The quality of products is an element of the sustainable development of fisheries because it aims at guaranteeing health-related reliability of the landings and their optimum valorization. In the case of anchored FAD fishing activities, undecked vessels used to capture large pelagic fish are not big enough to be fitted with adequate (regulatory) means of conservation of the catches.
Small-scale fisheries cannot follow the migrations of fish. Their landings are consequently irregular (depending on the presence of fish) and not numerous, which makes them less competitive when compared to large-scale fisheries fueling the imports of sea products, particularly in island-countries. The short duration of the tides and fishing techniques used (hand-line) give small-scale fisheries the possibility to land fresh quality products, providing that such exceptional quality is preserved and valorized in an adequate manner.
A global and pragmatic approach to quality by the entire profession simultaneously is necessary to improve the quality of anchored FAD fishing products. To do so, the coordination of different activities is needed; namely:
- Adapting fish processing and conservation protocols to the means fisherfolk and sellers have at their disposal
- Improving the equipment of landing and sale points
- Equipping or conceiving vessels better adapted to the conservation of large fish
- Creating a guide of good practices recalling all the rules to comply with so as to guarantee health safety and the highest level of freshness of products
- Training fisherfolk and sellers to hygiene, post-capture treatment and conservation regulations of sea products
- Informing consumers on the quality criteria of sea products and associated requirements
To perform such work, it is necessary to appoint a quality coordinator with good theoretical knowledge of sea products quality (scientific and regulatory aspects) as well as experience of current practices and constraints governing them.
The results presented below come from scientific works essentially performed in Martinique mainly on undecked vessels (Dromer et al. 2015).
1) Post-capture treatment and onboard conservation practices
Post-capture treatmentcomprises several steps:
- Gaffing ensures the immobilization of the fish near the vessel
- Fish stunning is performed by hitting the head of the animal with a bludgeon, for large fish, before lifting them on board
- Decerebration enables desensitization of the animal by destructing its brain. It is rarely practiced
The extraction of the spinal marrow completes the previous step by also destroying the spinal marrow. It is rarely practiced on small vessels in the Caribbean region
The decerebration and extraction of the spinal marrow limit the burnt-flesh phenomenon observed on black fin tuna in the upper part of the photograph.
- Bleeding aims at eliminating the blood from the animal’s body. It is rarely performed so as to satisfy customers’ demand. When it is practiced it is only done partially.
- Evisceration consists in removing the viscera (digestive, reproductive, excretory and respiratory systems) without perforating them and while limiting the size of the cut made on the fish to extract them. This operation is generally performed on large fish and more rarely on smaller ones. It is done on board, right after the capture or not, and sometimes after the landing.
2) Onboard conservationis is done in different ways
According to the size of the animal, the vessel’s equipment and the availability of ice, the fish can be:
- Put into ice
- Set on ice
- Set on a fish layer isolating it from the ice
- Set on the bottom of the vessel
3) Impact of the different treatment and conservation modes on the quality of products
The impacts of the different treatment and conservation modes as well as the quality of the products after the landing were measured thanks to different methods.
a) The monitoring of the fish surface temperatures
The monitoring of the fish surface temperatures (subcutaneous temperature probe) depending on the onboard conservation mode:
Only the conservation into ice enables a rapid drop of temperature below 5°C, but vessels are rarely equipped to stow large fish in good conditions.
b) Microbial analyses
Microbial analyses show that hygiene regulations are not always respected (presence of coliform bacteria). Fisherfolk are not sensitized enough to those regulations but they also lack equipment to clean the vessels (rinse after chlorination and collection of wastewater), cutting tools and disinfection…
c) Histamine analyses
Histamine analyses performed over several days evidence the positive effect of fish bleeding to reduce the production of histamine.
d) The color
The color is better preserved and less intense when the fish was bled.
e) Sensory analyses
Sensory analyses reveal that fish bleeding gives a firmer texture, a better hold of the fillets, a less persistent smell and less salty taste.
f) Conservation modes and durations
Under vacuum conservation is the best compromise to preserve the qualities of the product for 7 days. It is cheaper when compared to packing under modified atmosphere and preserves better the texture than putting the product into ice.
Fresh tuna locally produced and frozen imported tuna do not present differences as far as the taste is concerned.
Keeping tuna kept under ice for 6 days does not change its sensory qualities.
4) Chemical contamination of the flesh
The contaminant content analyzed in the flesh of the fish captured near FADs is inferior to that set by European regulations for PCB and dioxins. The heavy metal rates measured are also below regulations, except for one blue marlin with cadmium and 2 individuals (one black fin tuna and one blue marlin) for total mercury.
The chlordecone analyzed in samples of black fin and yellow fin tuna and blue marlins always revealed to be in compliance with rates inferior to 20 μg per kg of flesh.
Several families of parasites were observed in the flesh of the fish. This leads to advise freezing as far as the center for 24 h at - 20°C prior to raw or slightly cooked consumption.
6) Chemical composition of the flesh
The chemical composition of the flesh of the fish (tuna and blue marlins) evidenced that it is lean fish with a high rate of proteins (about 24%) and little lipids (between 0 and 2%). The average energetic value brought by the consumption of 100 g of flesh is of about 100 Kcal.
Works to implement
- Elaborate a guide of good practices regarding hygiene, post-capture treatment and conservation of sea products
- Advise fisherfolk and sellers so that they produce the best quality with the means they have at their disposal
- Sensitize fisherfolk and sellers to the safety conditions associated to the improvement of the quality of products: use of Personal Protective Equipment (PPE), avoid the extraction of the spinal marrow of large fish on small vessels when there is only one person on board.
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