Artisanal fishers in the developing world are unaware that fish are capable of suffering or experience discomfort, though researches have shown that fish do feel pain. Five fish welfare domains have been identified which constitute their rights in their environment. The needs of wild fish are usually provided in their natural, undisturbed and unperturbed aquatic environment, of which the fish will prefer. However, various anthropogenic activities by humans (including artisanal fisheries themselves) and some natural perturbations in the watershed, riparian zone, water body of the fish habitat and on the fish tend to take away these needs thereby compromising the fish welfare. These activities include environmental degradation, boat/canoe building, use of motorized boats/canoes, use of active and passive fishing gear, obnoxious cultural, religious and social fishing practices, fish harvesting, handling and processing among others. One way to understand the welfare needs of an individual fish is to understand its biology. Poor welfare conditions can then be assessed by how far the individual fish has deviated from the normal conditions. Non-intrusive signs based on the health, behaviour, morphological anomalies, swimming, reduction in population and growth, outbreak of parasitic infections, injuries and loss of condition can be used to assess fish whose welfare has been compromised. Artisanal fishers should not only be concerned with catch, but, also the welfare of the fish being caught. This is because if the welfare of the fish is compromised, it is going to definitely affect the catch. As indispensable as fish are to humans, humans should not derive their pleasure at the expense of fish suffering. Human activities that impinge on the welfare of wild fish may not necessarily be stopped, but should at least minimized in order to have continued sustainable artisanal exploitation of the fisheries.
High concentrations of nitrate and phosphate which was above the normal natural background levels which ranged between 1.4 mg l-1 ±0.1 - 6.4 mg l-1 ±0.3 and 0.7 mg l-1 ±0.0 - 2.2 mg l-1 ±0.2 were recorded in Oyun reservoir, Offa, Nigeria, a shallow tropical African reservoir. The relatively high nitrate and phosphate load was observed to have come from a non-point source of run-off of nitro-phosphate fertilizers from nearby farmlands into the reservoir. This resulted in slow cultural eutrophication. This was observed to have impacted on the catch and fish assemblages of the reservoir with high abundance and dominance of pelagic phytoplanktivorous fishes such as cichlids, while benthic and non-phytoplanktivorous species were found in low abundance. Other possible impacts of the eutrophication when it becomes accelerated were discussed. Measures to reduce the eutrophication in order to enhance adequate fish assemblages and management techniques for sustainable exploitation of the fisheries in the reservoir were suggested.
Fish need adequate welfare in culture even more than when they are in the wild. This is because they are held in captivity against their ‘will’. The welfare of farmed fish should start from production to consumption. Several factors have been identified as compromising the rights and welfare of fish in aquaculture. These include the aquacultural holding devices, stocking density, water quality, food and feeding regimes, diseases and parasite infestation, treatment of the diseases and parasites, handling, netting and removal before and during slaughter, methods of slaughter, fasting/ food withdrawal, unnatural dark/light photoperiods, selection for fast growth, selective and induced breeding, genetic manipulations, exposure to predators, polyculture, tagging, crowding, grading, transport and harvesting, fish attractors and accidental or deliberate introduction of genetically modified farmed fish. The best way to achieve good welfare and health of fish in aquaculture is to respect, maintain and improve the rights of fish, otherwise known as the “five freedoms.” Lack, deficiency or difficulty in having or providing any one of the five freedoms in aquaculture is an indicator of poor welfare for the fish which could be observed through physical, physiological, morphological, behavioural or environmental indicators in the fish. The best strategy for a reliable assessment of fish welfare/suffering and their impact on product quality is a multidisciplinary approach using several assessment parameters and comparing the deviations from the normal biological state with those from the wild which live in their natural, unperturbed environment. Some of the ways to achieve good welfare and safeguard the rights of the farmed fish in reducing the welfare problems were highlighted. Welfare of farmed fish should be considered in terms of ethics, productivity, economic viability and consumer’s acceptability of the final product. Consumers are becoming aware of the quality of farmed fish arising from poor welfare of the fish during culture. Improvement in fish welfare will increase profits, productivity and acceptability of the farmed fish because fish that are less stressedand humanely slaugh tered are healthier, grow better and have better meat quality. There is the need to develop common standard welfare indices for fish in culture in order to detect, correct and improve any deviation from the normal state of the fish in their aquacultural holding devices (AHD). It should be known that whatever is good in terms of welfare to humans should also be good to the fish in captivity.