Purpose of study

Traditional fish processing is regarded with contempt and excluded largely in the food and nutrition schemes in Nigeria. This paper provides information on the importance of traditional fish processing interventions by the small-scale fishers to achieving food and nutrition security in the country. It seeks to redirect attentions of stakeholders towards activating the many provisions in the food and energy policy, as well as other documents that impact on food and nutrition. And which adopted will ginger a general renewal, standardization and safer product and at the same time remedy misgivings against traditional fish processing interventions.

Definitions of fish, food, and nutrition security

The terms “fish” and “seafood” are defined as finfish (vertebrates) and shellfish (invertebrates), whether of marine or freshwater origin, farmed or wild [4]. At the global level, fish and seafood consumption has gained increasing attention compared to other food sources. This development is easily adduced to greater understanding of the unique qualities of the nutrients found in fish.

Food security refers to the condition in which all people, at all times, have physical, social, and economic access to sufficient, safe, and nutritious food that meets their dietary needs and food preferences for an active and healthy life [5]. Food availability, stability of supplies, and food access are related determinants of food security. In addition, the term “food and nutrition security” is used to emphasize the access and appropriate utilization of micronutrient-rich foods, including the process through which they are cooked and absorbed in the body, and then used in physiological functions at the individual level [6]. This outlook was adopted in this review. Nutrition security is achieved for a household when secure access to food is coupled with a sanitary environment, adequate health services, and adequate care to ensure a healthy life for all household members.

Fisheries as a food security mechanism

The importance of fish in seeking food and nutrition security for all is a frequently overlooked but extremely important part of global food and nutrition security [7]. Fish is nutrient rich and provides high-quality protein that is low in saturated fat and rich in polyunsaturated fats, especially the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) [8].

The contribution of both fish protein in general and small-scale fisheries in particular to food and nutrition security has been recognized and advanced at the national and international level [6]. According to the Food and Agriculture Organization (FAO), all West African fishing grounds are either fully exploited or over-exploited [9]. As a result, many development projects since the 1950s aimed at expanding fishing effort in West Africa have often ended in failure [10]. However, neither domestic fish stocks nor the sources of imported fish can be expanded to the drastic extent needed to meet at least the global average of 20 kg per capital consumption in a short timeframe. Moreover, the focus on fish within the food security context has been mainly limited thus far to questions of accessibility and stability, leaving huge gaps in policy implementation with respect to utilization and availability. Therefore, there is a need to consolidate management efforts towards directly reducing fish loss specifically within SSF in order to guarantee availability and utilization, social equity, and sustainability of the fisheries resource.

Using the United Nations International Children’s Emergency Fund (UNICEF) conceptual framework [11] as a basis for analysis, this review discussed determinants of nutritional security of fish as a food resource at the level of SSF. The relationship linking traditionally processed fish and nutritional well-being is not causal, but is determined by many basic and underlying factors. The study provides insights into a number of intervention technologies available locally which currently are not being adopted but could ameliorate fish loss if adopted. Furthermore, this study recommends the adoption of creative and sustainable strategies for bridging identified gaps and enacting enduring strategies with strong potential for increasing the competitiveness of traditionally processed fish.

Context of food security and fish consumption in Nigeria

Individual nutritional status is determined by various factors. In this review, the UNICEF [11] conceptual framework for nutritional status is employed (Fig. 1). The technology available at the national level defines the ability to translate or change the status of a resource from potential to available. The availability of a resource, particularly food-related resources, determines national nutritional outcomes in terms of survival, growth, and long-term development. Specifically, the level of technological development to harvest the fisheries resources is just localized and crude (Table 2). On a broader conceptual level, the political, ideological superstructure, and economic structure of Nigerian fisheries act to prevent traditional fish processing technology from realizing its own potential. For these reasons, there is a high level of post-harvest fish losses within the SSF sector. Within all fisheries, but especially SSF, resource constraints, institutional controls, and technological limitations hinder the full development of capture fisheries.

Activities	Basic determinant	Underlying determinant	Immediate determinant
Issues to address	Rustic technology and safety Per capital fish consumption	Utilization	Hidden hunger (micronutrient deficiency)
Focus	Inculcate tastes for fish/seafood especially processed forms	Improving on the chain management of traditionally processed fish to enhance household access Increasing household income	Increasing micronutrient intake by promotion of traditionally processed seafood and artisanal fisheries
Interventions	Modernization, adoption, and promotion of traditional fish processing technology by government agencies, viz. Federal Department of Fisheries, Energy Commission of Nigeria, Federal Department of Forestry, Ministry of Science of Tech Mass communication: National Committee on Food and Nutrition, National Agency for Food and Drug Administration and Control, Academic and Research Institution	Engaging traditional fish processor towards adoption more efficient and effective technology Granting repayable credit facilities guaranteed by the processors’ cooperative and thrift societies for purpose of securing modern and improved local facilities Improving the quantity of smoked and sun-dried fish sourced from the cultured sources (marine and inland water)	Utilizing smoked and sun-dried fish as complementary food to improve nutritional status of children Encouraging consumption of smoked and sun-dried prawns, shrimps especially by children and women at household levels Improving diet of children to providing fish as a school lunch
Expected effects	Decrease in fish loss Increased production by fish processors	Safer and increased consumption of sun-dried and smoked fish products	Reduction in incidence of hidden hunger
Indicators	Better regulated traditional fish processing sector	Increased prosperous individuals	More virile and healthier citizens Reduced cases on nutrition related diseases such as obesity

