What Happened with the Scallops Dying Again at Zhangzidao? Breeding Methods to Prevent Death

Scallops are a type of shellfish widely distributed across the world's seas and an important shellfish aquaculture species in China. Among them, Zhangzidao scallops are extremely famous, so what is the situation with the recent die-off of Zhangzidao scallops again? How can they be farmed so they don't die?

1. What is the situation with Zhangzidao scallops dying again?

In fact, on the evening of November 11, the listed company Zhangzidao issued an announcement stating that, based on the summary of per-mu yield data from sampling points taken by the company on November 8-9, the average per-mu yield of bottom-sown Yesso scallops from the 2017 stock in the sampled areas was less than 2 kg; the average per-mu yield of bottom-sown Yesso scallops from the 2018 stock was about 3.5 kg, a per-mu yield level greatly lower than the average per-mu yield of 25.61 kg for the first 10 months, and the company preliminarily judged that this constituted a major risk of inventory impairment for bottom-sown Yesso scallops.

According to the company's explanation, this time they did not run away, but died en masse. The announcement's sampling results showed that, based on the condition of the scallops harvested on site during sampling, the bottom-sown scallops recently experienced a large-scale die-off, with the proportion of dead shells in some sea areas accounting for more than about 80%. The time of death was relatively close to the time of sampling and harvest, there was no obvious difference in shell size between dead shells and surviving scallops, most dead shells still had elastic ligaments between the shells, and some shells still contained undecomposed soft tissue.

In other words, these scallops in stock suffered a large-scale die-off, and the time of death happened to be just before the company's sampling time.

When trading opened on November 12, Zhangzidao's stock price indeed hit the daily limit-down from the opening, and during that morning session sell orders continuously piled up on the limit-down board as funds fled frantically.

2. How can scallops be farmed so they don't die?

1. Selection of sea area

Choose a sea area with clear water and gentle currents, no strong winds or waves, abundant feed, and a water temperature above 13°C.

2. Rearing methods

There are mainly three methods: rearing in net cages, plastic buckets, and mesh bags. Taking net cage rearing as an example, use a round net cage with a diameter of 30 cm, divided into 6-7 layers, with 15 cm spacing between layers and a mesh size of 4-8 mm. For seedlings with a shell height less than 1.5 cm, place 500 per layer; for those greater than 1.5 cm, place 200-300 per layer. A 60 m long float can hang 100 cages.

3. Daily management

Split the seedlings in time, inspect frequently, and often wash and scrub the net cages. The farming water layer is generally at a depth of 2-3 m. In addition, after scallop seedlings enter the pond, assign a dedicated person to watch over them; if some seedlings are found floating on the water surface with gas, use a thin bamboo pole to release the gas. Ten days after entering the pond, observe the growth condition of the scallop seedlings; if the scallop seedlings grow quickly and are numerous, immediately replace the seedling bags, generally using 30-mesh seedling bags. Then replace the seedling bags again after about twenty days. About ten days after entering the pond, begin changing the water, with the daily exchange amount at about one quarter of the total; if the water color is too dense, increase the water exchange amount, and do not change water on windy days because the water is too turbid. If the water color is found to be too light, fertilize in time, and the principle of fertilization is to apply frequently and in small amounts. Photosynthetic bacteria and EM bacteria can also be added.

Scallop farming requires mastering good farming techniques to succeed, and friends without experience should invest cautiously.