4.1 CAPTURE AND IMMEDIATE HANDLING ON BOARD
Offer consumers of fish of excellent quality, to prevent its degradation throughout the process. Alteration starts with the death of fish and can so be initiated before the fishermen only go back the catches on board. In some countries, it is customary to leave gill nets ‘wet’ for long periods, where losses ranging up to more than 25 percent according to some studies conducted as part of the program of the Bay of Bengal (FAO, 1991). Fish caught fishing, seining of beach and with other active gear are generally of better quality that the machine doesn’t “wet”. One of the ways to prevent alteration of fish in gillnets is so put together them more frequently. However, this suggestion will be little popular with fishermen because it requires more work, can be more costly and divert them to other activities.
It follows that ice cannot be in itself a guarantee of a better quality fishing landing nets unless the fish has been properly handled before icing in dry-dock. Even when the nets or other gear went frequently, the deterioration is sometimes quick, especially when catches are left in the Sun and heat on the bridge, which negates any improvement in quality as a result of a more frequent recovery of the craft.
The alteration process is continuous and unavoidable; regardless of the amount of used ice, a thirsty fish won’t find its first quality.
In short, the time elapsed between the capture or death of the fish, and icing should be as short as possible, and the fish must be the least possible exposed to high temperatures. In the tropics, this means putting the fish in the shade and not in full sun. When it is not possible to freeze the fish immediately, we cover it sometimes with wet bags until its storage. On some boats, fishing bridge is often protected by a fixed or removable cover (see Figure 4.1) which houses the Sun crew and catches that are waiting to be gutted and stored in the hold.
In the absence of thermal insulation, the rate of loss and melting of ice in the fish hold will likely be high, especially in tropical and subtropical areas. Infiltration of heat and the alteration of the catch resulting from the merger of the ice are particularly pronounced on the sides of the boat and the ceiling of ceiling, as shown in Figure 4.2. To address this problem without isolating the hold, you can store a lot more ice against the sides of the boat before you store the fish and add a good thickness of ice between the last layers of fish and the ceiling ceiling, which allows to compensate for leakage of heat. Even if the thermal insulation of the hold seems expensive at first, it will be offset in some time by the economies of ice and the higher price obtained for better quality fish.
To keep the ice fully effective, consider the following points:
- Ice should always be clean and fragmented into small particles to allow maximum contact with the fish.The ice blocks must be finely ground to avoid lumps which can damage fish.
- The fish/ice report must be correct.In temperate climates, there are usually a part of fish for a piece of ice. In the tropics, it is not uncommon to three parts of ice for a portion of fish.
- Additional layers of ice must be added in areas of the hold of heat infiltration, as the wall of the room machines and flanks, to compensate for too fast fusion of ice, especially in the case of bad insulation.
- He must add a good thickness of ice between the last layers of fish and the ceiling ceiling to cover perfectly captures and protect them from any infiltration heat from the bridge.
- The ice and the fish must be regularly and carefully distributed.Do not stuff the boxes and shelves for fear of crushing the flesh of the fish.
- Landed, the fish must be at a temperature of 0 ° C to 2 ° C, and it has yet to be fully covered with a thick layer of ice.
- The fish must be protected on all sides by the ice.
Figure 4.3 illustrates the mode of storage of fish in a typical hold of a small fishing boat.
4.2 STORAGE OF FISH DEPENDING ON THE TYPE OF USED ICE
Fishing boats generally employ the type of ice that they can get in the factories down. The factories specialized in fishing normally produce sous-refroidie ice, in flake or flakes, or blocks. In countries where most modern facilities, you can also get liquid ice.
The ice must be properly used to provide a quick and effective cooling. The fish must be totally surrounded and fully in contact with the ice. Therefore, ice comes in very small pieces or in liquid form, and even in ice-water as the EMRG grout. Can’t get the same cooling scattering a few chunks of ice on the fish by surrounding it on all sides small particles of ice. They are put in boxes or stored in bulk in the compartments to fish, catches should be carefully interspersed in layers of ice. Figure 4.4 shows a well made frosting and a bad frosting of the fish.
