The dwindling community-based management strategies in the brush park fishery of a tropical estuary: Need for co-management

Ocean and Coastal Management 167 (2019) 145–157

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The dwindling community-based management strategies in the brush park fishery of a tropical estuary: Need for co-management

T

Menake Gammanpilaa, M. Jayantha S. Wijeyaratneb, Upali S. Amarasingheb,∗ a b

National Aquatic Resources Research and Development Agency, Regional Research Centre, Kadolkele, Negombo, Sri Lanka Department of Zoology and Environmental Management, University of Kelaniya, Kelaniya, Sri Lanka

A R T I C LE I N FO

A B S T R A C T

Keywords: Community-based fisheries management Co-management Fish aggregating devices Small-scale coastal fisheries Traditional ecological knowledge

Importance of participatory approaches in the management of small-scale fisheries is being increasingly highlighted today throughout the world. Brush park fishery in Negombo estuary, Sri Lanka is a small-scale fishery where traditional ecological knowledge (TEK) accumulated over generations is utilized to optimize the harvests. In the present study, the institutional robustness of the community-based management system of this fishery, which is based on TEK was assessed using Ostrom's modified design principles. Results showed that the degree of community-based management is not effective in successful management of this fishery due to common pool nature. Nevertheless, there is potential for integrating some institutional design principles through intervention of centralized management authorities. As such, co-management regimes that empower local communities are needed for the sustainability this fishery.

1. Introduction Many small-scale fisheries in the world are in crisis today due to over-exploitation and non-implementation of management strategies. In this context, importance of participatory approaches in fishery resource management, especially in labour-intensive small-scale fisheries has been highlighted (Berkes et al., 2000; Johannes et al., 2000; Berkes, 2018; Lobe and Berkes, 2004; Richmond and Levine, 2012). Fishers have a wealth of knowledge and long experience, which can be used for resource management, especially in small scale fisheries (Fisher et al., 2015). In Sri Lanka, there are several traditional coastal fisheries, which are managed through customary fishing rights (Ruddle, 1994; Amarasinghe et al., 1997). However, with the increase in human population and economic diversification, many fishing communities are faced with the challenge of preserving their traditional fishing rights. Diverse mechanisms used in the management of common pool resources have been highlighted in recent literature (Cox et al., 2010; Fischer et al., 2015; Deepananda et al., 2016a, 2016b; Berkes, 2018). Traditional community based management of coastal fisheries is recorded in many regions of the world including Asia-Pacific (Ruddle, 1994), Southeast Asia (Pomeroy, 1995; Dang et al., 2015), India (Ramachandran and Sathiadhas, 2006), Bangladesh (Hossain et al., 2004), Pacific Islands (Richmond and Levine, 2012; Friedlander et al., 2013) and Latin America (Fischer et al., 2015). Amarasinghe and

∗

Bavinck (2011) have shown that both the state and non-state institutions play a significant role in the management of coastal fisheries in southern Sri Lanka. Ability of coastal fishing communities to successfully manage their own common pool resources through institutional architecture and customary fishing rights has been reported in many small scale fisheries in Sri Lanka including the stake net fishery in Negombo estuary (Amarasinghe et al., 1997), kraal (Ja-kotu) fisheries in the Madu Ganga estuary (Atapattu, 1987), coastal marine fisheries (Wickramasinghe and Bavinck, 2015) and stilt fishery in southern province (Deepananda et al., 2016a) and beach seine fisheries in the north-western and southern provinces (Kulatunga and Edirisinghe, 1995; Deepananda et al., 2015; Gunawardena and Amarasinghe, 2016). Institutional robustness (Deepananda et al., 2016b) in the beach seine fisheries of the southern province and in shrimp aquaculture practices in the north-western province of Sri Lanka (Galappaththi and Berkes, 2014) are also reported. However, indigenous knowledge is largely underutilized and not considered by the management authorities in decision making. Such knowledge is often considered as “anecdotal” and “unscientific” (Berkes, 2018). In 1960s, the small scale-fisheries were considered as opportunities for increasing fish production. However, in 1970s, over-exploitation of these resources was resulted in due to lack of property rights, mismanagement, use of destructive fishing gear, habitat degradation, population growth, poverty, urbanization and globalization. In the recent

Corresponding author. E-mail address: [email protected] (U.S. Amarasinghe).

https://doi.org/10.1016/j.ocecoaman.2018.10.008 Received 22 April 2018; Received in revised form 7 September 2018; Accepted 13 October 2018 0964-5691/ © 2018 Elsevier Ltd. All rights reserved.

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past, conflicts with industrial fisheries as well as with conservation priorities have been highlighted in many instances (Basurto et al., 2017). The Nobel Prize winning economist, Elinor Ostrom (1990) emphasized that resource users could be organized to solve problems and take responsibility to monitor common resources. In her book “Governing the Commons”, Ostrom (1990) introduced the idea of sustainable management of commons by self-organizing resource users rather than through regulations imposed by the external organizations. Further, she defined a set of eight core design principles that local communities could use to develop more robust institutions for managing common pool resources (CPR). Subsequently, these were expanded to 11 principles, which could be used to investigate institutional arrangements in community based management of natural resources to avert CPR dilemma (Cox et al., 2010). Brush parks are piles of branches of trees, especially mangroves placed in shallow waters to attract fish. These are ubiquitous in many tropical rivers, shallow lakes, lagoons and estuaries (Welcomme, 2002). Due to their traditional nature, bush park fisheries are expected to possess strategies for resource management based on traditional ecological knowledge (TEK) of the fishing communities. Such management strategies based on TEK are considered to be useful in the conservation of coastal environment too (Berkes, 2018). However, such strategies in most fisheries are not in record. The objectives of the present study was to gather information on the TEK of brush park fishers of Negombo estuary and to evaluate its compliance with Ostrom's modified design principles.

