WO2021119865A1 - A system for the culture of baby clams of the species venus antiqua - Google Patents

Abstract

A system for the culture of baby clams of the species Venus Antiqua is disclosed, using a long-line type system. The culture system is manufactured from a high-density plastic and comprises, at least, an upper anchoring structure wherefrom the system is suspended; culture units stacked on each other and supporting the trays, and the culture trays. The latter are separated from each other by 30-60 cm; this free space enables a flow of water with nutrients; a substrate, preferably sand, must be placed in each tray, said substrate having a minimum thickness of 30 cm in order to enable the seeds to be buried.

Description

A system for growing baby clams of the species

Venus antiqua

Technical sector

This technology is related to the aquaculture industry, in particular a rack-type assembly plastic device is presented, which is used as a suspended culture system in the sea.

State of the art

The world production of clams is supported mainly by the aquaculture production of China (FAO, 2014). This country allocates all its production to the domestic market, which, however, remains unsatisfied, which has generated the development of the production of new species of clams to try to replace the traditional ones (Yan et al., 2006; Zhang and Yan, 2006; Liu et al., 2006). The demand for clams from other countries such as Spain and the USA is also maintained, which cannot be satisfied with the current local and external supply. This situation is related to the limited availability of new cultivation sites in Europe and North America (FAO, 2014), a situation that is aggravated by the contamination of water bodies and increasingly frequent changes in the local conditions of cultivation areas such as salinity, dissolved oxygen, primary productivity, intra and interspecific competition, among others (Putnam, 2011; Weber et al., 2008; Baker et al., 2010; Dickinson et al., 2013; Hurley and Walker, 2000; Baker et al. al., 2006; Matoo et al., 2013). Production statistics without China (FAO, 2014) clearly show that world wild clam production is decreasing due to lower harvest, where existing aquaculture crops in the world are not able to cover this drop, which leads to an annual demand gap unsatisfied of more than 320 thousand tons with respect to the historical maximum of landings of the year 2000 (1.5 million tons, without considering China).

Small caliber clams (3 to 4 cm) are part of the world production described. This type of clams is a valuable niche product with high demand, mainly in markets such as the USA, Europe (Spain, Italy, Portugal) and Asia (China and Japan, mainly). In the USA, depending on the commercialization formats, their prices are normally between US $ 12-17 / kg; in Europe it can be close to US $ 30 / kg and in Japan to US $ 15 / kg.

Spain and Italy are the main markets in Europe. In Spain, the market for frozen seafood is around 300 thousand tons per year, with an annual growth of around 11.5% and with the per capita consumption of fish products over 40 kg / year. It is estimated that frozen seafood represents around 42%, mainly squid, mussels (choñtos), clams and cockles. Spain and Italy are the main producers of small caliber clams and today they seek to differentiate their products through organic aquaculture, eco-labeling and quality accreditations, since this is a highly appreciated product that is related to special occasions and celebrations. There are several species of clams, the most valued being the fine clam (Rudithapes decussatus). Small caliber products can reach prices of the order of US $ 30 / kg.

Japan is a major consumer of seafood products worldwide, since it represents about 2% of the world's population and is a relevant consumer power for many of the goods traded internationally. It is considered an exceptional and attractive market for food exporters, since it imports annually around US $ 60.5 million in this type of products. It is estimated that in seafood this country generates a minimum demand of the order of US $ 15 million. Like other seafood, clams are widely marketed, found in supermarkets, specialty stores, and seefods markets. Small caliber clams are highly appreciated, with prices in the order of US $ 25 / kg.

The techniques of seed production and fattening of clams in the natural environment have been described for the fine clam (/ ?. decussatus) and the Japanese clam (/ ?. philippinarum) by Paesanti and Pellizzato (1994) in Italy, and Pérez Camacho (1991) and Patiño (2007) in Spain, among others. In crops grown in the Ría de Arousa (Galicia, Spain), the clam fattening is carried out on the beach, with juveniles of 3 to 5 mm in length, obtaining clams of size 40 mm in 2 years. For the fine clam from the same region, growth is slower, obtaining 41 mm specimens in 3 years (Pérez Camacho, 1991). Studies carried out by Pech (1993) in the Ebro Delta (Catalonia, Spain) indicate that 11 mm Japanese clam seeds, from hatchery, sown directly on unprepared beaches, are obtained after 18 months with an average size of 41 mm.