Food and nutrition security can only be achieved if adequate food (quantity, quality, safety, and sociocultural acceptability) is available, accessible, and satisfactorily used by all individuals at all times to live a healthy and active life. Household food security, maternal and child care, and health services and healthy environment are three pillars of underlying determinants of nutritional status. Diversifying livelihoods to increase household income sources is a way of improving household food security. Although fisheries-related literature often does not focus these other pillars, a consideration of children’s nutritional status requires the examination of determinants such as child care, especially breastfeeding, and their importance in ensuring child nutrition. Access to health services and the living environment are also important factors in determining the risk of disease.

Therefore, adequate dietary intake and the absence of disease are immediate determinants of nutritional status. The three factors of household food security, care for children and women, and access to quality health services and environment are necessary but not sufficient conditions for adequate nutrition. If all three are fulfilled, however, it is likely that dietary intake will be satisfactory, disease will be controlled, and adequate nutrition will be secured. Individuals with adequate dietary intake are able to develop appropriate immune systems and are thus better equipped to fight infectious diseases. As a result, breastfeeding mothers with adequate dietary intake will be able to pass on adequate and quality nutrients to their children during the first six months of exclusive breastfeeding, which required as foundation preparatory to subsequent life stages.

In several of the diverse cultures of Nigeria, a meal is not considered complete without some form of fish or fish product as the main animal protein component, or as a condiment. Fisheries’ contribution to animal protein in the average Nigerian diet has been rising steadily and currently is at 28% [12]. Fish’ contribution to animal protein consumption is 35% for urban and rural dwellers in Nigeria (national figure).¹ The value is very low compared to the Ghanaian average value of 63.2% [13]. Investment aimed at reducing food losses, therefore, offers an important pathway towards improving food security, alleviating poverty, and improving nutrition. In addition, reducing PHL in food generally has positive impacts on the environment as it enhances farm-level productivity and reduces the utilization of production resources or expansion into fragile ecosystems to produce food that will be lost and not consumed [14].

Nigeria’s per capita fish consumption of 9.38 kg and population of 170 million classify it as a modest fish-consuming nation, yet in the NPFN 2001² document, fisheries were mentioned only in passing as a means of improving food intake compared to the greater emphases on grains or crops. Similarly, the National Plan of Action on Food and Nutrition (NPAN)³ in Nigeria barely made mention of fisheries despite highlighting the need to improve food harvesting, processing, and preservation as a strategy towards enhancing food and nutrition security. The document also noted the need to improve the nutritional status of all Nigerians and particularly the most vulnerable groups such as children, women, and the elderly.

Through indigenous knowledge (IK) and traditional knowledge (TK), humans globally have employed salting, frying, sun-drying, and smoking for centuries as means by which the process of spoilage in fish is controlled [15]. However, the literature on SSF has largely overlooked the reliance of this category of fisheries on these kinds of traditional preservation methods. These simple methods remain the prevailing means for distributing fish products for either household consumption or sale in local markets within the fishing community [15], as well as distant ethnic markets in Europe, Asia, and North America, and regional fish trade within Africa. Also, these methods are the precursors for advanced food preservation or processing procedures, including freezing and canning, which are undertaken to prevent fish spoilage and reduce PHL.

Overview of small-scale fisheries in Nigeria

Nigeria’s fisheries sector is almost exclusively artisanal or small-scale, grossly underdeveloped, and highly heterogeneous. It contributes over 70% to domestic fish production, providing livelihoods to approximately 6.4 million fisher folk [12]. The main fishing and fishing-related activities are carried out in fishing settlements located in the Atlantic coastal area of the southern part of the country. Species-rich brackish water and estuarine canoe fisheries occupying about 12,904 km² exist in the creeks, estuaries, lagoons, and mangrove wetlands. Women fishers play prominent roles in this fishery [12]. Marine fishing is dominated by the coastal mechanized and canoe fisheries operating within five nautical miles of the sea shore, which is statutorily designated as non-trawling zone and 39,644 km² continental shelf area adjacent to the country’s 853 km coastline.

Migrant fishers from neighbouring West African nations exploit fisheries resources 120 nautical miles within the extensive frontiers of the country’s 216,325 km² Exclusive Economic Zone in the Gulf of Guinea [17]. Further inland, freshwater fisheries thrive consisting of nationwide network of rivers such as the Niger and Benue with several tributaries, natural lakes (e.g. Lake Chad), man-made lakes (e.g. Lake Kainji), reservoirs, and flood plains totalling an estimated 12.5 million hectares [17].

