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Assessment of fishing-related plastic debris along the beaches in Kerala Coast, India
Marine Pollution Bulletin xxx (xxxx) xxxx
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Assessment of fishing-related plastic debris along the beaches in Kerala Coast, India Damaris Benny Daniela,∗, Saly N. Thomasb, K.T. Thomsona a b
School of Industrial Fisheries, Cochin University of Science and Technology, Lake Side Campus, Cochin, India ICAR – Central Institute of Fisheries Technology, Matsyapuri P.O, Cochin, India
A R T I C LE I N FO
A B S T R A C T
Keywords: Beach litter Plastics Pollution Fishing Marine debris Derelict fishing gear
An assessment of quantity, composition and seasonal variation of fishing-related plastic debris was conducted in six beaches along the Kerala coast of India during 2017–2018. Plastic items were the most dominant type of waste constituting 73.8% by number and 59.9% by weight. In the total debris recorded, 5540 pieces (36%) weighing 198.4 kg (39.8%) were fishing related trash. On an average 14.4 ± 12 fishing related items/100 m2, corresponding to mean weight of 0.55 ± 0.7 kg/100 m2 was recorded from these beaches. Results indicated that the fishing-related plastic items were concentrated four times more in the beaches with higher fishing intensity, as compared to the other beaches. Also, the concentration of fishing-related plastic was recorded higher in the post-monsoon season compared to the lowest during monsoon, which was significant with p-value < 0.05. The results emphasize the role of fishing activities in the generation of marine litter.
1. Introduction
sandy beaches in Mumbai was quantified by Jayasiri et al. (2013). Another study of 2017 (Kaladharan et al., 2017), graded 254 selected beaches along the Peninsular coast of India & Union Territories with colour codes according to the levels of beach litter. Similar studies have been conducted in Seeniappa Dargha beach, Gulf of Mannar (Anand et al., 2018) and along the Marina beach in Chennai (Kumar et al., 2016). Even though research on beach debris has been carried out on Indian coast of late, debris characteristics, its sources, accumulation, seasonal variation and transport pathways along the Indian coastline are still inadequately studied (Arun Kumar and Sivakumar, 2016). There is still a huge gap in the complete understanding of the extent and impact of beach debris issue at the national level. A recent United Nations Environmental Program (UNEP) report on ‘Marine plastic debris and microplastics’ revealed fishing industry as a significant contributor to marine litter in the oceans (Kershaw Peter, 2016). Abandoned, lost or otherwise discarded fishing gear (ALDFG) is considered to have a vital role in marine plastic pollution and a cause of major ecological concerns like ghost fishing (Gilman et al., 2016). ALDFG contributes to about 10% of global marine litter by volume (Macfadyen et al., 2009). According to Matthews and Glazer (2009), the majority of ALDFG was underwater (60.1%) while the remaining 24.6%, on shorelines and 15.3% floating at sea. Commercial fishing create marine debris when the fishers or sailors onboard discard ship
Accumulation of plastic litter in the marine environment is one of the most rapidly amplifying global environmental issues today. The substitution of traditional materials with plastics began along with the large-scale production of plastic from the 1950s. It is estimated that about 8 million tonnes of plastic make its way into the sea every year (Jambeck et al., 2015) and by 2050 plastics will outweigh fishes in the ocean (MacArthur et al., 2016). Long-term durability of plastics and our failure to manage end of life plastic efficiently, have led to marine plastic debris becoming a significant problem in recent times (Thompson et al., 2009). Floating debris tend to accumulate on nearby beaches (Santos et al., 2009) and thus, beach litter surveys are being conducted across the globe to study the distribution and variation in debris type and quantity (Silva-Iñiguez and Fischer, 2003; Walker et al., 2006; Martinez et al., 2007; Zhou et al., 2015; Purba et al., 2018). The marine debris quantification and reporting are comparatively weak from India compared to other countries. The first systematic work in India on marine debris was done by Sridhar et al. (2007) through a beach litter quantification study in Karnataka. Later, Ganesapandian et al. (2011) identified plastic as the highest debris type in Northern Gulf of Mannar region of India. Kaladharan et al. (2012) reported notable quantities of polythene carry bags, sachets and ropes from the beaches in eight major coastal centres of India. Plastic litter on four
∗
Corresponding author. E-mail address: [email protected] (D.B. Daniel).
https://doi.org/10.1016/j.marpolbul.2019.110696 Received 30 July 2019; Received in revised form 27 October 2019; Accepted 27 October 2019 0025-326X/ © 2019 Elsevier Ltd. All rights reserved.
Please cite this article as: Damaris Benny Daniel, Saly N. Thomas and K.T. Thomson, Marine Pollution Bulletin, https://doi.org/10.1016/j.marpolbul.2019.110696
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Table 1 Site characteristics of beaches surveyed. Beach
Characteristics
Major Activity
Access to public
Thanur Malipuram Vizhinjam Kappad Kuzhippily Cheriazheekal
Sandy beach protected by sea walls on either side Wide sandy beach bordered with mangroves behind Narrow sandy beach limited by rocky headlands on the backshore Sandy beach with moss-covered rocks extending into sea Sandy beach bordered with Casuarina trees. Sandy beach famous for its rich placer deposits
Fishing Fishing Fishing Tourism, fishing to a lesser extent Tourism, fishing to a lesser extent Mining, fishing to a lesser extent
Open Open Open Open Open Open
Fig. 1. Map showing sampling locations along the southwest coast of India.