To get the full benefit refrigerant properties of ice, some fishing boats in narrow bridge operating in hot countries install insulated tubs on the deck. The bins are filled with ice and EMRG and used to cool quickly captures pending their icing to hold. The advantage of this system, although sea water is cooled with ice, is that it reduces the amount of necessary ice in the hold to bring fish to 0 ° C; If the hold is small, we can thus store more fish. As the fish can be refrigerated almost immediately after his capture, this system allows to keep all his quality.
4.2.1 blocks of ice/crushed ice
The factories of blocks of ice are still very common in many countries because of their simplicity of operation and maintenance. They were often built to power stores, bars, markets and the housing sector as well as the fishing boats.
In many parts of the world, the ice blocks have preference for fishermen because they last longer and take less space in the hold. However, as already mentioned, it must first grind them into fine particles to fully exploit the properties of ice and refrigerate the fish. The most common practice is to load and store the blocks and crushing them to the needs. To ensure a good contact with the fish, it is crucial to crush it into small pieces. We often just to break it up with a hammer or with an ice pick, which is not enough to reduce it into particles small enough to allow a good contact with the fish, which is then exposed to room temperature. For efficiency, use a grinder or a crusher that will produce chunks of 1 cm x 1 cm or less, as described in section 3.3.
4.2.2 ice flakes
Compared to the blocks, the Flake ice is more simple to use since there is no crush beforehand. As it is slightly sous-refroidie to manufacture and can her Pack carefully all around the fish, it probably offers better cooling than the crushed ice. However, as she is more surface and it contains a lot of air, it takes more space in the hold and melts more quickly than the blocks.
4.2.3 liquid ice
Liquid ice is an agent cooling extremely effective for fish and allows you to very quickly bring it to 0 ° C. It is mainly used to store fish in closed containers, such as unions or insulated trays. When the catch is stored on shelves, its usefulness is based on its liquidity. If the mixture is too watery, it will tend to flow and to expose the fish. Liquidity is a factor that you can control if the ice machine is on board. Otherwise, get dry ice to which we add the clean sea water needs. This type of ice is more and more appreciated on the boats that target high-value species, as shrimp which are directly responsible to the capture in large insulated, covered with liquid ice bins and delivered such what on the markets or at the treatment plant, and so are little or not at all damaged. From the point of view of refrigeration, the liquid ice has similar characteristics to those of the EMRG.
4.2.4 seawater cooled to ice (EMRG)
The EMRG is a very effective refrigerant environment because the fish is completely drowned. However, it requires to equip the hold of tanks or waterproof cases, where additional costs which are not always justified. This type of installation is mainly used in the following cases:
- boats targeting high-value species;
- preservation of the fish when it happens any time between capture and delivery to treatment plants, as in the case of sardines and anchovies;
- preservation of small pelagic fish (for example), it is not possible to individually under ice.On seiners, catches are so loaded directly in the vats of EMRG, which allows a fast and efficient refrigeration.
The tanks reduce the available dock space, sometimes up to 20 percent.
The proportions of the mixture of ice, water and fish in the tanks and isothermal containers depending on the climate. The circular on fisheries No 773 of FAO (FAO, 1984) gives the following figures for tropical and temperate climates:
- temperate: 1 kg of water: 1 kg of ice: 4 kg of fish
- tropical: 1 kg of water: 2 kg of ice: 6 kg of fish
According to the authors of this circular, it is the volume of ice required to bring fish to 0 ° C. If the fish has already been cooled, it will decrease the volume of ice as much. Although even all other factors remain the same, remember it takes the ice to cool the water of the system as well as the fish. so the EMRG refrigeration requires in theory more than a simple glaze ice.
