Help with logic math problem

Chris just adked me to check his answer:  :)    

It all checks out A OK     

Another perhaps easier way to present it would be like this.

(1) Large Male Cod: 12

(2) Small Female Herring: 11

(3) Large Cod: 31

(4) Male Cod: 29

(5) Large Males (Fish): 35

(6) Cod total: 69

(7) Male (Fish) total: 68

(8) Large fish total: 72

Total fish caught: __

(3) Large Cod - (1) Large Male Cod  = 31 - 12  = 19 = Large Female Cod

(8) Large Fish Total -  (5) Large Males  = 72 - 35  = 37  = Large Females

Large Females - Large Female Cod = 37 - 19  = Large Female Herring = 18

Total Female Herring = Small Female Herring + Large Female Herring = 11 + 18 = 29

(7) Male Fish - (4) Male Cod  = 68 - 29 =  39  = Male Herring

So.......Total Male and Female Herring   = 39 + 29 = 68 = Total Herring

So.....(6) Total Cod + Total Herring  = 69 + 68  = Total Fish  137