generated trash overboard or fail to retrieve fishing gear (Sheavly, 2005). Moreover, fishing nets made of low quality material discarded after a seasons use contribute considerably to marine plastic debris (Thomas et al., 2013). Kim et al. (2014) estimated that 11436 tonnes of traps and 38535 tonnes of gillnets are abandoned annually in South Korea. Derelict blue crab pots were widely found in the Virginia waters of Chesapeake Bay and about 32000 of them were recovered from there during a study (Bilkovic et al., 2014). Possatto et al. (2011) reported that nylon fragments from cables used in fishery activities played a major role in contaminating marine environment. In the United Kingdom, fishing debris is the second biggest source of marine debris (about 13.8 percent) after visitor's litter (Marine Conservation Society, 2008). In India, studies on fishing-related marine debris are limited to reports of net washed ashore with entangled carcasses of fishes or other aquatic organisms and occasional reporting of fishing-related trash during beach litter surveys. In a preliminary marine litter assessment along the beaches of Mangalore, Sulochanan et al. (2014) observed that nylon and plastic rope were in abundance in the beach litter. Similarly, fishnet pieces were reported as a major beach litter component on the beaches of Gulf of Mannar and Palk Bay, Tamil Nadu (Thirumalaiselvan et al., 2018). These studies point to the possibility of the fishing
industry having a significant contribution to marine plastic debris in India. However, there is lack of information available on this subject which has systematically analysed it. The coastal state of Kerala, located in the south-western part of India is bordered by Arabian sea in the west and is one of the leading marine fish producing states in the country. Majority of the beaches along the long coastline, thus act as fishing centres with varying degree of fishing activity. Vizhinjam, in southern Kerala, is a prominent commercial fishing region with the beach and surrounding areas acting as a major fishing harbour. Common fishing activity in this region is by single day and multiday fishing vessels fitted with outboard motors (9.9 hp and above) and an array of fishing gears like gillnets, hooks and line, boat seines etc. Single day vessels operate up to 15–20 nautical mile away from the coast while multiday fishing is done up to 60 nautical mile. Tanur, in northern Kerala is a similar commercial fish landing centre where motorized vessels (single and multiday), using gillnet and boat sienes are dominant. They operate within 12–30 nautical mile from the coast. Since the nearest harbour Ponnani is 32 km away, majority of the fishing vessels land directly on Tanur beach. Fishing in Malipuram (Cental Kerala) is predominantly by single day fishing vessels fitted with outboard motors of 9.9hp, operating within 12 nautical mile from the coast. Multiday motorized fishers operating in this region 2
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Fig. 2. Photographs showing location of beaches – a) Thanur beach b) Vizhinjam beach c) Malipuram beach d) Kuzhippilly beach e) Kappad beach f) Cheriazheekkal beach.
berth their vessels in nearby Kalamukku fishing harbour, 6 km away. Only single day fishing vessels are landed in Malipuram beach. On the other hand, fishery in Kappad, Kuzhippily and Cheriazheekal is artisanal in nature operating mostly non-motorized fishing vessels near the coast, within 10 km. Traditional fishing vessels such as catamaran, dugout canoe and indigenous gears namely, gillnet, boat seine, hooks and line are the major craft/gear combination used in this area. The present study aims to assess the extent of fishing-related plastic debris in total beach litter in six selected beaches of Kerala, India, quantitatively as well as qualitatively.
2. Materials and methods 2.1. Study area Six beaches were selected for beach litter survey, along the 590 km stretch of Kerala coast, in the south west region of India (Table 1). A pair of high and low fishing intensity beaches each, were chosen from north, central and south Kerala by stratified random sampling (Figs. 1 and 2). Beaches were classified into high and low fishing intensity based on the number & type of fishing vessels and intensity of fishing 3
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Fig. 3. Schematic representation of a shoreline section (100 m) showing four perpendicular transects (T1, T2, T3, T4) selected for beach litter survey. The section extends from low water mark to the first barrier/vegetation at the back of the beach.
2.2. Survey method
Table 2 Classification of observed litter items as per UNEP guidelines. Material type
Plastics
Non fishing related
Fishing related
Clothes Glass Metals Paper & Cardboard Rubber Wood Other Fishing Related Others
Litter item
UNEP Litter Code
Plastic carry bags Food packets Plastic bottles Bottle caps & lids Plastic chappals Plastic cup & food containers Cigarettes & butts Foamed plastics (thermocols & foam sponges) Other plastic items Floats & buoys Monofilament line Rope Fishing nets Cloth items Glass items Metal items Paper & cardboard items Rubber items Wood items Sinkers, Hooks, Fishing vessel pieces Electronic items, batteries etc
PL PL PL PL PL PL
Every beach was sampled once during three seasons, viz, premonsoon (February–May 2017), monsoon (June–September 2017) and post-monsoon (October–January 2017) with a total of 18 surveys. During the survey, four transects of 5 m width were randomly selected on a 100 m stretch of each beach parallel to the water line as prescribed by National Oceanic and Atmospheric Administration (NOAA) for standing stock studies (see Fig. 3) (Opfer et al., 2012). Along each transect, all anthropogenic surface debris items that measured over 2.5 cm (~bottle cap size) were collected by walking along the width of the selected transect and were then sorted, counted and weighed.
07.1 07.2 02 01 24 06
PL 11 FP 04
2.3. Classification and quantification of the data PL 24 PL 14 PL 18 PL 19 PL 20 CL GC ME PC RB WD OT FR
Data were recorded on UNEP data sheets and the collected litter was assigned litter codes based on their material composition as per UNEP/ IOC guidelines (Cheshire et al., 2009) (Table 2). It was then grouped into 8 major categories according to the type of materials namely plastic, glass, rubber, metal, wood, paper and cardboard, cloth and others. The plastic debris was further classified into two broad categories by origin namely, fishing related and non-fishing related types. The litter density was expressed as ‘number of items per 100 m2 of beach’ and ‘weight of items per 100 m2 of beach’. Further, the quantity (number and weight) of total marine debris, plastic debris and fishing related plastic debris in high and low fishing intensity beaches was compared along with its seasonal variation.
OT
operations in the region – viz., the beaches, from where a minimum of 100 fishing vessels (n ≥ 100) having an overall length of 8.5–11 m, fitted with outboard motors (9.9 hp and above) and operated for more than 20 days/month were classified as high fishing intensity beaches. Likewise, the beaches from where a lesser number of motorized vessels (n ≤ 10), operated for less than 20 days were classified as low fishing intensity beaches. In Thanur, Malipuram and Vizhinjam the number of motorized fishing vessels operated ranged from 120 to 700 while in Kappad, Kuzhippily and Cheriazheekal it was 0–7. Total number of fishing vessels (Motorized + Non-motorized) operating in Kappad, Kuzhippily and Cheriazheekal were in the range of 10–15, while that in Thanur, Malipuram and Vizhinjam were 130–1140. Thus, Thanur, Malipuram and Vizhinjam were categorized as high fishing intensity beaches and Kappad, Kuzhippily and Cheriazheekal as low fishing intensity beaches. Actual fishing days in a month ranged from 21 to 25 in high fishing intensity beaches and 15–18 days in low fishing intensity beaches.
2.4. Analysis of data Marine debris concentrations are represented as mean values ± SD (standard deviation). Normality of data was tested by Shapiro Wilk test. Further, to assess the variation in fishing related debris among beaches and across different seasons, a two-way ANOVA was conducted (significance level = 0.05). Analyses were conducted using software PAST v 3.25 (Hammer et al., 2001). 3. Results and discussion 3.1. Abundance of beach litter A total of 15360 items weighing 497.6 kg were recorded in the three seasonal surveys conducted on six beaches, out of this, 11335 items (73%) weighing 298.2 kg (59.9%) were plastics. In the total debris, 5540 items (36%) weighing 198.4 kg (39.8%) were fishing related debris. Further, the number of fishing related items ranged from an average of 6.3 ± 1.7 items/100 m2 in Kuzhippilly to 22.8 ± 14.7 items/100 m2 in Thanur (Mean 14.4 ± 12.4 items/100 m2). In terms of 4
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Fig. 4. Variation in abundance of plastic and fishing related debris by number (a, c) and by weight (b, d) in six surveyed beaches during different seasons.
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Fig. 5. Percentage composition (by number) of A) Total beach litter B) Plastic debris C) Fishing Related Plastic debris obtained along beaches of Kerala Coast.
weight, the amount of debris related to fishing ranged from 0.19 ± 0.09 kg/100 m2 in Kuzhippilly to 0.8 ± 0.6 kg/100 m2 in Thanur (Mean 0.5 ± 0.7 kg per 100 m2) (Fig. 4). Fishing related plastic debris was found to be highest in Thanur beach with maximum fishing vessels operated (n = 1140) and the lowest was recorded in Kuzhippilly with only 15 operated vessels. Further, it was noted that the debris related to fishing reported at higher fishing intensity beaches (4420 items) was more than four times compared to the lower fishing intensity beaches (1120 items). The above finding was basically due to the possibility of generation of considerable quantity of litter during the operation of fishing vessels. Similar findings was also earlier reported by Edyvane et al. (2004) and Unger and Harrison (2016). The majority of litter washed on shore within the Great Australian Bight was reported to be originated from commercial fishing activities (Edyvane et al., 2004). Similarly, a positive correlation between litter abundance and proximity to fishing grounds was observed by Unger and Harrison (2016) on beaches of United Kingdom. It was found that beaches near to intensive fishing activities tend to have an increased overall debris load, which included debris related to fishing as well as others. The other waste consisted of the debris items caught in their nets during fishing, which lead to reflotation of this trash lying on the seafloor and its drift to the nearby shores (Topçu et al., 2013).
discarded waste and its persistence in environment. Fishing related debris (PL14 + PL18 + PL19 + PL20) was the most dominant component (48% by number and 68.5% by weight) among plastic debris, followed by food packaging (PL07.1)-13% (Fig. 5). Ropes, netting, floats, buoys and monofilament fishing lines were the major fishing related debris encountered (Fig. 6). High share of fishing related debris in total debris weight, can be attributed to the large sized discarded fishing nets on beach. Non plastic fishing related debris such as sinkers, hooks, parts of fishing vessels etc formed a very negligible portion (0.91% by number of fishing related debris). This was in consonance with Sheavly (2007) who reported fishing nets, ropes, fishing lines, fish baskets, buoys, floats, traps and pots as the major fishingrelated debris on beaches in United States National Marine Debris Monitoring Program. In fisheries, thermocol/styrofoam boxes are extensively used for storage of fish with ice and thermocol pieces are used as floats in fishing gear. Apart from these fishing related uses, thermocols find myriad of applications in domestic & industrial sectors for packaging of electronic items, glasswares, pharmaceutical products, food items as well as decorative purposes. However, it was impossible to trace the exact source of thermocol pieces found on the beaches surveyed. Thus, thermocol/ styrofoam were counted in a separate category of “foamed plastics” and not included in fishing related plastic debris in this study. High incidence of fishing-related debris in this study was comparable to the reports from Brazil and Korea. In Brazil, fishing related litter represented 46% of the total marine debris (Oigman-Pszczol and Creed, 2007). Hong et al. (2014) highlighted fishing activities including commercial fisheries and marine aquaculture (51.3%) as the major sources of beach debris in Korea. Also, 46% of the trash in Great Pacific garbage patch is reported to be fishing related items (Lebreton et al., 2018). On the contrary, fishing related debris was lesser in studies
3.2. Composition of beach litter Plastic items constituted the major share of the total debris items collected on the beaches (73.8%), during the survey period. The dominance of plastics in overall beach debris is comparable to several other studies (Derraik, 2002; Ryan et al., 2009; Topçu et al., 2013), probably due to high floatation characteristics of plastics, its major input in 6
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Fig. 6. Fishing related plastic debris encountered during beach litter survey – (A), (C) abandoned/discarded fishing nets (Thanur) (B) Abandoned/discarded fishing nets entangled with other debris (Malipuram) (D) Fishing ropes entangled in other debris (Vizhinjam) (E) Bouy (Thanur) (F) – Float (Malipuram) (G) Styrofoam float (Vizhinjam).