In its most basic form, it gets the EMRG by adding fresh sea water to the ice contained in the bins, the compartments seals or the vats of the fish hold.This system is suitable for short periods of time, but a problem of stratification of temperatures. This is due to the rise of water in the tank and the fact that the ice and the fish tend to float in the water. If you do not stir frequently EMRG/fish mixture, we risk an improper refrigeration of fish. On the other hand, can lead to damage the fish stirring the mixture too suddenly; methods have therefore been developed to ensure good circulation water in the tank without damaging the fish. We usually use the following two methods:
- Introduction of compressed air inside tank EMRG through perforated pipes.In general, an air pump is installed for this purpose near the tank. Back to the surface, the air bubbles hunt fresh water from the bottom of the tank and promote their mixing with the upper layers of water. Because of the many bubbles produced by this device, it is often called ‘champagne system ‘. It is a relatively simple and economic formula that allows to limit the stratification of temperatures and which is also well suited to small-scale fishing vessels where there is little space.
- The EMRG provided by pumps to water traffic.For this system to be effective, it must be equipped with a filtering device that prevents fish, shells and other debris to block the return pipes. For more information on this system, refer to Chapter 2.
4.3 HANDLING OF ICE AT THE TIME
As time passes, the pieces of ice tend to agglomerate and become difficult to handle and mix with the fish. The federal Department of fisheries of the Canada has conducted research on the issue by measuring the agglomeration of the ice according to the following parameters:
- pressure required to break the surface of the ice;
- depth of penetration of the gauge;
- pressure needed to stir a shovel pushed into ice;
- size conglomerated fragments of ice.
This research resulted in the following conclusions:
- The ice remained totally manageable seven days lasted the tests.
- The Flake ice remains manageable 48 hours at most; It remains manageable, but difficult after 96 hours.
- Ice from crushed blocks is almost impossible to handle after 24 hours.
In most cases, the vessels that use blocks of ice load them whole and crush them to the needs, which explains that the problem of the settlement of the pieces of ice does not arise.
Visual observations relating to the different types of ice
|Hours||Flake ice||Ice flakes||Crushed ice blocks|
|0||The glitter of ice are of variable size (10-100 mm), thick 6 mm; no large lumps; can be discharged without difficulty into a container/box insulated with lid.||The scales are 30 mm × 2 mm thick. They are irregularly shaped.
No settlement, may be discharged into a container/box insulated with lid
|Have the appearance of a dense and heavy snow, with small isolated pieces of clear ice (10-100 mm).
Ice tends to agglomerate and to take the form of credit unions
|24||Retraction at 5 mm from the edges; the sequins keep their shape||Retraction at 10 mm from the edges; the scaly appearance disappears; training of small clods; formation of a crust frozen;appearance slightly dirty.||Solid surface with compact ice fragments.|
|48||Retraction at 10 mm from the edges;reduction in the size of the flakes which have a pitted surface.||Essentially composed surface of a solid crust; the shovel was folded during the test.||Ice is solidified.|
|96||Shrink more than 10 mm; obvious decrease in the size of glitter; ice tends to compact, but can still break it and manipulate it easily with a shovel.||And very dirty surface||Retraction in 20 mm; some fragments isolated strong and small agglomerates of particles of snowy appearance; ice to look very dirty.|
|168||Retraction between 20-40 mm aspect clearly dirty; no real caking; get crushes easily.||Retraction between 20-50 mm||(192 hours)
Shrink to 30 mm; It is extremely difficult to push the shovel into the ice.
Source: DFO Canada, 1993.
Table 4.1 summarizes Visual observations of a general nature on the handling of different ice types tested.
4.4 AMOUNT OF ICE REQUIRED ONBOARD
The space required for the storage of ice will depend on the size of the boat, the duration of the fishing trip, the likely volume of catches and the availability of an on-board ice machine.
4.4.1 refrigeration of fish
Table 4.2 shows the amount of ice required to refrigerate 10 kg of fish at 0 ° C depending on the temperature of the fish. For a larger volume, multiplied the amount of ice by the weight of the fish stored in dock. A temperature of 30 ° C, a load of 1,000 kg of fish will require 340 kg of ice, or ice/fish slightly greater than 1:3 ratio, to bring the fish to 0 ° C. This ratio does not account for losses due to heat, or the amount of additional ice infiltration to maintain fish at this temperature until the end of the fishing trip.
In practice, therefore, amounts of ice far superior to maintain fish at 0 ° C and keep refrigerated for a while.