The SSF sub-sector is also multi-gear and multi-species in character. The craft and type of net depend on the type of fishery operated. Gears such as purse-seine net, set gill net, cast nets, encircling nets, traps, fyke nets, bag nets, pots, wounding gears, baskets and traps, drift and set gill nets, long lines, and trawl nets are used to target different fish species. Crafts (3–13 m long) used range from paddled, small-sized planked, or dugout canoes to larger, motorized canoes (half dugout/half plank) with outboard engines ranging from 15 to 45 hp, which are more like the vessel type commonly employed in Ghana.

Major freshwater fishes are fished year-round. Target species commonly caught include Nile perch (Lates spp.); tilapias (Oreochromis and Hemichromis spp.); catfishes (Clarias, Heterobranchus and Synodontis spp.): silver catfishes (Chrysichthys and Bagrus spp.); elephant snouts (Gnathonemus and Momyrus spp.); trunk fish (Gymanarchus spp.); tongue fish (Heterotis spp.); and moon fish (Citharinus) spp. [18]. The fish community inhabiting the estuaries, creeks, and coastal waters consists of small pelagics of the family Clupeidae. Bonga (Ethmalosa sp.) dominates the coastal pelagic fishery. Sardines (Sardinella sp.), shad (Ilishaafricana ) various jacks (Caranx spp.), and Atlantic bumpers (Chloroscombrus chrysurus) are also caught in modest quantities. Croakers (Pseudotolithus spp.) constitute the main commercial demersal stock [18] in coastal and brackish fisheries. Other exploited species include grunters (Brachydeuterus sp.), soles (Cynoglossus spp.), marine catfish (Arius sp.), brackish water catfish (Chrisichthys), Sphyraena spp. (barracuda), snappers (Lutjanus sp.), threadfins (Galeoides decadactylus, Pentanemusquinquarius), and groupers (Epinephelus). Common exploited shellfish resources are estuarine/white shrimps (“crayfish”) (Palaemon sp.) which supports a major creek fishery in the Niger Delta, Macrobrachium vollenhovenii (African river prawn); M. macrobrachion (Brackishwater Prawn); marine and estuarine Penaeus notialis (Southern pink shrimp); Parapenaeopsisatlantica and (Guinea shrimp). Other shellfishes include crabs of the genus Callinectes in the families Portunidae and Geryonidae, molluscs such as the mangrove oyster (Crassotreagasar), periwinkles (Tympanostomus spp.), and certain bivalves [19].

Actual production figures from SSF could be grossly undervalued. There is limited information on the state of fisheries resources nationwide. Many water bodies have not been assessed for their fisheries potentials, and stock assessments available are very few in number and out-dated. There is potential underestimation in catches ranging between 100,000 and 180,000 mt annually for artisanal shrimp fisheries, part-time fishermen, and brackish water areas [20]. When combined with poor availability of data from freshwater fisheries, this implies an enormous gap in overall fish landings for the country. Fishing communities are numerous and generally highly scattered in remote, inaccessible settlements due to poor or non-existent access roads and susceptibility to flooding during the rainy seasons. They usually do not have access to basic social infrastructures. Facilities such as cold storage and processing plants are very poorly developed. There is, therefore, heavy reliance on traditional fish processing and preservation methods which, unfortunately, are bedevilled by gross under-capacity and improper handling particularly during the peak fishing period.

PHLs are characteristics of SSF in developing nations, and an accurate estimation of total losses is problematic. In Nigeria, these have been reported to exceed 30% of the total catch [21]. A seasonal glut occurs between November to May for sardines and Bonga (Clupeids). Under these circumstances, fisherfolk are unable to cope with heavy fish catches, resulting in substantial quantities of fish being wasted, leading to putrefying gluts of spoilt fish which litter the sandy beaches and buried spoilt fish in the sands [22, 23]. The difficulty experienced in the evacuation, distribution, and marketing of fish products further contributes to a high percentage of PHL along the entire value chain from harvest to consumption. Ultimately, regardless of the quantity of fish wasted, this waste also translates into huge financial losses, reduction in the quantity of available fish supplied, and animal protein for human consumption, respectively, thus threatening food security.

Fish trade and food and nutritional security: Nigeria scenario

Nigeria is ranked among 55 nations classified as being low-income food-deficit countries (LIFDCs). This list, created by the FAO in 2014, is based on three criteria. First, a country should have a per capita gross national income (GNI) below the “historical” ceiling used by the World Bank to determine eligibility for International Development Association (IDA) assistance and for 20-year International Bank for Reconstruction and Development (IBRD) terms, applied to countries included in World Bank’s categories I and II. The 2014 LIFDC list is based on the GNI for 2011 (estimated by the World Bank using the Atlas method) and the historical ceiling of USD 1 945 in 2011.

The second criterion is based on the net (i.e. gross imports less gross exports) food trade position of a country averaged over the preceding three years for which statistics are available. Trade volumes for a broad basket of basic foodstuffs (cereals, roots and tubers, pulses, oilseeds and oils other than tree crop oils, meat and dairy products) are converted and aggregated by the calorie content of individual commodities. Thirdly, the self-exclusion criterion is applied when countries that meet the above two criteria specifically request to be excluded from the LIFDC category.

This designation means that the country must pursue a policy of balancing the quest for fish trade and food security in relation to fish as a food or commodity. Fish is an important component of the National Economy and Trade, since Nigeria is both a fish exporting and importing nation. Fish has an inherent tendency to be commoditized, and seafood have been commodities that were preserved and traded since the Bronze Age [24]. Therefore, fish have played an important role in the first phase of the emergence of a global economy and a singular role in the international expansion of trade before becoming an internationally traded commodity in its own right.

Specific to fish, Nigeria has a positive net food trade averaged over the previous three years [12]. Products emanating from the industrial fisheries, and shrimp in particular, are destined for the European and American markets where they attract premium values. The protein needs for the domestic markets are, therefore, met largely by supply from the artisanal fisheries, importation, and, by far less, aquaculture. The poor state of infrastructure, especially electricity supply and irregularity of fish supply from SSF occasioned by unpredictability of catch, fuel the need to resort to traditional means of processing by fishmongers. Generally speaking, infrastructure required driving both the quest for fish food security and trade has been reported [25] and will include fish landing centres, processing facilities, link roads, stable electricity, portable water supply, housing, and sanitary and environmental engineering works. These infrastructures can be broadly grouped as livelihood and trade related.

The scenario we have today is that investment directions in infrastructure development have been tilted largely in favour of trade-related infrastructure development favouring exportation and importation. Although the traditional food processing business invariably benefits from increased link roads and improved electricity, it presently suffers from neglect over the years to ensure broad-based investment in provision of processing facilities, storage, good hygienic practices (GHP)/good manufacturing practice (GMP), or sanitation standard operating procedures (SSOP), or prerequisite programmes for food safety. In contrast, food safety and quality management have become standards in the formal fish trade markets. The fish processing business requires that effective hygienic, quality, and safe food be promoted. A good healthy environment is crucial if food supplies are to ensure food security and nutritional well-being.

Fish in the Nigerian Food Policy have been largely directed towards increasing production, with lessening emphasis on getting the processing and distribution right. Efficient and effective domestic fish marketing is the ground rules for achieving sustainable fish food, nutritional well-being, and, ultimately, sustainable development. Presently, traditional fish processing techniques of salting, smoking, and sun-drying are at the centre of guaranteeing fish protein, food security, and nutritional well-being. The more lucrative export fish trade is the focus of medium fish processors whose major supply is from the aquaculture supply. The traditional fish processing methods are faced with serious challenges in view of the increased consumers’ awareness on matter of food safety and qualities.

There is a general sense of apathy from government for monitoring, regulating, and intervening in the business of traditional processing by means of interventions such as the modernization of PHL reduction technologies, product standardization, and regulation. The need for government to give direction is of the utmost importance, given that the small-scale operators are not organized to create the necessary structures that must be put in place to bring about the required changes. They do not enjoy the economic stimulus offered by foreign international markets.

Nutritional status of children in Nigeria

The 2013 Nigeria Demographic and Health Survey provided new insight on the nutritional status of children and adults in the country [26]. About 37% of children under 5 years old in Nigeria are stunted, thus reflecting chronic malnutrition. National figures show that approximately 10–20% encountered acute malnutrition and 29% are described as underweight, reflecting chronic or acute malnutrition or a combination of both [26]. Under-nutrition is described as an outcome of insufficient food intake and repeated infectious diseases, while malnutrition refers to both under-nutrition and over-nutrition [27].

The problem of micronutrient deficiencies is different in nature as it results from an inadequate quality of diet. Micronutrient deficiencies increase the general risk of infectious illness (e.g. measles) and non-infectious diseases such as malaria and pneumonia, or even diarrhoea. Adequate intake of essential micronutrients, especially by pregnant women and young children, is important to attaining nutritional security. Appropriate nutrition includes feeding children with a variety of foods to ensure that nutrient requirements are met. It is well known that plant-based complementary foods (food given to a child after exclusive breastfeeding) by themselves are insufficient to meet the needs for certain micronutrients [1, 2]. It has been advised that meat, poultry, fish, or eggs should be eaten daily, or as often as possible. Fish has been variously suggested to be an important part of infant feed or complementary food [1, 2].

Contribution of fish and SSF to food security and nutrition in Nigeria

To understand the importance of SSF in contributing to food security, it is necessary to grasp the significance of underlying factors which affect fish consumption patterns. In 2002, the FAO estimated that fish provide about 19% of the protein intake in developing countries with the following qualification: “the figure, however, represents an average at a global level and does not reflect the very large heterogeneity at the national or, even more importantly, at the local level. Similarly, fish contribution to animal protein consumption can be as low as 23% in Liberia and as high as 63.2% in Ghana” [13].

In Nigeria, fish is reported to be the most frequently consumed animal protein consumed by households [28]. Per capita fish consumption in Nigeria increased from an estimated 13.71 kg in 1993 to 14.49 kg in 2000 [20]. However, comparing Nigeria’s per capita fish consumption of 13.9 kg to the global average of 18.9 kg in 2011 [29] shows that fish consumption is still inadequate. Disaggregating national data [25], (see footnote 1) the percentage of fish as animal protein at the national level is 35, or between 41.15 and 43.1 of animal source protein and 39.7 of animal-source food [29]. While cultural standards appear to have no bearing on motivations to consume fish [30], decisions around the consumption and choice of fish product form is governed by factors such as income and market values. Other important factors are the urban–rural divide, non-fishing households versus fishing households, and relative distance or proximity to common-pool resources. However, much of the sector’s contribution to rural household consumption is often undervalued, and their importance ignored. In the Nigerian context, small-scale fisheries supply as much as 75% of animal protein intake in coastal or inland fishing communities [31]. Generally, fishing households have greater access to fish for direct consumption. Fish from common-pool resources or open-access regimes are literally free for harvesting and contribute in large part to nutritional security at the local level, particularly in the diets of poor people. Subsistence fishing of small fish, crustaceans, and molluscs, though almost marginal in terms of quantity, plays an important role in the food and nutritional security of household members. Consequently, per capita annual consumption of fish in fishing households (an average 230 g per day) is usually higher compared to non-fishing households [31].

Pathways linking traditional fish processing and nutritional security to national development

The national aggregate wealth generated from inland fish production and consequently traditionally processed fish are estimated between US$ 230–330 million and US$ 280 million per year.^{4 , 5} Processing is an important activity within the fishing industry, although it is often ignored. However, it is very evident that traditional processing like small-scale fisheries, in general, is an activity that is too big to ignore. As a sub-sector, its economic output provides an important dimension and interlinked pathways to national development in many ways.

Directly, traditional fish processing contributes to food and nutritional security in terms of the utilization, availability, and stability of price at the individual or household, regional, and national levels. Increased levels of protein, carbohydrates, fat, and energy were recorded in boiled, grilled, and fried fish in comparison with the raw forms [32]. Smoked products offered the healthiest advantage with the lowest values of saturated fatty acids, index of atherogenicity, index of thrombogenicity, and the highest omega-3/-6 ratios, which are important for reducing coronary heart disease (CHD) in food consumption [1]. Furthermore, smoking increases the concentration of alanine, threonine, tyrosine, and cysteine and accounts for a sweeter taste of the shrimp over other product forms, while sun-dried specimens were found to have increased levels of histidine and arginine [1, 2].

In a country with high levels of malnutrition among children in many regions, the eradication of malnutrition is a critical national development goal. It is well established that fish products as a form of animal protein can effectively be used as complementary foods to fight malnutrition. In addition, since nutrients from seafood are cheaper than other sources of animal nutrients, consuming processed fish products (which are reported to compare even better than raw fish) provides affordable high-quality protein. It is cheaper to eat processed fish forms such as sun-dried, smoked, grilled, and boiled (authors’ experience).

The present disdain and apathy with which traditional fish processing methods are viewed require a change in policy direction to ensure increased fish availability, particularly in a country where every gram of protein and energy is crucial for reducing considerably the nation’s high protein–energy malnutrition (PEM). The national average protein and energy intake of 53 g and 2071 kcal is below the World Health Organization (WHO) standard. Thus, it is crucial to provide support to the traditional fish processing sector and to improve the access of citizens, especially children, to processed fish protein.

Traditional fish processing activities and gender

Fish value chains are highly gendered and fraught with inequalities, creating food security and nutrition challenges at local, regional, and national levels. It is well known that of workers in SSF, women working in processing outnumber men. Unfortunately, much of the work performed by women in post-harvest processing is not compensated or is poorly recorded. Hence, to understand the gendered dynamics between actors in the value chain in the production of traditionally processed fish, it is essential to consider the governance structure for this important sub-sector.

In Nigeria, the traditional culture of the people is the basis of community-level governance structures, including in fishing communities [15, 33]. Artisanal fish processing and preservation activities are primarily carried out by women. However, in rare instances cultural norms restrict the participation of women in post-harvest activities at landing sites, thus leaving post-harvest activities to men. Women often engage in fish processing as their sole economic activity, or combine this with tasks upstream or downstream the value chain, or outside of fishing altogether [15]. Fish processing is carried out at different scales, depending on the quantity of fish being handled. The producer–processor group, which occurs the most, is prevalent in rural fishing communities and may involve male fishers [34]. Women processors obtain their supplies from within their family (usually the husband), while a small number of women engage in fishing themselves with the use of both trap setting and gear netting. Sometimes, women fishers obtain fish under different purchase arrangements from their male counterparts. Processor–sellers/traders form another category which mostly consists of women who combine functions of processing and marketing [35]. Lastly, women engaged solely in the trading of processed fish buy their products at either wholesale or retail markets. They also sell via commission agents or brokers to different market intermediaries. Sometimes commission agents or brokers serve as links between the many intermediaries along the value chain.

Evaluation of traditional fish processing technologies

Technology drives many human endeavours at all levels of human activities and history, from rudimentary tools to advanced modern-day technology. Community-based knowledge, which has evolved in every culture over a long period of time in many generations, is referred to as indigenous knowledge (IK) or traditional knowledge (TK). However, TK/IK may have borrowed extensively from the process of technological adaption as people began to borrow from other knowledge outside of their geographical location and traditional practices. In the case of fisheries and fish processing in particular, women employ the use of TK/IK in preserving fish in order to increase its shelf life and ensure value addition. Common traditional methods include gutting, washing, splitting, filleting, and sticking the fish, cooking, salting (brining), smoking, curing, fermentation, and sun-drying (drying).

Cooking

It is the most common and simple method requiring no more than basic household equipment which provides short-term preservation of fish usually for a few days before any deterioration becomes noticeable. Although warming after cooking does extend the period, a loss in value quickly becomes discernible. Different methods are used for cooking fish, but the principle of these processes is similar. The flesh of the fish softens, enzymes become inactivated, and the process kills many of the bacteria present on the surface of the fish.

Salting

Salting is by far the most influential form of fish preservation and trade, serving as the precursor for international commodity trading. The principle is based on the knowledge that food-poisoning bacteria cannot live in salty conditions and a concentration of 6–10% salt in fish tissue will prevent bacterial activity, thereby impacting a longer shelf life. However, a group of micro-organisms known as “halophytic bacteria” are salt-loving and will spoil the salted fish even at a concentration of 6–10%. Traditional methods of using salt usually involve removing the guts and gills and cutting the flesh into pieces before rubbing salt into the flesh or making alternate layers. The recommended levels of salt usage are 30–40% of the prepared weight of the fish.

However, the concentration of salt in the flesh is not sufficient to preserve the fish if it is not uniformly applied. Brining offers a better preservation over the direct application of salt to the fish muscle and tissues. This process involves immersing the fish into a pre-prepared solution (36% salt). The advantage is that the salt concentration can be more easily controlled and salt penetration is more uniform.

In most fish preservation, it is a usual practice to use salt in combination with other means of preservation. Nevertheless, the use of salt curing for food preparation must be approached with a high degree of caution, since high salt intake is deleterious to good health. The growing concern is founded in reports of increased heart palpitations in some individuals. This occurrence could predispose pre-hypertensive and hypertensive individuals to additional health risks. Thus, there is a need to investigate and ensure safe concentrations of domestic salt in fish preservation.

Sun-drying

This process consists of the use of the sun and movement of air to remove moisture and preserve the fish. In order to prevent spoilage, the moisture content needs to be reduced to 25% or less. The time it takes to dry fish products depends on the nature of the product, the intensity of the sun, and the surfaces used for drying. The simplest form of drying involves exposing whole small fish or split large fish to heat from the sun by placing products either directly on the ground, roofs, nets, and mats placed on the ground or on racks. However, this technique makes the fish susceptible to predations by animals. This method is commonly used in the Northern parts of the country, due to the sun’s intensity and other favourable conditions such as dry weather, low humidity, and clear skies [2]. Fish is typically sun-dried for three to ten days, but drying periods of one to three days are more common [36].

Sun-drying has found favour with fishmongers for centuries, producing fish meat that is condensed, saturated with oil, translucent and amber in colour, dense in consistency, and pleasant in taste. Impediments to the use of this method are related to product quality as well as safety. Sun-drying does not allow very much control over drying times, and it also exposes the fish to attack by insects or vermin and there are all possibilities of contamination by sand and dirt. Other constraints include considerable product losses, lower fish quality because of contamination by foreign materials, reduced protein quality, insects and micro-organisms as well as discolouring by ultraviolet radiation [36].

During the drying process, the fish surface dries faster and hardens, thereby locking moisture inside, which slows the drying process and encourages degradation of protein and fatty acid oxidation. Degradation of protein is accelerated when fish products are subjected to high temperatures for an extended period. Since traditional sun-drying is weather dependent, some losses in quality also result from inadequate drying.

Smoking

Smoking is used mainly to preserve fish, partly by drying and partly by adding naturally produced anti-microbiological constituents such as phenols from the smoke to the fish. Smoking is a preferred method of preservation because it dries the fish, melts some fat out of the fish, and reduces microbial growth. When this is achieved, smoking is expected to extend the shelf life of most fish products to several weeks. However, in recent times it is being used in addition to preservation to achieve the characteristic taste and appearance of the smoked fish. Heat from the fire causes drying, and if the temperature is high enough, the flesh becomes cooked. Both of these factors prevent bacterial growth and enzyme activity, thus preventing spoilage.

The wholesomeness of smoked fish products using the traditional kiln depends on the following factors: the type of wood used for the smoking process; the temperature used; the duration of smoking; the type of kiln used; the proximity of the fish from fire; the type of fish being smoked; and the fat content of the fish [37]. The primary challenge with the traditional kiln technology common across Nigeria, and West Africa in general, has to do with the temperature regulatory system of the design, which poses difficulties for the commercial fishmongers operating this type of technology.

Smoking temperatures result in the release of a wide range of antioxidant and antimicrobial chemicals like polycyclic aromatic hydrocarbons (PAHs), phenols, aldehydes, and acetic acids, some of which are known to be carcinogenic, mutagenic, and endocrine disrupting [38, 39]. PAHs produced in wood smokes are known to originate from the thermal pyrolysis (depolymerization) of lignin and subsequent condensation of the lignin components in lignocelluloses at temperatures above 350 °C. Charcoal used as filters in modified traditional smoking kilns is effective in removing PAHs from the smoke generated, thus potentially posing little or no health effects on consumers. Therefore, the adoption of this method may help reduce the levels of PAH-associated health effects like cancer and other cancer-related ailments which is reported to be on the increase in Ghana [40]. A typical system for traditional fish smoking in Nigeria is shown in Fig. 2.

Certain traditional fish processing practices constitute occupational and health hazards to consumers, processors, and the environment. A study in Nigeria indicated that smoked catfish/sole fish from commercial fishmongers using a traditional smoking kiln showed elevated levels of PAHs compared to the modern kiln [41]. The study postulated that this trend may be associated with increasing cases of cancer and cancer-related ailments in the nation. Generally, fish that is smoke-cured with hardwoods (e.g. acacia and mangrove) for a longer duration (≥4 h) using the traditional kiln may be unsafe for consumption, but sugarcane bagasse-cured fish using the traditional kiln was both the safest and the best fish smoking practice for short-duration smoking [37]. There may be elevated risks of cancer and non-cancerous diseases associated with lifelong (70 years) consumption of mackerel and sardine that is smoke-cured with hardwoods, especially at longer smoking durations due to their high lipid content.

Long hours and many years spent smoking fish have negatively impacted the health of women processors. Exposure to smoke from the burning of biomass fuels, including firewood, is a major risk factor for several respiratory ailments, such as asthma, chronic obstructive pulmonary disease (COPD), respiratory tract infections, and lung cancer [42]. A study in the rural fishing community of Obaka has shown that women processors are exposed to increased risk of developing COPD compared to women who do not work in the fish smoking business [43]. The smoke also causes redness/swelling of the eye, poor vision, rashes, eczema, pile, rheumatism, diarrhoea, dysentery, and heat [44]. Fish processors could also be exposed to smoke particles that contain potential or confirmed carcinogens such as PAHs. Milder forms of occupational hazards linked to fish processing include sting from fish spines, minor cuts, and scrapes [45]. Overall, poor socio-economic status, poor nutrition, exposure to other sources of indoor air pollutants such as mosquito coils and kerosene lamps, and risk of injuries, combined with poor access to sanitation and healthcare facilities, increase risks of developing health hazards linked to fish smoking [45].

In addition, the use of firewood as the major energy source in traditional smoking kilns has drawn some other criticism on the bases of economic and environmental consequences. The supply of fuel wood is characterized by scarcity, rendering it costly for fish smoking [46]. The practice is also time-consuming and considered wasteful due to the small quantities of fish that are smoked at a time [45]. Exploitation and consumption of firewood for fish drying and other uses is a contributory factor to continued deforestation in the country, particularly in the arid Northern region where this practice is contributing to desertification [47]. Although heat treatments may impact on the nutritive values of traditionally preserved fish, the overall quality has been demonstrated not to have significant differences from the fresh or raw fish [1, 2]. In many instances, the reduction in nutritive value may be due to the method used for the analyses rather than due to impact of intervention [1].

Curing

These techniques reduce the water content in the flesh of the fish, thereby preventing the growth spoilage caused by micro-organisms. Curing is not widely used in Nigeria, along with fish fermentation and deep frying.

Walking the talk: implementing the strategies on food processing in the National Policy on Food and Nutrition in Nigeria

The agency in charge of implementation is the National Planning Commission (NPC), with the National Committee on Food and Nutrition (NCFN) being the Siamese (being both connected to deliver food and nutrition security). There is a lot to be done in order to align these bodies to ensure the delivery of their mandates, especially regarding the utilization dimension of food security. These two agencies must devise ways by which fish: (a) is fully integrated into inter-sectoral national food security and nutrition policies and programmes and (b) is more systematically included in national nutritional programmes and interventions aimed at tackling micronutrient deficiencies, especially among children and women. The NCFN should pursue the multi sectoral approach in dealing with the issue of food and nutrition programming and bring to bear the utilization dimensions of fish in the context of food security. This approach will require regular monthly meetings of identified stakeholders within the food and nutrition spectrum to review their success at meeting departmental mandates and ensure the larger involvement of developmental agencies internationally and locally.

Voice and visibility to the role of fish and fishery products

Aside from the promotion of the accessibility, availability, and, perhaps, stability of food and nutrition security (as the cardinal principle which respective governmental agencies and ministry are following to make progress), there is an urgent need to promote the consumption of fish products as part of the overall objective of promoting food and nutrition security at the household and national level.

The 35% fish consumption rate out of all animal protein at the household, regional, and national level is grossly inadequate and far below some countries of Africa and Asia, where fish accounts for more than 50% of the total animal protein intake. There is the urgent need for the NCFN to work assiduously in promoting required change. The present dietary habit which favours consumption of staple plant-based food over that of animal protein has been proven to be grossly inadequate in meeting the present nutritional needs of the present generation in Nigeria, especially in the case of children.

