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Post-harvest fish losses are a major concern and occur in most fish distribution chains throughout the world. Not only do losses constitute lost income to fishers, processors and traders, they also contribute to food insecurity a loss of fish means less fish available for the consumer.

What does "post-harvest fish loss" mean?

This chapter introduces the main types of PHFLs encountered in SSFs and the main causes of these losses.

Generally speaking, PHFL refers to fish that is either discarded or sold at a relatively low price because of quality deterioration or owing to market dynamics.

This means that fish operators (fishers, processors, traders, and other stakeholders involved in ancillary operations) lose potential income.

It also means that less fish is available to consumers, or that consumers are supplied with low-quality fish and fish products. There are also important negative implications for food security.

Post-harvest fish losses are often caused by biochemical and microbiological spoilage changes that occur in fish after death. A live fish has natural defence mechanisms that help to prevent spoilage. However, once a fish dies, its defence mechanisms stop and enzymatic, oxidative and microbiological spoilage begins to cause quality deterioration.

Several factors tend to influence the rate of spoilage of fresh fish:

    • Time between death and final use or consumption: Even if fish are chilled using ice, they will gradually spoil over time; processed fish quality also deteriorates over time.

 

    • Temperature abuse: High ambient temperatures, such as 20 °C, create favourable conditions for fish spoilage. Low temperatures, such as 5.0 °C and below, slow the action of bacteria and the rate of spoilage, helping to reduce losses.

 

  • Handling practices: Poor handling practices lead to sustained and increased microbial contamination, hastening the spoilage rate of fish. Such practices include: using dirty canoes, equipment, fish boxes and baskets; not washing fish; washing fish in dirty water; placing fish on dirty surfaces; and physically damaging fish by throwing or standing on them.

Besides spoilage, PHFLs are caused by:

    • discarding of bycatch at sea because fish is too small or not valuable enough to land for sale;

 

    • poor processing techniques damaging fish;

 

    • animal predation and insect infestation;

 

    • inadequate packaging and storage practices leading to damage of the end product;

 

  • market dynamics, especially fluctuations in demand and supply of fish and fish products, affect price and therefore income.

Main types of losses covered in this manual

There are three types of loss considered in this guide that affect SSF stakeholders:

  • physical loss;
  • quality loss;
  • market force loss

Physical loss

Physical fish loss refers to fish that, after capture or landing, is not used. It is either thrown away accidentally, voluntary or as authorized. Physical loss can be caused by theft, by insects eating the fish, or by bird or animal predation.

Examples

    • Fish have spent many hours caught in the fishing gear. The fish have been dead in the water and have begun to spoil. By the time the fishing gear is hauled into the canoe, the fish have become too spoiled to fetch a good price and market and are not worth landing, and, therefore, they are thrown away at sea.

 

    • In many tropical countries, small-sized fish such as sardine and anchovy are sun dried in the open air before being packed and distributed. When catches are high, e.g. during the rainy season, the fish cannot be dried properly and spoil. Severe spoilage means that the fish are often thrown away.

 

  • Fishing for high-value species such as shrimp is often associated with high levels of bycatch. In some fisheries, most bycatch is discarded at sea as it consists of low-value, small fish that are not worth landing.

Quality loss

Quality loss refers to fish that has undergone changes owing to spoilage or physical damage and has suffered quality deterioration. Such fish is sold for a lower price than that which would have been achieved if the fish were of “best quality”. This is the most common PHFL in many areas.

Examples

    • Poor transport as well as inadequate market information result in operators storing their fish and fish products for long periods. In the process, spoilage occurs and the quality of fish is degraded, leading to low selling prices.

 

    • Some fresh-fish traders do not use ice. They buy fresh tilapia early in the morning and struggle to sell the bulk during the day. The fish is exposed to high ambient temperatures and sold for about $1 per kilogram in the morning, and the price gradually declines during the course of the day to less than US$0.5 per kilogram in the evening.
      Any leftover fish at the end of the day has to be sold for less than $0.2 per kilogram to traditional fish processors. Given the situation, most customers wait until evening, when a fish seller is desperate for buyers as the quality is degrading fast. If ice were available, the trader could slow the rate of spoilage and maintain quality, keeping the fish in good condition for a few days and hopefully obtaining more consistently higher prices for the product.

 

    • In some communities, consumers think that fish that has been iced is not good quality and they are suspicious of such fish. Such customers prefer to buy fish that has been exposed to ambient temperatures. They need to be educated about the benefits of using ice and the positive effect it has on fish quality. Otherwise, it will be difficult to implement loss reduction interventions, such as good use of ice.

 

  • The first-in, first-out rule is not always applied in many small-scale fish markets where the most recently arrived fish is the first to be sold and fish already in storage is left and can suffer quality deterioration, which will affect its eventual selling price. In such situations, good business practices and good storage practices can help to ensure good-quality fish.

Market forces loss

Market force loss is a loss caused by unexpected market demand and supply situations. These cause operators to sell their product at a price below expectations. The loss is the difference between the expected price and the actual price.

Examples

    • Increased supply during the peak season may flood the market with the fish, and the price can then fall regardless of its quality.

 

    • Inadequate market information and barriers can prevent the producer from gaining access to the right market with the right product at the right time.

 

    • Storing fish, whether it be fresh, frozen or smoked, will often incur costs, e.g. electricity, and storage rent. Hence, if not careful, the owner of the fish can end up making a loss if the fish is not sold quickly.

 

    • Sometimes, marketing malpractices can lead to improper pricing or cheating. This can cause a loss to operators.

 

    • Some of the rural fish markets operate on established market days only. On such days, more fish is supplied in the market and price is affected by supply and demand.

 

  • Specific festive periods are celebrated with preference to particular foodstuffs. If these are vegetables and meat, the demand for fish will drop along with its price .

There are many things that can influence markets, demand, supply and fish price. Consequently, it can be difficult to determine or know the real reasons for a market force loss. Experience from loss assessments has shown that a market force loss may evolve over time into quality and/or physical losses.

Summary Of Causes Of Different PHFLS

Physical, quality and market force losses occur throughout the post-harvest chain from harvesting to consumption. These result in lost income and contribute to food insecurity. Table 1 summarises the main causes of the three types of loss according to different stages of the distribution chain.

September 2011

Lucy Towers

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