Theoretical weight of ice to refrigerate 10 kg of fish at 0 ° C depending on the initial temperature of the fish
|Temperature of the fish||Amount of ice required|
Empirically, it is considered to a ratio of 1:1 ice/fish in the tropics. However, it happens very often that the ratio is 3:1. The duration of the fishing trip is the main factor that affects this ratio.
We’ll find a more detailed account of the issue in Chapter 7.
4.4.2 duration of the fishing trip, volume and composition estimated catches
It does not help to ship ice if it lasts for only a portion of the planned fishing trip. Therefore, carefully calculate the amount of ice required for average output. For this purpose, several factors must be taken into account, including: the duration of the fishing trip; the average volume of catches, usually directed by fishing trip; the type of fish, namely small or medium size or sizes mixed; available in wedge and/or containers storage; the planned ice losses due to leakage of heat in the hold or containers; the room temperature.
The target market can also have an influence on the quantities of ice shipped. For example, for pelagic species with high value – such as swordfish, yellow tuna, southern bluefin and the mahi mahi – export, need more ice than for fish for local consumption.
Ideally, it should still stay ice in the hold once all the fish landed at the end of the fishing trip. There are as well as the necessary ice volume has been correctly estimated. Do not keep the ice in dock in order to reuse it. Throw it away, wash the hold water and disinfect it with a solution of chlorine or any other agent commercially available. All surfaces of the wedge should be brushed to remove traces of blood or mucus dry. You can load the ice for the next fishing trip to the moment the hold was perfectly cleaned.
The amount of on-board ice is function of available space before the start of fishing operations. It means finding a balance between transported ice, the expected volume of catches and their composition. This last parameter is important because rates cale cubic meter storage depends both on the storage method – on shelves or in boxes – and the size of the catch. This report is illustrated in tables 4.3 and 4.4. In practice, considered that the volume of ice shipped may be higher by 30 percent or more to the minimum necessary to compensate for losses due to the heat. The necessary volume will be much more important in the holds who are not thermally isolated.
Example: a boat equipped with a cold 6 m3 sailed for a trip of three to four days and table, altogether, about 1,500 kg of fish of medium to large-sized.The fish will be stored in bulk. The amount of ice required for the fishing trip can be calculated as follows:
- 1 500 / 10 × 3.4 = it will take 510 kg of ice to bring the fish to 0 ° C (see table 4.2).
- An ice/fish of 1:2 ratio, to still 750 kg of ice.
- A supplement of 30% should also be provided to compensate for losses due to the heat: 30/100 × (510 + 750) = 378 kg.
That means a total of 1 638 kg of ice. For not taking risks, the fishing pattern will do 2,000 kg, or a ratio of 1.3: 1 ice/fish which is slightly higher than the empirical minimum. Ice will occupy about 4 m3 in the hold to fish (see table 4.3) when the boat put to sea. When he leaves the fishing grounds, the hold will contain 1,500 kg of fish mixed with about 750 kg of ice. Here again, a volume of 4 m3 will be busy in the hold (see tables 4.3 and 4.4).
Table 4.4 shows the amount of ice required for 1 ton of fish, according to three different methods of storage, for a fish/ice 2:1 ratio.
The weight of the ice compared to its volume varies according to the type of ice (see table 4.3 and Figure 3.2). The refrigeration of the catch depends on weight used ice and not its volume; for a same refrigeration capacity, therefore compare equal weights of ice.
Materials, rate and storage methods
|Material||Storage method||Stocking rates|
|Small fish (sardine or related)||Without ice||800-900|
|Small fish (sardine or related)||In bulk in the ice||650|
|Small fish (sardine or related)||In of the EMRG||700|
|Fish of medium or large size||In bulk in the ice||500|
|Fish of medium or large size||In boxes under ice||350|
Stocking rates in bulk, in boxes or on shelves
|Storage method||Average stocking rates||Average stocking rates|
|(m3/tonne of fish)||(piedt3/tonne of fish)|
(2:1 fish: ice)
(2:1 fish: ice)
(2:1 fish: ice)
4.4.3 storage considerations
On board storage methods differ depending on the size and type of boat.
