294
13. Nile Perch Population Dynamics in Lake Victoria :
0)+(IF(Fishwt[10»(. 3 *Fishwt[ 11))) AND (sus_mass [10»0)
THEN( can[lO) * (NP_mass[ll) /sus_mass[lO))) ELSE 0)
Natural_Morta lity (1 2) = (IF (Fishwt[1»(.3 *Fishwt[12)))
AND (s u s _ma s s [1 » 0 )
THEN(can[ 1) * (NP_mass [12) /sus_mass[l))) ELSE
0 )+ (I F (Fi s hwt [2» (. 3* Fi s hwt [12 ) ) ) AND (s u s _ma s s (2»0)
THEN (c an [2 )* (NP_ma s s [12 ) / sus _ma s s [2 )) ) ELSE
0)+(IF(Fishwt[3»( .3 *Fishwt[1 2))) AND (s u s _ma s s (3»0)
THEN(can[3) *(NP_mass[12) /sus_mass[3))) ELSE
0)+(IF(Fishwt[4»(. 3 *Fishwt[12))) AND (sus_mass [4]>0)
THEN(can[4] *(NP_mass[ 12] /sus_mass[4))) ELSE
0)+(IF(Fishwt[5»(.3 *Fishwt[12))) AND (sus_mass (5»0)
THEN(can[5)*(NP_mass[12) /sus_mass[5])) ELSE
0)+(IF(Fishwt[6»(.3*Fishwt[12])) AND (sus_mass [6]>0)
THEN(can[6)*(NP_mass[1 2) /sus_mass[6))) ELSE
0)+(IF(Fishwt[7»(.3 *Fishwt[12))) AND (sus_mass (7»0)
THEN(can[7)*(NP_mass[12) /sus_mass[7))) ELSE
O)+(IF(Fishwt[8»(.3*Fishwt[12))) AND (sus_mass (8»0)
THEN(can[8)*(NP_mass[12) /sus_mass[ 8))) ELSE
0)+(IF(Fishwt[9»(. 3 *Fishwt[12))) AND (sus_mass (9»0 )
THEN(can[9) *(NP_mass[12) /sus_mass[9))) ELSE
O)+ (IF(Fishwt[10»( . 3*Fishwt[12))) AND (sus_mass (10 »0)
THEN(can[ lO) *(NP_mass [1 2) /sus_mass[ lO) ) ) ELSE
O)+(IF (Fishwt[l l»( .3 *Fishwt [12] ) ) AND (s us _ma s s [11 ]>0)
THEN(can[ll) * (NP_mass[1 2 ) /sus_mass[l l)) ) ELSE 0)
Natura1_Mortali t y(13 ) = (I F (Fi s hwt [l ] > (.3* Fi s hwt [13 ) ) )
AND (sus_mass (1»0)
THEN(can[l) *(NP_mass [1 3] /sus_mass[l))) ELSE
0)+(IF (Fishwt[ 2»(. 3*Fishwt[ 13]) ) AND (sus_mass (2»0)
THEN(can[ 2) *(NP_mass[ 13)/sus_mass[2))) ELSE
0)+(IF(Fishwt[ 3»(.3 *Fishwt[13))) AND (sus_mass (3»0)
THEN(can[3)*(NP_mass[13) /sus_mass[3)) ) ELSE
O)+(IF(Fishwt[4»(.3 *Fishwt[13))) AND (sus_mass (4»0)
THEN(can[4)*(NP_mass[13) /sus_mass[4))) ELSE
0)+(IF(Fishwt[5»( .3*Fishwt[13))) AND (sus_mass (5»0)
THEN(can[5)*(NP_mass[13) /sus_mass[5))) ELSE
O)+(IF(Fishwt[6»( .3*Fishwt[13))) AND (sus_mass (6»0)
THEN(can[6) *(NP_mass[13) /sus_mass[6))) ELSE
O)+(IF(Fishwt [7»(.3 *Fishwt[1 3))) AND (sus_mass (7»0)
THEN(can[7) *(NP_mass[13) /sus_mass[7))) ELSE
0)+ (IF(Fishwt[ 8»(.3 *Fi shwt[13))) AND (sus_mass [8»0)
THEN(can[ 8 ) *(NP_mass[ 13) /sus_mass[ 8))) ELSE
0 )+(IF (Fishwt[9» ( .3 *Fishwt[13))) AND (sus_mass[9»0 )