SU1746964A1 - Method for raising young stock of mullet - Google Patents

Abstract

The invention relates to mariculture, in particular to the cultivation of young piliengas under artificial conditions. The method consists in planting fingerlings at the age of 30-40 days in ponds with a density of 45-55 thousand pcs / ra. at the same time, during the period of their growing, feed is introduced into the pond at the rate of 10-15% by weight of the fish and water exchange is set at 40-60 m / m3 / h. 1 tab.

Description

The invention relates to mariculture, in particular to the cultivation of young piliengas under artificial conditions.

The method is carried out as follows.

Ponds stock up to 30–40 daily viable young fawns. The density of planting viable young 45-55 thousand units / ha, water exchange in the pond support 40-60 l / m / h. Feed, for example, RGM-58, is applied at the rate of 10-15% of body weight depending on t ° water and is distributed to 8-10 feeds per day. Spread feed is placed on the feeders, systematically monitor palatability.

During cultivation, regular monitoring of the main indicators of the hydrochemical regime is carried out. The amount of oxygen dissolved in water is 4.5-6.5 mg / l, temperature 10-27 ° C, salinity 0-20%. Survival rate of fingerlings is 90%. average mass 28.9 ± 0.8.

Example 1.7 ponds with an area of 600 m2 and a depth of 1 m were stocked with viable fry of the pilingas at the age of 40 days, 2.5-4.0 cm long and 0.2-2.0 g weighed. Water exchange in 1 pond was created 30 l / m3 / h. Planting density of fry is 40 thousand pcs / ha. Young fish were fed with carp artificial food of RGM-58 at the rate of 5% of the weight of fish, the rest of the food was natural food (Acartiaclausi, Diamtomus sp., Etc.). The daily ration was divided into 8–10 feedings for better digestibility, as the feed in water lost its properties for half an hour. The amount of dissolved oxygen is 4.0 mg / l.

The results of the experiment were summarized earlier in the winter before transplanting; the young of the year had a weight of 18.3 ± 0.9.

Despite the sparseness of planting, the mass of fingerlings is insufficient for a safe wintering due to a lack of feed (5% of the weight of the fish) and a low oxygen content of 4.0 mg / l, which is close to critical (3 mg / l).

Example 2. Analogously to Example 1, the water exchange in the pond was 40 l / m / h, the density of planting was 45 thousand pcs / ha. Food was given at the rate of 10% by weight of fish. The amount of dissolved oxygen mg / l.

The mass of fingerlings at the end of cultivation was 24 ± 0.2 g due to insufficient feeding intensity.

Example 3. Analogously to Example 1, the water exchange in the pond was 50 l / ml / h.

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with

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planting density of 50 thousand units / ra. the feed was made at the rate of 12% by weight of the fish. The amount of dissolved oxygen is 5.9 mg / l.

The final mass of fingerlings was 20.2 ± 0.9 g.

Example 4. Analogously to example 1, the water exchange in the pond is 60 l / m / h, the density of planting is 55 thousand pcs / ha, feeding was carried out on the basis of 15% of the mass of fish. The amount of dissolved oxygen is 6.5 mg / l.

The final mass of fingerlings is 28.1 ± 0.3.

Example 5. Analogously to Example 1, water exchange in the pond was created equal to 70 l / m / h, planting density was 60 thousand pcs / ha, feed was made at the rate of 20% by weight of fish. The amount of dissolved oxygen is 4.7 mg / l.

The rate of individual growth in fish did not increase, the final mass was 28.4 ± 0.4, despite the increased water exchange.

Example 6. Analogously to example 3, the density of planting was reduced to 40 thousand units / ha. The oxygen content is 5.0 mg / l. The mass of fish at the end of cultivation was 35 ± 0.2 g.

The results of the experiments are tabulated.

As can be seen from the table, the optimal results were obtained in experiment 3 - fish weight 30.2 ± 0.9 with a landing density of 50 thousand pcs / ha. Water exchange of less than 40 l / m3 / h (example 1) leads to a decrease in the amount of oxygen to critical, despite the sparseness of the landing (40 thousand units / ha), the fish did not gain weight well, and an insufficient amount of feed also affected (5% by weight fish).

Water exchange of more than 60 l / m, / h leads to

large consumption of water and energy (example 5). A simultaneous increase in the amount of feed to 20% by weight of fish does not contribute to the increase in the mass of fish. since the excess feed is not assimilated, oxygen is reduced (as compared with example 4. where there is less water exchange, but less amount of feed to be applied). As regards the density of planting, a high rate of individual growth was observed at low densities (example 6). but overall productivity is lower. At elevated densities (Example 5), the rate of individual growth drops sharply.

Thus, the proposed method is effective, provides 90% survival of fingerlings, allows to obtain for wintering fish with a mass of 30 g, the fish productivity of experimental ponds

amounted to 1-1.5 t / ha.

Claims (1)

Claims of Invention The method of growing juvenile mullet Pilengas, which consists in planting young plants at the age of 30-40 days in ponds with a density of 45-55 thousand pcs / ha, while feeding them into the pond at the rate of 10-15% from the mass of fish and establish a water exchange of 40-60 l / m3 / h. Results of growing perenagus fingerling under various conditions.