noun
Refers to a person who fishes, often with a nuance of skill or dedication.
彼は週末になると釣り師になる。
He becomes an angler on weekends.
noun
Internet troll
Internet slang; refers to someone who posts inflammatory or off-topic messages to provoke others.
あの掲示板には釣り師が多い。
That forum has many trolls.
Compound of 釣り (fishing) and 師 (master, specialist). The Internet slang sense is a metaphorical extension, likening a troll to someone who 'fishes' for reactions.