like there are more adults than small juveniles. Of course, that's not biologically possible, and the reverse should be true.
In other words, at the moment the model is trying to predict a population with few recruits and many adults, which we clearly need to fix. @DanOvando suggested rescaling the survey data to account for size selectivity, which I'll look into. I also think we may need to model presence and abundance separately (i.e. a delta model) so the population model is just trying to predict positive counts rather than tons of zeroes.
Adding size structure in the model is unfortunately a little more complicated than just fitting the model to the data over an additional dimension. Because of survey size selectivity, small fish are very rare, so the data makes it look like there are more adults than small juveniles. Of course, that's not biologically possible, and the reverse should be true.
In other words, at the moment the model is trying to predict a population with few recruits and many adults, which we clearly need to fix. @DanOvando suggested rescaling the survey data to account for size selectivity, which I'll look into. I also think we may need to model presence and abundance separately (i.e. a delta model) so the population model is just trying to predict positive counts rather than tons of zeroes.