to pre-monsoon season and was the lowest during monsoon season (Fig. 4). Higher debris density during post-monsoon season can be attributed to increased wave heights during monsoon months, which result in larger wrack lines that trap more debris items on the shoreline (Jayasiri et al., 2013). Substantial abundance of fishing-related plastic debris on beaches, where a great deal of fishing vessels were operated and during the seasons when fishing activity was high, point to the contribution of fishing activities in generating fishing-related plastic litter in the marine environment. Moreover, the high quantity of plastic debris pertaining to fishing observed along the beaches of Kerala coast, holds the possibility of these items getting washed into the sea and becoming a threat to marine organisms due to entanglement and ingestion. This in turn can have a direct impact on the livelihood of fishers by causing a decline of fishery stocks, in addition to loss of fishing opportunities while diverting time to remove trash entangled in fishing nets and propellers (MacFayden et al., 2009). Creating awareness among fisherfolks about these consequences, through community outreach programs can help in bringing about a behaviour change in the fishing community, whereby careless discard of fishing gears on beaches or into the sea can be reduced.
reported from United Kingdom (13.8%), Japan (12%) and China (13.5%) (Watanabe et al., 2002; Marine Conservation Society, 2008; Zhou et al., 2015). 3.3. Seasonal variation The average number of fishing-related debris in the higher fishing intensity beaches during pre-monsoon season was 30 ± 9.2/100 m2 while that of lower fishing intensity beaches was 7.3 ± 3.4/100 m2. During the post-monsoon season this variation was 30.7 ± 4.2/100 m2 in the higher fishing intensity beaches and 8.6 ± 4/100 m2 for lower fishing intensity beaches. However, there was a significant difference during monsoon season, with both type of beaches recording almost the same low level of fishing-related debris i.e., 5.7 ± 2.3/100 m2 in high fishing intensity beaches and 3.8 ± 1.3/100 m2 in low fishing intensity beaches. The weight based estimation also showed a similar variation between seasons and fishing intensity (Fig. 7). There was significant seasonal and beach wise difference in the number of fishing-related debris (two-way ANOVA p < 0.05; Seasons F (5,2) = 8.64, p = 0.006; Beaches F (5,2) = 5.431, p = 0.011). A similar significant variation was observed in weight of fishing related debris across seasons and beaches (Seasons F (5,2) = 4.2, p = 0.047; Beaches F (5,2) = 3.535, p = 0.042). The average number of items and weight was relatively higher in the post-monsoon season as compared 7
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Fig. 7. Comparison of fishing related debris in high and low fishing intensity beaches during different seasons A) By number B) By weight.
4. Conclusion
Acknowledgement
In the present investigation, a quantitative and qualitative assessment was emphasised to understand the debris status of six fishing beaches of Kerala coast, along with the seasonal variation. The results posit that fishing beaches of Kerala coast were polluted to a significant level due to fishing-related debris, and it varied according to fishing intensity and seasons. Thus, the fishing industry could be constituting a considerable share in beach litter along the Kerala coast. Monitoring more regions for extended periods is essential to accurately determine the quantity of fishing-related debris in the marine environment, thereby developing strategies to reduce fishing industry's input into accumulating marine debris. Educating the fishing community about the environmental and economic consequences of fishing-related debris and providing proper collection mechanisms for damaged fishing gear can reduce the fishing-related debris on beaches to a large extent.
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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.
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ijfs.12122. Gilman, E., et al., 2016. Abandoned, lost and discarded gillnets and trammel nets. In: Methods to Estimate Ghost Fishing Mortality, and the Status of Regional Monitoring and Management. FAO Fisheries Technical Paper, pp. 1–4. Hammer, Ø., Harper, D.A.T., Ryan, P.D., 2001. PAST: paleontological statistics software package for education and data analysis. Palaeontol. Electron. 4 (1), 9. Hong, S., Lee, J., Kang, D., Choi, H.W., Ko, S.H., 2014. Quantities, composition, and sources of beach debris in Korea from the results of nationwide monitoring. Mar. Pollut. Bull. 84, 27–34. https://doi.org/10.1016/j.marpolbul.2014.05.051. Jambeck, J.R., Geyer, R., Wilcox, C., Siegler, T.R., Perryman, M., Andrady, A., Narayan, R., Law, K.L., 2015. Plastic waste inputs from land into the ocean. Science 347, 768–771. https://doi.org/10.1126/science.1260352. Jayasiri, H.B., Purushothaman, C.S., Vennila, A., 2013. Quantitative analysis of plastic debris on recreational beaches in Mumbai, India. Mar. Pollut. Bull. 77, 107–112. https://doi.org/10.1016/j.marpolbul.2013.10.024. Kaladharan, P., Vijayakumaran, K., Singh, V.V., Asha, P.S., Sulochanan, B., 2012. Anthropogenic interventions and their impacts along the Indian coastline. Fish. Technol. 49, 32–37. Kaladharan, P., Vijayakumaran, K., Singh, V.V., Prema, D., Asha, P.S., Sulochanan, B., Hemasankari, P., Loveson Edward, L., Padua, S., Veena, S., Anasukoya, A., Bhint, H.M., 2017. Prevalence of marine litter along the Indian beaches : a preliminary account on its status and composition. J. Mar. Biol. Assoc. India 59, 19–24. https:// doi.org/10.6024/jmbai.2017.59.1.1953-03. Kershaw Peter, J., 2016. Marine Plastic Debris and Microplastics : Global Lessons and Research to Inspire Action and Guide Policy Change, vols. 40 – 41 UNEP (United Nations Environment Programme). Kim, S.G., Lee, W.I.L., Yuseok, M., 2014. The estimation of derelict fishing gear in the coastal waters of South Korea: trap and gill-net fisheries. Mar. Policy 46, 119–122. https://doi.org/10.1016/j.marpol.2014.01.006. Kumar, A.A., Sivakumar, R., Reddy, Y.S.R., Bhagya Raja, M.V., Nishanth, T., Revanth, V., 2016. Preliminary study on marine debris pollution along Marina beach, Chennai, India. Reg. Stud. Mar. Sci. 5, 35–40. https://doi.org/10.1016/j.rsma.2016.01.002. Lebreton, L., Slat, B., Ferrari, F., Sainte-Rose, B., Aitken, J., Marthouse, R., Hajbane, S., Cunsolo, S., Schwarz, A., Levivier, A., Noble, K., Debeljak, P., Maral, H., SchoeneichArgent, R., Brambini, R., Reisser, J., 2018. Evidence that the great pacific garbage patch is rapidly accumulating plastic. Sci. Rep. 8, 4666–4667. https://doi.org/10. 1038/s41598-018-22939-w. MacArthur, D.E., Waughray, D., Stuchtey, M.R., 2016. The New Plastics Economy, Rethinking the Future of Plastics. World Economic Forum Report, pp. 14–15. Macfadyen, G., Huntington, T., Cappell, R., 2009. Abandoned, Lost or Otherwise Discarded Fishing gear., UNEP Regional Seas Reports and Studies, vol. 185. UNEP/ FAO, Rome, pp. 1–2 FAO Fisheries and Aquaculture Technical Paper, 523. Marine Conservation Society, 2008. Beachwatch. In: The 16th Annual Beach Litter Survey Report. Marine Conservation Society, Ross-on-Wye, UK Summary data available from: website. https://www.mcsuk.org/downloads/pollution/beachwatch08.pdf. Martinez-Ribes, L., Basterretxea, G., Palmer, M., Tintoré, J., 2007. Origin and abundance of beach debris in the Balearic Islands. Sci. Mar. 71, 305–314. https://doi.org/10. 3989/scimar.2007.71n2305. Matthews, T., Glazer, B., 2009. Assessing options on abandoned, lost, or discarded fishing gear in the Caribbean. Proc. 62nd Gulf Caribb. Fish. Inst. 62, 13–22. Oigman-Pszczol, S.S., Creed, J.C., 2007. Quantification and classification of marine litter on beaches along armação dos búzios, rio de Janeiro, Brazil. J. Coast. Res. 421–428. https://doi.org/10.2112/1551-5036(2007)23[421:qacoml]2.0.co;2. Opfer, S., Arthur, C., Lippiatt, S., 2012. NOAA marine debris shoreline survey field guide.
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Assessment of fishing-related plastic debris along the beaches in Kerala Coast, India Damaris Benny Daniela,∗, Saly N. Thomasb, K.T. Thomsona a b
School of Industrial Fisheries, Cochin University of Science and Technology, Lake Side Campus, Cochin, India ICAR – Central Institute of Fisheries Technology, Matsyapuri P.O, Cochin, India
A R T I C LE I N FO
A B S T R A C T
Keywords: Beach litter Plastics Pollution Fishing Marine debris Derelict fishing gear
An assessment of quantity, composition and seasonal variation of fishing-related plastic debris was conducted in six beaches along the Kerala coast of India during 2017–2018. Plastic items were the most dominant type of waste constituting 73.8% by number and 59.9% by weight. In the total debris recorded, 5540 pieces (36%) weighing 198.4 kg (39.8%) were fishing related trash. On an average 14.4 ± 12 fishing related items/100 m2, corresponding to mean weight of 0.55 ± 0.7 kg/100 m2 was recorded from these beaches. Results indicated that the fishing-related plastic items were concentrated four times more in the beaches with higher fishing intensity, as compared to the other beaches. Also, the concentration of fishing-related plastic was recorded higher in the post-monsoon season compared to the lowest during monsoon, which was significant with p-value < 0.05. The results emphasize the role of fishing activities in the generation of marine litter.
1. Introduction
sandy beaches in Mumbai was quantified by Jayasiri et al. (2013). Another study of 2017 (Kaladharan et al., 2017), graded 254 selected beaches along the Peninsular coast of India & Union Territories with colour codes according to the levels of beach litter. Similar studies have been conducted in Seeniappa Dargha beach, Gulf of Mannar (Anand et al., 2018) and along the Marina beach in Chennai (Kumar et al., 2016). Even though research on beach debris has been carried out on Indian coast of late, debris characteristics, its sources, accumulation, seasonal variation and transport pathways along the Indian coastline are still inadequately studied (Arun Kumar and Sivakumar, 2016). There is still a huge gap in the complete understanding of the extent and impact of beach debris issue at the national level. A recent United Nations Environmental Program (UNEP) report on ‘Marine plastic debris and microplastics’ revealed fishing industry as a significant contributor to marine litter in the oceans (Kershaw Peter, 2016). Abandoned, lost or otherwise discarded fishing gear (ALDFG) is considered to have a vital role in marine plastic pollution and a cause of major ecological concerns like ghost fishing (Gilman et al., 2016). ALDFG contributes to about 10% of global marine litter by volume (Macfadyen et al., 2009). According to Matthews and Glazer (2009), the majority of ALDFG was underwater (60.1%) while the remaining 24.6%, on shorelines and 15.3% floating at sea. Commercial fishing create marine debris when the fishers or sailors onboard discard ship
Accumulation of plastic litter in the marine environment is one of the most rapidly amplifying global environmental issues today. The substitution of traditional materials with plastics began along with the large-scale production of plastic from the 1950s. It is estimated that about 8 million tonnes of plastic make its way into the sea every year (Jambeck et al., 2015) and by 2050 plastics will outweigh fishes in the ocean (MacArthur et al., 2016). Long-term durability of plastics and our failure to manage end of life plastic efficiently, have led to marine plastic debris becoming a significant problem in recent times (Thompson et al., 2009). Floating debris tend to accumulate on nearby beaches (Santos et al., 2009) and thus, beach litter surveys are being conducted across the globe to study the distribution and variation in debris type and quantity (Silva-Iñiguez and Fischer, 2003; Walker et al., 2006; Martinez et al., 2007; Zhou et al., 2015; Purba et al., 2018). The marine debris quantification and reporting are comparatively weak from India compared to other countries. The first systematic work in India on marine debris was done by Sridhar et al. (2007) through a beach litter quantification study in Karnataka. Later, Ganesapandian et al. (2011) identified plastic as the highest debris type in Northern Gulf of Mannar region of India. Kaladharan et al. (2012) reported notable quantities of polythene carry bags, sachets and ropes from the beaches in eight major coastal centres of India. Plastic litter on four
∗
Corresponding author. E-mail address: [email protected] (D.B. Daniel).
