Open vbartolino opened 8 years ago
I think WeigthJones, and other consumption dependent growth functions, should be usable for your case. Similarly otherfood consumption can be estimated as a realistic time-series but I don't think that is not necessary, you can work with fixed proportions and/or specific consumption intervals. This "should" all be estimable, given that you have some data that indicates starvation such as mean weight at age.
I'm still struggling with the implementation of the weightJones growth model for the cod model. Weight-at-age data and ALK haven't helped much so far...
Is there any chance I can compare the consumption and growth related parameters that I'm using (some from literature, other estimated from evacuation rate models) with ie the cod parameters used in the cod-shrimp model? Or do you have any other suggestion? I've included my parameters at the bottom.
I think that the main problem are the growth parameters, but because I'm limitedly confident on the consumption part, I do not know where the problem is...
prey preference (eq. 4.21)
pref = 1 (for all preys)
max consumption (eq. 4.22) calculated using Baltic cod data and Jones (1978)
m0 = 0.661 ; m1 = 0 ; m2 = 0 ; m3 = 2.6549
half-feeding parameter (eq. 4.23)
H = 0
growth in weight (eq. 4.7) derived by adjusting estimates from Jones 1978 converting into KJoules and for dt=90 days
q0 = 14.976 ; q1 = 0.15 ; q2 = 56.843 ; q3 = 0.65 ; q4 = 0.081 ; q5 = 0
(eq. 4.8-9) params selected to fix f(r) = 1
p0 = 0 ; p1 = 0 ; p2 = 0 ; p3 = 0.5 ; p4 = 0.5 ; p5 = 1
length implementation (eq. 4.10)
p6 = 7 * 1e-6 ; p7 = 3
Your guess is as good as mine, the Icelandic cod-shrimp model doesn't use the Jones growth function so your are flipping a switch in Gadget that hasn't been used for aaaages (this inspires confidence I'm sure ;) ). But when I think about it there is a crucial likelihood component missing in Gadget and that is a length-based catchstatistic (instead of age).
It would be still helpful having some "good" cod consumption parameters to compare with.
ie. those used in the cod-shrimp model (or any other solid cod-multispecies model).
Trenkel et al. (2004) assumed m0 = 6.93e-05
for cod in the Celtic Sea which is on a completely different scale compared to what I've estimated (see plot below). Am I missing something?
Food availability and consumption are highly relevant for cod growth in the Baltic. To account for this feedback in my cod-sprat-herring model I'm using the 'WeightJones" growth for cod.
In the manual under consumption I can read that "The summation over preys is over all preys that the predator consumes, including non-modelled prey, given as otherfood”
Questions: