Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania

Special Issue (Article)／特集（論文） Exploitation and Conservation of Middle East Tree Resources in the Oil Era

NAKAMURA Ryo

Ⅰ . Introduction Ⅱ . Maritime Environments and Life on Kilwa Island Ⅲ . Three Ecological Sea Zones of Kilwa Island Ⅳ . The Mangrove Inland Sea and the Kilwa Kingdom Ⅴ . Direct and Environmental Uses of Mangroves Ⅵ . Conclusions: The Importance of Mangroves in Past, Present, and Future Maritime Life

スワヒリ海岸南部タンザニア・キルワ島におけるマングローブ資源の直接利用と環境利用

中村亮

東アフリカのスワヒリ海岸はアフリカでも有数のマングローブ面積を保有する地域である。ここのマングローブは、紀元前よりのインド洋交易をつうじて、木材資源が少ない

215 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) アラブ・ペルシャ地域へ建築材として輸出されてきた歴史背景をもつ。スワヒリ海岸のなかでも、タンザニア南部のルフィジ川流域とキルワ沿岸部は、国内のマングローブ面積の 64%(69,785ha)を保有する海資源の豊かな地域である[Wang et al. 2002]。本論文の目的は、タンザニア南部のキルワ島を事例に、住民によるマングローブ資源利用の現状について、「直接利用」と「環境利用」にわけてその多面的利用法を解明することと、居住空間と資源が限定されている海村社会（とくに島嶼部）におけるマングローブ資源の重要性を提示することである。キルワ島は中世のインド洋交易において金交易を独占することにより興隆した海洋イスラーム王国であったが、現在は 1000 人弱の住民が、マングローブとサンゴ礁に囲まれた海で主に半漁半農の生業形態でくらす小海村である。キルワ島は、島と大陸との間のマングローブに囲まれた内海と、インド洋に面してサンゴ礁が発達した外海という、自然環境が対照的な二つの海をもつ。その海環境は、生態海域１：マングローブ内海、生態海域２：サンゴ礁をもつ外海、生態海域１と２の自然条件を兼ね備えた生態海域３(境海)、の三生態海域に分かれる。生態海域１に面する場所に、キルワ王国時代（10C半）から居住空間が歴史的に形成されてきた。ここは北モンスーンの影響を受けて、暑気に涼しくマラリア蚊の少ないことより居住空間として適しているばかりではなく、キルワ王国にとっては、外海から奥まった遠浅の海に面しているので、外敵からの防衛という点でも適していた。また、キルワ島の半数近くの漁場が生態海域１に集中しており（30/66）、かつ、全漁法の半数以上が生態海域１でおこなわれることより（23/41）、マングローブ環境が生業空間としても適していることがわかる。キルワ島には８種類のマングローブが自生している。その利用は、マングローブを建築材や燃料などとして使用する｢直接利用｣と、マングローブが作り出す環境を漁場や塩田として使用する｢環境利用｣に大別される。七通りの直接利用（建築材、船材、漁具材、燃料、薬、飼料、玩具）と五通りの環境利用（漁場、航路、塩田、養蜂、防波風林）が確認された。この二つの利用法の関係は、微妙なバランスの上に成り立っているといえる。マングローブの過度な伐採はマングローブ環境を壊してしまうし、マングローブ環境の保全のために伐採を禁止してしまうと、マングローブの直接利用に依拠した住民生活に支障をきたしてしまうからである。しかし現在までのところ、人びとがマングローブの重要性を伝統的な知識をつうじて理解しており、また、この地域の人口密度が少ないこともあって、キルワ島周辺のマングローブ資源は良く保全されているといえる。キルワ島におけるマングローブは、材料や生業空間としの重要性だけではなく、キルワ沿岸部の地域社会を形成する媒介の場所としての重要性ももっている。マングローブ内海には住民が日常的に移動する航路が網の目のように張り巡らされており、このマングローブ内海を媒介としてキルワ島周辺地域には、親族関係、友人関係、近距離交易などをつう

AJAMES no.26-1 2010 216 じた親密な地域関係が存在している。マングローブ資源が歴史的に果たしてきた役割、同時に、現在の住民によるマングローブ利用法をしっかりと認識することが、近年の沿岸部開発や観光化によって海環境への人的圧力が高まってきたタンザニア南部沿岸地域における、人と自然との持続可能な関係を模索するために必要不可欠である。

I. Introduction

1. Objectives The objectives of this paper are (1) to show how the people on Kilwa Island, located just off the southern Swahili Coast, Tanzania, make use of mangrove resources by analyzing the two ways in which they use them: directly as a material resource (direct use) and indirectly as an environment that sustains life (environmental use); and (2) to consider how harmonious coexistence between humans and the natural environment may be achieved and sustained in this maritime society with otherwise limited living space and resources. The multiple roles of the mangrove resources as materials, occupational spaces, and a medium for the formation of a regional society on Kilwa Island are clarified from the perspectives of direct and environmental uses. Kilwa Island was once an influential Islamic kingdom; in the Middle Ages, it was an international trading port, but it is now home to a small seashore village with fewer than a thousand habitants living an almost self-sufficient life, sustained by the surrounding seas with their mangroves and coral reefs. This small island population is currently in the midst of social changes arising from development, including maintenance of traffic infrastructure, restoration of the stone ruins of the old Kilwa Kingdom, conservation of the maritime environment, coastal development (oil drilling), and tourism. With such a changeable social situation, human pressure on the natural environment is increasing.