In the fattening stage, different systems have been used, such as culture in ponds, in an open or closed circuit. Also in open systems and bays, through parks, on elevated and suspended. In Italy, Japanese clam is produced almost exclusively, which is more resistant to disease and high temperatures in the northern section of the Adriatic Sea. The habitat of this clam is the intertidal zone, the preferred substrate is sand-mud and reproduction occurs in the second and third year of life (length 2.0 to 3.5 cm) (Cataudella and Carrada, 2000). Annual production in Italy is about 40 thousand tons, concentrated mainly in the Emilia Romagna and Veneto regions, in the north of the country.

In Chile there is no clam culture and it is one of the main benthic fisheries, which is characterized by being multispecific, since it comprises at least 10 species of bivalves, where the clam (Venus antiquá), known internationally as "Chilean clam" is the most economically important, representing 90% of the landings in the clam fishery. Among the group of commercial clams in our country are also the Juliana clam (Tawera gay i), the tumbao (Semele solida) and the box-office clam (Mulinia edu / is) (Jerez and Figueroa; 2010) as the most important. Natural banks have been subjected to high exploitation in the last 20 years, registering a 50% drop in landings from the historical maximum of 40,000 tons, in 1988, to 20,000 tons in 2010 (FAO, 2014; Jerez and Figueroa 2010). Currently, landings of this resource fluctuate around 15,000 tons, although in 2012 there was an increase in landings, reaching almost 22,000 tons. As for the beach prices of the clam resource in Chile, these have decreased, reaching an average of 297 $ / kg (U $ 0.4 / kg), while exports reached 5,933 tons in 2015, mainly in frozen formats and canning.

Chile has an enormous opportunity for the production of small caliber clams (3 to 4 cm in harvest size) for the growing world market centered on the USA, Italy, Spain, Portugal, China and Japan. This product has, in the aforementioned markets, low growth of individuals from the wild, generating a gap that can be covered by our country, with high prices, which normally they are between 12 and 25 US $ / kg. The problem is that this fishing resource, endemic to Chile, has a regulation of minimum size of extraction from the natural environment, leaving it out of the market, since the regulation requires a caliber of 5.5 cm for its commercial extraction, which prevents generate this format in our country and satisfy the international demand for small caliber clams (30 to 40 mm in length). However, this restriction disappears if the V antiqua clam can be cultivated, which is assimilated in international markets to two species of high commercial value, which are Mercenaria mercenaria (cultivated in the USA) and Venus magaiiina (cultivated in Italy). Both species of clams have the highest prices in those countries and, both for their external appearance and for their organoleptic characteristics, are similar to the Chilean clam, which makes Venus antiqua a potential product to enter international markets for small clams. caliber. Then, the generation of aquaculture production and cultivation technology by V antiqua promotes the development of a new product that does not exist in the national market, moving from the extraction of a limited resource (due to the restriction of the minimum harvest size of 5.5 cm ) to a higher value market, starting from the production of seed in hatchery, developing systems and cultivation equipment for this purpose, reaching a small caliber format of 3 to 4 cm, which is highly valued in international markets.

• Some similar technologies are presented below:

Patent application CN107801675 Resource-conserving type seafood produt stereo culture device: discloses a shellfish culture apparatus, which comprises a base, a post fixedly attached to the base perpendicularly, multiple culture plates or trays attached at the base. post. The apparatus comprises a water circulation system or growth medium, which allows the arrival of nutrients to all the trays, this system has an inlet tube and multiple outlets on each tray.