ln DW = 4.262 + 2.103 ln di

2. Materials and methods

Biomass = 0.251 ρ dbh2.46

The study was conducted in three fishing areas (Katunayake, Munnakkaraya, and Talahena) of the Negombo estuary (7°6′-7°12′ N and 79°40′-79°53′ E) on the west coast of Sri Lanka (Fig. 1) from April 2014 to April 2016. Brush parks are constructed placing mangrove branches in shallow areas (1.0–1.5 m in depth) of the estuary in a circular manner. During harvesting, they are surrounded by a net (1.25 cm stretched mesh) held in place by wooden poles and all the mangrove branches are removed. Then, using a tie string attached to the bottom line and the head line, the net is drawn together and the fish trapped in this bowl of netting are harvested using a scoop net or hauling the net on to a canoe. Brush park is then reconstructed using the same mangrove branches. The net is cleaned and spread on wooden poles or on land for sun-drying. The whole fishing operation takes about 4–8 h for one fisher. Material such as old vehicle tyres and non-mangrove hard wood branches are also used to supplement the mangrove branches.

where dbh is the diameter at breast height and ρ is density of wood. It was assumed that mangrove branches of different sizes comply with the above relationships. The yield (Y) of fin fish and crustaceans (in kg m−2 month−1) were estimated assuming the shape of the brush park to be cylindrical (Amarasinghe et al., 2002).

A total of 100 branches of mangroves in four size categories (< 1 m, 1–2 m, 2–3 m and > 3 m in length) from each species (Rhizophora mucronata, Avicennia marina, Lumnitzera racemosa, Excoecaria agallocha) were used to measure mean diameter of mangrove branches. Length of each mangrove branch was measured to the nearest centimetre using a measuring tape and diameter was measured to the nearest millimetre using a vernier caliper. Dry weight (in g) of branches of Rhizophora mucronata and Avicennia marina which were commonly used to construct brush parks was determined using the following relationships described by Amarasinghe and Balasubramanium (1992). For Rhizophora mucronata: (1)

For Avicennia marina:

ln DW = 4.074 + 2.299 ln di

(2)

where, di is the mean diameter (in mm) of mangrove branches. The following relationship between the diameter at breast height (dbh) and above ground biomass developed by Perera and Amarasinghe (2014) was used to estimate the dry weight of Lumnitzera racemosa branches.

Above ground biomass = 0.114 dbh2.523

(3)

Dry weight (biomass) of the branches of Excoecaria agallocha was determined by the following equation derived by Komiyama et al. (2005).

Y= (C × 30)/(π ×(D2 /4)×(N))

(4)

(5)

where, C is the total harvest in kg (fin fish and crustacean) from the brush park, π = 3.1416 and D is the diameter (m) of the brush park and N is the period of installation of the brush park (in days). Total dry weight (W) of all mangrove branches was then determined and their branch density (kg m−3) was estimated using the following equation.

Branch density = W/(π ×(D2/4)×(H))

2.1. Traditional ecological knowledge (TEK)

(6)

where H is the height of the brush park (m). The relationship of branch density with brush park yield and value of the catch were determined using the data for 245 brush parks studied. In addition, based on the market values of species groups and their composition in brush park catches, value of catch in each brush part in relation to branch density was determined.

There are about 526 brush parks established in the Negombo estuary, which are owned and operated by 33 fishers (Fig. 1). A total of 28 brush park fishers (85%), who own and operate 476 brush parks in the estuary were randomly selected for the study.

ii. Effect of duration of brush parks on fish yield

2.1.1. Quantification of fisheries management related aspects For this analysis, data were collected from 245 brush parks. Data sheets were provided to 28 randomly selected fishers who owned these brush parks to obtain information on mangrove species used, number and the size of the branches used, height and diameter of the brush park, finfish and crustacean yields and total income from each operation. Information about the period between installation and harvesting of the brush parks was also gathered. Further, strategies that fishers apply to maximize benefits from fishing were also recorded. Information provided by fishers in the data sheets were verified through field observations.

The relationships between duration of brush park, i.e., the time period between installation and harvesting of brush park, and the yield and value of the catch were determined for the 245 brush parks studied. Further, based on the market values of species groups, and their composition in brush park catches, value of catch in each brush park in relation to duration was determined. iii. Other aspects related to fish production Information on the factors used to choose the installation site, availability of mangrove branches and methods of collecting them, methods of ensuring year-round income for brush park fishers and

i. Effect of twig density on fish yield in brush parks

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Fig. 1. Map of Negombo estuary showing the distribution of brush parks.

et al., 2010). In addition, group discussions were held with fishers and visual observations were also made. The responses were collected according to a five-point Likert scale (Likert, 1932) ranging from 1 to 5 where 1 was assigned for noncompliance, 2 for low compliance, 3 for moderate compliance, 4 for high compliance and 5 for very high compliance. These levels of compliance were evaluated for each of the eight modified design principles. Interviews were done in fishers' native language, Sinhala.

alternative activities carried out to supplement income were collected through interviews.

2.1.2. Institutional robustness for averting CPR dilemma A total of 28 brush park fishers who owned and operated 90% of total number of brush parks in the estuary were interviewed using a semi-structured questionnaire, which focused on preliminary demographic information including educational level, number of years of experience, indigenous knowledge in fishing operation, appreciation of fishing rights for equity sharing of the resource as well as information relevant to institutional robustness for averting CPR dilemma as articulated in Ostrom's modified design principles (Ostrom, 1990; Cox

2.2. Data analysis Based on the period between installation and harvesting, brush 147

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characteristics of the fishery relevant to each design principle are also indicated in Table 2.

parks were grouped into two categories, i.e., those which are harvested within a short period (≤35 days) and those which are left for a long period (> 35 days). Similarly, they were grouped as those having low branch density (≤2 kg m−3) and those having high branch density (> 2 kg m−3). As catch rates in fisheries are generally known to be lognormally distributed (Gulland, 1983), yield from each brush park, estimated as kg m−2 of brush park, month−1, was ln (x+1) transformed before analysis. Using student's t-test, mean yields and mean commercial values of catches of brush parks harvested within a short period were compared with those of the brush parks harvested after a long period of installation. Similar analysis was done for the commercial value of the catches too. Based on the mean and median values of the Likert scale for each component of Ostrom's modified design principles, the institutional robustness for averting CPR dilemma was determined.

3.2.1. User boundaries Due to easy construction and convenience of fishing, brush parks are usually confined to shallow waters of 1–1.5 m depth. In addition to the factors based on TEK, proximity to existing brush parks and close vicinity to homesteads of fishers are also considered in selecting the new construction sites. The distance between two brush parks varies from 50 m to 100 m. This distance is also decided by fishers through experience to ensure more-or-less equal harvests and to minimize conflicts. Currently there is no proper legislation to define user boundaries for brush park fisheries, when compared to traditional fisheries, such as stake net (Amarasinghe et al., 1997) and beach seine fisheries (Deepananda et al., 2016b) in Sri Lanka. However, general practice is that no fisher tends to establish a brush park without the concurrence of other fishers. Every fisher uses a particular landing site and occupies a particular space for landing the catch, craft and gear. The user boundaries are established through the consensus of fishers and therefore, this fishery has weak user boundary rights.

3. Results 3.1. Quantification of fisheries management related aspects The average market values, life strategies, size ranges and relative abundance (> 10% very common; 5–10% common; 1–5% uncommon and < 1% rare), of the fin fish and shell fish species caught in the brush parks are given in Table 1. General socio-demographic profile of the brush park fishing community in Negombo estuary is shown in Fig. 2. Majority of the brush parks fishers were in 40–60 years age group having over 20 years of experience in fishing. Many of them did not have sufficient formal education. About 64% of respondents were full time brush park fishers. Number of brush parks owned by a fisher ranged from 5 to 35 (mean ± SD: 17 ± 8). About 36% of the fishers were self-employed, engaged in other fishing activities (e.g., shrimp fishing during September to November) and worked as labourers. About 96% of the interviewed fishers stated that the ownership of brush parks was passed down from father to son. Higher yields were recorded in inter-monsoonal periods than in other periods (Fig. 3A), which appears to be associated with salinity variation (Fig. 3B). Almost all fishers were of the view that fish yields from brush parks are associated with salinity variation. About 65% of brush parks fishers, majority of brush parks were harvested within 35 days after installation (Fig. 4A). Branch density of nearly 75% of the brush parks has a branch density of ≤2 kg m−3 (Fig. 4B). Mean yield of brush parks harvested within 35 days after installation was significantly higher than that of the brush parks harvested after 35 days of installation (p < 0.002) (Fig. 5A[i]). Mean yield of brush parks with branch density ≤2 kg m−3 was significantly lower than that of the brush parks having branch densities > 2 kg m−3 (p < 0.001; Fig. 5A[ii]). The mean commercial value of the total fish catch of the brush parks installed for ≤35 days was significantly higher than that of the brush parks installed for > 35 days (p < 0.01; Fig. 5B[i]). The mean commercial value of the total catch of the brush parks with branch density ≤2 kg m−3 was however significantly lower than that of the brush parks having branch densities > 2 kg m−3 (p < 0.01; Fig. 5B[ii]). Diversity of the catch composition in the brush parks installed for ≤35 days was lower than that of the brush parks installed for over 35 days (Fig. 5C[i]). The commercial value of the total catch depends on that of the individual fish species. In brush parks with lower branch density (≤2 kg m−3), proportion of high valued shell fish (shrimps and crabs) was higher than in brush parks with higher (> 2 kg m−3) branch density (Fig. 5C[ii]).

3.2.2. Resource boundaries Brush park catches are essentially dependent on the attraction of fish species. Hence, the resource boundaries also are very weak in the fishery (Table 2). However, fishers tend to optimize catches using their TEK. Except in areas where mangroves are cultivated by resource users, access to mangrove forests is not restricted by members of the community. Of course, there are regulations for mangrove protection which are not adhered to by majority of fishers. 3.2.3. Congruence with local conditions Selection of a suitable site to establish a brush park is influenced by many factors such as prevalence of moderate water currents, water depth, bottom condition, minimization of resource competition with other brush parks, etc., which are determined based on TEK of fishers. However, a lower mean value was reported from the Likert scale for this design principle due to large variation in the experience and knowledge among fishers (Table 2; Fig. 6A). Temporal allocation rules, which promote methodical and equitable sharing resources do not exist. During harvesting, under-sized and low-valued individuals are thrown back into the lagoon alive. This minimizes mortality of small and juvenile fish and thus ensure sustainability of resources reducing by-catch. 3.2.4. Congruence between appropriation and provision Mangrove vegetation in Negombo estuary is gradually becoming a dwindling resource and as a result, there is a scarcity of mangrove branches to be used in brush park fisheries. In the recent past, mangrove cultivation has become vital for the existence of brush park fishery (Amarasinghe et al., 2002). Plantation of mangroves to enhance brush park fisheries has been suggested about 30 years ago by Wijeyaratne and Costa (1987). However, no attention was not paid to that recommendation by the community and relevant authorities at that time. Mangroves are cultivated by some fishers on the state lands, mostly in a few islands located in the northern part of the estuary. Also, some mangrove cultivators lease out cultivated mangrove woodlots at a rate of Rs. 1000–1500 per ha for a two-month period or for 4–5 kg of fish per month. Fishers are compelled to use low branch densities to construct brush parks due to scarcity of mangrove branches. Fishers are aware that during the monsoonal rainy seasons, harvests from brush parks are low and therefore many fishers refrain from fishing during rainy season. Fishers' knowledge on the periods of high catches, i.e., during inter-monsoonal periods, is accurate as evident from the seasonal variation pattern of brush park yields (Fig. 3). Occasional windy days, traditionally termed as the days of “Uthuru sulan”,

3.2. Institutional robustness for averting CPR dilemma Levels of compliance of brush park fishery with different components of Ostrom's design principles are given in Table 2. The 148

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Table 1 The abundance, average market value, life strategies and size ranges of the fish species caught in the brush park fishery of Negombo estuary during the study period from April 2014 to April 2016. (VC = Very common, C = Common, UC = Uncommon, R = Rare, JR = Juvenile recruit, MA = Migratory adult, PR = Permanent resident). In February 2018, US Dollar 1 ≈ Sri Lanka Rupees (LKR) 155.00. Family High-valued fin fish Carangidae Centropomidae Lethrinidae Lutjanidae

Serranidae

Sillaginidae Sparidae Sphyraenidae Low-valued fin fish Acanthuridae Ambassidae Anguillidae Apogonidae Ariidae Cichlidae

Eleotridae Gerreidae

Haemulidae Leiognathidae Monodactylidae Mugilidae

Plotosidae Scatophagidae Siganidae

Terapontidae High-valued shell fish Portunidae Penaeidae Palaemonidae

Scientific name

Abundance

Average market value (LKR/kg)

Life strategies

Size range (cm)

Caranx sexfasciatus Carangoides talamparoides Lates calcarifer Lethrinus rubrioperlulatus Lutjanus argentimaculatus Lutjanus fulviflamma Lutjanus kasmira Lutjanus russelli Epinephelus malabaricus Epinephelus coioides Epinephelus tauvina Sillago sihama Acanthophagus berda Sphyraena jello

C UC C R C UC UC C C UC R UC C R

400–600 400–600 400–650 400 400 400 400 400 800 800 800 350–1200 400–450 800

JR JR MA/JR JR JR MA/JR MA/JR MA/JR JR JR JR MA/JR MA/JR JR

9.2–17.3 12.4–17.7 18.1–48.3 9.0 14.3–33.0 10.4–15.7 10.6–15.9 8.0–26.9 13.8–40.1 10.1–31.5 35.7 12.5–32.7 9.2–33.5 30.8

Acanthurus gahhm Ambassis gymnocephalus Anguilla bicolor bicolor Apogon hyalosoma Arius jella Arius maculatus Etroplus suratensis Oreochromis mossambicus Oreochromis niloticus Ophiocara porocephala Gerres abbreviates Gerres filamentosus Gerres oyena Gerres oblongus Plectorhinshus gibbosus Leiognathus equulus Leiognathus fasciatus Monodactylus argenteus Liza macrolepis Liza melinoptera Liza parsia Liza sascasia Liza subviridis Mugil cephalus Valamugil buchanani Valamugil seheli Plotosus canius Scatophagus argus Siganus jarvus Siganus lineatus Siganus vermiculatus Terapon puta

UC UC R UC C C VC UC UC R UC R UC UC UC R R VC C C UC UC C UC C C UC VC VC UC R R

20 per fish 50 250–350 50 100 100 250–300 200 200 100 50 50 50 50 100 100 100 10 per fish 250–300 250–300 250–300 250–300 250–300 250–300 250–300 250–300 200–300 200 250 250 250 50–100

MA/JR JR MA JR MA/JR MA/JR PR PR PR JR JR JR JR JR JR JR JR JR MA/JR MA/JR MA/JR MA/JR MA/JR MA/JR MA/JR MA/JR MA MA/JR JR JR JR JR

6.2–17.4 8.1–17.4 60.3 8.9–13.2 14.6–30.5 10.6–28.7 5.5–23.5 25.3–29.5 21.4–22.3 14.2–20.7 7.5–14.4 8.6 9.9–13.5 9.1–15.2 7.1–22.1 7.7 9.1 6.9–9.2 17.1–50.0 11.3–45.2 13.6–27.3 21.8–23.4 15.2–49.2 18.2–54.4 12.2–50.3 12.6–28.5 34.4–59.0 7.2–22.7 8.8–22.9 10.9–23.2 11.7–20.3 10.9

Scylla serrata Penaeus indicus Penaeus monodon Macrobrachium rosenbergii

C VC UC UC

600–2500 900–1000 1500 400–1000

MA/JR MA/JR MA/JR MA/JR

where wind blows from north, and the days of “Dakunu kaluwava”, where wind blows from south are unfavourable for fishing. Furthermore, fishers refrain from fishing during full moon days since they are aware that high visibility in water during these days reduces assembling of fish resulting in low yields. Fishers indicated that prevalence of calm water during two days following the new moon day, traditionally called as “Kuranawaduwa”, brings higher yields. Brush park fishers are able to predict the degree of attraction of mugilid species to brush parks based on their swimming and schooling behaviour. In a study carried out in 1980–1982, Wijeyaratne and Costa (1987) reported that the most of the brush parks in Negombo estuary were harvested within 4–5 weeks. The TEK of the fishers is in agreement with the results of the present study, which indicate that fishers maximize benefits through installing brush parks for about 35 days (Fig. 5).

The profit from the harvest was equally shared between the helper and the owner in most occasions. However, some owners give only onethird of the income to the helper. They justify it indicating that the cost of the craft and nets has to be borne by them. Such benefit sharing mechanisms ensure trust between the brush park owner and the helper.

3.2.5. Collective-choice arrangements One brush park is owned by either one, two or three fishers. When a particular location is ear-marked by a fisher for installing a brush park, other fishers refrain from installing a brush park in the same location. In general, brush park fishing rights are endowed from father to son and therefore, the property rights are somewhat strong. However, there are rare instances where property rights are transferred to another member of the community. There are no formal institutions to regulate the 149

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Fig. 2. Distribution of fishers by (A) age group; (B) year of experience operating brush parks; (C) educational level; (D) involving of brush park fishery; (E) number of brush parks owned by one fisher; and (F) ownership of brush parks in Negombo estuary.

3.2.8. Graduated sanctions Brush park fishing is carried out throughout the year. However, no fishing is done on the days of high winds and heavy rains, especially during the south-west monsoon season because it is difficult to harvest brush parks due to high waves and high water level. The time of harvesting brush parks is not specified in any regulation. Generally, it is done from around 04 00 a.m. to 08 00 a.m. There are no closed season stipulated for harvesting brush parks. As such, there are no graduated sanctions in this fishery.

number of brush parks or transfer of user rights. Government involvement in these is minimum and the community organization is also weak. Number of brush parks that are operated by individual fishers depends on their operating capacity and availability of resources (e.g., mangrove branches). 3.2.6. Monitoring of users In brush park fisheries, annual registration of crafts and licensing of fishing operations are compulsory as per the Fisheries and Aquatic Resources Act No. 2 of 1996 of Sri Lanka. However, majority of brush park fishers do not adhere to this requirement.

