An overview of the artificial breeding of spear-tailed gobies

An overview of the artificial breeding of spear-tailed gobies

Spear-tailed goby (Synechogobius hasta), commonly known as fathead fish, sandfish, sea catfish, throwing barramunk, pointed barracuda, pointed barracuda. Compound goby is a warm temperature small and medium-sized bottom omnivorous fish, with strong temperature and salt tolerance, mainly distributed in the western part of the North Pacific Ocean, China's Yellow Bohai Sea is widely distributed. Gobies are tender, have a smooth taste, are rich in nutrients, especially high in protein and fat, and have few bone spurs and are soft and are favored by consumers.

1 Spear-tailed goby life history

Spear-tailed goby life cycle is only one year old, into the summer and early autumn season of the year most of the fry in the shallow water on the shore of the bait fattening, autumn speartail goby into the accelerated growth stage, especially in late autumn and early winter, near the shore shallow area goby large, fat, and then enter the wintering stage, the next year to breed offspring, broodstock early spring after April death.

2 Resource status of spear-tailed gobies

With the large-scale development of Jiangsu coastal areas, tidal flats, ponds, salt pans, reed ponds, offshore ditches, etc. have been thrown in large areas, resulting in a continuous reduction in the living space of spear-tailed goby, and the engineering construction of reclamation and wharves has changed the original resource environment of the beach. The expansion of marine freshwater aquaculture area and the increase of aquaculture density, as well as the disorderly discharge of aquaculture tailwater without treatment, have led to changes in the living water environment of spear-tailed gobies. With the rapid development of industrialization and urbanization, a large amount of industrial wastewater and domestic wastewater are discharged into the near beach, which makes the coastal water pollution situation worse and worse. The above situation seriously affects the survival of spear-tailed goby, its production shows a downward trend year after year, and the market price of goby is also rising year by year.

3 Overview of artificial breeding of spear-tailed gobies

3.1 Shanghai Fisheries Research Institute test

In 2014, Zhang Zhonghua of Shanghai Fisheries Research Institute and others conducted an ecological early breeding experiment in a marine farm in Fengxian, and in order to achieve the ecological early reproduction of speartail goby, the breeding test of speartail goby was carried out in the wintering pond of Chrysanthemum Oriental Puffer at the end of 2014. The main wintering fish is 1-year-old chrysanthemum oriental puffer species with an average size of 45.0 g/tail and a stocking density of 3 033 fish/667 m2. On 19 November 2014, 90 broodstock of spear-tailed gobies were selected, with a herd-to-male ratio of 1:1, and the average size of females and males was 150 g/tail and 200 g/tail, respectively, with an average stocking volume of 10 per 667 m2. Test results: On 28 April 2, a total of 1 860.0 kg of chrysanthemum oriental pufferfish were caught, with an average size of 69.0 g/tail, a wintering survival rate of 98.7%, and a total of 135 100 spear-tailed gobies were obtained, with an average size of 4.19 cm/tail, and an average of 3 002 fish per female broodstock. The results showed that the broodstock broodstock of spear-tailed gobies were stocked in the wintering pond of Chrysanthemum Oriental Pufferfish, the broodstock with suitable specifications were selected, and the ratio of broodstock to male and female, the number of stockings, etc. were mastered, and the whole ecology of self-breeding seedlings could be realized without artificial intervention such as injection of oxytocin in the later stage.

Case analysis: The use of chrysanthemum oriental puffer wintering pond to achieve the earthen pond breeding of spear-tailed goby is undoubtedly a better breeding method, especially the choice when there is no breakthrough in the full artificial breeding technology, but to promote the industrialization of spear-tailed goby, this method is still far from meeting the demand.

3.2 Test of fishery technology extension station in Lianyungang District, Lianyungang City

In April 2011, Li Li and others of the Fishery Technology Extension Station of Lianyungang City conducted an indoor artificial breeding experiment of spear-tailed gobies, and they used indoor nursery facilities for fry breeding. The procedure taken is to collect broodstock in this area, with a body length of 30 to 48 cm. Body mass 200 to 350 g, broodstock collected 350 kg. It is equipped with broodstock breeding ponds, hatchery ponds and biological bait breeding ponds, with a salinity of 32 to 35 and a pH of 7.8 to 8.9.

The artificial breeding work began in February 2011 and ended in June, lasting more than 100 days, resulting in more than 7.7 million juvenile fish of 8 to 15 mm.

Case Analysis: The breeding experiment of spear-tailed goby has been very successful, but it is still lacking in improving the breeding rate and reducing the mortality rate of broodstock and juvenile fish. According to the gonadal development law of spear-tailed goby, it may be very difficult to repeat such breeding experiments, and some problems need to be further explored.

3.3 Test situation of Huaihai Institute of Technology

On February 26, 2012, Yang Haifeng and others of Huaihai Institute of Technology conducted a breeding experiment on spear-tailed gobies, using about 54 females and 46 males, with an average commodity weight of about 410 g/tail. Temporarily raised in 2 cement pools indoors, the treated hollow bricks are placed in the pool, 2 /m2, stacked near the pool wall. Shade the light and feed the shrimp and silkworms. The water temperature rises from 10 °C to 18 °C and the daily temperature rises by 1 °C, keeping it at a constant temperature for 8 d. Water change regulates water quality, and micro-inflation provides dissolved oxygen. There are 10 temporary ponds and nursery ponds, with a size of 8.0 m× 4.0 m× 1.5 m.