Patent application US2014 / 041596 Multi-level aquaculture device for benthic organisms such as bivalves, aquaculture method, and biofilter using the same: discloses a culture apparatus for benthic organisms, particularly referring to the culture of bivalves, comprising a plurality of stacked boxes so vertical in a rack type structure, this device is used immersed in a body of water which facilitates the development of organisms.

Patent application US2005 / 145189 Method of establishing clam bed colonies and mobile floating hatchery for implementing the same: discloses a mobile floating platform, for early stage cultivation of clams, presents a closed system that allows the growth of the clam outside the reach of natural predators.

In addition, suspension culture systems should be considered for the cultivation of bivalves of the lantern or Chinese lamp type, which is presented as a set of discs stacked one on top of the other, with a separation of 15 to 20 cm between them, these discs are They are covered by a Ratschel-type mesh which allows the system to be closed through a sailboat.

Brief description of the figures

Figure 1: Scheme of the rack-type cultivation system with 6 trays. Figure 2: Scheme of the basic unit of the cultivation system. Figure 3: Diagram of the anchoring system.

Figure 4: Scheme of the culture trays.

Figure 5: Suspended culture system configuration.

Figure 6: Minimum pressures on the sand substrate.

Figure 7: Clam growth in suspended culture

Disclosure of the invention

The present technology corresponds to a system for growing baby clams of the Venus antiqua species, which will be used as a suspended culture system in the sea, which comprises a plastic rack-type assembly with at least 4 trays for each unit, in which each one of them carries sandy type sediment inside where the clam seeds are placed. Each cultivation unit is suspended in a 100 m long long-line flotation system, with 350-liter buoys located every 5 meters. The development of floating culture systems is designed for the characteristics of clam culture in small caliber format, adapted to national geographic and oceanographic conditions, through designs that consider biology, the nutrients available in the water, the Hydrodynamics that optimizes the exchange of water in the systems and that also facilitates the management in the operations of sowing, maintenance, transfers and harvests.

The system is made up of basic support units for the cultivation trays, which are assembled to form rack-like structures, these can comprise between 4 to 8 units, so the length varies depending on this. They are preferably composed of 6 cultivation units that house 6 trays of the same material where the cultivation is carried out with substrate, preferably sand.

The rack-type structure is made of high-density plastic with a diameter of 35-55 millimeters and a thickness of 3-6 mm. The structure comprises 3 sections, namely: a) Upper anchoring structure, from which the rack is suspended; b) Cultivation units, which are stacked between them and which support the trays; and, c) Culture trays.

Figure 1 shows a diagram of the rack-type cultivation system assembled with six units: A is the front view, B is the side view and C is three-dimensional. In its preferred form of 6 basic cultivation units, the system comprises the following measurements: length (1) of 2.5-3.5 meters; width (2) 60 cm, composed of trays 40-70 cm long, 35-55 cm wide and 20-40 cm high. The spacing between each tray is 40-60 cm, which allows the flow of water and food. Each growing unit (tray) is assembled to the other through four stainless steel bolts to form a growing structure. In the upper part of the cultivation structure is the anchoring piece that is made up of a clamping structure that measures 40 cm high, attached to the central structure with stainless steel bolts. Figure 2 shows the basic support unit for the trays; A shows the front view, B the side view, C the top view, and D the three-dimensional view. This unit is made up of a tubular structure 50-70 cm long (6), 40-60 cm wide (8) and 40-80 cm high (5), which form a rectangle, where the trays are positioned For this, in the corners formed between the tubes there are stops that support the trays.

In figure 2D it is observed that, in the upper part, there is an extension (12) that covers the entire diameter of the tube, and that in its upper part it has a hole; in the same way, in the lower part the tubes have an outlet (13) that also has a hole, which allows the cultivation units to fit one on top of the other and fix it with a galvanized screw; Through the hole the pieces are joined, forming the rack-type structure.

