Dear SS experts,
I am fitting a model with simulated data in which all biological
parameters (growth, M, etc.) are fixed. The observed fleet selectivity
and LFDs are consistent and the SSB trend is similar to the simulated
reference one. However, I think there is a problem with the scale of
the model.
As I have seen trough different trials, the model can explain the
catches with a low F and a high SSB but it could also explain the same
catches with a higher F and a lower SSB.
In the current best model, the estimated annual F values are quite
low (0-0.06) and the estimated SSB displays huge values (around e+07),
while the simulated reference B0 value is around e+06.
Following some pieces of advice in the forum, I have R0 in phase 1
(M and steepness are fixed). In addition, I tried to set a lower phase
for DN selectivity slopes (p3 & p4 from 6 to 4) but then the
estimated selectivity shapes were not good anymore.
If anyone knows has an idea about how could I solve this problem I
would really appreciate it.
Many thanks in advance.
Fran