2. Studies on the Mangroves of the Swahili Coast The Swahili Coast stretches some 2,000 km from southern Somalia to northern Mozambique, including Madagascar and the Comoro Islands, and is home to one of the richest mangrove forests in Africa (total mapped mangrove area, about

217 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) 1,143,200 ha) [Taylor, Ravilious and Green 2003]. Mangroves are salt-tolerant forest or swamp ecosystems that occur along tropical and subtropical coastlines [Wang et al. 2002: 36]. Small mangrove colonies are also found along arid coastlines in regions including the Red Sea and the Persian Gulf [ISME 1997]. Studies on the mangroves of the Swahili Coast have emphasized the historical use of mangroves as a trading item in the Indian Ocean trade with the Arab states. Gilbert [2004], for example, addressed the mangrove pole trade in the Indian Ocean for the case of Zanzibar Island, Tanzania. However, fewer studies have examined the current daily use of mangroves by the people live in Swahili maritime societies, although a brief explanation is given in A Field Guide to the Seashores of Eastern Africa and the Western Indian Ocean Island [Richmond 2002: 26-30]. Local mangrove use, such as the direct use for building and shipbuilding materials, firewood, and charcoal making, is often used as an example of overexploitation. However, local people also recognize the value of the mangrove environment as a fishing ground and fish-breeding forest. Do these people nevertheless continue to log mangroves to the point of environmental disruption? Using the case of Kilwa Island, this study demonstrates that the range of daily mangrove usage by the local people does not disrupt the mangrove environment. Rather, problems arise from illegal logging by outsiders and large-scale development and exploitation by salt panning and prawn farming enterprises. Before planning and carrying out conservation, we must first understand the historical significance of mangroves and how the local people sustainably use mangrove resources. Mangroves also serve a crucial purpose as they are a medium of community formation in the region. The early Swahili trading ports of Kilwa, Songo Mnara, Pate, Lamu, and Mombasa were established on islands in mangrove-covered inland seas where the calm conditions were suitable for embarkation ports. The current Swahili maritime societies formed regional societies linked through these safe sea transportation routes.

3. Mangroves in Tanzania The Swahili Coast and the Arabian/Persian regions, which are separated by about 4,000 km, have been connected by Indian Ocean trade for over a thousand years. As a building material, mangrove wood had, by the mid-nineteenth century, become the single most important cargo carried via the Indian Ocean trade to dry

AJAMES no.26-1 2010 218 Arabian/Persian regions that lacked tree resources [Curtin 1981; Gilbert 2004]. This historical mangrove trade destroyed vast mangrove areas along the Swahili Coast. For example, Pemba Island, located off the shore of Tanzania, was once called Green Island (Al Jazeera Al Khadra) because of the richness of its mangroves, but now little of its mangrove area remains. Population growth in Tanzania has also impacted the mangroves. For example, the Michamvi area of Zanzibar had about 800 ha of mangroves in 1949, but only 43 ha in 1989; the Maruhubi area had 1,040 ha in 1949 and 76.5 ha in 1989 [Taylor, Ravilious and Green 2003: 17]. In recent years, the Tanzanian mangrove forest has been well preserved; a report titled Remote Sensing of Mangrove Change along the Tanzania Coast indicated that the area covered with mangroves in Tanzania remained nearly unchanged between 1990 and 2000, encompassing 109,593 ha in 1990 and 108,138 ha in 2000 [Wang et al. 2002: 43]. The southern coastal districts of Tanzania around Rufiji (48,030 ha), which has the largest single mangrove forest in eastern Africa, and Kilwa (21,755 ha) made up about 64% of the domestic mangrove area in 2000 [Wang et al. 2002: 43]. Based on the author’s field studies(1) , this paper describes the mangrove use in the Kilwa coastal regions, especially on Kilwa Island (Kilwa Kisiwani), Kilwa District, Lindi (Wilaya ya Kilwa, Mkoa wa Lind), Tanzania.