The anchoring structure is positioned in the upper part of the rack and allows the structure to be attached to a long Une type flotation system. A diagram is shown in Figure 3, where A corresponds to the front view, in B the side view, in C the top view and in D the three-dimensional view. It has a pyramidal shape, where at the base it comprises 4 structures with notches (13) for anchoring with the cultivation units. The height of the anchoring structure is 30-50 cm (14), the widest part is 50-70 cm (15) and the narrowest part is 40-60 cm (16). The structure has 4 inward projections, which converge on a central structure reinforced by a solid segment where there is, in the middle part, a hole for fastening to the long line.

Schemes of the culture trays are shown in Figure 4, showing the front view in A, the side view in B, the top view in C and the three-dimensional view in D. The trays have a rectangular base with beveled corners, which are 60-80 cm long (10) and 40 cm wide (11); The trays are 30-50 cm high (20) and, in their upper part, they have four edges or plastic ears (22) facing the outside, allowing them to be fixed to the base cultivation structure. The separation between tray and tray in the rack is 30-60 cm; this allows a free space between them that serves for the flow of water with food. Inside each tray, a bed of sand must be placed, which must have a minimum thickness of 30 cm so that the seeds can be buried. In the long Une cultivation systems, the cultivation racks presented, given their total weight, are installed every two 350-liter buoys at 5 m distance from each other, in a zigzagging manner in a long-line cultivation system. According to the estimated weight of the submerged rack, which corresponds to the maximum, close to the harvest time, it is possible to install a maximum number of two racks between 350-liter buoys. Figure 5 shows a diagram of the long line system composed of 350-liter buoys (23), separated by a distance of 5 m (24) between them; the diagonal distance between the racks is 5 meters (25). Application Examples

Example 1: Modeling and construction of the rack-type cultivation system.

First, a computational model was carried out in order to model the behavior of the culture structure. The rack was located at a depth equal to or greater than 4 meters, with reference to the upper edge of the first tray. The trays were oriented longitudinally to the direction of the current.

To determine the maximum number of racks allowed by the buoy configuration, an estimation of system weights was made (Table 1), considering the buoyancy provided by the elements to determine the effective weight of the rack being submerged. Table 1: Determination of weight and buoyants.

BOYANTES

WEIGHT

BOYANTS

Numerical simulation

The discretization of the domain is composed of approximately five million elements of the tetrahedral type. The elements that make up the tray and rack have a maximum size of 15 millimeters; The entire nearby environment was meshed with a higher density of elements than the rest of the domain for a more accurate representation of the flow in that entire area. The simulation was carried out with a 1: 1 scale model, where the current that flows in the direction of the positive x axis (+ x,) enters the domain with velocities, as indicated in Table 2. Table 2: Velocity simulation current.

Current speed m / s knots

0.0514 0.1

0.1029 0.2

0.1543 0.3

0.2058 0.4

Flow velocity inside the tray

The rack was exposed to different current speeds defined previously. In each of the cases, the resulting velocities were recorded inside the trays, at a distance close to the surface of the substrate. Table 3 below shows the average speeds inside the tray and a percentage ratio in relation to the current to which it is exposed. In all cases the resulting velocity in the interior is approximately 50% of the current velocity. However, in the case of the 400 millimeter configuration, this ratio tends to decrease because the turbulence phenomena become more intense as the speed of the stream is increased.

Table 3: Average speed inside the tray

Flow pressure on the substrate surface

Table 4 shows the evolution of the pressure field on the substrate at the different speeds. As can be seen in both graphs, in the case of the 400-millimeter configuration, the pressure variation is more intense than in the 500-millimeter configuration, so displacements of the substrate into the tray are more likely.

Table 4: Maximum and minimum pressures on the substrate

Current force on the rack

Table 5 shows the results of drag forces produced by the sea current on the rack. In both configurations the results are similar for each one of the current speeds due to the greater resistance offered by the trays, which, in both cases, have six units. The difference is provided by the greater length of pipes in the rack of 500 millimeters.

Table 5: Forces acting on the rack.

