Post-harvest losses in marine fisheries of Bangladesh

Abstract

Existing literature highlights significant income loss due to Post-Harvest Loss (PHL) across the fisheries value chain in developing countries like Bangladesh. This is attributed to inappropriate fishing tools, poor infrastructure, inadequate storage facilities, and inefficient transportation. This study estimated PHL and its determinants in Bangladesh's marine fisheries using the Questionnaire Loss Assessment Method (QLAM) based on data collected from 1132 respondents, including fishermen and traders, from October 2019 to March 2021. The results reveal that physical, market, and monetary PHL in marine fisheries are 0.82 %, 6.41 %, and $228.52 per ton, respectively. Annually, the country loses approximately $151 million due to PHL in marine fisheries, with the highest market losses in Snapper, Pomfret, and Hilsa fish. The main reasons for PHL include the duration of fish remain in the net after being caught, insufficient ice, lack of insulated containers and storage facilities, delayed marketing, and oversupply. The study suggests adopting modern harvesting technology, enforcing regulations for scientific gear, and increasing storage capacity at landing and selling points to reduce PHL in marine fisheries.

1. Introduction

Food losses during post-harvest is global concern that impacts food and nutrition security, leading to lost income for poor fishermen and higher prices for poor consumers [1,2]. Perishable products, especially fish, are particularly vulnerable, with losses being more significant in developing countries [[3], [4], [5], [6], [7], [8]]. These losses can be both physical and operational, occurring due to rotting, fragmentation, size discrepancies, and by-catch discards [[9], [10], [11]]. Additionally, there can be qualitative losses, such as the reduction in the nutritional value of fish, which affects public health [10,12]. Consequently, losses can be classified into four types: physical loss, quality loss, nutritional loss, and market forces loss, accounting 14 % of total global food production [13,14].

Post-harvest loss refers to the qualitative and quantitative reduction in food throughout the value chain, from harvest to consumption or final use [[15], [16], [17], [18], [19]]. This includes decreases in both the quantity and quality of food production. Quality losses occur when the nutrient/calorie content, acceptability, and edibility of a product are compromised. Developed nations typically experience higher incidences of these losses [18,20], while quantity losses are more common in developing nations [[21], [22], [23]].

The primary causes of post-harvest losses include mishandling by laborers, damage during loading and unloading, unfair marketing practices, price reductions, and discrepancies between the potential and actual value of fish due to quality deterioration [[24], [25], [26], [27]]. Recent studies [[28], [29], [30], [31], [32], [33], [34]] also highlight significant economic losses as a contributing factor. Physical (quantitative) and qualitative post-harvest losses occur due to factors such as physical damage, spoilage, predation by birds, inadequate icing, improper handling, high temperatures, long fishing cycles, inexperienced handling techniques, and lack of fishing expertise [6,33,[35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45]]. Animal predation and insect infestation further contribute to PHL [6,33,[35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45]]. Economic or monetary losses are attributed to changes in fish quality, unexpected market fluctuations, high environmental temperatures affecting storage, delays in marketing, harvesting immature fish, predation, and environmental factors like flooding, as indicated by studies [6,37,and 46].

Several empirical studies (e.g., Refs. [28,35,and 47]) have identified and measured post-harvest losses (PHL) in Bangladesh's fisheries sector. However, these studies are based on small samples from limited geographical areas and lack comprehensive PHL estimation. For instance Refs. [28,35], focused on a few selected species in freshwater capture and culture fisheries, while [47] examined inland capture fisheries. These studies did not include marine species or cover the entire marine fish value chain. Consequently, they do not provide a comprehensive estimation of losses in marine fisheries, which differ significantly from freshwater fisheries in terms of fishing methods, tools, handling strategies, and involved stakeholders.

Furthermore, other studies (e.g., Refs. [31,48,49]) have recommended that government agencies, researchers, and related organizations conduct large-scale, in-depth quantitative studies on PHL in marine fisheries. Such studies are essential to develop more effective strategies for reducing post-harvest losses and improving the sustainability of marine fisheries.

Therefore, this study aims to fill this gap by measuring PHL in Bangladesh's marine fisheries across major species, actors, and stages from harvest to market. It also investigate the determinants of PHL using survey data, contributing to a more comprehensive understanding of the challenges and opportunities in reducing PHL in marine fisheries.

2. Material and methods

2.1. Study area and sample size

The study was conducted on the Barishal and Chattagram division, which consists of four (4) major prominent areas, namely Patuakhali, Barguna, Chattagram, and Cox's Bazar district, which is divided into ten (10) upazilas, namely Kalapara, Patharghata, Amtali, Barguna Sadar, Chattagram Sadar, Raojan, Sandwip, Cox's Bazar Sadar. The study area was selected based on the basis of concentration of large number of fishermen, huge production and marketing of marine fisheries which considered artisanal fisheries. First, a multi stage sampling technique was used to select the division, district, upazila, and market for data collection. Based on stratified sampling, the population was then divided into strata such as fishermen, arathder,1 wholesalers, retailers, processors (freezing), processors (drying), and processors (salting). Finally, samples were drawn from each stratum using the convenience sampling technique. A total of 1132 respondents were chosen from four areas, including 376 fishermen and 756 traders.

Sample size calculation through Cochran's Formula:

$$n=\frac{{\mathrm{Z}}^2\text{pq}}{{\mathrm{e}}^2}$$

Where,

n = Sample size

e = Desired level of precision (i.e. the margin of error)

p = Estimated proportion of the population

q = 1 – p.

Z = z-value is found in a Z table.

Here this study consider at 95 % confidence level gives us Z values of 1.96 and margin of error e = 5 %

The information was gathered from 86 marine fish species in Bangladesh that were classified under 25 common categories. Data were collected from 376 fishermen for fish harvest, post-harvest loss and its causes, and out of 756 traders from 125 arathders, 179 wholesalers, 283 retailers, 100 drying fish processors, 19 freezing fish processors, and 50 salting fish processors for marketing information, loss of marine fishes and its causes. The distribution of samples (fisherman and fish traders) is provided in Table 1 and the calculation of sample size based on Cochran's formula is given above.

Table 1.

Sample size of fishermen and traders.

Study Area		Fisherman	Traders
Division	District	Fisherman	Arathder	Wholesaler	Retailer	Freezing fish processor	Drying fish processor	Salting fish processor	Total Traders	Total Sample
Barishal	Patuakhali	138	35	46	51	3	29	27	191	329
	Barguna	69	20	33	94	1	4	3	155	224
Chattagram	Chattagram	100	35	50	69	12	15	11	192	292
	Cox's Bazar	69	35	50	69	3	52	9	218	287
Total	–	376	125	179	283	19	100	50	756	1132
Total populationa		140,000	325,000

^aThe total population of fishermen and traders are about 140,000 and 325,000 respectively. However, it is difficult to identify the exact population lack of accurate and reliable data.

A review of existing studies [24,27,29,and 30] served as the basis for the development and organisation of the interview schedule. Prior to drafting the final interview schedule, the study's objectives were considered when formulating the interview schedule. The interview schedule included information on PHL in various fish species, the various stages of value addition (fishing/harvesting, landing, processing, transport, and storage), and the causes of PHL in Bangladesh. To make the questionnaire more focused and user friendly, the researcher employed precautionary measures such as a pilot testing, a local resident who accompanied the researcher and enumerator, observation and field experience, editing, and rechecking after data collection.

2.2. Analytical techniques of post-harvest loss assessment

This study utilized the Questionnaire Loss Assessment Method (QLAM) due to the large area, vast species diversity, and variation in post-harvest losses (PHL) and their causes across different marine fish species [[26], [27], [28]]. PHL in marine fisheries encompasses both quantitative and qualitative losses [27]. Quantitative loss includes both physical and market losses. Market loss specifically refers to losses due to quality degradation and market forces such as excess supply and lower demand [27]. This study estimates physical and market losses based on the framework presented in Fig. 1. Fig. 1 illustrates the actors and types of losses occurring for various reasons among fishermen, arathders, wholesalers, retailers, freezing fish processors, drying fish processors, and salting fish processors in marine fisheries.

Fig. 1.

Conceptual framework of PHL of marine fisheries of different actors.

However, in this study, market loss is defined as the loss incurred due to a decline in quality and market dynamics, while physical loss refers to the quantity of fish that is discarded because it is not edible or saleable. The monetary value of discarded fish is determined by the market value of good quality fish of a specific species. The physical loss is calculated using the following equation:

$$Q_{pl}=\frac{Q_{df}}{Q_{hf}}\times 1000$$ (i)

$$M_{pl}=\frac{\left(Q_{df}\times P_{mgqf}\right)}{\left(Q_{hf}\right)}\times 1000$$ (ii)

Where, ${\mathrm{Q}}_{\text{pl}}$ = Quantity of physical loss (Kg/MT); ${\mathrm{M}}_{\text{pl}}$ = Monetary value of physical loss in ($/MT); ${\mathrm{Q}}_{\text{df}}$ = Quantity of discarded fishes (Kg); ${\mathrm{Q}}_{\text{hf}}$ = Quantity of harvested fishes (Kg); and ${\mathrm{P}}_{mgqf}=$ Market price of good quality fish ($/MT).

The financial value of the market loss was determined by calculating the depreciated price multiplied by the quantity sold at this reduced price. Initially, the study assessed the quantity sold at a reduced price due to poor fish quality and unexpected imbalances in supply and demand. Finally, the actual market loss was computed by comparing this depreciated value to the value of high-quality fish at the study's actual market price.

Accordingly, the monetary value of market losses was quantified using depreciation due to market instability or price depreciation, which is expressed as:

$${PL}_f=P_{mgqf}-P_r$$ (iii)

Where, ${\text{PL}}_{\mathrm{f}}=$ Per Kg price loss of the fishes and $P_r$ = Reduce price (per Kg fish) due to the volatility of the market or quality decline. In this study, market losses are calculated by combining the costs associated with a decline in quality with market forces. Based on the severity of their flaws, fish with moderate, poor, or severe quality losses are classified into three categories and frequently sold at a discount. If the price is less than or equal to 50 % of the market value, the quality loss is deemed "medium quality." If the price of the fish falls by more than 50 % of the market value, it is considered to be of "poor quality” as determined by the following equation:

$${ML}_m=\frac{\left(Q_m\times {PL}_f\right)}{\left(Q_{hf}\right)}\times 1000$$ (iv)

$${QL}_m=\frac{{ML}_m}{P_{mgqf}}\times 1000$$ (v)

Where, ${ML}_m=$ Monetary loss due to selling the medium quality fish ($/MT); $Q_m$ = Quantity of medium quality fish (Kg), ${QL}_m$ = Quantity loss on market price due to the sold of medium quality fish (Kg/MT).

$${ML}_p=\frac{\left(Q_p\times {PL}_f\right)}{\left(Q_{hf}\right)}\times 1000$$ (vi)

$${QL}_p=\frac{{ML}_p}{P_{mgqf}}\times 1000$$ (vii)

Where, ${\text{ML}}_{\mathrm{p}}=$ Monetary loss due to selling the poor quality of fish ($/MT); ${QL}_p$ = Quantity loss on market price due to the sold of poor-quality fish (Kg/MT) and ${\mathrm{Q}}_p=$ Quantity of poor quality fish (Kg).

The actual loss for "severe quality" refers to fish that cannot be consumed but are sold at a low price due to various reasons, is calculated using the formula below:

$${ML}_s=\frac{\left(Q_s\times {PL}_f\right)}{\left(Q_{hf}\right)}\times 1000$$ (viii)

$${QL}_s=\frac{{ML}_s}{P_{mgqf}}\times 1000$$ (ix)

Where, ${\text{ML}}_{\mathrm{s}}=$ Monetary loss due to selling the severe quality of fish ($/MT); ${QL}_s$ = Quantity loss on market price due to the sold of severe quality fish (Kg/MT) and ${\mathrm{Q}}_s=$ Quantity of severe quality of fish (Kg).

Moreover, operators are often compelled to sell fish of inferior quality at reduced prices [24] due to excess supply during peak seasons and low demand during religious holidays. Losses resulting from price declines are attributed to market forces. A loss resulting from a price decline was attributed to market forces. The following formulas are used to calculate the loss resulting from an oversupply:

$${ML}_{es}=\frac{\left(Q_{es}\times {PL}_f\right)}{\left(Q_{hf}\right)}\times 1000$$ (x)

$${QL}_{es}=\frac{M_{Les}}{P_{mgqf}}\times 1000$$ (xi)

Where, ${\text{ML}}_{es}=$ Monetary loss due to excess supply of good quality fish ($/MT) and ${QL}_{es}$ = Quantity loss on best price due to excess supply of good quality fish (Kg/MT) and ${\mathrm{Q}}_{es}=$ Quantity of excess supply of good quality fish (Kg).

The loss due to lower demand is estimated as follows:

$${ML}_{ld}=\frac{\left(Q_{ld}\times {PL}_f\right)}{\left(Q_{hf}\right)}\times 1000$$ (xii)

$${QL}_{ld}=\frac{{ML}_{ld}}{P_{mgqf}}\times 1000$$ (xiii)

Where, ${\text{ML}}_{ld}=$ Monetary loss due to lower demand of good quality fish ($/MT) ${QL}_{ld}$ = Quantity loss on best price due to lower demand of good quality fish (Kg/MT) and ${\mathrm{Q}}_{ld}=$ Quantity of lower demand of good quality fish (Kg).

2.3. Analytical technique of determinants of PHL in marine fisheries

The following multiple regression model was also used in the study to investigate the causes of PHLs in Bangladeshi marine fisheries.

$$\mathbf{Y}={\mathrm{\beta }}_{\mathbf{0}}{+\mathbf{\beta }}_{\mathbf{1}}{\mathbf{X}}_{\mathbf{1}}{+\mathbf{\beta }}_{\mathbf{2}}{\mathbf{X}}_{\mathbf{2}}{+\mathbf{\beta }}_{\mathbf{3}}{\mathbf{X}}_{\mathbf{3}}{+\mathbf{\beta }}_{\mathbf{4}}{\mathbf{X}}_{\mathbf{4}}{+\mathbf{\beta }}_{\mathbf{5}}{\mathbf{X}}_{\mathbf{5}}{+\mathbf{\beta }}_{\mathbf{6}}{\mathbf{X}}_{\mathbf{6}}+\mathbf{Ɛ}$$

where,

Y= Post harvest loss (Kg/metric ton)

β₀₌ Intercept

β_1-6 = Coefficient of variables.

X₁ = Insufficient ice and insulated container.

X₂ = Insufficient storage.

X₃ = Fish is attached more time with the net.

X₄ = Delayed marketing.

X₅ = Fish finder.

X₆ = Tide pressure.

Ɛ = It denotes the study's random error, which is treated as null for this study.

3. Results

Table 2 shows the socio demographic and economic condition of the marine fishermen of Bangladesh. The findings indicate that 99.47 % of fishermen in Bangladesh are men. In this study, we found that 78.99 % fishermen's age was 30–50 years because in fishing, they need to more energy for trawling the net and lift the net. In terms of schooling, about 35.11 % fishermen did not have any schooling experience and 48.40 % fishermen having primary level education was found. The survey indicated that the average family size of fishermen was 5.80, where 47 % of the fishermen was found to 3–5 family members and 53 % had above 5 family members. Fishermen was found long experience in fishing career where their average experience was identified about 17 years. The estimated average monthly income of the fishermen was found to $ 350.94 which indicates that marine fishermen are poor and low-income population in Bangladesh.

Table 2.

Socio demographic and economic condition of the marine fishermen in Bangladesh.

Characteristics	Category	Frequency (number)	%	Mean
Sex	Male	374	99.47	1.01
	Female	2	0.53
Age	<30	58	15.43	38.12
	30–50	297	78.99
	50>	21	5.59
Education	No schooling	132	35.11	3.59
	Primary	182	48.40
	Secondary	49	13.03
	Higher secondary	13	3.46
Subsidiary occupation	Agriculture	18	4.79	0.15
	Business	4	1.06
	Labour	9	2.39
	Service	1	0.27
	No subsidiary	344	91.49
Family members	3–5	178	47.34	5.80
	5>	198	52.66
Earning members	1–3	366	97.34	1.40
	4–5	10	2.66
Fishing experience	1–20	302	80.32	16.60
	21–40	73	19.41
	40>	1	0.27
Monthly income	$ 235-369	214	56.91	$ 350.94
	$ 370-480	100	26.60
	$ 481-600	62	16.49

(1 US $ = 84 BDT).

3.1. Overall post-harvest loss of marine fisheries in Bangladesh

Table 3 summarises the overall post-harvest loss in Bangladesh's marine fisheries, taking into account both quantity and monetary value loss. The marine fisheries contain a significant amount of PHL, which was around 72.30 kg/MT. Physical and market loss in marine fisheries totaled 8.22 kg/MT and 64.08 kg/MT, respectively. Regarding quality loss, fisher sold 28.08 kg/MT fish at a price less than or equal to 50 % off (referred to as medium quality loss), resulting in a 16.68 kg/MT fish loss at actual market price. Furthermore, losses from poor and severe quality fish sales contributed significantly to the market loss, 6.53 kg/MT and 7.44 kg/MT, respectively, with monetary values of $ 21.61/MT and $ 21.72/MT.

Table 3.

Overall PHL in marine fisheries.