II. Maritime Environments and Life on Kilwa Island

Kilwa Island is a small lagoon island off the southern Swahili Coast of Tanzania. It is 12 km² in area and 23 km in circumference. Situated at the mouth of three rivers (the Mavuji, Msekela, and Gongo rivers), the island is surrounded by two contrasting seas: an inland sea (lagoon) covered with mangroves and the open sea fringed with coral reefs (Figure 1). Kilwa Island is located at 9 degrees south latitude and is included in the East African monsoon area, with high winds all year long. Isolated about 300 km from the nearest metropolitan areas in Tanzania (Dar es Salaam in the north and Mtwara in the south) because of bad road conditions, the island is almost completely cut off from modern economic development. According to Tanzania’s 2002 population and housing census, the population density in the Lindi region is the lowest in the

219 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) Figure 1 Natural Environments in the Kilwa Coastal Region

Mavuji riv. S market ٨

S Kilwa Masoko mangrove tideland fringing reef ٨ harbor Luayo S salt pan

S harbor ٨ village 0 1 2 3 km Kilwa Island

Indian Ocean

Mgongo S9°00’

Sangarungu sea

Msekera riv. Sanje ya kati

Nisasu sea Songo Mnara

Pwani Creak

Pande region N Gongo riv.

(Source) Made by the author based on Nakamura [2007b: 51].

AJAMES no.26-1 2010 220 country at only 12 people/km² (cf. 1,793 people/km² in Dar es Salaam, the biggest city in Tanzania) [The United Republic of Tanzania 2003: 6-7]. The climate of the Kilwa region is tropical savanna, with about 1,000 mm rainfall per annum. It has two rainy seasons and two dry seasons. Thanks to the comparatively rich rainfall, most families have fields and cultivate maize, cassavas, rice, lady’s fingers, peanuts, cashew nuts, and so on. But as each family’s field is less than one ha, almost all products are for self-consumption. Fishing activities provide the main source of income. Fishermen use small wooden canoes called mtumbwi and traditional wooden crafts called dau, which are plank-structured boats with keels and Latin sails. Nowadays, Kilwa Island is populated by a small seashore village, whose inhabitants subsist on an almost self-sufficient economy, which is sustained mainly by fishing, gathering sea products from the surrounding seas, and some cultivation. Yet, in the Middle Ages, the island flourished as an influential Islamic trading port known as the Kilwa Kingdom. The Kilwa Chronicle, a local sixteenth- century Arabic text, stated that the Kilwa Kingdom was founded in the middle of the tenth century by Ali bin al-Hassan when he and his followers migrated there from Shiraz in Persia (Iran) [Sutton 2000: 6-7]. Ibn Baṭṭūṭa, a Moroccan Muslim traveler who visited the Kilwa Kingdom in the fourteenth century, wrote, “Kilwa is one of the most beautiful and well-constructed towns in the world” [Ibn Baṭṭūṭa 1998(1964); Davidson 1991: 142-143]. Many stone buildings of the Kilwa Kingdom era remain and were classified as an UNESCO world cultural heritage site in 1981 [Nakamura 2006]. Recently, attention has been given to the ruins on Kilwa Island and the neighboring islands of Songo Mnara and Sanje ya Kati as a tourism resource [Kamamba 2001; Moon 2005].

III. Three Ecological Sea Zones of Kilwa Island

Kilwa Island is surrounded by two distinct seas: an inland sea covered with mangroves (Mangrove inland see) and the open sea fringed with coral reefs. The island’s maritime environments can be divided into three ecological sea zones or ecozones (Figure 2) [Nakamura 2007b]. Ecozone 1 includes the inland sea covered with mangroves that extends

221 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) Figure 2 Ecological Sea Zones of Kilwa Island

mangrove Kilwa Masoko tideland fringing reef village

Ecozone 3

Indian Ocean Kilwa Is. Ecozone 2

Ecozone 1

Mainland

(Source) Made by the author based on Nakamura [2007b: 52].

AJAMES no.26-1 2010 222 approximately a kilometer width between Kilwa Island and the mainland and the mangrove forest. The water here is brackish, shallow, and calm, with little wind or wave activity. The seafloor in this zone is composed mainly of mud and some seagrass beds. The main sea products here are small- and medium-sized fish (e.g., Lutjanus fulviflamma, Diagramma pictum, and Aetobatus narinari), prawns (Fenneropenaeus indicus), mangrove crabs (Scylla spp.), sea cucumbers (e.g., Holothuria scabra, Stichopus spp., Bohadschia atra, and Colochirus quadrangularis), and seashells (of Anadara erythraeonensis). Ecozone 2 is the open sea fringed with coral reefs that face the Indian Ocean. This zone is characterized by deep water, rough waves, and strong winds influenced by the monsoons and the East African Coastal Current. The seafloor in this zone is mainly composed of coral and sand. The main sea products are large migratory fishes (e.g., Thunnus albacares , Rachycentron canadum (Linnaeus), Makaira indica), large benthic fishes (e.g., Scarus sordidus, Leptoscarus vaigiensis), lobsters (Panulirus ornatus, Panulirus homarus), octopus (Octopus cyanea), and sea cucumbers (e.g., Bohadschia vitiensis, Actinopyga mauritiana, Holothuria nobilis, and Thelenota anax). Ecozone 3 is the intermediate region between the inland and open seas. This zone is characterized by a combination of the qualities seen in ecozones 1 and 2, i.e., it has both mangroves and coral reefs. Except for sea cucumbers, the sea products in ecozones 1 and 2 are also present in this zone. The island’s inhabitants have a well-developed maritime life in each of these three ecozones—particularly ecozone 1, the inland sea covered with mangrove (the mangrove inland sea(2)).

IV. The Mangrove Inland Sea and the Kilwa Kingdom

1. Stone Ruins of the Kilwa Kingdom The heritage of the Kilwa Kingdom is plentiful. It is not limited to the stone ruins, but rather includes a legacy of Islam (religious heritage), influences of the Swahili language cosmopolitan identity, and the now almost destroyed ethnic identity. This section mainly deals with the relationship between the maritime environments and the location of stone ruins on Kilwa Island. The ruins consist of

223 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) Figure 3 Distribution of Stone Ruins on Kilwa Island

N Kilwa Is.

Ԛ Gereza Mangrove ԞMalindi Msikitiiti Ԥ Makaburi ya Malindi Ԙ Msikititi kubwakb Husuni kubwa ԙ ԟ Greata house Ԣ ԛ Husuni ndogog Makutani Ԝ Msikiti ndogo

Ԡ Jangwani Msikiti

ԝ Makaburi ya Shirazi stone ruin Jangwani ԡ Makaburi ya mashehe arubaini mangrove ԣ Makaburi ya Sake tideland foot route

0 100 200 300 400 m

(Source) Made by the author based on Chittick [1974]; Nakamura [2006: 320]. six mosques: Msikiti kubwa (11 c.), Husuni ndogo (fortress, mosque, or caravanserai, 14 c.), Msikiti ndogo (15 c.), Jangwani msikiti (15 c.), Malindi msikiti (15 c.), Mvinje msikiti (15 c.); three palaces or houses: Husuni kubwa (14 c.), Great house (14–15 c.), Makutani (15–18 c.); four cemeteries of Arabian/Persian origin: Makaburi ya Shirazi (16–18 c.), Makaburi ya Malindi (18 c.), Makaburi ya mashehe arubaini (18 c.), Sake (13 c.); and a fortress of Portuguese origin: Gereza (16 c.) [Chittick 1974; Nakamura 2006].

2. Distribution of the Stone Ruins The stone ruins of the Kilwa Kingdom are distributed among three regions (Figure 3): 1) around the village: 1. Msikiti kubwa; 3. Gereza; 4. Makutani; 5. Msikiti ndogo; 7. Malindi Msikiti; 8. Great house; 9. Jangwani Msikiti; and 13. Makaburi ya Malindi 2) in the bush: 6. Makaburi ya Shirazi; 10. Makaburi ya mashehe arubaini; and 12. Makaburi ya Sake 3) on a small hill approximately two km from the village: 2. Husuni kubwa and 11. Husuni ndogo The location of Msikiti kubwa is important as it was the mosque where the

AJAMES no.26-1 2010 224 inhabitants came to worship every Friday. It may be supposed that the inhabitants of the Kilwa Kingdom resided around the Msikiti kubwa, near the mangrove inland sea. This northwest side of Kilwa Island, which faces the mangrove inland sea, is the most satisfactory place to live on Kilwa Island because of the region’s relative coolness and low prevalence of malaria mosquitoes in the summer season (November to April) due to the northern monsoon wind (kaskazi). Many wells providing good- quality water are to be found here. Villages on other islands off the Swahili Coast, such as Pare, Lamu, Mombasa (in Kenya), and Ibo (in Mozambique), also tend to be situated on the northeastern side, near the mangrove inland sea. In addition to the abovementioned benefits, because of the shallow sea, this site also enabled inhabitants of the Kilwa Kingdom to defend themselves against enemies coming across the Indian Ocean in big boats. At low tide, large mud-floored tidelands appear, and there is a great range of tides along the Kilwa coastal region, about 3.4 m on an average [Tanzania Harbours Authority 2003]. Therefore, big boats with keel structures would have found it hard to directly enter the shallow harbor of the Kilwa Kingdom. That is why the sultan’s palace—Makutani—was located at the innermost place from the open sea. The main residential area of the Kilwa Kingdom appears to have been formed near the mangrove inland sea, which was the most satisfactory place for living and for defense against enemies. The present village is also situated there; thus, people on Kilwa Island have lived close to the mangrove inland sea for a long time.

V. Direct and Environmental Uses of Mangroves

Eight species of mangroves are found in mainland Tanzania: Rhizophora mucronata (mkoko), Bruguiera gymnorrhiza (mshinzi), Ceriops tagal (mkandaa), Avicennia marina (mchu), Heritiera littoralis (mkungu), Lumnitzera racemosa (mkandaa dume), Sonneratia alba, (mpira or mliana), and Xylocarpus granatum (mkomafi); all of these species are present in the Kilwa region(3). Maritime life in Kilwa has developed using the mangrove resources in many ways. This section describes mangrove use on Kilwa Island by analyzing two types of mangrove use: direct use and environmental use.

225 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) 1. Direct Use of Mangroves Direct use of mangroves refers to the use of mangrove timbers, poles, branches, roots, leaves, and seeds. Seven kinds of direct use(4) can be observed in the local population: 1) House-building materials: poles 2) Boat-building materials: timber, poles, and branches 3) Fishing-gear materials: poles and roots (aerial roots of Sonneratia alba are used for net floats) 4) Firewood for cooking and lime burning: branches 5) Medicine for stomachache: seeds of Xylocarpus granatum 6) Fodder for goats and sheep in the dry season (rare cases): leaves 7) Toys: children make tops using the seeds of Sonneratia alba and boat figures using the aerial roots of the same species. This section gives examples of direct use of mangroves for house and boat building.

(1) House-building Materials Standard mud houses (nyumba ya udongo) on Kilwa Island are built using mangrove poles in the framework for the walls and as the beams of ceilings (Figure 4). Because some mangrove species contain tannin (e.g., Rhizophora and Bruguiera), they are resistant to worms and are thus recognized as a good building material by local people. To cut poles, people must pay a license fee to the Mangrove Office (ofisi ya mkoko) in Kilwa Masoko (a prefectural administration office in Kilwa). Staff members of the Mangrove Office manage mangrove logging. More than 700 mangrove poles are needed to build a house with three or four rooms. The poles have different names depending on their diameter: nguso kubwa or vigingi (16.5–20 cm), nguso (14–16.5 cm), boriti (11.5–14 cm), mazio (7.5 –11.5 cm), pau (3.8–7.5 cm), and fitto (under 3.8 cm). A mangrove pole used for the framework of walls is a pau and that used for the beams of ceilings is a boriti. Boriti were among the main trading goods for Swahili trading ports to trade with Arab regions in the past, and they remain such today. In the era when trade across the Indian Ocean was most prolific, many boriti were cut down. One report says that the mangrove area of the Swahili coast was reduced by half. Serious damage was caused by logging on the northern Swahili coast, but the mangroves on the southern Swahili

AJAMES no.26-1 2010 226 Figure 4 Mangrove Use for House-building Materials on Kilwa Island

(Source) Taken by the author in 2005

coast, including those in the Kilwa region, were comparatively untouched. The beams of the stone buildings of the Kilwa Kingdom era are still supporting the massive coral-rag walls well. Many mangrove beams can be seen in the Makutani palace, which was built in the fifteenth century.

(2) Boat-building Materials Boats, one of the most important tools of maritime life, are built using mangroves in the Kilwa coastal region. Seven kinds of boat are in use there [Nakamura 2007a]: 1) Dugout canoe (mtumbwi) 2) Double-outrigger canoe (ngalawa): not in use on Kilwa Island but used on Songo Mnara Island, about five km to the south 3) Boat for fishing lamps or dinghy (dingi): not in use on Kilwa Island but used on Kilwa Kivinje, about 40 km to the north 4) Flat-bottomed boat (mbare) 5) Plank-structured boat with a keel (dau) 6) Plank-structured boat with a keel and bowsprit (mashua) 7) Plank-structured boat with a keel and out-engine (boti)

227 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) Of these types of boats, mbare, dau, and mashua and sometimes boti are built using mangrove materials for the mast, keel, ribs, bowsprit, beam, and so on. Poles, paddles, and oars are also made with mangrove materials. Depending on the characteristics of each mangrove species, the parts used for boat building differ (Table 1). For example, Bruguiera gymnorrhiza (mshinzi) is recognized as the strongest tree on Kilwa Island and is used for parts that need the most strength such as the keel, mast, and ribs. On the other hand, Lumnitzera racemosa (mkandaa dume) and Heritiera littroralis (mkungu) are rarely used for boat building because of their soft and heavy nature. Local people, especially boat builders (fundi) and fishermen (wavuvi), possess knowledge of the differences among the varieties of mangroves and their relative merits.

Table 1 Mangrove Use for Boat building depends on the Strength of Mangrove Local name Scientific name Strength Part mshinzi Bruguiera gymnorrhiza +++ keel, mast, and ribs mkoko Rhizophora mucronata ++ ribs, mast, and beam mkandaa Ceriops tagal ++ ribs and mast mpira Sonneratia alba + bowsprit, ribs, mast, keel, and beam mkomafi Xylocarpus granatum － ribs mchu Avicennia marina － ribs mkandaa dume Lumnitzera racemosa －－ none mkungu Heritiera littoralis －－ none (Note) + means strong, － means weak. (Source) Made by the author on the basis of field research.

2. Environmental Use of Mangroves Environmental use of mangroves refers to the use of the natural environment of the mangrove inland sea, which is calm, shallow, and rich in sea products. Five uses of the mangrove environment(5) have been observed: 1) Fishing grounds 2) Sea transportation routes 3) Salt panning: in the tideland between the mangroves and the mainland using the process of solar evaporation 4) Beekeeping grounds: beehives are kept to collect honey in the mangrove forests. Inside of the forest is cool, dark, and with mangrove flowers

AJAMES no.26-1 2010 228 Figure 5 Distribution of Fishing Grounds on Kilwa Island

mangrove Kilwa Masoko tideland fringing reef

㧥 Ԙ࡯ fishing ground ٨ Ecozone 3 Ԥ Ԙ 㧞 ԥ Village Ԛ Ԧ ԧ Kilwa Is. Ԩ Ecozone 2 㧠 Ecozone 1 Ԝ Ԫ 㧢

Ԟ 5q̉

㧤 N MO

(Note) The numbers used for the fishing grounds correspond to those used in figure 6. (Source) Made by the author based on Nakamura [2008a: 40].

229 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) 5) Wind- and wave-breaks: mangroves grow in a belt along the shore and protect the shore from wind- and wave-based soil erosion This section gives examples of the environmental uses of the mangrove areas as fishing grounds and sea transportation routes.

(1) Fishing Grounds Figure 5 shows the distribution of fishing grounds around Kilwa Island [Nakamura 2008a: 40](6). Of the total 66 fishing grounds, 30 (45%) are in ecozone 1, the mangrove inland sea. This inland sea contains many sea products, including small- and middle-sized fish, prawns, sea cucumbers, and mangrove crabs. The inland sea area that is covered with mangroves has good feeding, breeding, and nursery grounds for a large variety of invertebrates and fish and is thus an ideal fishing ground. Forty-one kinds of fishing methods are practiced on Kilwa Island [Nakamura 2008a: 29](7). Of these, 23 methods (56%) are practiced in ecozone 1, which includes the mangrove inland sea and the mangrove forests (Table 2). The fishery of Kilwa Island is well adapted to the mangrove environments. Fishermen are aware of the natural characteristics of the fishing grounds in the mangrove inland sea, for example, their depth, floor quality (Figure 6), catches, and tidal level. In the shallow and calm mangrove inland sea, it is possible to fish with a small boat or on foot. Here, fishermen engage in gathering-based fishing practices, including shellfish gathering, gathering and diving for mangrove crabs and sea cucumbers, four kinds of fish-fence fishing (wando wa miti, wando wa nyavu, dufu, and uriro), and three kinds of fish-basket fishing (dema ya kutosa, kufinga, and kugongea). The natural conditions of the mangrove inland sea provide many opportunities for participation in fishing activities, even for those without expensive fishing gear such as nets or boats. The mangrove inland sea seems to have been an important and traditional occupational space on Kilwa Island since a long time.

(2) Sea Transportation Routes Because the mangrove inland sea is shallow and calm, people use it as a safe sea route to connect villages in the Kilwa coastal region. It is rare to use the open sea as a transportation route for daily movements. During high tide, big boats with keel structures such as dau, mashua, or boti

AJAMES no.26-1 2010 230 Table 2 Fishing Methods practiced in Mangrove Environments Fishing methods Local name English name Misadaka Gillnet (middle size) Nyavu za kupigia Gillnet (pressure with a stick) Juya Seine net (large size) Nyavu za kavogo Seine net (small/middle size) Net Nyavu za kokoro Ring net Kinyia Cast net Msembwe Ring net (pressure) Nyavu za tandiyo Scoop net Mshipi Hand line fishing Urimasi Hand line fishing (from sea shore) Fishhook Matozi Long line Kocho Angling (fixed with poles) Wando wa miti Fish fence (wood) Wando wa nyavu Fish fence (wood and net) Dufu Fish fence (wood and canoe) Uriro Fish fence (coconut fibers) Dema ya kutosa Fish basket (large size, sinker) Dema ya kufinga Fish basket (intermediate size, fixed Gathering at sea shore) Dema ya kugongea Fish basket (small size, long line) Kuzamia jongoo maji Sea cucumber diving Kuokota kombe Shellfish gathering Ugonyo Fish pod Kaa Mangrove crab gathering (Source) Made by the author on the basis of field research.

