Studies Of Artificial Breeding And Early Cultivation Of Urechis Unicinctus

Urechis unicinctus commonly known as sea intestines,is a large benthic organism widely distributed in the Intertidal and subtidal zones of the Korean Peninsula,Hokkaido,Japan,Russia,and the Yellow and Bohai coasts of China.Because of its delicious taste,it is an important Marine treasure with significant economic and ecological value.With the increase of market demand year by year,overfishing leads to a sharp decline in the number of its natural resources,affecting the sustainable use of resources.Artificial breeding and breeding can quickly increase the amount of resources to meet their resource needs.This thesis aims to provide basic theories for artificial breeding and breeding by studying the breeding process and ecology of Urechis unicinctus at room temperature.By studying the artificial breeding process of Urechis unicinctus at room temperature,the effects of feeds with different sizes on the growth of Urechis unicinctus larvae,the effects of different types of substrates on the growth and survival of larvae,and the water filtration rates of larvae at different temperatures and body weight,the following research results are obtained:1.Normal temperature seedling experiment: The experiment is conducted in Dongyuan Aquaculture Breeding Center,Jinzhou District,Dalian for artificial breeding of Urechis unicinctus,where vigorous and non-mechanictus are selected for anatomy,bright renal tubetus collect cells,and the sperm and egg solutions obtained are mixed in a ratio of 1:100,with the fertilization rate above 88%.The ratio of spermatozoa is too high or too low,will reduce its fertilization rate.Urechis unicinctus fertilization rates are more affected by salinity,while hatching rates and late development are more affected by temperature.In this paper,normal temperature water is used to raise seedlings,and a total of 700,000 Urechis unicinctus larvae with a body length of 1.0～2.0 cm are successfully cultivated,with an overall hatching rate of more than 10%.2.Effects of baits with different sizes on the growth and survival of Urechis unicinctus larvae: Compare the growth of Urechis unicinctus with different sizes of bait(150 μm,100 μm,and 75 μm).Experimental results show that,when Urechis unicinctus has the same size and different sizes of bait,the total increase of body weight in small size group was 75 μm > 100 μm > 150 μm.The total increase of body weight in medium size group was 150 μm > 75 μm >100 μm.The total increase of body weight in large size group was 150 μm > 100 μm > 75 μm.When the bait sizes are the same Urechis unicinctus with different sizes,and the sizes are all 150 μm,the total weight increase is large>medium>small,and the total weight increase differs significantly between groups(P<0.05).When the size of each diet was 100 μm,the total increase of body weight was large size>medium size>small size,and the difference of total increase of body weight among each group was significant(P<0.05).When the feed size was 75 μm,the total increase of body weight was medium size>small size>large size,but there was no significant difference between each group(P>0.05).Urechis unicinctus when small,Urechis unicinctus prefers filter feeds of about 75 μm,and Urechis unicinctus is better for feeds of about 150 μm when the body length is more than 3 cm.3.Effects of different substrates on the growth and survival of Urechis unicinctus larvae: Compared the Urechis unicinctus in different substrate(70% full mud,mud,sand bottom,70% sand bottom)in the growth situation,the experimental results show that the growth rates of Urechis unicinctus in all-sediment and 70% mud groups are significantly higher than those in 70% sand and all-mud groups,indicating that Urechis unicinctus larvae are more suitable for growth in all-sediment or sediment accounts for 70% mud.Urechis unicinctus larvae have the highest survival rates in70% sand,while Urechis unicinctus larvae in pure mud deposits have the lowest survival rates,and the survival rates in the sediment mixed groups are higher than those in the pure mud and sand groups.4.Effects of different temperatures and body mass on water filtration rates of Urechis unicinctus larvae: Compare studies of water filtration rates of Urechis unicinctus unit weight with different sizes under constant temperature.Experimental results show that,at the same temperature,the water filtration rate of Urechis unicinctus is adult>medium sprout>small sprout,and the water filtration rate of Urechis unicinctus unit weight is small sprout>medium sprout>adult.With the same specifications,within a certain temperature range,the water filtration rate of Urechis unicinctus increases as the temperature increases,but beyond a certain temperature range,the water filtration rate of Urechis unicinctus decreases as the temperature increases,and the temperature resistance of Urechis unicinctus adults is lower than that of Urechis unicinctus juveniles.5.Changes in Urechis unicinctus water filtration rates at variable temperatures:Compare the water filtration rate studies of Urechis unicinctus unit body weight with different sizes under variable temperatures.Experimental results show that,at the same time,the water filtration rate of Urechis unicinctus is adult>medium sprout>small sprout,and the water filtration rate of Urechis unicinctus unit body mass is small sprout>medium sprout>adult.With the same specifications,Urechis unicinctus’ water filtration rate does not change significantly(P>0.05)because temperature changes are too small.