PHL types	Kg/MT*	$/MT**(%)
A. Physical loss	8.22	29.93 (1.56)
B. Market loss
i) Quality loss
Medium qualitya	16.68 (28.08)	52.70 (2.74)
Poor qualityb	6.53 (11.65)	21.61 (1.12)
Severe qualityc	7.44 (11.47)	21.72 (1.13)
ii) Market forces loss
Excess supply	18.63 (32.95)	57.06 (2.97)
Lower demand	14.80 (25.33)	45.51 (2.37)
C. Total market loss (i + ii)	64.08 (109.48)	198.59 (10.33)
D. Total PHL (A + C)	72.30 (117.70)	228.52 (11.89)
Loss at national level (quantity in MT and $ in Million)	47711.57 (77671.52)	150.80

Note: * parentheses represents the sold quantity (Kg/MT) as a result of the lower price than the market price.; **(%) represents the monetary value loss as a percentage of total marine harvest. ^a If the fish price falls by less than or equal to 50 % of the current market price, ^b If the fish price drops by more than 50 % of its actual market price, ^c Fish cannot be consumed but must be sold. National loss is calculated by multiplying the country's total harvest [50] by the estimated PHL of marine fisheries. (1 US $ = 84 BDT).

The total post-harvest loss of marine fisheries was 72.30 kg/MT. Furthermore, the monetary value of PHL for marine fisheries was estimated to be $ 228.52/MT. However, it was found that the overall PHL in marine fisheries was estimated to $ 150.80 million at the national level, representing a significant economic loss.

The percentage loss of PHL was calculated based on the total marine PHL, as shown in Fig. 2. Excess supply loss was found to be the highest (25.77 %) of total PHL (100 %) for marine fish. However, the losses for medium and severe quality fish were 23.07 and 10.29 % of the total loss, respectively. Poor quality loss accounted for only 9.03 % of total PHL in marine fisheries.

Fig. 2.

Different types of PHL in marine fish (per 100 kg loss).

3.2. Species wise post-harvest loss of marine fisheries in Bangladesh

For marine fish, the average market loss was 64.08 kg/MT, while the physical loss was 8.22 kg/MT, and it varied by species (Table 4). Physical losses for the major marine fish species ranged from 0.00 to 16.75 kg/MT, with an average of 8.22 kg/MT. Physical PHL was greater than 11 kg/MT (11.03–16.75 kg/MT) in Bombey duck, Shrimp, Lady fish, Indian Salmon, Others, Pomfret, Mackerel, Skipjack Tuna, Croaker, and Faisha Gangetic. Physical losses for Snapper, Sardine, Paradise thread fin, Chandona, Ribbon, and Hard tail scads ranged from 6.37 to 9.32 kg/MT. Hilsa, Purple spotted big-eye, Pale-edged stingray, Shark, Marine cat fish, Cuttle fish or Squid, and Red fish had the lowest physical loss of PHL when compared to other marine fishes. These are the most commercially important marine fish and the most targeted species by fishermen. However [36], found that the post-harvest loss of fishermen for Croaker, Catfish, and Shrimp was 8.15 %, 7.76 %, and 7.57 %, respectively.

Table 4.

Species wise post-harvest loss of marine fish.

Species	Physical loss		Market loss		Total
	Kg/MT	a$/MT	(Kg/MT)	$/MT	(Kg/MT)	$/MT
Snapper (Lates calcarifer)	9.32	65.42	144.16 (216.85)	773.88	153.48 (226.17)	839.30
Pomfret (Pampus/Stromateus chinensis)	11.86	89.71	101.23 (135.47)	589.78	113.09 (147.33)	679.49
Hilsha (Tenualosa ilisha)	6.18	53.49	95.32 (107.04)	505.13	101.50 (113.22)	558.61
Shrimp (Penaeus monodon)	15.67	90.35	92.34 (109.48)	290.06	108.01 (125.15)	380.40
Indian Salmon (Eleutheronema tetradactylum)	14.52	65.62	98.18 (119.25)	277.14	112.70 (133.77)	342.75
Mackerel (Rastrelliger kanagurta)	11.74	40.71	85.44 (194.23)	296.28	97.18 (205.97)	336.99
Ribbon (Trichiurus haumela)	6.86	24.36	84.27 (191.67)	299.26	91.13 (198.53)	323.62
Marine catfish(Rita rita)	3.33	10.51	88.47 (166.39)	279.10	91.80 (169.72)	289.60
Croaker (Otolithoides pama)	11.15	44.55	40.41 (78.93)	161.45	51.56 (90.08)	206.00
Sardine (Gudusia chapra)	9.00	24.30	140.76 (171.80)	175.53	149.76 (180.8)	199.83
Hard tail scads (Megalaspis cordyla)	6.37	11.88	93.93 (196.24)	175.12	100.30 (202.61)	186.99
Pale-edged stingray (Dasyatis zugei)	4.39	15.61	41.34 (104.06)	146.94	45.73 (108.45)	162.55
Skipjack Tuna (Euthynnus lineatus)	11.31	35.09	36.74 (95.98)	113.97	48.05 (107.29)	149.05
Butterfly Rays (Gymnura micrura)	0	0.00	63.56 (118.15)	135.29	63.56 (118.15)	135.29
Lady fish (Sillaginopsis panijus)	14.89	39.17	35.99 (69.93)	94.70	50.88 (84.82)	133.87
Shark (Carcharhinus limbatus)	3.64	7.99	55.51 (102.10)	121.79	59.15 (105.74)	129.78
Faisha Gangetic (Setipinna phasa)	11.03	23.36	45.23 (80.54)	95.78	56.26 (91.57)	119.14
Paradise thread fin (Polynemus paradiseus)	8.87	30.94	24.22 (44.40)	84.48	33.09 (53.27)	115.42
Chandona (Tenualosa toil)	8.12	15.35	47.67 (91.05)	90.12	55.79 (99.17)	105.47
Bomby duck (Harpadon nehreus)	16.75	24.25	57.34 (81.07)	60.29	74.09 (97.82)	84.54
Purple spotted big-eye (Priacanthus Sagittarius)	5.29	6.99	25.20 (52.92)	33.31	30.49 (58.21)	40.30
Mud crab (Scylla serrate)	0	0.00	17.94 (42.05)	23.84	17.94 (42.05)	23.84
Cuttle fish/Squid (Sepia apama)	2.12	2.03	22.06 (37.23)	21.09	24.18 (39.35)	23.12
Redfish (Lesiostomus xanthurus)	0.37	0.77	5.47 (17.14)	11.32	5.84 (17.51)	12.08
Other marine fishesb	12.65	25.72	59.32 (113.01)	109.21	71.79 (125.66)	134.93
Average	8.22	29.93	64.08 (109.48)	198.59	72.30 (117.70)	228.52

The figure in parenthesis represents the quantity of fish available at a discounted price.

