This is impossible to answer with just a single number. Those trolling with braid and conventional gear might use line strengths upwards of 30- or even 50-pound test. While this is overkill for the size of the fish, it makes handling easier, and tangles less likely with that type of tackle. If trolling with mono or fluoro, using line in the 8- to 20-pound range is far more common. If you’re casting with medium action gear, your best bet is between 8- and 20-pound-test. With mono or fluoro, you will start to sacrifice casting distance and have increased drag in the water the heavier you go, so best to stick to lighter line (8- to 12-pound). My best advice: Ask your local shop what they use based on your local water and techniques. (This is the best way to pick the perfect pound-test for your water.)