In the same vein, the high preference for meat over fish consumption suggests that we are not doing enough to prevent, rather than treat, the malnutrition that affects a large population of children, as well as non-communicable diseases of aged adult such as diabetes, cancer, coronary heart diseases, and obesity. The activities of NPC and NCFN related to food and nutrition security need to be made transparent to the public. There must be concise efforts to promote the culture of fish consumption as well as the establishment of a national policy on dietary food intake in favour of fish products by means of establishing an Expert Consultative Forum on fish and fish products as food with an emphasis on: the neurological development benefits of fish consumption to the children of women of childbearing age; the reduction in mortality from coronary heart disease (and the risks of mortality from coronary heart disease associated with not eating fish) among the adult population; and the potential to use dried fish products, especially shell fish, as an ingredient in complementary or weaning food items for infants following the period of exclusive breastfeeding.

The Fisheries Act of 2014 pragmatically gave a holistic approach to understanding fish and fisheries governance. The framing of fish as food is an important step that is necessary for achieving food and nutritional security on a national level and strengthening the various pillars of food security. However, it is imperative that the Fisheries Act 2014 be signed into law. The 8th National Assembly should consider initiating this proposed legislation. NPC and NCFN should consider incorporating the voice of relevant fisheries and nutrition-based Civil Society Organizations (CSOs) and coordinate public engagement activities to include these groups in lobbying to pass the Act into law.

Proper nutrition, especially in terms of ensuring the standard protein–energy ratio (PER) balance, has been known to be an appropriate prevention method for malnutrition and diseases associated with old age. The current situation in Nigeria points to the need to revise the stale definition of food security in terms of caloric intake but widen food security indices to include such as food availability, affordability, percentage of fish caught with maximum sustainable yield, land areas affected by desertification as percentage of total land mass, per capita protein and energy intake, income indices, level of unemployment, average real income, and income distribution index. There is a need for a paradigm shift in the operational terminology of what constitutes food security and its unit of measurement.

Adoption of homegrown technological packages in small-scale fish processing

There has been remarkable progress in implementing certain aspects of these strategies. Researchers in academic institutes and tertiary institutions have helped in responding to this call. There are many homegrown technological packages that can modernize the traditional fish processing technologies of the sun-drying and smoking of fish. There have been many innovative and spectacular ingenuity creations of solar dryers (Kainji Solar Tent Dryer (KSTD), Plastic Driers, Mosquito Net Driers, Glass Driers, Aluminium Driers, and Glass Driers (which contain black stones). Localized fish drying technologies include the Kanji Solar Tent Dryer (Fig. 3) [48]. Solar and cabinet dryers, plastic drier (constructed using a thermopile plastic material), mosquito net drier [constructed by using plywood for the frame (edges) and subsequently covering the dryer with mosquito net all around the wooden frame), glass drier (made of transparent glass), aluminium drier (constructed from aluminium sheets and coated both inside and outside with black paint), and glass drier containing black stones. This is similar to the glass drier in every respect but with a black (igneous rock) stone placed in it. There have also been local variants of kiln which seek to replace the traditional mud and drum kiln which dominate the landscape.

The challenge has been that many of these technologies have not been adopted in the field. Thus, there is a need to demonstrate and situate the applicability of many of these technologies and their variants at the level of small-scale fishmongers in relation to their socio-economic status. Present outcomes of these research outputs offer a suite of opportunities which can be adopted based on the circumstances of state and local government areas. Once the fishmongers buy into any technology package, there is a need to have a credit scheme in place that is co-managed by the operators’ thrift and cooperative societies as well as interested financial bodies.

Definite action implementing the energy issue with regards to fish smoking

Climate and energy smart food processing ultimately is the direction to move. Most of the modern kiln is not able to meet the disposition of the small-scale fish processors. The practice of traditional fish processors throws up many issues on environment, deforestation, health, and energy use. The adoption of the modern smoking kiln (Fig. 4) [49] is non-existent at the level of the small-scale fish processors, and therefore, emphasis should be laced on wood fuel technology. The NEP document provides enough strategic direction to take in ameliorating the conflict between conservation and utilization of wood fuel. However, no direct mention of the small-scale fish processors was made. In our views, they are too big to be ignored. Among the strategies on fuel wood proposed by NEP include:

1. 1.

   Encouraging the establishment of private and community woodlots for supply of fuel wood in the short term.

    
2. 2.

   Establishing micro-credit facilities for entrepreneurs, especially for women’s groups, for the establishment and operation of commercial fuel wood lots and the production of renewable energy devices and systems.

    

The National Food and Drug Administration (NAFDAC) must step up its control mandate on food at the level of small-scale fish processors. This measure would ensure that the operators have safe fish while guaranteeing good health and well-being.

At the African level, the Federal Government adopted the CAADP. A highlight of the declaration is the resolve to halve the current levels of PHL, by the year 2025 [50]. Two years after the Malabo Declaration, it is encouraging that significant progress is being made towards including the development of strategies and key guidelines to support the CAADP country process and extensive engagements made at country, regional and continental levels.