Post-harvest Loss of Fish at Alwero Reservoir in Abobo, Gambella, Ethiopia

Introduction

Fishery contributes a lot to the animal protein requirements of many communities in both the industrialized and developing worlds [1]. Besides, it can also generate income which serves as a source of livelihood for millions of people [2]. However, small-scale fisheries are facing many challenges including post-harvest loss, illegal fishing, and over-fishing [3]. A high level of post-harvest losses occurs during the handling, processing, storage, transportation, and marketing of fish [4, 5]. The level of post-harvest fish losses in the fishing communities determines the income level of the fishers [6]. Post-harvest losses in developing countries estimated to be up to 50% of domestic fish production [7]. In Indonesia, a post-harvest fish loss is estimated as high as 30-40% [8]. Fish is a highly perishable food that needs to be suitably handled, processed, and marketed to reduce post- harvest losses [2]. Fishermen are faced with fish spoilage which is one of the several ways of post-harvest fish losses that results in increased poverty [9]. 30% of landed fish are lost through microbial activity alone [10]. Fresh fish spoilage can be very rapid after it is caught. The spoilage process (Rigor mortis) will start within 12 hours of their catch in the high ambient temperatures of the tropics [11]. the lack of ice boxes for proper storage of fresh fish onboard after hauling of fishing net and unsuitable fish handling method are the causes of losses [12]. Ethiopia loses one-third of its annual production and this was about 10,000 tons of fish per annum [13]. In studying the post-harvest fish losses at Lake Zipway, the total tilapia losses estimated to be 15.17% [14]. In Ethiopia, there is a severe shortage of information on fish post-harvest loss and its impacts on fish diversity. This study is therefore planned to gather baseline information on fish post-harvest loss at Alwero reservoir, Gambella, upon which appropriate conservation strategies would be planned.

Discussion

The demographic nature of a fishing society has a general impact on fishing activities. In this study, the average age of fishers was found to be 24.18±3.85 years indicating how important a fishing activity is in accommodating the youngsters who otherwise would have been unemployed. Besides, more married people are engaged in this activity assuring household food security with more people in the household participating in fishing activities. However, 75% of the respondents had no formal schooling which might be related to low awareness of environmental issues and 91% of them are not a member of any organization working on environmental conservation activities, worsening the already existing mismanagement of the natural resources in and nearby the reservoir. In line with this result, it has been indicated Olusumbo AA [12] that a low level of educational status increases the post-harvest fish loss in Ondo state, Nigeria. Moreover, 91% of the respondents are living at a distance that takes only less than half an hour from the reservoir putting more pressure on it. The relatively high mean fish catch (30.35±16.76kg) per trip and frequency of fishing in a week can also indicate the high exploitation of fish resources in the reservoir. The harvested fishes, which are not sold fresh, are mostly processed by solar and smoking methods that are traditional and not effective to preserve large quantities of fishes as compared to the modern processing techniques. Traditional practices such as exposing fish for long periods to weather elements coupled with traditional methods of preservation (hot smoking, sun- drying, and deep-frying) and poor storage are subjecting fish to different kinds of degradation [19]. A very high level of post-harvest loss occurs during pre-processing, processing, storage, and transportation of fishery products [5]. Absence or shortage of storage, transportation facilities, and quality fishing gears were reported to be the main challenges of the fisher society in the study area, resulting in a very high amount of fish post-harvest loss. After the fishes arrived at the landing site, they are transported by a synthetic plastic bag made from polyethylene (sack) on a motorbike to Gambella city, which is 45 km away from the reservoir. The other option is hanging the fish and taking it to the nearest local market at Abobo town (5km away from the reservoir) where there are no facilities (e.g., shade, water) to handle fresh fish. They are just displayed on the ground while flies are covering the fishes. These very unhygienic ways of handling and transportation methods fasten the loss of fish quality, hence a low market price or full spoilage of the product. This can also be a source of the public health threat that needs due attention. Consumption of low-quality fish has a dangerous effect on human health [20]. Bacterial spoilage in fresh fish can produce toxins that cause food poisoning [21]. The quality loss is also caused by the length of time the fish remains in nets before hauling, predators, and high ambient temperature. Because the fishers have no proper storage facilities, they let the product stay some time in the landing site while dropping their net for the next round of fishing. This exposes the fish to predators. The extreme environmental temperature, together with the absence of refrigeration, spoil the product so fast, especially from January to March. A high temperature of about 200C creates an avenue for fish spoilage [22], but the average yearly ambient temperature of the study area is well above this vividly showing how fast a product can get spoiled. The postmortem formation of amino acids and their rapid decarboxylation biochemically or microbiologically are temperature-dependent that leads to spoilage [23]. The same causes of fish post-harvest loss (high environmental temperature, the presence of predators, the length of time the fish remains in nets before hauling, absence of refrigeration facilities, and delay before marketing) have been reported by other authors Amos B, Asma AA, Diei-Ouadi Y, Yvette, Tesfay S, Olusumbo AA [10, 12, 22, 24, 25, 26] as well. According to the respondents of this study, 6.78±1.287kg of fish spoiled per trip. However, they practice selling the product at a low market price to protect complete loss. But, generally, the price of a fish depends on the season. In the study area, the price of all fish species is relatively lower during the high catch season (May to October) because of high supply and higher at low catch season (January to March) as supply goes down. Based on the information provided by the respondents, a yearly fish catch of a fisherman is estimated to be 4,370.4kg, out of which 972kg of fishes (22%) is lost because of the above-mentioned points. This result is in line with what Nowsad, 2007 reported whereby post-harvest loss is presumed to be about 20 - 30% in different fish and fishery products. In some developing country situations, the post-harvest loss estimated to be 25% of fish caught [27]. Besides, In Tanzania, the post-harvest loss of Rastrineobola argentea/sardine was estimated at 20 – 40% and in Uganda, the loss of Rastrineobola argentea/sardine was 26 – 40% [28]. To estimate the fish loss at Alwero reservoir in terms of money, the average price of a kilogram of fish of all abundantly available different species in the study area was taken as a standard price of one kilogram of fish (regardless of the species) and multiplied with the calculated amount of fish loss per month. As a result, it is estimated that a fisher can lose 5,264 ETB in a month. The fish yield/production and the amount which was being properly utilized by the fishers were not equivalent. A huge amount of fish is lost after harvest threatening the abundance and diversity of fish species in the reservoir.

Different factors can govern the level of post-harvest loss in any water bodies where fish exists. In this study, the economic activity respondents depend on affected the post-harvest loss negatively and significantly (P<0.01). As the number of economic activities respondents relied on increases, the amount of fish post-harvest loss decreases mainly because of a decrease in pressure that was exerted on the fishing sector. This result is in line with the work of Asma AA [24] which indicated that limited opportunity for alternative income-generating activities can affect the distribution of fresh or wet fish, hence increased loss. The existence of high ambient temperature, shortage of storage facilities, quality fishing gears, and transportation problems in the study area affected the post-harvest loss positively and significantly (P=0.011). The high ambient temperature, which is the main cause of fish loss in the area, fastens the fish quality deterioration and spoilage. The absence or extreme shortage of storage facilities in the area also triggers very low market prices and complete spoilage of the product. Shortage of quality fishing gear in the area is considered as one of the causes for physical damage to the product because the traditional fishing gears being used are causing the fish body to be broken and becomes a conductive media for bacterial growth. The extreme problem of means of transportation of the fishes from the landing site to both local market at Abobo and Gambella city is the other major point causing loss of quality of a fish. All the above-identified causes are in line with the findings of Ward AR [29] who reported that fish post-harvest losses can be exacerbated by unreliable transportation, inadequate preservation techniques, adverse weather conditions, species of fish, type of processing methods, fish supply greater than demand, and the fish market not developed.

The other variable that affected post-harvest loss negatively and significantly (P<0.01) was the average price of the abundant fish species, Oreochromis niloticus during high catch season in Ethiopian birr. As the price increases, the post-harvest loss decreases because the harvested fish do not stay long in the market (high demand). In this study, different significant correlations of variables were observed. The number of household members was negatively and significantly correlated with the amount of fish loss (kg) because of the condition/quality of fish during distribution. As the number of household member’s increases, the loss decreases because more people (labor force in the household) are involved in marketing the product before it gets spoiled. The number of household members also positively and significantly correlated with the amount of fish catch (kg) per trip. The higher the household members involved in fishing, the more the amount of fish they catch. The amount of fish catch per trip (kg) was negatively and significantly correlated with the major problems (increased ambient temperature, shortage of storage facilities and quality fishing gear, transportation problem) fishers face in the study area. When the problems intensified, the amount of fish they catch in a single trip decreases. These intensified problems were also positively and significantly correlated with the amount of fish loss caused by condition/quality during distribution. Post-harvest loss in the study area is very high. The fishermen caught a large amount of fish which got spoiled before it reaches the intended end-user, the consumer. This has a direct impact on the fish species abundance and diversity of the reservoir. If no conservation activities and law enforcement are implemented in the area, the rich species diversity and abundance of the reservoir will probably be under a threat of extinction. In line with this result, Felicia C [30] reported that overfishing results in a direct loss of exploited species and the associated biodiversity. Systematic overfishing of freshwaters is largely unrecognized because of weak reporting and because fishery declines take place within a complex of other pressures [31]. Moreover, the ecosystem consequences of changes to the species, size, and trophic composition of fish assemblages are poorly understood. But at Alwero reservoir, according to the respondents, the loss is at an alarming state requiring the immediate contribution of everybody.

Conclusion

This study showed that there is a high amount of fish (30.35±16.76 kg) being caught as compared to the total area of the reservoir. But out of this, 6.78kg of different fish species is being lost per single trip resulting in a loss of 22% of the catch in a year. Many factors were identified as the cause for the loss, among which: Absence or shortage of storage, refrigeration, transportation facilities, quality fishing gears, and the length of time the fish remains in nets before hauling, the existence of predators, and high ambient temperature were the major ones. The observed high amount of fish loss in the reservoir, in one way or the other, affects the abundance and diversity of fish species in the reservoir. Therefore, a holistic approach to solving the existing cause of post-harvest loss in the reservoir is considered to be the remedy for the problem in the area.