Background technology
Nacre (Pinctada margaritfera (linne)) popular name black lip shell is present unique pearl shell that can manufacture black pearl, and shell is thick big, can make shell carving and handicraft, the economic worth height.Nacre inhabits the torrid zone, sea area, subtropics, mainly be distributed in the uncommon dike of tower, Cook, the native archipelago of native Ah not of the South Pacific Ocean, in Chinese Hainan Province, there is distribution in Guangdong Province, Guangxi district, coastal of Taiwan Province, perch mostly in the seabed of subtidal zone to tens of meters of the depth of waters.
The breed present situation of nacre: the black pearl particle is big, and particle diameter can reach more than the 1cm, pearl bed thickness, good luster, and the huge market demand costs an arm and a leg.About 15 of present global black pearl annual productions, the producing region mainly concentrates on the uncommon dike of tower, Cook, the native archipelago of native Ah not of South Pacific region, abound with nacre owing to its unique location and sea situation, can utilize the natural shellfish of natural waters carry out half-artificially cultured, grow cultured pearls.In China, 1970 and extra large Ling Zhenzhuchang in 1986 and South Sea aquatic products research institute obtain the initial success of growing seedlings, culture, growing cultured pearls respectively at port, residential district, Hainan.Guangdong Ocean University in 2002 sets up scientific research group and has carried out the research that total man worker cultures and grows cultured pearls; and obtain the success that nuclear was cultured and planted in artificial breeding large-scale production, big-and-middle shellfish in batches; but the shell height is the Xiao Bei of 3~25mm, and to culture survival rate low, causes the black pearl can't large-scale production.Shell length is that to cultivate into shell length be the breed of 25~30mm Xiao Bei to the artifical pearl shell fry of 3~5mm, adopt traditional arch cage hanging method to produce in batches in the inner bay sea area, survival rate is about 1%, highest record 9.4%, adopting net cage to mark thick method survival rate is about 12%, reaches as high as 24.7%.So it is the comparatively ideal cultural method in artifical pearl shell inner bay sea area that net cage is marked thick method.
Artifical pearl shell fry is marked the low analysis of causes of thick survival rate: 1, offshore pollution is serious.Greatly develop mariculture the nineties in 20th century, hundreds thousand of mu of prawn high-elevation breeding ponds have been increased on the seashore, the bay has increased tens thousand of fish cultures in net pen, the pearl culture area several times in shallow sea increase, in recent years increased again large-scale scallop prolong the rope hang foster, be characterized in high density, high production, high investment, high pollution, because to beach, the bay, the shallow sea does not have unified planning and development and use, ignore long-range ecology and environmental benefit, cause ocean current not smooth, the inner bay coastal waters is low with outer seawater exchange rate, form and culture the sea area water quality inferiority, the sea-bottom deposit aggravation, the bay shoals and narrows down; 2, the secondary nutrient laden of seawater, attachment aggravation, chemical oxygen consumption (COC) height; 3, Pinctada off-lying sea property shellfish is to the inadaptability of neritic zone; 4, the close shellfish that carries out artificial breeding at present all is wild shellfish, and its first filial generation is to inadaptability of breeding environment, density and breeding way or the like.
Traditional artificial seedling of pearl shellfish is cultivated 25~30mm from the long 3~5mm of shell and is adopted arch cage hanging method more, being about to spat scrubs from hapteron, being contained in the etting mesh is in 20~60 purpose arch cages, keep hanging on sea area 2~4m water layer, according to the increase of the growth of spat and etting attachment and 2-3 scrubs etting or change cylinder mould.Its shortcoming has: 1, spat damages byssus gland easily or damages shell when attachment is scrubbed, and causes to infect and dead; 2, dead volume is stayed and is infected other spats in the cage and destroy water quality; 3, the etting mesh is little, and attachment is many, influences the inside and outside exchange of seawater of cage, causes in the cage food organisms few, and dissolved oxygen is low, is unfavorable for the growth of spat and because of the anoxic mortality; 4. spat adheres to agglomeratingly mutually in the cage, is unfavorable for evenly obtaining bait, and it is asynchronous to grow; 5, scrubbing etting or changing cylinder mould repeatedly caused mechanical damage to spat, improves lethality.
Summary of the invention
The purpose of this invention is to provide a kind of artifical pearl shell fry net cage intermediate rearing method, establish the floating mat net cage that etting is arranged all around in the inner bay sea area, the two-layer light transmittance of net cage surface cover is 95% shading net, will be fixed on the horizontal rope of net cage with the strip hapteron of artifical pearl shell fry.The other end is tied up a weight, hangs and supports in the floating mat net cage, and 10-15 changes etting and collects and comes off at the seedling alive of spacer screen, is that to cultivate into shell length be the Xiao Bei of 25~30mm for the artifical pearl shell fry of 3~5mm with shell length.
The present invention includes following steps:
(1) the floating mat net cage of etting is arranged around establishing in the inner bay sea area, floating mat 6~12 net cages, the net cage length of side 3.0~3.5m, dark 2.0~2.5m, etting mesh 1.5~2.0cm all around, spacer screen mesh 0.3cm;
(2) on the net cage face, draw a horizontal rope and fixing as lifting rope every 30cm;
(3) with the end of 9 polyethylene rope binds with the strip hapteron of 3~5mm pearl oyster spat, be fixed on the lifting rope, the other end of hapteron is tied up a weight, keeps hanging in the seawater dried up the 20~30cm in hapteron upper end;
(4) according to the growth with spat of increasing of etting attachment, changed ettings in 10-15 days and collected the spat that spacer screen survives;
(5) cultivated 2~3 months, pearl oyster shell length can reach 25~30mm, and survival rate can reach about 12%, reaches as high as 24.7%.
The present invention improves the survival rate of artifical pearl shell fry intermediate rearing effectively, and traditional intermediate rearing method survival rate 1% is brought up to 12%, solves black pearl and cultures the shellfish source problem, has profound significance to promoting China black pearl to culture large-scale production.
Embodiment
The present invention can establish the floating mat net cage in the inner bay sea area, around the floating mat net cage etting is arranged, and is 95% shading net at the two-layer shading rate of net cage face loam cake.Floating mat 6~12 net cages, the net cage length of side 3.0~3.5m, dark 2.0~2.5m, etting mesh 1.5~2.0m all around, spacer screen mesh 3mm; On the net cage face, draw a horizontal rope and fixing as lifting rope every 30cm; With the end of little polyethylene rope bind with the strip hapteron of 3~5mm pearl oyster spat, be fixed on the lifting rope, the other end of hapteron is tied up a weight, keeps hanging in the seawater dried up the 20~30cm in hapteron upper end; The unified strip that adopts of hapteron is as attached ropes, sun cloth.Along with the growth with spat of increasing of etting attachment, regularly change etting and collect the spat that spacer screen survives; Cultivated 2~3 months, pearl oyster shell length can reach 25~30mm, and survival rate can reach about 12%, reaches as high as 24.7%.The present invention solves black pearl and cultures the shellfish source problem, has profound significance to promoting China black pearl to culture large-scale production.