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13. Nile Perch Population Dynamics in Lake Victoria:
fishable_mass [Cohorts] =
NP_mass[Cohorts]*fished[Cohorts]
fishable_number [Cohorts] =
fished[Cohorts]*NP_number[Cohorts]
Mean-perch_weight = ARRAYMEAN(Fishwt[*])
seinable_mass[Cohorts] =
NP_mass[Cohorts]*Seined[Cohorts]
seinable_number[Cohorts] =
NP_number[Cohorts]*Seined[Cohorts]
Total_fishable_mass = ARRAYSUM(fishable_mass[*])
Total_fishable_number = ARRAYSUM(fishable_number[*])
Total-perch_biomass = ARRAYSUM(NP_mass[*])
Total-perch_number = ARRAYSUM(NP_number[*])
Total_seinable_mass = ARRAYSUM(seinable_mass[*])
Total_seinable_number = ARRAYSUM(seinable_number[*])
{total number of fish of seinable size}
Prey Populations
hap_standing_stock(t) = hap_standing_stock(t-dt) +
(hap_growth-hap_consumption) * dt
INIT hap_standing_stock = 4*(10A13) {joules of haps
standing stock}
INFLOWS:
hap_growth = (hap_R*hap_standing_stock)*(l(hap_standing_stock /hap_K))
OUTFLOWS:
hap_consumption = ARRAYSUM(haps_cons[*]) {total joules
of haps removed from the standing stock per day}
other_standing_stock(t) = other_standing_stock(t-dt) +
(other_growth-other_consumption) * dt
INIT other_standing_stock = .5*(10All) {joules of
standing stock for other}
INFLOWS:
other_growth = IF(other_K = 0) THEN 0
ELSE((other_R*other_standing_stock)*(l(other_standing_stock /other_K)))
OUTFLOWS:
other_consumption = ARRAYSUM(other_cons[*]) {total
joules of other removed from standing stock per day}
hap_K = 4*(10A13) {maximum joules of standing stock}