Force on rack

In general, it is possible to indicate that low current speeds (such as those that occur in protected areas where the study has been developed, condition results of little influence in relation to the pressures and turbulences generated on the rack model for proposed clam cultivation. baby On the other hand, the low current speeds allow to obtain much more reliable results, because the turbulence model used in the simulation has a more stable resolution.

The pressures on the surface of the culture substrate have a behavior that is also attributed to the separation that exists between trays (Figure 6). The closer the trays are, the more pressures (positive and negative) exerted by the flow increase on the surface of the growing medium. In Figure 6 these effects can be verified. The speed correlation in the sand shows that it does not move and, therefore, allows the settlement of the clams. In general terms, the highest pressures are obtained near the outlet face of the tray, where the flow is forced to descend towards the substrate (generating a pressure edge), to then rise on the leading face of the tray (generating a suction rim). The fact that the maximum and minimum pressures are present in a rack configuration where the distance between trays is less, is explainable due to the effect of turbulence that generates vector speeds perpendicular to the growing substrate, while the flow inside the tray The rack with greater spacing is more uniform with vectors much more parallel to the growing substrate. The turbulent effects that occur are explained by the narrowing of the flow path, which is easy to solve with variations in the spacing between the trays of the same rack.

Example 2: Manufacture of the prototype

The system was made of high-density plastic with a diameter of 40 mm and a thickness of 4.5 mm. The structure comprises 3 sections, namely: a) Upper anchoring structure; b) 5 culture units; and c) 5 culture trays.

In Figure 1 a diagram of the rack-type cultivation system assembled with six units is presented, 2 prototypes were elaborated with a space between each tray of 40 and 50 cm, which translates into a total length (1) of the system of 3.3 or 3.7 meters, depending on the space between trays.

Figure 2 shows the basic support unit for the trays, which is made up of a tubular structure 50-70 cm long (6), 40-60 cm wide (8) and 40-80 cm high (5). those that form a rectangle, where the cultivation trays were positioned. In the corners formed between the tubes there are stops that support the trays.

In Figure 2D it can be seen that there is an extension (12) that covers the entire diameter of the tube, and that in its upper part it has a hole; in the same way, in the lower part the tubes have an outlet (13) that also has an orifice; In this way the cultivation units were assembled, one on top of the other, and fixed with a galvanized screw; Through the hole the pieces are joined, forming the rack-type structure.

The anchoring structure (Figure 3) was positioned in the upper part of the rack, allowing the structure to be attached to a long line type flotation system. This has a pyramidal shape, where at the base it comprises 4 structures with notches (13) for anchoring with the cultivation units; the height of the anchoring structure is 40 cm (14), the widest part is 60 cm (15) and the narrow part is 50 cm (16). The structure has 4 inward projections, which converge into a central structure reinforced by a solid segment where a hole is arranged in the middle part to hold the long line.

Figure 4 shows diagrams of the culture trays, which have a rectangular base with beveled corners, have a length of 60 cm (10) and a width of 40 cm (11); The trays have a height of 40 cm (20) and in their upper part it has four edges or plastic ears (22) facing the outside that allow it to be fixed to the base cultivation structure.

Figure 5 shows the distribution of cultivation units in a long line type flotation system, the distance (24) between two 350-liter buoys (23) is presented, where two cultivation units are placed. The separation between buoys of each culture unit fluctuates between 1-2 m (25).

Figure 6 shows the effect on the sand of each tray, subjected to different current speeds, in the two models used of cultivation units, with a separation between 500 and 600 mm. Significant differences were found between the two, observing a greater pressure on the sand grains in the 400 mm model, which prevents the sand from leaving the box and at the same time allows the seeds to be buried and without movement.

Example 3: trial with clams.

The culture prototypes were manufactured, assembled and installed in a long line type system in a mitilid culture center. Two types of treatments were carried out (400 and 500 mm of separation between each tray) with 5 units each. These cultivation systems were installed in a 100 m long long-line, which was built with 350-liter buoys; each unit was placed every 5 meters apart.

