An apparatus (1, 21) for harvesting aquatic animals, comprising: a cod end portion having an open leading end and a closed trailing end and one or more side walls between the leading end and the trailing end, wherein the side wall(s) comprise(s) a flexible membrane; and an elongate lengthener portion (3, 23) having a leading end (3a, 23a), a trailing end (3b, 23b), and one or more side wall(s) between the leading end and the trailing end, wherein at least a major part of the side wall(s) of the elongate lengthener portion comprise(s) a flexible membrane that is substantially impervious to water, and wherein the trailing end (3b, 23b) of the lengthener portion is operatively connected to the leading end of the cod end portion; wherein the elongate lengthener portion (3, 23) comprises a plurality of escapements (9, 10, 25) through which water can pass from an interior of the apparatus to an exterior of the apparatus to cause a general reduction in the water flow rate inside the apparatus from the leading end (3a, 23a) of the elongate lengthener portion toward the trailing end (3b, 23b) of the elongate lengthener portion and toward the trailing end of the cod end portion when the apparatus is submerged in a body of water and there is water flow relative to the apparatus, characterized in that the side wall(s) and the trailing end of the cod end portion are substantially impervious to water, and in that aquatic animals that are smaller than a desired size can pass through the escapements (9, 10, 25) formed in the flexible membrane of the elongate lengthener portion from the interior of the apparatus to the exterior of the apparatus. a cod end portion having an open leading end and a closed trailing end and one or more side walls between the leading end and the trailing end, wherein the side wall(s) comprise(s) a flexible membrane; and an elongate lengthener portion (3, 23) having a leading end (3a, 23a), a trailing end (3b, 23b), and one or more side wall(s) between the leading end and the trailing end, wherein at least a major part of the side wall(s) of the elongate lengthener portion comprise(s) a flexible membrane that is substantially impervious to water, and wherein the trailing end (3b, 23b) of the lengthener portion is operatively connected to the leading end of the cod end portion; wherein the elongate lengthener portion (3, 23) comprises a plurality of escapements (9, 10, 25) through which water can pass from an interior of the apparatus to an exterior of the apparatus to cause a general reduction in the water flow rate inside the apparatus from the leading end (3a, 23a) of the elongate lengthener portion toward the trailing end (3b, 23b) of the elongate lengthener portion and toward the trailing end of the cod end portion when the apparatus is submerged in a body of water and there is water flow relative to the apparatus, characterized in that the side wall(s) and the trailing end of the cod end portion are substantially impervious to water, and in that aquatic animals that are smaller than a desired size can pass through the escapements (9, 10, 25) formed in the flexible membrane of the elongate lengthener portion from the interior of the apparatus to the exterior of the apparatus.