^a1 $ = 84 BDT (Bangladeshi currency).

^bOther Marine Fishes indicate all fishes other than those mentioned above Table.

As a result, commercially important fish species such as Snapper suffered the greatest monetary loss ($ 839.30/MT), followed by Red fish, Cuttle fish/Squid, and Mud crab at $ 12.08, 23.12, and 23.84/MT. However, Hilsa fish suffered a total monetary loss of $ 558.61/MT. Furthermore, the average total PHL in marine fishes was 72.30 kg/MT, translating to $ 228.52/MT. Shrimp (108.01 kg/MT) had higher total losses than Hilsa (101.50 kg/MT). Between these two species, Shrimp are mixed with various varieties, all of which are much smaller in size than Hilsa. Furthermore, all Shrimp have carapace, swimming, and walking legs, which usually become softer with rough handling and delayed preservation, resulting in greater physical losses to Shrimp than Hilsa. Butterfly rays have a higher total loss (63.56 kg/MT) than other marine fish in Bangladesh, owing to lower consumer preference/food habits. The total financial loss was even higher ($ 679.49/MT) due to the commercial importance and high value of Pomfret.

3.3. Actor wise post-harvest loss in marine fisheries

Table 5 shows the various divisions of PHL in Bangladesh's marine fisheries by different actors. Retailers suffered the greatest physical loss (19.11 kg/MT) among all actors, followed by fishermen (12.59 kg/MT). The financial value of this physical loss to fishermen was $ 40.90 per MT and $ 91.86 per MT to retailers. The overall severe quality loss was 7.44 kg/MT, with a monetary value of $ 21.72 per MT, with the frozen fish processor's loss being the highest (58.28 kg/MT) because they store fish more times in cold storage or small freezers, resulting in fish quality loss. Furthermore, the problem of electricity is sometimes one of the main problems of quality reduction. Medium quality loss was the highest (25.20 kg/MT) for fishermen due to a lack of proper storage facilities, a long fishing cycle, delayed marketing, and other factors. Furthermore, arathders have the highest loss of poor quality fish (22.06 kg/MT), followed by retailers (9.54 kg/MT). These actors have a longer holding period than others, resulting in a loss of fish quality. The results also showed that approximately 18.63 kg/MT of marine fish were sold at a lower price due to excess supply, and 14.80 kg/MT of fish were sold at a lower price due to lower demand, the highest losses among all types (Table 5). As a result, PHL affects the actor's profitability because of lower selling price of marine fishes in Bangladesh.

Table 5.

Actor-wise post-harvest loss of marine fisheries.

Actors	Physical loss		Quality loss						Market force loss				Total PHL
			Medium quality loss		Poor quality loss		Severe quality loss		Excess supply		Lower demand
	Quantity (Kg/MT)	Value ($/MT)	Quantity (Kg/MT)	Value ($/MT)	Quantity (Kg/MT)	Value ($/MT)	Quantity (Kg/MT)	Value ($/MT)	Quantity (Kg/MT)	Value ($/MT)	Quantity (Kg/MT)	Value ($/MT)	Quantity (Kg/MT)	Value ($/MT)
Fisherman	12.59	40.90	25.20 (36.24)	75.96	5.56 (12.84)	16.75	3.08 (16.80)	9.28	23.34 (33.83)	70.37	17.13 (23.99)	51.64	86.90 (136.29)	264.89
Traders
Wholesaler	1.20	5.23	13.24 (35.16)	44.33	5.08 (7.24)	17.02	0.64 (0.57)	2.13	9.70 (32.64)	32.47	9.27 (28.23)	31.05	39.13 (105.04)	132.24
Arathder	0.27	0.74	12.56 (28.91)	39.55	22.06 (30.37)	69.47	4.12 (3.96)	12.97	22.47 (66.00)	70.75	21.56 (66.51)	67.90	83.04 (196.02)	261.36
Retailer	19.11	91.86	13.54 (29.45)	47.43	9.54 (13.90)	33.41	5.15 (6.63)	18.05	16.58 (40.72)	58.08	9.55 (23.29)	33.46	73.47 (133.10)	282.30
Processor (Freezing)	0.00	0.00	1.67 (3.89)	4.47	1.07 (0.80)	2.85	58.28 (23.48)	155.88	31.99 (37.46)	85.56	29.93 (24.91)	80.07	122.94 (90.54)	328.82
Processor (Dry fish)	1.72	11.97	2.09 (9.29)	12.38	1.06 (1.75)	6.31	2.69 (2.19)	15.98	2.37 (13.33)	14.09	1.80 (8.72)	10.69	11.73 (37.00)	71.41
Processor (Salting)	0.81	3.92	5.90 (12.80)	28.50	6.15 (8.70)	29.73	0.00 (0.00)	0.00	0.32 (2.30)	1.53	2.71 (8.40)	13.10	15.89 (33.01)	76.77
Average	3.85	18.95	8.17 (19.92)	29.44	7.49 (10.46)	26.46	11.81 (6.14)	34.17	13.91 (32.08)	43.75	12.47 (26.68)	39.38	57.70 (99.12)	192.15
Overall average	8.22	29.93	16.68 (28.08)	52.70	6.53 (11.65)	21.61	7.44 (11.47)	21.72	18.63 (32.95)	57.06	14.80 (25.33)	45.51	72.30 (117.70)	228.52

The figure in the parenthesis represents the quantity of fish at a reduced price.

3.4. Stage wise post-harvest loss in marine fisheries

Table 6 shows the stage-wise PHL with physical and market loss of marine fisheries in Bangladesh. Bangladesh's marine fisheries value chain has identified the stages of fishing, landing, processing, transportation, storage, and sale. According to the findings, the physical loss at the fishing or harvesting stage was 5.28 kg/MT, the highest of all levels of physical loss (8.22 kg/MT) in marine fisheries, and the lowest (0.11 kg/MT) at the processing stage. Bangladesh's total physical loss in marine fisheries was estimated to be $ 29.93/MT. According to Table 6, the greatest market loss occurred at the selling stage (45.93 kg/MT) of the fish value chain because of delayed marketing, temperature, or poor handling, which is sold at a lower price. PHL storage was the second highest (12.28 kg/MT) stage. In addition, some market losses occurred during fishing or harvesting (4.01 kg/MT), transportation (0.83 kg/MT), processing (0.63 kg/MT), and landing (0.40 kg/MT). Bangladesh's total market loss from marine fisheries was estimated to be 64.08 kg/MT. The monetary cost of this loss was $ 198.59 per MT.

Table 6.

Stage wise post-harvest loss of marine fish.

Species	Physical loss		Market loss		Total
	Kg/MT	$/MT	Kg/MT	$/MT	Kg/MT	$/MT
Fishing	5.28	19.22	4.01 (6.79)	12.32	9.29 (12.07)	31.54
Landing	0.84	3.06	0.40 (0.48)	0.87	1.24 (1.32)	3.93
Processing	0.11	0.40	0.63 (0.77)	1.40	0.74 (0.88)	1.80
Transport	1.11	4.04	0.83 (1.00)	1.81	1.94 (2.11)	5.85
Storage	0.26	0.95	12.28 (20.93)	37.97	12.54 (21.19)	38.91
Selling	0.62	2.26	45.93 (79.51)	144.23	46.55 (80.13)	146.49
Total	8.22	29.93	64.08 (109.48)	198.59	72.30 (117.70)	228.52

The figure in parenthesis represents the quantity of fish offered at a discounted price.

However, the majority of the PHL in marine fisheries in Bangladesh occurred at the selling stage of the value chain (46.55 kg/MT). The implication is that PHL at selling stage increase price of fish making fish less affordable to the poor people. Fishing or harvesting losses totaled 9.29 kg/MT after the sale. The processing stage had the lowest loss, with 0.74 kg/MT of fish lost. Finally, the total PHL calculated for marine fisheries in Bangladesh at various stages was 72.30 kg/MT. In terms of monetary value, $ 228.52/MT of marine fisheries in Bangladesh has been lost at various stages of post-harvest.

3.5. Causes of physical and market loss of marine fisheries

Physical and market loss were measured and reported in Table 7, Table 8 based on data from interviews. This study identified several causes that contribute to physical loss among fishermen during the harvesting stage. The most significant causes of physical loss were more time attached with the net because fish tried to escape from the trap and put pressure on the net, causing physical damage to the surface of the fish body. This accounted for roughly one-fourth (23.72 %) of total physical loss in marine fisheries at the fishing stage (Table 7). In addition, delayed post-harvest marketing accounts for 16.79 % of total physical loss of marine fish, while a lack of ice and insulated containers accounts for 17.76 % of total physical loss. Physical loss of marine fisheries was estimated to occur due to pressure from below-level fish at trawlers (10.46 %) and other causes (9.91 %), which included a long fishing cycle, improper handling, and maximum catch during peak harvesting season, all of which supported the causes of the [38,51] study.

Table 7.

Causes of physical loss of marine fisheries.

Causes	Physical loss		Rank
	Kg/MT	%
Physical loss for more time attachment with net	1.95	23.72	I
Use of insufficient ice and insulated container	1.46	17.76	II
Delayed marketing after harvesting fish or high temperature	1.38	16.79	III
Fish damaged for pressure under below level fish at trawler	0.86	10.46	IV
Others causesa	0.82	9.91	V
Lack of communication and transportation facility	0.31	3.71	VI
Fish attachment with net for current pressure	0.29	3.47	VII
Insufficient storage facility	0.29	3.47	VIII
Unavailability of storage input material such as ice and processing materials	0.28	3.35	IX
Fish damaged during transportation period	0.25	2.98	X
Fish damaged during harvesting period by net or hock	0.23	2.74	XI
Fish damaged during loading and unloading period	0.12	1.40	XII
No fish finder at trawler	0.02	0.24	XIII

^aOthers causes – All causes which is not mentioned in the table.

Table 8.

Causes of market loss of marine fisheries.

Causes	Market loss		Rank
	Kg/MT	%
Excess supply	29.35	28.53	I
Lower demand	24.28	23.60	II
Delayed marketing	12.26	11.92	III
Use of insufficient ice and insulated container	8.83	8.59	IV
Other causesa	5.82	5.65	V
Fish damaged during transportation period for pressure	5.79	5.63	VI
Delayed receiving at arath after harvesting fish or high temperature	3.99	3.88	VII
Fish damaged during loading and unloading period	3.13	3.04	VIII
Lengthy bidding time in high temperature	2.92	2.83	IX
Wrong icing procedure	1.11	1.08	X
Attack by insects	1.04	1.01	XI
Unavailability of storage input material such as ice and processing materials	0.93	0.90	XII
Insufficient market information such as supply, price etc.	0.66	0.64	XIII
Discolour of fish for open hand handling	0.63	0.61	XIV
Unhealthy environment	0.58	0.56	XV
Wrong time market supply of fish	0.50	0.48	XVI
Lack of communication and transportation facility	0.39	0.37	XVII
Limitation of buyers and sellers purchasing power	0.37	0.36	XVIII
Intentionally delayed purchasing fish by businessman	0.32	0.31	XIX

^aOther causes – All causes which is not mentioned in the table.