are used as regular ferryboats between Kilwa Masoko harbor and Mutandura harbor in the Pande region. Small boats such as mtumbwi or mbare also come and go frequently via the mangrove inland sea route (Figure 7). People travel and commodities and local specialty products are exchanged via these mangrove inland sea routes. The network set up in the mangrove inland sea connects the villages along the Kilwa coastal region and contributes to the formation of the local community there. For example(8), of the 101 married women on Kilwa Island, about 63% came from the neighboring regions, including 35% from the Pande region, 5% from the Mavuji region, 3% each from the Kilwa Masoko and Mgongo

231 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) Figure 6 Depth and Floor Quality of the Fishing Grounds

Depth (pima) floor No. Fishing ground sea 10 20 30 40 50 60 70 80 mud sand grass rock coral 1 Kisukutini Ũũ 2 Maji ya Buni ũ Ũ 3 Ruvula ũ 4 Kikomboo ũ Ũ 5 Kisanga Shululu ũŨ 6 Rasi kwa Habasi ũ Ũ 7 Mariamu ũŨţ 8 Jashi Pwani ũ 9 Sikitiko ũ 10 Jito Mikunga Ũ ũ 11 Kwa Chuki ũŨ

12 Mtimbini ũ Inland sea 13 Tobweni ũŨ 14 Mambo Leo ũ Ũ 15 Selenge ũŨ 16 Vungwi ũ Ũ 17 Faki ũţŨ 18 Habasi ũ ţ Ũ 19 Ujajia kati ũŨ 20 Ujiajia kubwa ũ Ũ 21 Kipama Kikubwa ũ 22 Kipama Kidogo ũ 23 Tumbawe Ũũ 24 Mponda ũ 25 Mgongo ũŨţ 26 Kikaango ũ Ũ 27 Mikumbi ũŨ 28 Mtoni ũ 29 Matekete ũŨ 30 Msekera ũ 31 Minazi Mingi ũ 32 Boyani namba 3 ũ 33 Mkoko mmoja ũ 34 Boyani namba 2 ũ 35 Luwanje ũ ũ 36 Rasini Ruwanje Open sea 37 Kipakoni ũ 38 Rasini Jiwe la Jahazi ũ Ũ 39 Mkurungangaja 150 ũ 40 Msanga Mula ũ 41 Ngururuni ũ 42 Msanga Mula rasini ũ 43 Bwejuu 200 ũ Ũ 44 Chani rasini ũ Ũ 45 Sangarungu ũ 46 Mtoni Msanga Mura ũ reef Fringing 47 Lindi Kuu ũ 48 Chani mtoni ũ Ũ 49 Fundi Husein ũŨ 50 Husuni ũ Ũ 51 Masakasa (ndogo, kubwa) ũŨţ 52 Ufunguo (ndogo, kubwa) ũ Ũ ţ Intermediate sea (north) 53 Nguruni ũŨţ 54 Kumsu ũ Ũ 55 Matuso ũŨ 56 Jimbiza ũ 57 Jomani ũ 58 Bandari Hutereza ũ 59 Boyani namba 1 ũŨ 60 Kwa Duka ũ 61 Bandari Huru ũ 62 Makuburi ũ 63 Kwa Nbonde ũ

64 Ruvulangwe Shani ũŨsouth 65 Kilangaza ũ Ũ 66 Bote ũŨ

(Notes) 1 pima is about 1.8 m. The numbers used for the fishing grounds correspond to those used in figure 5. (Source) Made by the author based on Nakamura [2008a: 41].

AJAMES no.26-1 2010 232 Figure 7 Mangrove Inland Sea Routes in the Kilwa Coastal Region

5 N Kilwa Masoko 5 0 1 2 3 km Masoko harbor Luayo

Village Kilwa Island Indian Ocean

Mgongo S9°00’ open sea route ferry route small boat route

Sanje Is.

Songo Mnara Is.

Mutandura harbor

Pande region

(Source) Made by the author based on Nakamura [2008a: 203].

233 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) regions, and an additional 3% from Songo Mnara Island. The kinship network of Kilwa Island is spread across the Kilwa coastal region due to the practice of inviting brides from other areas. This widely expanded kinship network in the Kilwa coastal region has been formed because of the use of the mangrove inland sea routes. In addition to the abovementioned factors, Kilwa coastal regional societies are strongly tied by other relationships, such as shared religion (Islam: Sunni, al-Shāfi‘ī), friendship(9), and short-range trade. This set of regional relationships helped in forming the Mangrove inland sea regional society.