https://doi.org/10.1016/j.marpolbul.2019.110696 Received 30 July 2019; Received in revised form 27 October 2019; Accepted 27 October 2019 0025-326X/ © 2019 Elsevier Ltd. All rights reserved.
Please cite this article as: Damaris Benny Daniel, Saly N. Thomas and K.T. Thomson, Marine Pollution Bulletin, https://doi.org/10.1016/j.marpolbul.2019.110696
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Table 1 Site characteristics of beaches surveyed. Beach
Characteristics
Major Activity
Access to public
Thanur Malipuram Vizhinjam Kappad Kuzhippily Cheriazheekal
Sandy beach protected by sea walls on either side Wide sandy beach bordered with mangroves behind Narrow sandy beach limited by rocky headlands on the backshore Sandy beach with moss-covered rocks extending into sea Sandy beach bordered with Casuarina trees. Sandy beach famous for its rich placer deposits
Fishing Fishing Fishing Tourism, fishing to a lesser extent Tourism, fishing to a lesser extent Mining, fishing to a lesser extent
Open Open Open Open Open Open
Fig. 1. Map showing sampling locations along the southwest coast of India.
generated trash overboard or fail to retrieve fishing gear (Sheavly, 2005). Moreover, fishing nets made of low quality material discarded after a seasons use contribute considerably to marine plastic debris (Thomas et al., 2013). Kim et al. (2014) estimated that 11436 tonnes of traps and 38535 tonnes of gillnets are abandoned annually in South Korea. Derelict blue crab pots were widely found in the Virginia waters of Chesapeake Bay and about 32000 of them were recovered from there during a study (Bilkovic et al., 2014). Possatto et al. (2011) reported that nylon fragments from cables used in fishery activities played a major role in contaminating marine environment. In the United Kingdom, fishing debris is the second biggest source of marine debris (about 13.8 percent) after visitor's litter (Marine Conservation Society, 2008). In India, studies on fishing-related marine debris are limited to reports of net washed ashore with entangled carcasses of fishes or other aquatic organisms and occasional reporting of fishing-related trash during beach litter surveys. In a preliminary marine litter assessment along the beaches of Mangalore, Sulochanan et al. (2014) observed that nylon and plastic rope were in abundance in the beach litter. Similarly, fishnet pieces were reported as a major beach litter component on the beaches of Gulf of Mannar and Palk Bay, Tamil Nadu (Thirumalaiselvan et al., 2018). These studies point to the possibility of the fishing
industry having a significant contribution to marine plastic debris in India. However, there is lack of information available on this subject which has systematically analysed it. The coastal state of Kerala, located in the south-western part of India is bordered by Arabian sea in the west and is one of the leading marine fish producing states in the country. Majority of the beaches along the long coastline, thus act as fishing centres with varying degree of fishing activity. Vizhinjam, in southern Kerala, is a prominent commercial fishing region with the beach and surrounding areas acting as a major fishing harbour. Common fishing activity in this region is by single day and multiday fishing vessels fitted with outboard motors (9.9 hp and above) and an array of fishing gears like gillnets, hooks and line, boat seines etc. Single day vessels operate up to 15–20 nautical mile away from the coast while multiday fishing is done up to 60 nautical mile. Tanur, in northern Kerala is a similar commercial fish landing centre where motorized vessels (single and multiday), using gillnet and boat sienes are dominant. They operate within 12–30 nautical mile from the coast. Since the nearest harbour Ponnani is 32 km away, majority of the fishing vessels land directly on Tanur beach. Fishing in Malipuram (Cental Kerala) is predominantly by single day fishing vessels fitted with outboard motors of 9.9hp, operating within 12 nautical mile from the coast. Multiday motorized fishers operating in this region 2
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Fig. 2. Photographs showing location of beaches – a) Thanur beach b) Vizhinjam beach c) Malipuram beach d) Kuzhippilly beach e) Kappad beach f) Cheriazheekkal beach.
berth their vessels in nearby Kalamukku fishing harbour, 6 km away. Only single day fishing vessels are landed in Malipuram beach. On the other hand, fishery in Kappad, Kuzhippily and Cheriazheekal is artisanal in nature operating mostly non-motorized fishing vessels near the coast, within 10 km. Traditional fishing vessels such as catamaran, dugout canoe and indigenous gears namely, gillnet, boat seine, hooks and line are the major craft/gear combination used in this area. The present study aims to assess the extent of fishing-related plastic debris in total beach litter in six selected beaches of Kerala, India, quantitatively as well as qualitatively.
2. Materials and methods 2.1. Study area Six beaches were selected for beach litter survey, along the 590 km stretch of Kerala coast, in the south west region of India (Table 1). A pair of high and low fishing intensity beaches each, were chosen from north, central and south Kerala by stratified random sampling (Figs. 1 and 2). Beaches were classified into high and low fishing intensity based on the number & type of fishing vessels and intensity of fishing 3
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Fig. 3. Schematic representation of a shoreline section (100 m) showing four perpendicular transects (T1, T2, T3, T4) selected for beach litter survey. The section extends from low water mark to the first barrier/vegetation at the back of the beach.