Marine fisheries have also suffered market losses due to a variety of causes. The findings (Table 8) indicated that fisherman and traders lost 29.35 kg/ton due to excess supply, the highest loss (228.53 %) of any cause. Increased supply during peak season can wreak havoc on the fish market, causing prices to fall regardless of quality. Low fish demand has resulted in a market loss of 24.28 kg/MT, accounting for 23.60 % of total market loss to marine fisheries. Due to a lack of demand, the price and quality of fish suffer. Delayed marketing causes quality to deteriorate, resulting in a lower price, which accounts for a 12.26 kg/MT loss. It is critical to use enough ice and an insulated container to prevent quality loss during storage and transportation. However, the study discovered that insufficient ice and insulated containers resulted in a loss of 8.83 kg/MT of marine fish, accounting for 8.59 % of total market loss by fishermen and traders.

The findings also show that fishermen and traders face a variety of challenges in their fish business, including social, economic, institutional, technical, and infrastructural issues. There were no auction houses, packing houses, landing terminals, walkways, pontoons, or proper drainage or sanitary facilities. Among the causes identified in this study, the least important cause (0.36 %) were an unhealthy environment (0.56 %), intentionally delayed fish purchases (0.31 %), and limited purchasing power of buyers and sellers. These causes’ results lower prices of marine fishes which ultimately occurs market loss while in severe conditions in terms of quality may result huge physical loss.

3.6. Determinants of PHL in marine fisheries

The study is determined postharvest losses of marine fisheries using OLS regression as presented in Table 9. The Pearson's determinants of post-harvest loss correlation value, r = 0.893 > 0.50 which means there was highly correlation between the variables and adjusted R square was 0.793 which denotes that about 79 % variation of the dependent variable was explained by independent variables included in this model. The results show that the F-statistic value is significant at the 1 % level. It indicates that there is a significant relationship between the dependent variable, PHLs, and the independent variables, such as insufficient ice and insulated container, insufficient storage, fish is attached to the net for a longer period of time, delayed marketing, fish finder, and tide pressure. Hence, the findings indicate that the variables investigated in this study are relevant and will aid in explaining PHLs. The regression results are presented in Table to investigate the factors (causes) affecting PHLs in Bangladesh. It shows that the use of insufficient ice and insulated containers, insufficient storage, more time attached with net, delayed marketing, and tide pressure are positively related to PHLs, while only the use of a fish finder is negatively related to PHLs. The coefficient value of use of insufficient ice and insulated container is found to be 0.387, indicating that if use of insufficient ice and insulated container is increased by 1 %, PHL will increase by 0.38 % ceteris paribus. The coefficient of insufficient storage (0.325) was positive and significant at the 1 % level, implying that PHL would be 0.325 % due to 1 % insufficient storage use. The coefficient of fish is attached more time with the net (0.134) was also positive and significant at the 1 % level, indicating that fish is attached more time with the net accounts for at least 0.13 % of post-harvest losses. Similarly, positive and significant delayed marketing coefficients and tide pressure influence PHLs by at least 0.13 and 0.26 %, respectively.

Table 9.

Multiple regression model.

	Coefficients (β)	t	Sig.
(Constant)		8.043	0.000
Use of Insufficient ice insulated container	0.387	11.912	0.000
Insufficient Storage	0.325	11.829	0.000
Fish is attached more time with the net	0.134	5.600	0.000
Delayed marketing	0.125	4.289	0.000
Fish finder	−0.111	−4.646	0.000
Tide Pressure	0.256	8.310	0.000
R = 0.893, Adjusted R Square = 0.793, F statistics = 240.795*

Note: *denote the statistical significance at 1 % level of significance.

Only a negative and statistically significant fish finder coefficient (−0.111) indicates that the use of fish finders reduces post-harvest losses. A fish finder can detect schools of fish, aiding in the harvesting of large quantities. By utilizing a fish finder, the net can be lifted promptly after harvesting, thereby reducing post-harvest losses.

4. Discussion

This study focuses on the socio-demographic and economic conditions of fishermen and the determinants of post-harvest losses (PHL) across various species, actors, and value-adding activities in Bangladesh. It examines both physical and market losses in marine fisheries, considering the impact on fishermen and traders. The research aims to provide a comprehensive understanding of the factors contributing to PHL and the socio-economic challenges faced by those involved in the marine fisheries value chain.

The findings indicate that the majority of fishermen in Bangladesh are men. This gender disparity is attributed to women's lower interest in marine fishing and limited access to fishing gear, boats, and related resources due to socioeconomic constraints and cultural barriers. Traditional gender norms and expectations discourage women from pursuing careers in fishing. Safety concerns, such as the risk of accidents and inclement weather, also deter women from the profession. Overall, cultural norms and social expectations significantly influence the division of labor within households and communities.

Most fishermen have not attended primary school, primarily due to a lack of awareness about the importance of education and their parents' desire to involve them in fishing activities at an early age to earn more money. Fishing is often the sole occupation for these fishermen, as they adhere to traditional views that their parents' profession should be their own.

However, the study showed that the average family size in Bangladesh is 4.18 [54], indicating that marine fishermen tend to have larger families compared to the national average. Most of the sampled fishermen were found to be the main income earners in their households, with occasional support from one or two other family members.

The results show that the anticipated overall market loss was greater than the physical loss due to the market's and the fish's relative lack of quality control (Table 3). Furthermore, of all types of losses, the market loss caused by an oversupply of marine fish was the greatest because no one could control it. It is determined by nature and the weather. However [31], discovered that post-harvest losses of marine fish in Bangladesh were 11.67 %, compared to 7.23 % previously observed total post-harvest losses of marine fisheries in Bangladesh. The results also show that the maximum physical loss was the Bombey duck's extremely delicate physical structure and body contents, which contain more than 90 % water. Because of higher body water percentages, this species is more vulnerable to damage. Snapper, Pomfret, and Hilsa fish suffered the greatest market losses due to their high commercial value.

