We present two protocols for information exchange between multiple identical senders and a single receiver. At each instant, every sender sends one bit, and the bits from all of senders are or-ed together into one bit before being received by the receiver. If a sender has a data message to send, it sends the message bits one by one: otherwise it sends zero bits. Clearly, if the sending of two messages by two senders overlap, then the resulting "collision" can result in a corrupted message, i.e., one that was not sent by either sender. The function of the protocol is to deliver those and only those messages that are not corrupted by collision. (In other words, the receiver acts as a discriminating seine that catches and delivers only uncorrupted messages; hence the title.) The two protocols presented here are based on Manchester codes and general balanced codes, respectively.