2.2. Survey method
Table 2 Classification of observed litter items as per UNEP guidelines. Material type
Plastics
Non fishing related
Fishing related
Clothes Glass Metals Paper & Cardboard Rubber Wood Other Fishing Related Others
Litter item
UNEP Litter Code
Plastic carry bags Food packets Plastic bottles Bottle caps & lids Plastic chappals Plastic cup & food containers Cigarettes & butts Foamed plastics (thermocols & foam sponges) Other plastic items Floats & buoys Monofilament line Rope Fishing nets Cloth items Glass items Metal items Paper & cardboard items Rubber items Wood items Sinkers, Hooks, Fishing vessel pieces Electronic items, batteries etc
PL PL PL PL PL PL
Every beach was sampled once during three seasons, viz, premonsoon (February–May 2017), monsoon (June–September 2017) and post-monsoon (October–January 2017) with a total of 18 surveys. During the survey, four transects of 5 m width were randomly selected on a 100 m stretch of each beach parallel to the water line as prescribed by National Oceanic and Atmospheric Administration (NOAA) for standing stock studies (see Fig. 3) (Opfer et al., 2012). Along each transect, all anthropogenic surface debris items that measured over 2.5 cm (~bottle cap size) were collected by walking along the width of the selected transect and were then sorted, counted and weighed.
07.1 07.2 02 01 24 06
PL 11 FP 04
2.3. Classification and quantification of the data PL 24 PL 14 PL 18 PL 19 PL 20 CL GC ME PC RB WD OT FR
Data were recorded on UNEP data sheets and the collected litter was assigned litter codes based on their material composition as per UNEP/ IOC guidelines (Cheshire et al., 2009) (Table 2). It was then grouped into 8 major categories according to the type of materials namely plastic, glass, rubber, metal, wood, paper and cardboard, cloth and others. The plastic debris was further classified into two broad categories by origin namely, fishing related and non-fishing related types. The litter density was expressed as ‘number of items per 100 m2 of beach’ and ‘weight of items per 100 m2 of beach’. Further, the quantity (number and weight) of total marine debris, plastic debris and fishing related plastic debris in high and low fishing intensity beaches was compared along with its seasonal variation.
OT
operations in the region – viz., the beaches, from where a minimum of 100 fishing vessels (n ≥ 100) having an overall length of 8.5–11 m, fitted with outboard motors (9.9 hp and above) and operated for more than 20 days/month were classified as high fishing intensity beaches. Likewise, the beaches from where a lesser number of motorized vessels (n ≤ 10), operated for less than 20 days were classified as low fishing intensity beaches. In Thanur, Malipuram and Vizhinjam the number of motorized fishing vessels operated ranged from 120 to 700 while in Kappad, Kuzhippily and Cheriazheekal it was 0–7. Total number of fishing vessels (Motorized + Non-motorized) operating in Kappad, Kuzhippily and Cheriazheekal were in the range of 10–15, while that in Thanur, Malipuram and Vizhinjam were 130–1140. Thus, Thanur, Malipuram and Vizhinjam were categorized as high fishing intensity beaches and Kappad, Kuzhippily and Cheriazheekal as low fishing intensity beaches. Actual fishing days in a month ranged from 21 to 25 in high fishing intensity beaches and 15–18 days in low fishing intensity beaches.
2.4. Analysis of data Marine debris concentrations are represented as mean values ± SD (standard deviation). Normality of data was tested by Shapiro Wilk test. Further, to assess the variation in fishing related debris among beaches and across different seasons, a two-way ANOVA was conducted (significance level = 0.05). Analyses were conducted using software PAST v 3.25 (Hammer et al., 2001). 3. Results and discussion 3.1. Abundance of beach litter A total of 15360 items weighing 497.6 kg were recorded in the three seasonal surveys conducted on six beaches, out of this, 11335 items (73%) weighing 298.2 kg (59.9%) were plastics. In the total debris, 5540 items (36%) weighing 198.4 kg (39.8%) were fishing related debris. Further, the number of fishing related items ranged from an average of 6.3 ± 1.7 items/100 m2 in Kuzhippilly to 22.8 ± 14.7 items/100 m2 in Thanur (Mean 14.4 ± 12.4 items/100 m2). In terms of 4
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Fig. 4. Variation in abundance of plastic and fishing related debris by number (a, c) and by weight (b, d) in six surveyed beaches during different seasons.
5
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Fig. 5. Percentage composition (by number) of A) Total beach litter B) Plastic debris C) Fishing Related Plastic debris obtained along beaches of Kerala Coast.
weight, the amount of debris related to fishing ranged from 0.19 ± 0.09 kg/100 m2 in Kuzhippilly to 0.8 ± 0.6 kg/100 m2 in Thanur (Mean 0.5 ± 0.7 kg per 100 m2) (Fig. 4). Fishing related plastic debris was found to be highest in Thanur beach with maximum fishing vessels operated (n = 1140) and the lowest was recorded in Kuzhippilly with only 15 operated vessels. Further, it was noted that the debris related to fishing reported at higher fishing intensity beaches (4420 items) was more than four times compared to the lower fishing intensity beaches (1120 items). The above finding was basically due to the possibility of generation of considerable quantity of litter during the operation of fishing vessels. Similar findings was also earlier reported by Edyvane et al. (2004) and Unger and Harrison (2016). The majority of litter washed on shore within the Great Australian Bight was reported to be originated from commercial fishing activities (Edyvane et al., 2004). Similarly, a positive correlation between litter abundance and proximity to fishing grounds was observed by Unger and Harrison (2016) on beaches of United Kingdom. It was found that beaches near to intensive fishing activities tend to have an increased overall debris load, which included debris related to fishing as well as others. The other waste consisted of the debris items caught in their nets during fishing, which lead to reflotation of this trash lying on the seafloor and its drift to the nearby shores (Topçu et al., 2013).