Disposable intramuscular injection is used to induce labor, and two combinations of drugs are used in A and B pools. Oxytocin include chorionic gonadotropin (HCG), luteinizing hormone-releasing hormone analogues (LRH-A2), and diosterone (DOM).

After incubation for 5 d, drain the water and fish the broodstock for incubation. After examination, there were 46 spawning broodstock and 8 non-spawning females. During incubation, the water depth is about 0.8 m, the temperature (18±1) °C, the salinity is 22±0.5, the pH is 7.9 to 8.5, micro-inflated, DO≥5 mg/L, shading dark incubation.

On March 21, when the water sample was taken, the hatchlings were seen, and on the 24th and 25th, the juvenile fish were cultivated in an average pond, and a total of about 960,000 juvenile fish were obtained, which were cultured in 4 ponds. On the 28th, a small amount of livewheel worms were fed, and the feeding amount was increased on the 30th. Composition of the bait: inoculate bone algae liquid water 3 cm (add 3 cm algae liquid water in the nursery pond, such as the original water depth of 100 cm, after adding algae liquid water, the water depth is 103 cm) + rotifer + soy milk + shrimp larvae No. 1 + fish worms (freshwater copepods). During the incubation period, the temperature (20±2) °C, salinity 22±0.5, pH 7.9~8.5, micro-inflated, DO≥5 mg/L. After more than 40 days of cultivation, a total of more than 620,000 fry were harvested.

Case study: The test description looks like the whole test is relatively complete, but the data and practices of the test are not very appropriate, and it is very difficult to rely on this method to guide the industrialization of artificial breeding of spear-tailed goby.

3.4 Yancheng Institute of Technology test situation

A three-year artificial breeding trial of spear-tailed goby was conducted from 2015 to 2017.

In 2015, the earthen pond overwintering test was carried out, in December 2015, the speartail gobies were purchased into the pond to overwinter, and the survival rate of broodstock out of the pond in March 2 was only 36%, the egg-bearing rate of female parents reached 89%, and the male parental gonads were completely degraded and could not be bred.

In 2016, the earthen pond wintering trial was also carried out, in November 2016, the spear-tailed gobies were purchased into the pond to overwinter, and the survival rate of broodstock in the pond in March of the second year was only 41%, the egg-bearing rate of female parents reached 76%, and the male parental gonads were completely degraded and could not be fertilized.

In 2017, the indoor pool wintering trial was switched to, and by February of the second year, the survival rate of wintering reached 84%, the egg-bearing rate of female parents reached 91%, and the male parental gonads were mostly degenerated, and by April, it was all degenerate, and it was impossible to produce sperm and breed.

4 Technical bottleneck analysis of artificial breeding of spear-tailed gobies

From the above 4 tests, the breeding of spear-tailed goby has been successful or unsuccessful, and in general, it has not yet met the requirements of industrialization, and the reasons for its analysis are as follows.

4.1 Spear-tailed goby have deteriorated physical fitness after wintering, and it is difficult to carry out artificial breeding operations

Spear-tailed goby into the winter when the body fat and strong, in the case of no injury, catch, transportation, selection is no problem, to the 2nd year speartail goby physique, tolerance dropped significantly, especially in March, April, artificial injection or slightly mobile case fatality rate is particularly high, up to 50% to 90%, to achieve the success of artificial breeding is very unlikely.

4.2 Spear-tailed gobies spawn in basal caves, and the mechanism of their fertilization is not well understood

From the experience of coastal fishermen, it is known that spear-tailed gobys overwinter by digging burrows in tidal flats and seawater ditches and laying eggs in caves, whether it is female or male eggs protection, or intersex egg protection is not yet known. There is also no evidence to confirm the timing of spawning and fertilization.

4.3 Male gonadal degeneration after overwintering in spear-tailed goby

After overwintering, the two sexes are inconsistent in development, the male gonadal degeneration is very serious, and there is no effective artificial control method. 5 Active innovation to find a new way to breed spear-tailed goby In 2016, when the earthen pond overwintered, it was found that the young spear-tailed gobies found in December that the young spear-tailed gobies were found to be about 1 cm in length. It shows that spear-tailed goby can be bred before wintering, spear-tailed goby can lay eggs and fertilize in early winter, it may be first spawned and fertilized in the cave in nature, after a winter egg protection, in the spring the water temperature rises, the fish eggs develop into seedlings.

According to the above findings, it is recommended that the breeding method can be changed, the spring breeding can be changed to winter breeding, the artificial laying ovary nest can be established, the broodstock can be spawned and fertilized by artificial intervention, the fertilized eggs can be collected for overwintering preservation, and then hatched and larvae are carried out after the water temperature rises in the next year and when the bait organisms are abundant.