3.2.9. Conflict-resolution mechanisms Although locations of installation of brush parks are not demarcated, new fishers are required to keep a minimum distance of 50 m from nearby brush parks. This would minimize conflicts among fishers. Since there is no external authority to enforce rules, monitoring is done by the appropriators themselves. Brush park fishers frequently spend time and effort for monitoring, but appropriators who violate

3.2.7. Monitoring of resources Fishing activities and resources are voluntarily monitored by individual fishers. However, fishing activities of other fishers disturb the movement of fishes thus affecting the brush park fishery. 150

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Fig. 3. (A) Variation of mean yields from brush park fishery and (B) Variation of salinity in three sampling locations during the four seasons in Negombo estuary, Sri Lanka. NEM=North-east monsoon (December to February), SWM= South-west monsoon (May to September), IM1 = Inter-monsoon 1 (March to April) and IM2 = Inter-monsoon 2 (October to November).

support to traditional activities as brush park fisheries. However, the environmental issues faced today were not in existence in the past. Hence, in present day context, some of the traditional customs of fishers are challenged by the government bureaucracy. Brush park fishers are able to make independent decisions up to a certain level for managing the fishery and related resources. However, such decisions cannot be implemented today since there are no interventions from the Government.

3.2.11. Multi-level of institutional structure Due to limited number, brush park fishers are not well organized as a fisheries society. They are the members of the common fisheries society of the estuary. Brush park fishers do not share information or have discussions among themselves or with other neighbouring communities. Such sharing of information and discussions are important to manage their fisheries efficiently and effectively. Establishing community associations (Samithi), is the key towards taking collective action ensuring the effectiveness of management at community level and facilitating sustainable use of resources. Although horizontal integration between communities is rather weak and insufficient, vertical integration appears to be comparatively strong. Vertical integration is expected to facilitate coordination between different levels of governance institutions, such as Fisheries Inspector, District Fisheries Officer, Secretary to the Provincial Ministry of Fisheries and Secretary to the Ministry of Fisheries and Aquatic Resources Development (MoFARD) of the central government. However, none of these officers has sufficiently contributed to manage the brush park fishery. The government fisheries agencies do not intervene in local fishers' rights. This has resulted in poor recognition of the management decisions taken by the community made through customary norms.

Fig. 4. Relationships between (A) the period of installation and ln yield +1, and (B) twig density and ln yield +1. Vertical broken lines indicate arbitrary groupings of brush parks according to yield.

operational rules are not punished. Violation of customary rules is resolved through discussions. However, serious violation are reported to the Fisheries Inspector or police. Mechanisms for graduated sanctions are remarkably low in this fishery. There are some concerns from other fishers involved in other fishing activities because brush parks obstruct navigation of fishing crafts, interfere with migration of fish, increase siltation in the estuary, etc. However, they do not impose strong pressures on the traditional fishing methods such as brush parks.

3.3. Compliance with modified design principles Institutional arrangement of brush park fisheries were not completely in accordance with the eight modified design principles of Ostrom (1990). According to results of questionnaire survey, there were different levels of compliance of institutional structure of brush park fisheries in Negombo estuary. The design principles 2B, 4A and 4B showed higher compliance, design principle 3 showed moderate compliance, design principles 2A, 6, 7 and 8 showed low compliance and design principles 1A, 1B and 5 showed non-compliance (Table 2; Fig. 6A and B).

3.2.10. Minimal recognition of rights to organize Some regulations enforced by the government to protect the environment such as those aimed at conservation of mangroves do not 151

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Fig. 5. (A)[i] Ln (yield+1) of brush parks installed for ≤ 35 days and > 35 days; [ii] Ln (yield+1) of brush parks with branch density of ≤2 kg m−3 and > 2 kg m−3. (B)[i] Value of catch of brush parks installed for ≤ 35 days and > 35 days; [ii]Value of catch of brush parks with branch density of ≤2 kg m−3 and > 2 kg m−3; (C)[i] Yield of major fish categories of brush parks installed for ≤ 35 days and > 35 days; [ii] Yield of major fish categories of brush parks with branch density of ≤2 kg m−3 and > 2 kg m−3.

152

153

Collective-choice arrangements

Monitoring of users

Monitoring of resources

Graduated sanctions

Conflict-resolution mechanisms

4A

4B

5

6

Congruence with local conditions

2A

3

Clearly defined resource boundaries

1B

Congruence between appropriation and provision

Clearly defined user boundaries

1A

2B

Design principle

No.

1) Compliance with clearly defined user boundaries for resource users 2) User boundaries are accepted by non-appropriators 3) User boundaries are accepted by government authority/ legitimacy 4) User boundaries are used for resource management purpose 5) User boundaries exist for resource (mangrove) availability 6) User boundaries are used from generation to generation 7) User boundaries exist at proximity to the home 1) Clearly defined resource boundaries exist 2) Resource boundaries are accepted by non-appropriators 3) Resource boundaries are accepted by government authority/ legitimacy 4) Resource boundaries are used for resource management purposes Similarity exists between resource environment and governance structure (rules) Excludability rules: 1) Eligibility rules exist 2) Intercommunity access rules exist Subtractability rules: 3) Temporal allocation rules exist 4) Rules restricting time/place/gear/technology exist 5) Fishing behaviour rules exist 6) Conservation rules exist 1) Analogy between cost and benefits exists 2) Mechanism to share the cost proportionally exists 3) Mechanism to distribute the benefits proportionally exists 4) A mechanism to distribute the benefits to appropriators during non-temporal allocations exists 1) Operational and collective-choice rules exist (cutting of mangroves, harvesting methods) 2) Resource users have right to make, enforce and change existing rules 3) Effectiveness of these rules 4) External authorities accept these rules (legitimacy) 1) An effective mechanism to monitor the enforced rules (fishing activities, violations, violators) exists 2) Frequency of monitoring appropriators/non-appropriators activities/behaviour 3) The effectiveness of these monitor appropriators behaviour 1) An effective mechanism to monitoring resources (mangrove and fishes) and fishing territory exists 2) Frequency of monitoring the resource 3) The effectiveness of these monitoring of the resources 1) A mechanism for graduated sanctioning exists 2) The effectiveness of the mechanism 3) Government bureaucratic authorities accepts the mechanism/ legitimacy 4) There is an official accountable for appropriators 1) Low-cost mechanisms exist to resolve conflicts between resource users

Components

Brush park fishers monitor all fishing activities, violations, violators throughout the year.

Those who excessively violate of community rules are likely to be punished by graduated sanctions (Minor issues solved within community. Others are reported to Fisheries Inspector (FI), Department of Fisheries (DFO) or Police.

4.00 (3.67)

1.00 (1.00)

(continued on next page)

There is a mechanism to resolve conflicts among appropriators or between appropriators and relevant officials. Authority: brush park fishers, FI, DFO, Police

Monitoring by brush park fishers exists. 4.00 (3.67)

2.00 (2.67)

Brush park fishers affected by the operational rules can participate in modifying such operational rules and strategies, particularly when local conditions have changed.

Existing operational rules are in congruence with local conditions (place, technology and/or maximize quantity of resources).

2.00 (2.50)

3.00 (2.75)

Resource boundaries are basically social. Geographic boundaries for fish resources and harvesting areas of mangrove twigs are not defined.

1.00 (1.50)

Mechanism to share the cost and benefits proportionally by set of rules exists. Major costs are those for labor and material (encircling net, craft, mangrove woodlots).

Existence of well-defined user boundaries around the resource system of brush park community.

1.00 (1.86)

4.00 (3.50)

Characteristics

Median (and mean) values of compliance

Table 2 The characteristics of Ostrom's modified design principles (Cox et al., 2010) and evaluation of institutional robustness relevant to the brush park fishery in Negombo estuary. Mean values are given within parentheses. (MoFARD – Ministry of Fisheries and Aquatic Resources Development).

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Ocean and Coastal Management 167 (2019) 145–157 Multiple layers of nested enterprises with horizontal and vertical integration exists: Horizontal integration: intercommunity linkage among user groups. Vertical integration: Connections between multiple jurisdictional levels among FI, DFO, Secretary to the Fisheries Ministry of Provincial Council and the Secretary to the MoFARD of Central Government.

Anis et al. (2015) pointed out that low level of income and higher demand of fish force brush park fishers to go for shorter harvesting time (14–21 days). Further, the majority of ornamental fish caught are juveniles and this may threaten the sustainability of fishery. Table 3 illustrates the major issues identified by fishers and possible approaches that could be taken to improve the current situation through co-management. 4. Discussion The brush park fishery in Negombo estuary dates back to 1910 (Senanayake, 1981). This traditional fishery was highly productive until 1990s (Wijeyaratne and Costa, 1987; Costa and Wijeyaratne, 1994; Jayakody, 1996; Amarasinghe et al., 2002). Senanayake (1981) reported that there were around 2200 brush parks in Negombo estuary during June–July 1981. According to Jayakody (1996), in early 1990s, there were 1800–2200 brush parks in this estuary. There are different estimates about the contribution of brush parks to the total fish production of the estuary. According to Ward and Wyman (1975), brush parks accounted for more than 80% of the fish production of this estuary in 1970s. However, according to later studies conducted in 1980s and 1990s, brush parks account for around 36% of the total fish production (Wijeyaratne and Costa, 1987; Jayakody, 1996). According to the present study, this traditional fishery is rapidly declining and at present there are only about 526 brush parks in the entire estuary. Present study further revealed that scarcity of mangrove branches to construct brush parks, and mangrove management strategies implemented by the Government which alienated resource users who significantly contributed to mangrove conservation through silvicultural practices (Amarasinghe et al., 2002) made brush park fishers to switch to other livelihoods including more lucrative fishing practices. Further, the reluctance of young generation for fishing, non-availability of manpower, disturbance from other fishing activities, habitat degradation and less intervention of the government are other reasons for declining trend of the fishery. Remnants of community based fisheries management (CBFM) exist in the brush park fishery of Negombo estuary. For example, somewhat strong property rights such as exclusive rights that come from generation from generation exist in the fishery. This helps to prevent CPR issues. CBFM is not a formal fisheries management system; it only devolves the right of managing the fishery to a group of people in the respective community (Arnason, 2003). Such CMFM systems tend to disappear with time as a result of structural adjustment of national economies (Kapetsky, 1981). Due to intensification of fishing in acadjas, a brush park fishery in Lake Volta in Ghana, social and economic transformations have taken place creating a situation which had led to social tension and intra-community conflicts (Béné and Obirih-Opareh, 2009). However, intensification of brush park fisheries in Negombo estuary was not reported in the recent past. The knowledge of brush park fishers about productive seasons and lean seasons (ex-ante) in relation to seasonal salinity variations in the estuary caused by monsoonal rains was found to be accurate (ex-post). De Silva and Silva (1979) also attributed the seasonal variations of fish yields in brush parks to seasonal variation of salinity in the estuary, caused by seasonal rainfall and intrusion of sea water. In an estuary in Sundarban, India, higher abundance of fish has been recorded during pre-monsoon season when the salinity is comparatively high (Mukherjee et al., 2012). Accuracy of fishers' knowledge about the effect of wind conditions on the harvest, which was empirically verified in the present study, indicates that brush park fishers possess a wealth of indigenous knowledge that has been accumulated through their experience. Fishers utilize TEK to optimize harvests from brush parks and the mechanisms are essentially linked to customary rights, which inevitably

2.00 (2.40)

The rights of appropriators to make their own decisions within the community and institutions are not challenged by external governmental authorities. 2.00 (2.33)

3.4. Major issues and management strategies

Minimal recognition of rights to organize

Multi-level of institutional structure

7

8

2) The degree of effectiveness of the existing mechanism 3) Users support effective monitoring and enforcement of rules 1) Ability to compromise and device their own decisions within the community exists 2) Higher-level state authorities recognize the right of the community institution/resource users to self-govern 3) The effectiveness of community and collaborative decision making process with government authorities 1) There is a multi-layer institutional structure 2) Vertical integration exists 3) Horizontal integration exists 4) Frequency of each linkage measured 5) Degree of the effectiveness of these multilevel institutional structure

Design principle No.

