For full context: http://www3.nhk.or.jp/news/easy/k10011231671000/k10011231671000.html
The sentence in question: 来年は、今年より約１９％多い２万８２００ｔのクロマグロを取ってもいいことが決まりました。
First, my attempt at translation: "Concerning the next year, it was decided that fishing about 19% from this years..."
I didn't finish the sentence because when I include this 多い into my translation, it becomes gibberish. Judging from the context, I would say that this sentence tells us that it was decided that fishing about 19% of this years amount of fished pacific bluefin tuna would be okay. This years amount of fished p.b.t was ２万８２００ｔ or 28200 tonnes. However, I'm also guessing a bit at this point because I just don't know what function this 多い fulfills here and wether it means something like "amount" here instead of "many".