On the big boats who store the ice and the fish in bulk, good thermal insulation is required in the hold to fish that is usually divided into parks or compartments. Heat insulation delayed the merger of the ice due to infiltration of heat and can maintain a rate of correct icing. Furthermore, the compartments allow to keep unused ice away from the fish and the ice/fish mixture and sort by size and species, catches as the case. A typical model of compartmentalized fish hold is shown in Figure 4.5.
On the decked boats that have no cold room, insulated of adequate size to stand between the hatches and allow manipulation in the hold are a good solution to avoid retooling the hold. On the other hand, stores reduce the space available for storing ice and fish. Here again, the problem is less if it captures high value.
On small boats not bridge, used mainly funds or insulated containers to transport the ice, and then to store the captures in the ice. Boxes and insulated containers can also be used to transport the catch ashore, which avoids having to repack them after d-day.
Some boats of small-scale fisheries as the large canoes of Senegal, must use boxes of special shape to avoid wasting too much space. These crates can hardly be used for other purposes or for transport. However, the standard boxes which lend themselves well to other uses can easily find their place on the large canoes canoes common in South America, Central America and in some parts of Africa (see Figure 4.6).
In many countries, we see more and more small fibreglass fishing boats. Largely bridged, simply equipped boats of a floor and swim benches, which were designed as multi-purpose vessels and not not specifically intended for fishing. When you team them for fishing, sometimes added a small wedge to fish in the hull. Figure 4.7. shows a boat which has been modified in this way. In Central America and the Caribbean, we see many ships of this type, about 7 to 9 meters long, and they are already well proven. This type of installation has been developed at the request of the fishermen.
The wide bridge boats equipped with a fish hold generally carry wedge ice, where it is kept in compartments until the frosting shots. However, some decked boats, from 10 to 17 meters long, getting into isothermal containers full of ice that are stored directly in the fish hold or secured on the bridge. Some of the catch is put under ice in these containers. You can also keep the fish in the EMRG by adding water of clean sea ice in insulated trays, which allows the lower layers of fish to not be crushed at the bottom of the bins, especially when they are large. Be careful when moving heavy and large bins on the bridge as they can destabilize small craft.
When the catches are put in boxes, we can clear the hold and transport unions directly to the market or the processing plant, which limits the handling and allows to offer a better quality product. To get crates and bins full and voluminous of the hold and move them to dock, is sometimes used to lifting equipment.
If the ice factory is not directly located at the fishing port, the isothermal containers can also be used to transport ice from the factory to the boat, which allows to limit losses due to the melting of the ice.
Several types of boxes or insulated trays are available in the market. They are usually designed to be stackable and easy to move, whether manually or using sling or forklifts. Large insulated trays are manufactured by molding or moulding by injection. Rotational moulding is the most common technique today because the production of the hulls is generally less expensive; However, the manufacturing process does not easily lend itself to series production. The insulation used is normally polyurethane foam injected into plastic shells.
Injection molding requires much more expensive equipment which allow to produce a unique size. Indeed, some molds different must be made for each shape or size of Fund. One of the advantages of injection molding is that it lends itself perfectly to a serial production and can be more precisely control the thickness of the shells.
These boxes come in various sizes, small models with a capacity of about 60 liters while the big ones go up to 1,000 litres, and several intermediate sizes are also available for various applications. If they are not full, the small models can be moved by hand, while fat require mechanical means, such as simple pallet with arms that can also be used on board, fork lift trucks or the winch and the mast of the boat load. Common insulated plastic models are shown in Figure 4.8.
Instead of containers or insulated boxes, also is often used crates to ordinary (often plastic) fish that is stacked in the isothermal wedge ice and fish are stored. They allow good icing the fish and sort by size and species catches before glazing. The fish can then be directly unloaded cash and transported to the market or treatment plant, without having another handling need. We find cases of forms and different sizes, suitable for several applications. This method requires more room than other modes of storage, a disadvantage which is often compensated by his side practice.
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