Table 2 (continued)

Components

Median (and mean) values of compliance

Characteristics

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Fig. 6. (A) Boxplot diagram and (B) Radar diagram for exhibited levels of compliance (indicated in shaded areas) of institutional robustness in the brush park fisheries in Negombo estuary with Ostrom's modified design principles (1A, 1B, 2A, 2B, 3, … 8; see Table 2 for definitions). Axis labels are indicated as, 5 (very high compliance); 4 (high compliance); 3 (moderate compliance); 2 (low compliance); and 1 (non-compliance). In the box plots, thick cross bars indicate medians, whiskers are minimum and maximum values, and lower and upper limits of boxes are 25% and 75% percentiles respectively.

Table 3 Issues in the brush park fishery in Negombo estuary and possible solutions. Issues

Solutions

Excessive harvesting of juvenile and mature fish - overfishing

Implementation and strict monitoring of licensing system for operating of brush parks, regulation of period and frequency of fishing for particular species based on their spawning season, regulation of mesh size of encircling nets and size of fish landed, by the MoFARD. Zoning of the estuary area for commercial and recreational activities by the government authorities including Divisional Secretary, MoFARD and other related government and non-government organizations. Replanting and maintaining mangrove forests in suitable areas to supply mangrove branches. Allowing control harvest of mangrove branches from natural forests with regular monitoring by the government authorities, including Department of Forest Conservation. Demarcating areas to install brush parks and controlling access to those areas. Formation of brush park fisher societies that support intercommunity communication to facilitate sustainable use of resources. Introduction of a co-management system. Provide credit facilities with low interest rates from rural banks for the initial expenses such as purchasing of encircling net and canoe for brush park fishery. Further funding for mangrove replantation in suitable areas in the estuary in collaboration with Government authorities and NGOs.

Conflict between other fishing and recreational activities

Destruction of mangrove habitats and regulations enforced by the government to conserve mangrove forests Community issues

Financial issues

estuary, fish species are attracted to brush parks depending on their morphological correlates with diets (Gammanpila et al., 2017) and as such, low harvests in brush parks installed for a longer (> 35 days) period may be attributed to equilibrium of the fish community attracted and relinquishment of some fish species with time. Although high yields were evident in brush parks with high branch density (> 2 kg m−3), majority of fishers constructed brush parks with low (≤2 kg m−3) branch density. The major reason for this is the scarcity of mangrove branches in the surrounding areas as a result of accelerated mangrove deforestation, which is associated with various economic activities. Mangroves are subjected to severe human pressure and are destroyed either directly, or indirectly due to anthropogenic alteration of habitat conditions (Amarasinghe and Perera, 2017). In brush park fisheries in West African coastal lagoons (Dahomey and Nigeria) positive relationship of branch density with the harvest was recorded (Welcomme, 1972; Ahmed, 2015). A significant positive linear relationship between the abundance of native species and the abundance of large woody debris was also observed in Murray-Darling Basin, Australia (Nicol et al., 2004). Fishers' knowledge about attraction of high valued crustaceans to brush parks with low branch density may have also motivated fishers to use low branch density in majority of brush parks. Opinions expressed by members of fishing community about the institutional robustness of community-based management in the brush

come with responsibilities. Brush park fishers believe that selective cutting of mangrove branches improved their regeneration. The rotational cutting of mangrove branches and silviculture practices in brush park fishing communities are major features of customary rights of this indigenous management system (Amarasinghe et al., 2002), comprising responsibilities for mangrove conservation. It is also evident from the present study that brush park fishers informally organize and make decisions on fishing season, sites for installing brush parks, fishing operations, target fish species and resource management. Brush park fishers strongly believed that the harvests are related to the mangrove species, density of branches and period of time between installation and harvesting. For example, fish species of ornamental value such as Scatophagus argus and Monodactylus argenteus are known to be caught in brush parks with more branches of Lumnitzera sp., while mangrove branches with leaves are used to target shrimp. According to fishers' knowledge, high valued fin fish species (Caranx sp., Lutjanus sp. Epinephelus sp. Lates calcarifer and crustaceans) probably leave the brush parks if they are not harvested within around 35 days after installation. Present study also indicated that the mean yield of brush parks harvested within 35 days of installation was significantly higher than those harvested after leaving for a longer (> 35 days) period. Significant positive relationship between time period from installation to harvesting and fish yield is reported in acadjas in Lagos lagoon, Nigeria also (Solarin and Udolisa, 1993). In Negombo 155

