Is a purse seine net being used in fishing for sea fish even after it has been pursed?

In Alexander v. Tonkin (1979) 1 W.LR. 629 the court considered the question, set out at p. 634 of the reasons, “whether a purse seine net is being used in fishing for sea fish [my emphasis] after it has been pursed so that no more fish can be caught but while it is being relied upon to confine the fish to enable them to be pumped aboard a fishing vessel”. In Tonkin, there being an assumption the fish were lawfully caught in the net before it was pursed, it was held that the vessel was fishing for sea fish even while pumping fish aboard from a pursed net. That was because the fish had not yet been reduced to useful possession.