discarded waste and its persistence in environment. Fishing related debris (PL14 + PL18 + PL19 + PL20) was the most dominant component (48% by number and 68.5% by weight) among plastic debris, followed by food packaging (PL07.1)-13% (Fig. 5). Ropes, netting, floats, buoys and monofilament fishing lines were the major fishing related debris encountered (Fig. 6). High share of fishing related debris in total debris weight, can be attributed to the large sized discarded fishing nets on beach. Non plastic fishing related debris such as sinkers, hooks, parts of fishing vessels etc formed a very negligible portion (0.91% by number of fishing related debris). This was in consonance with Sheavly (2007) who reported fishing nets, ropes, fishing lines, fish baskets, buoys, floats, traps and pots as the major fishingrelated debris on beaches in United States National Marine Debris Monitoring Program. In fisheries, thermocol/styrofoam boxes are extensively used for storage of fish with ice and thermocol pieces are used as floats in fishing gear. Apart from these fishing related uses, thermocols find myriad of applications in domestic & industrial sectors for packaging of electronic items, glasswares, pharmaceutical products, food items as well as decorative purposes. However, it was impossible to trace the exact source of thermocol pieces found on the beaches surveyed. Thus, thermocol/ styrofoam were counted in a separate category of “foamed plastics” and not included in fishing related plastic debris in this study. High incidence of fishing-related debris in this study was comparable to the reports from Brazil and Korea. In Brazil, fishing related litter represented 46% of the total marine debris (Oigman-Pszczol and Creed, 2007). Hong et al. (2014) highlighted fishing activities including commercial fisheries and marine aquaculture (51.3%) as the major sources of beach debris in Korea. Also, 46% of the trash in Great Pacific garbage patch is reported to be fishing related items (Lebreton et al., 2018). On the contrary, fishing related debris was lesser in studies
3.2. Composition of beach litter Plastic items constituted the major share of the total debris items collected on the beaches (73.8%), during the survey period. The dominance of plastics in overall beach debris is comparable to several other studies (Derraik, 2002; Ryan et al., 2009; Topçu et al., 2013), probably due to high floatation characteristics of plastics, its major input in 6
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Fig. 6. Fishing related plastic debris encountered during beach litter survey – (A), (C) abandoned/discarded fishing nets (Thanur) (B) Abandoned/discarded fishing nets entangled with other debris (Malipuram) (D) Fishing ropes entangled in other debris (Vizhinjam) (E) Bouy (Thanur) (F) – Float (Malipuram) (G) Styrofoam float (Vizhinjam).
to pre-monsoon season and was the lowest during monsoon season (Fig. 4). Higher debris density during post-monsoon season can be attributed to increased wave heights during monsoon months, which result in larger wrack lines that trap more debris items on the shoreline (Jayasiri et al., 2013). Substantial abundance of fishing-related plastic debris on beaches, where a great deal of fishing vessels were operated and during the seasons when fishing activity was high, point to the contribution of fishing activities in generating fishing-related plastic litter in the marine environment. Moreover, the high quantity of plastic debris pertaining to fishing observed along the beaches of Kerala coast, holds the possibility of these items getting washed into the sea and becoming a threat to marine organisms due to entanglement and ingestion. This in turn can have a direct impact on the livelihood of fishers by causing a decline of fishery stocks, in addition to loss of fishing opportunities while diverting time to remove trash entangled in fishing nets and propellers (MacFayden et al., 2009). Creating awareness among fisherfolks about these consequences, through community outreach programs can help in bringing about a behaviour change in the fishing community, whereby careless discard of fishing gears on beaches or into the sea can be reduced.
reported from United Kingdom (13.8%), Japan (12%) and China (13.5%) (Watanabe et al., 2002; Marine Conservation Society, 2008; Zhou et al., 2015). 3.3. Seasonal variation The average number of fishing-related debris in the higher fishing intensity beaches during pre-monsoon season was 30 ± 9.2/100 m2 while that of lower fishing intensity beaches was 7.3 ± 3.4/100 m2. During the post-monsoon season this variation was 30.7 ± 4.2/100 m2 in the higher fishing intensity beaches and 8.6 ± 4/100 m2 for lower fishing intensity beaches. However, there was a significant difference during monsoon season, with both type of beaches recording almost the same low level of fishing-related debris i.e., 5.7 ± 2.3/100 m2 in high fishing intensity beaches and 3.8 ± 1.3/100 m2 in low fishing intensity beaches. The weight based estimation also showed a similar variation between seasons and fishing intensity (Fig. 7). There was significant seasonal and beach wise difference in the number of fishing-related debris (two-way ANOVA p < 0.05; Seasons F (5,2) = 8.64, p = 0.006; Beaches F (5,2) = 5.431, p = 0.011). A similar significant variation was observed in weight of fishing related debris across seasons and beaches (Seasons F (5,2) = 4.2, p = 0.047; Beaches F (5,2) = 3.535, p = 0.042). The average number of items and weight was relatively higher in the post-monsoon season as compared 7
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Fig. 7. Comparison of fishing related debris in high and low fishing intensity beaches during different seasons A) By number B) By weight.
4. Conclusion
Acknowledgement
In the present investigation, a quantitative and qualitative assessment was emphasised to understand the debris status of six fishing beaches of Kerala coast, along with the seasonal variation. The results posit that fishing beaches of Kerala coast were polluted to a significant level due to fishing-related debris, and it varied according to fishing intensity and seasons. Thus, the fishing industry could be constituting a considerable share in beach litter along the Kerala coast. Monitoring more regions for extended periods is essential to accurately determine the quantity of fishing-related debris in the marine environment, thereby developing strategies to reduce fishing industry's input into accumulating marine debris. Educating the fishing community about the environmental and economic consequences of fishing-related debris and providing proper collection mechanisms for damaged fishing gear can reduce the fishing-related debris on beaches to a large extent.
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