Inside each tray, prior to installation, we proceeded to place fine sand (1-3 phi of particle size, which must form a minimum thickness of 30 cm so that the seeds can be buried). Once the systems were installed, by means of autonomous diving, clams of individual size between 15 - 20 mm in each of the culture systems at a density of 800 units per tray, which were monitored for a period of 11 months.

Figure 7 shows the growth of clams in suspended culture in two of the culture unit formats (40 and 50 cm separation between trays). It is worth mentioning that during a period of 11 months the clams reached a size of 35 mm in length, the ideal harvest size for the baby format, the mortalities reached 1%. It is worth mentioning that this baby type product cannot be marketed in our country today, since the minimum size of extraction from natural banks is 5.5 cm, which leaves it out of the market. Therefore, this system ensures 99% survival of the cultured organisms, with volumes per tray at a size of 35 mm of 35 - 45 kilos per tray.

Claims

1. A system for cultivating baby clams of the Venus antiqua species CHARACTERIZED in that it is made of high-density plastic 35-55 millimeters in diameter and 3-6 mm thick, and comprises at least the following sections: a . Upper anchoring structure, from which the system is suspended; b. Cultivation units, which are stacked between them and which support the trays; and, c. Culture trays. 2. A system for growing baby clams, according to Claim 1, CHARACTERIZED because each cultivation unit is assembled to the other through four stainless steel bolts to form a rack-type cultivation structure, which can comprise between 4 to 8 units and comprises the following measurements: length (1) of 2, 5-3.5 meters; width (2) 60 cm, composed of trays 40-70 cm long, 35-55 cm wide and 20-40 cm high, where the space between each tray is 40-60 cm, which allows the flow of water and food. 3. A system for growing baby clams, according to Claim 1, CHARACTERIZED because the anchoring structure is positioned in the upper part of the system and allows the structure to be attached to a long line type flotation system; It has a pyramidal shape, where at the base it comprises 4 structures with notches (13) for anchoring with the cultivation units; the height of the anchoring structure is 30-50cm (14), the widest part is 50-70cm (15) and the narrow part is 40-60cm (16); and it has 4 inward projections, which converge in a central structure reinforced by a solid segment where a hole is arranged in the middle part to hold the long line. 4. A system for cultivating baby clams, according to Claim 1, CHARACTERIZED in that the cultivation units comprise a tubular structure 50-70 cm long (6), 40-60 cm wide (8) and 40-80 cm high (5), those that form a rectangle, where the cultivation trays are positioned; for this, in the corners formed between the tubes there are stops that support the trays. 5. A system for cultivating baby clams, according to Claim 1, CHARACTERIZED in that the cultivation units comprise in the upper part, there is an extension (12) that covers the entire diameter of the tube, and that in its upper part has an orifice ; in the same way, in the lower part the tubes have an outlet (13) that also has a hole, allowing it to fit the cultivation units one on top of the other and fix it with a galvanized screw; Through the hole the pieces are joined, forming the rack-type structure. 6. A system for cultivating baby clams, according to Claim 1, CHARACTERIZED because the cultivation trays comprise a rectangular base with beveled corners, which has a length of 60-80 cm (10) and a width of 40 cm (11); The trays are 30-50 cm high (20) and on the upper part they have four edges or plastic ears (22) facing the outside that allow them to be fixed to the base cultivation structure. 7. A system for growing baby clams, according to Claim 1, CHARACTERIZED because the separation between tray to tray in the rack is 30-60 cm; what allows a free space between them that serves for the flow of water with food. 8. A system for growing baby clams, according to Claim 1, CHARACTERIZED because inside each cultivation tray a substrate must be placed, preferably sand, which must have a minimum thickness of 30 cm so that the seeds can be buried. 9. Use of the system for cultivating baby clams, according to Claim 1, CHARACTERIZED because it is used in a long line cultivation system, where every two 350-liter buoys are installed at 5m distance from each other in a zigzagging manner. 10. Use of the system for growing baby clams, according to Claim 1, CHARACTERIZED because it allows to obtain clams of a size of 35 mm in length, in a period of 11 months.