Exegesis:

kai touto poiēsantes ‘and after having done this,’ refers (again in the plural) back to chalasō ta diktua ‘I will let down the nets.’

sunekleisan plēthos ichthuōn polu ‘they enclosed a great quantity of fishes.’ The fact that ichthuōn stands between plēthos and attributive polu shows that semantically plēthos ichthuōn represents one concept.

sugkleiō ‘to enclose,’ without specific reference to fishing.

dierrēsseto de ta diktua autōn ‘and their nets were breaking.’ de is transitional. Semantically the clause describes the consequences of the preceding one, cf. e.g. An American Translation (“… such a shoal of fish that their nets began to break”). Syntactically and semantically the clause goes with the preceding rather than with the following clause.

The force of the imperfect tense dierrēsseto is best brought out by such renderings as, ‘were at breaking point,’ ‘threatened to break,’ since an actual breaking of the nets did not happen.

diarrēssō (also 8.29) ‘to tear,’ either intransitive or transitive.

Translation:

When they had done this, a transitional phrase, which has also been rendered, ‘this having been done,’ or, repeating the previous verb, ‘having let down’ (Ekari).

They enclosed, or, ‘they held/confined in it (or, in the net),’ ‘they brought together’ (Pohnpeian), or simply, ‘they caught.’

A great shoal of fish, or simply, ‘very many fish.’ — Fish may have to be described, e.g. ‘(edible) things that live in the water’; or the name of one species must do duty for all, e.g. ‘eel’ (Wantoat).

Were breaking, or, ‘almost tore’ (Toraja-Sa’dan; similarly Balinese, where one has moreover to specify whether the threatening event did, or did not, take place afterwards).

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.