GMAT Critical Reasoning (CR) | Re: A team of Swedish scientists recently concluded a fifteen

It seems that you got confused between lean fish and fatty fish.

1st sentence (before semicolon): fact (as you stated)
2nd sentence (after semicolon) : fact (as you stated) / evidence in support of conclusion
3rd sentence (independent clause): conclusion (omega 3 helps resist renal cancer)
3rd sentence (dependent clause - "though..... inconclusive"): fact against the conclusion (hence the "though" clause): BF1
4th sentence: supports conclusion(fatty fish eaters have less risk of renal cancer than lean fish eaters - fatty fish have more omega 3 than lean fish have (BF 2) ---> conclusion: omega 3 helps resist renal cancer