Given that fishermen, processors, and traders now have less weight to sell, the physical loss is undoubtedly accompanied by a value loss. This finding is consistent with [31], which found that shrimp and hilsa suffered greater financial losses. Furthermore, according to Ref. [52], the total loss in the salting sector was 2.5 %, despite the study finding a 1.59 % post-harvest loss at the salting fish processor (Table 5). Four commonly consumed species in Bangladesh—rohu (Labeo rohita), Ilish (Tenualosa ilisha), catfish (Pangasius sutchi), and tilapia (Oreochromis niloticus)—had higher loss rates than retailers, which ranged from 10 % to 19 % and 7–16 %, respectively [33]. Despite this, post-harvest losses at the processor, traders, and fishermen were 7.42 %, 2.9 %, and 2 %, respectively [53].

Table 4 shows the losses for all value-adding activities, indicating that the overall PHL was higher during selling than during other marine fisheries value-adding activities. PHL in Storage was 18.7 %, Marketing 7.9 %, according to Ref. [42]. Furthermore [45], discovered that post-harvest losses were 0.29, 0.19–1.57, 0.15–0.54, and 2.22 % in packaging centres, pre-processing units, processing units, and live fish transportation centres, respectively.

Fish handling, loading and unloading issues, fish damaged during transportation, damaged by net or hock, and insufficient storage facilities at fishing boats and ice, more time spent with nets, and delayed marketing were the causes of physical loss, according to studies [36,37,and 41]. Physical losses also occurred due to lack of adequate ice and insulated containers, high temperatures, insufficient storage facilities, transportation, and communication infrastructure (Table 7). The studies [6,[42], [43], [44]] came to a similar conclusion about physical post-harvest loss. According to the survey, fishermen and traders blamed market losses on an imbalance between supply and demand, which validates [6] arguments. Delayed marketing was the leading causes of market loss of both the fisherman and trader levels. Another causes was use of inadequate ice and insulated containers, fish damaged during transportation due to pressure, prolonged bidding time in high temperatures, fish damaged during loading and unloading period, delayed receiving at arath after fish harvesting or high temperature, improper icing procedure, and insect attack (Table 8).

It suggests that having adequate storage facilities would help significantly reduce PHLs, which is consistent with the findings of [36,41,42,55]. Sufficient storage facilities, sufficient ice and insulated containers, and timely marketing should be provided to preserve the quality of fish, which in turn will increase the income of fish farmers and greatly reduce post-harvest losses. Sometimes fishermen use banned nets and traditional fishing gear that do not comply with current rules and regulations. When using such equipment, small fish often get stuck in the net, resulting in damage when they are released. If fishermen adopt scientific or modern fishing gear, as introduced by Ref. [55] with innovative and low-cost technology, and adhere to the regulations set by the Department of Fisheries (DoF) and other relevant organizations, post-harvest losses (PHL) could be significantly reduced.

Post-harvest losses (PHL) in marine fisheries significantly impact food and nutrition security, as well as the income of fishermen and traders in Bangladesh. To achieve specific Sustainable Development Goals (SDGs) by 2030, it is crucial to minimize total PHL. Therefore, addressing the causes of PHL in marine fisheries is essential to enhance food security and profitability for all stakeholders involved. Taking specific measures to limit these losses will contribute to achieving these objectives and ensure a more sustainable future for Bangladesh's marine fisheries.

5. Conclusion

The study estimated the post-harvest losses (PHL) and its determinants in marine fisheries of Bangladesh considering major species, actors, and stage wise activities based on the survey data. Physical and market losses were estimated, and it was found that market loss was greater than physical loss for the selected marine fish species and actors. The maximum financial loss was faced by retailers, followed by fishermen. The processor of frozen fish had the highest PHL while the processor of dried fish had the lowest PHL.

Improper harvesting techniques and a lengthy fishing cycle found as the primary reasons for physical loss while insufficient ice use, poorly insulated containers, and excessive temperatures were also significant contributors to PHL. In addition, excess supply and lower demand were highly contributed for market loss of marine fisheries. Moreover, delayed selling and high temperature were also associated for market loss, as well as physical loss. Furthermore, unavailability of storage input material such as ice and processing materials accounted for both physical and market loss in marine fisheries in Bangladesh.

The government and related fisheries organization can play critical role in improving capacity of the actors of the marine fish value chain since the majority actors are poor and lack of improved knowledge in harvesting, processing and handling fish. For instance, the actors can be introduced with modern technology and providing financial supports for acquiring and following those technology, methods and process respectively. Training can be given to fishing community on efficient and effective harvesting techniques, tools and methods (i.e., fish finders, storage process, and high-quality ice insulated containers). Furthermore, for more active engagement and cooperation of stakeholder, there may have provision for sharing information, knowledge and resources supporting the PHL reduction strategies. Therefore, the future policies supporting PHL reduction strategies should address these issues for more engaged, efficient and effective management of marine fisheries in Bangladesh.

5.1. Limitations and scope for further study

Even though the study was conducted with caution and accurate data was collected, it has some limitations. The study is based on limited data covering only four districts in Bangladesh due to funding and resource constraints. In addition, the study explored only the factors influencing post-harvest losses at the level of fishermen and traders. Thus, there is room for further research on how to reduce post-harvest losses of marine fisheries at the farmer and trader levels, taking into account additional samples and coastal districts.

Ethical statement

This statement confirms that the study, " Post-harvest Losses in Marine Fisheries of Bangladesh" is an original research project and has not been submitted to or published anywhere in any format. The collected data from the selected samples were obtained with their full consent, and efforts were made to generate precise data. The data, which can be provided upon request, is accessible to the authors. These declarations are supported by the author's own works. No one in Bangladesh has ever completed a project of this nature, so the contribution made in this paper is unique. The document properly cites relevant sources, formulas, and equations from numerous articles, books, and periodicals.

CRediT authorship contribution statement

Anup Kumar Mandal: Writing – review & editing, Writing – original draft, Validation, Methodology, Formal analysis, Data curation, Conceptualization. Md Mamun Or Rashid: Writing – review & editing, Validation, Supervision, Investigation, Funding acquisition, Conceptualization. Md Sujahangir Kabir Sarkar: Writing – review & editing, Validation, Supervision, Investigation, Conceptualization. Badiuzzaman: Writing – review & editing, Supervision, Investigation, Conceptualization. Md Takibur Rahaman: Writing – review & editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.