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park fishery varied widely as shown by broad ranges of scores of the psychometric analysis (i.e., Likert scale) employed in the present study. Of the 11 Ostrom's modified design principles, only three (i.e., congruence between appropriation and provision, monitoring of users and monitoring of resources) had the mean score of 4 representing high compliance. Interestingly, all these three design principles are related to jealousy and selfishness to increase individual benefits. The design principle of collective-choice arrangements had moderate compliance in the fishing community. As the brush park fishing in Negombo estuary passes through generations, entrance of non-appropriators is negligible. Four design principles (i.e., congruence with local conditions, conflictresolution mechanisms, minimal recognition of rights to organize, and multi-level of institutional structure) had low compliance in the brush park fishing community indicating the need for intervention of a centralized management unit. The design principles of the lowest compliance in the fishing community were those related to clearly defined user boundaries, clearly defined resource boundaries and graduated sanctions. These three design principles are pertinent to open access property regimes. However, in brush park fisheries, fishing sites are confined to shallow waters, and resource boundaries are not found because the fishery relies on the fish attracted to brush parks. In the brush park fishery, there is no time allocation for fishers, and generally, fishing would be taking place from around 04 00 a.m. to 08 00 a.m. enabling fishers to sell their harvest at the local markets during morning hours. From the present study, it is evident that the institutional structure in the brush park fishery of Negombo estuary is rather weak, and does not conform to the benchmarks set by Ostrom (1990) and Cox et al. (2010), which may be one of the reasons for this fishery to be dwindling. The uncertainty of institutions in a society can be reduced by imposing formal and informal rules (North, 1990). For improvement of the current situation in the brush park fishery, robust participation of the centralized management authorities is needed (Table 3). The vertical integration involves graduated sanctioning following the law of the country. However, enforcement of formal rules should be carefully done considering needs and aspirations of resource users. Five mangrove islands in the northern part of the estuary have been declared as conservation forests under the forest ordinance (Anon., 2002), which had created disputes between centralized management institutions and resource users. The relationship between fisher communities and central government authorities is an important cost effective mechanism to avoid illegal fishing, poaching and disturbance from other fishing and commercial activities. As there are many fishing activities in the Negombo estuary (Jayakody, 1996), inevitably there are apparent user conflicts between brush park fishery and other fishing activities. Some concerns include that brush parks hinder navigation of fishing crafts in the estuary, affect migration of fish species and reduce space in the estuary for other fishing operations. However, as can be seen from Fig. 1, this fishing activity is restricted to shallow peripheral areas of the estuary. Nearly 74% of brush park fishers believed that the major threat to their fishery was the disturbance of fish movement caused by other fishers due to the nature of their fishing practices. Moreover, disturbances due to recreational activities such as water sport, boat rides, etc. also affect the attraction of fish to brush shelters resulting in lower harvest. Establishment and demarcation of recreational areas to minimize the impact on the fisheries in the estuary and regular monitoring by the relevant government authorities are therefore essential. These issues can be resolved by preparing a zoning plan for different fishing activities through governmental intervention with community participation. Such an intervention is feasible because many fishing activities in the estuary are restricted to specific locations. Co-management provides much attraction and potential for transitioning toward sustainability and achieving social and ecological benefits to the resource users (Friedlander et al., 2013). It generally involves shared management authority and responsibility between

resource users and the government (Hanna, 1998; Berkes, 2010; Cinner et al., 2012). As such, co-management regimes that empower local communities to make management decisions are essentially needed to be implemented for sustainability of the brush fishery and exploitation of allied resources in Negombo estuary. 5. Conclusion The degree of community-based fisheries management that exists in the brush park fishery of Negombo estuary is not sufficient for governance of the dilemma of CPR. The community rights and institutional structure of brush park fishers are not strong enough to make responsible fisheries management. However, due to the existence of TEK and some compliance with institutional design principles, there is potential for integrating some institutional design principles through intervention of centralized management authorities. Therefore, co-management using scientific knowledge and TEK, with the participation of law enforcement agencies and other stakeholders is essential for successful management of this fishery resource. Acknowledgements This study was funded by National Aquatic Resources, Research and Development Agency, Sri Lanka. We are thankful to Messrs. W.A. Sumanadasa and A.M.S. Pushpananda for their assistance in field work. The authors sincerely appreciate cooperation of brush park fishers in the Negombo estuary during field studies. We also wish to thank Mr. R.P.K.C. Rajapakse, Department of Zoology and Environmental Management, University of Kelaniya for the technical support provided in preparing the manuscript. Appendix A. Supplementary data Supplementary data to this article can be found online at https:// doi.org/10.1016/j.ocecoaman.2018.10.008. References Ahmed, G., 2015. A comparative study of the profitability of brush parks in two states in Nigeria. Int. J. Fish. Aquacult. 7 (10), 160–166. https://doi.org/10.5897/IJFA15. 0512. Amarasinghe, M.D., Balasubramaniam, S., 1992. Structural properties of two types of mangrove stands on the north-western coast of Sri Lanka. Hydrobiologia 247, 17–27. https://doi.org/10.1007/BF00008201. Amarasinghe, M.D., Perera, K.A.R.S., 2017. Ecological biogeography of mangroves in Sri Lanka. Ceylon J. Sci. 46, 119–125. http://doi.org/10.4038/cjs.v46i5.7459. Amarasinghe, O., Bavinck, M., 2011. Building resilience: fisheries cooperatives in southern Sri Lanka. In: Jentoft, S., Eide, A. (Eds.), Poverty Mosaics: Realities and Prospects in Small-scale Fisheries. Springer, Dordrecht, The Netherlands, pp. 383–406. Amarasinghe, U.S., Chandrasekara, W.U., Kithsiri, H.M.P., 1997. Traditional practices for resource sharing in an artisanal fishery of a Sri Lankan estuary. Asian Fish. Sci. 9, 311–323. Amarasinghe, U.S., Amarasinghe, M.D., Nissanka, C., 2002. Investigation of the Negombo estuary (Sri Lanka) brush park fishery, with an emphasis on community - based management. Fish. Manag. Ecol. 9 (1), 41–56. https://doi.org/10.1046/j.1365-2400. 2002.00250.x. Anis, M.U.M., Ellepola, G., Ranawana, K.B., 2015. Brush park fishery targeting ornamental fish in Negombo estuary, Sri Lanka. Int. J. Fish. Aquat. Stud. 2 (4), 378–381. Anon, 2002. Forest Ordinance, Regulation No. 1258/3, the Gazette of Sri Lanka (Extraordinary) of 14th October 2002. Colombo, Sri Lanka. Arnason, R., 2003. Community and cooperative fisheries management: possible application to Mediterranean fisheries. In: Spagnolo, M. (Ed.), Conference on Fisheries Management and Multi-level Decision Systems: the Mediterranean Case. IREPA, Salerno. Atapattu, A.R., 1987. Territorial use rights in fisheries (TURFs) in Sri Lanka. Case study on Jakottu fisheries in the Madu ganga estuary and kattudel fishery in the Negombo lagoon. In: Symposium on Exploitation and Management of Marine Fishery Resources in South Asia. 10. Indo-Pacific Fisheries Commission, pp. 397–410 RAPA Report. Basurto, X., Virdin, J., Smith, H., Juskus, R., 2017. Strengthening Governance of Smallscale Fisheries: an Initial Assessment of Theory and Practice. Oak Foundation. www. oakfnd.org/environment. Béné, C., Obirih-Opareh, N., 2009. Social and economic impacts of agricultural productivity intensification: the case of brush park fisheries in Lake Volta. Agric. Syst.

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