Kosonen:
Just for the record, there was a revamp of the WT understanding on this parable in 2008. Here is an extract from the WTLIB of the explanation:
*** w08 7/15 pp. 20-21 You Do Not Know Where It Will Have Success! ***
The Dragnet
15 More important than the number of those who claim to be disciples of Jesus Christ is the quality of those disciples. Jesus alludes to this aspect of Kingdom growth when he gives another illustration, one about a dragnet. He said: "Again the kingdom of the heavens is like a dragnet let down into the sea and gathering up fish of every kind."-Matt. 13:47.
16 The dragnet, which represents the Kingdom-preaching work, gathers fish of every kind. Jesus goes on to say: "When [the dragnet] got full they hauled it up onto the beach and, sitting down, they collected the fine ones into vessels, but the unsuitable they threw away. That is how it will be in the conclusion of the system of things: the angels will go out and separate the wicked from among the righteous and will cast them into the fiery furnace. There is where their weeping and the gnashing of their teeth will be."-Matt. 13:48-50.
17 Does this separating refer to the final judgment of the sheep and the goats that Jesus said would occur when he arrived in his glory? (Matt. 25:31-33) No. That final judgment will occur at Jesus' coming during the great tribulation. By contrast, the separating referred to in the illustration of the dragnet occurs during "the conclusion of the system of things." This is the time in which we are now living-the days leading up to the great tribulation. So how is a separating work taking place now?
18 Literally millions of symbolic fish from the sea of humanity have been attracted to Jehovah's congregation in modern times. Some attend the Memorial, others come to our meetings, and still others are happy to study the Bible. But do all of these prove to be genuine Christians? They may be "hauled up onto the beach," but Jesus tells us that only "the fine ones" are gathered into vessels, which represent Christian congregations. The unsuitable are thrown away, eventually to be cast into a symbolic fiery furnace, denoting future destruction.
19 As with the unsuitable fish, many who once studied the Bible with Jehovah's people have stopped studying. Some born to Christian parents have never really wanted to become footstep followers of Jesus. They have been unwilling to make the decision to serve Jehovah or after serving him for a while have ceased doing so. (Ezek. 33:32, 33) It is imperative, though, that all honesthearted ones allow themselves to be gathered into the vessellike congregations before the final day of judgment and to remain in a place of safety.
It is interesting reading this after several years of 'learning' since this came out in the WT. Just off hand, it has the typical WT over-explaining of every aspect of the parable. Specific meaning is assigned to every detail. For example, 'suitability of the fish' is determined at the time of a Bible Study. If you make it past that, your in.
The "vessels" represent "congregations." Why? Because we said so. I think chapters 2 and 3 of Revelation did not see it this way. Also see 2Tim 2:20-22.
Take Care