Are All Translations Wrong? (Mark 1:16)

Rarely do I find a translation that makes no sense to me, and since this particular one is replicated in all the translations, I am assuming I am missing something, but I have no idea what it could be. Can you help?

Jesus has just announced his public ministry, and in Mark 1:16 Mark writes, “As Jesus walked beside the Sea of Galilee, he saw Simon and his brother Andrew casting a net (ἀμφιβάλλοντας) into the lake, for they were fishermen (ἁλιεῖς)” (NIV).

ἀμφιβάλλω means “cast, a t.t. for the throwing out of the circular casting-net (δίκτυον)” (BDAG). A ἀμφίβληστρον is “a circular casting-net used in fishing, casting-net“ (BDAG). The fact that ἀμφιβάλλω is not followed by ἀμφίβληστρον suggests that ἀμφίβληστρον is implied and therefore unnecessary to state explicitly, and the word play is picked up in the next verse where we read, “‘Come, follow me,’ Jesus said, ‘and I will send you out to fish for people (ἁλιεῖς ἀνθρώπων).’”

It is common for Greek to omit the direct object when it is deemed repetitive and is clarified by context. Here ἀμφίβληστρον is unnecessary because it is contained in its cognate verb ἀμφιβάλλω.

But here is what I don’t understand. While v 16 does not specify how many nets were being used, “net” vs. “nets,” all the translations I consult go with the singular “net.” However, in the very next verse, it indicates a plurality of nets. “At once they left their nets (δίκτυα) and followed him.” So why not have a plural in v 16?

I don’t know enough about ancient fishing practices to know whether these nets required more than one person; I had assumed that was the case since all the translations have the singular “net.” However, v 16 makes it very clear that the two men were using multiple nets to fish.

So why does everyone go with “net” in v 16?