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How Are Warm-Water Fish Harvested? Key Technical Points Explained in Detail

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In summer and autumn, the fish-carrying capacity of intensive culture ponds reaches saturation, and some adult fish have reached marketable size and can be harvested for market. This not only benefits fish growth and the rearing of large-size high-quality fingerlings, but also reduces the fish-carrying load of the pond. According to production practice, the following key techniques should be grasped when harvesting warm-water fish. 1. Harvesting time is generally chosen in clear, fine weather, when the air temperature is cool, before and around dawn in the latter half of the night when fish are not gasping at the surface, or in the morning when the water temperature is relatively low (the specific time is determined according to the distance from the market and @#@136@#@ time). At this time, seining to harvest fish has little impact on the pond fish, and the freshly caught fish can be supplied to market in time. In overcast, muggy weather, or when pond fish show signs of gasping at the surface or fish diseases occur, seining should not be carried out, so as to avoid causing a large number of fish deaths. Seining cannot be done in the evening; otherwise it will cause premature convection between the upper and lower water layers, accelerate the consumption of dissolved oxygen in the pond water, and cause the pond fish to gasp at the surface.

In summer and autumn, the fish-carrying capacity of intensive culture ponds reaches saturation, and some adult fish have reached marketable size and can be harvested for market. This not only benefits fish growth and the rearing of large-size high-quality fingerlings, but also reduces the fish-carrying load of the pond. According to production practice, the following key techniques should be grasped when harvesting warm-water fish.

1. Harvesting time is generally chosen in clear, fine weather, when the air temperature is cool, before and around dawn in the latter half of the night when fish are not gasping at the surface, or in the morning when the water temperature is relatively low (the specific time is determined according to the distance from the market and @#@136@#@ time). At this time, seining to harvest fish has little impact on the pond fish, and the freshly caught fish can be supplied to market in time. In overcast, muggy weather, or when pond fish show signs of gasping at the surface or fish diseases occur, seining should not be carried out, so as to avoid causing a large number of fish deaths. Seining cannot be done in the evening; otherwise it will cause premature convection between the upper and lower water layers, accelerate the consumption of dissolved oxygen in the pond water, and cause the pond fish to gasp at the surface.

2. On the day before harvesting, especially in the afternoon, feeding should be stopped or the feeding amount reduced. Under no circumstances should large amounts of concentrated feed be given in order to increase the weight of the fresh fish for market. This is because after fish feed to satiation, their oxygen consumption increases, and when frightened during harvesting they jump and dart about, which easily causes injury and death, often making the loss outweigh the gain. One or two days before harvesting, residual bait and scraps in the pond, as well as debris floating on the water surface, should also be removed.

3. During harvesting, a sparse net (also called a sieve net, four-finger net, or five-finger net) should be added to the net. The length of the sparse net generally accounts for about one-fifth of the total net length. The mesh size of the sparse net is determined by the individual size of the fish being harvested, so as to allow fingerlings that do not meet market size to slip through. During harvesting, one generally enters the water at shallow areas and on the windward side, and it is best to close the net at deep areas and on the leeward side, to prevent fish from being stranded and suffocating.

4. Harvesting operations should be meticulous, skillful, and light and quick. This is because at this time the water temperature is high, the fish are vigorous, and the oxygen demand is great, so they cannot tolerate being crowded together for a long time; moreover, most of the fish caught in the net need to be returned to the pond. If they stay in the net too long, they are very likely to be injured or suffocate from lack of oxygen. Therefore, after the fish are gathered together, the small fish in the net that have not yet reached market size should first be quickly and gently released, and then the large marketable fish should be sorted out, or the marketable fish should be selected while the fingerlings to be retained in the pond are released at the same time. Under no circumstances should one blindly select only marketable fish, causing the small-size fingerlings retained for the pond to be injured or to suffocate and die from crowding and squeezing in the net.

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