3. Striking a Balance between Direct and Environmental Uses of Mangroves The relationship between direct and environmental uses of mangroves is delicately balanced. Immoderate mangrove pole logging destroys the environment, but prohibition of logging on conservation grounds leads to difficulties in the lives of the local people. Although the balance is tenuous, the mangrove environments in the Kilwa coastal region have not been destroyed by the local people’s daily use. This may be due to the low population density of the southern coastal regions, including Kilwa (12 people/km², Tanzanian census in 2002), and the stagnant economic conditions of the region. These two factors, which appear negative in terms of modern development, result in less pressure from human activity on the mangrove resources. Another key factor in the sustainable use of mangrove resources is that local people understand the importance of mangroves and possess valuable local knowledge about them; therefore, they treat mangroves with care. Recently, infrastructural and tourism developments in the Kilwa region have made good progress: UNESCO Tanzania, France, and Japan commenced restoration of the stone ruins on Kilwa Island in 2001; the infrastructure of overland roads has been maintained since 2000; a bridge spanning Rufiji River was completed in 2003; and offshore oil drilling started near the island in 2008. Moreover, the Tanzanian government plans to establish a national marine park to conserve maritime environments and develop tourism in the Kilwa coastal region(10) . Further studies and assessments of the coastal environments need to be carried out to ensure that both human and natural environments continue to coexist harmoniously, in the hope of conserving both the lifestyle of the local people and the maritime environments.

AJAMES no.26-1 2010 234 VI. Conclusions: The Importance of Mangroves in Past, Present, and Future Maritime Life

Kilwa Island has two seas: a mangrove inland sea and the open sea fringed with coral reefs. The maritime environments can be divided into three ecological sea zones, and the maritime life of Kilwa Island is well developed in all three of these ecozones. Ecozone 1, the inland sea covered with mangroves, is more important for the maritime life of Kilwa Island than ecozone 2. Both the present village and the remains of the former Kilwa Kingdom are situated near the mangrove inland sea. Fishing, travel, and short-distance trade are also well developed in and around the mangrove inland sea. In summary, mangroves benefit the people living on Kilwa Island by providing a source of materials, a suitable space for occupation, and a medium for the formation of regional societies. The mangroves are used directly for house building; for making fishing tools, boats, and other gear; and as fuel for cooking and lime burning. Thus, they are a very important resource for a maritime society where land and tree resources are limited. The mangrove inland sea provides both rich fishing grounds and safe sea transportation routes. The natural conditions of the mangrove inland sea provide opportunities for primitive forms of fishery such as gathering-based fishery on foot or with small boats. The mangrove inland sea provides many island inhabitants with opportunities to participate in fishing activity. Although the fishery here is a primitive one, the catches are varied and rich. More than half of the population’s fishing grounds are concentrated in this sea, and many fishing methods can be employed here. Mangroves have supported maritime life on Kilwa Island, as they form the basic natural environment. The mangrove inland sea provides not only fishing grounds but also sea transportation routes. Many local sea routes are spread across the mangrove inland sea, and the local community of the Kilwa coastal region is formed through the use of these sea routes. Based on shared Islamic values and relationships of reciprocity, exchange of products and information, and mutual help between relatives and friends, a regional society has been established in the Kilwa coastal region since, and possibly even before, the Kilwa Kingdom era. The mangrove resources provide countless benefits to the Kilwa Islanders.

235 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) Living space and natural resources of island are limited. However, thanks to the existence of mangroves, Kilwa Island has achieved a developed society—both as the Kilwa Kingdom in the Middle Ages and in the present time, where people live a rich maritime life. To ensure a sustainable future, consideration needs to be given to the appropriate management and use of mangrove resources, for example those used in, the use of natural resources on Kilwa Island, in order to cope with increasing human pressure on the maritime environment.

Notes

(1) The data used in this paper were obtained through field research conducted by the author between 2001 and 2009 in Tanzanian and Kenyan maritime societies, especially on Kilwa Island. (2) In this paper, I call the inland sea covered with mangroves as the mangrove inland sea. (3) In addition to the above species, Xylocarpus molluccensis is also found on Zanzibar Island [Masoud and Wild 2004: 281]. (4) Mangrove bark (of Rhizophora and Bruguiera) was an important trading item for the leather tanning industry in the Rufiji delta and Kilwa coastal region in the twentieth century [Gilbert 2004: 121-129]. (5) Mangrove environments also have potential as an ecotourism resource. Mangrove ecotours are already available at Chwaka Bay on Zanzibar Island, Tanzania [Masoud and Wild 2004]. (6) This figure was derived from interviews with local fishermen on Kilwa Island and direct observation. (7) These data are obtained from interviews with local fishermen on Kilwa Island. (8) These data are obtained from field interviews in 101 households; these interviews were conducted in 2005 by the author on Kilwa Island. (9) Friendships and fellowship among younger generations are formed through interregional soccer matches and groups (jando moja) formed for boys’ circumcision (jando) [Nakamura 2007c]. (10) In the case of the Mafia Island Marine Park (1991–to date), conflicts between residents and the government occurred during the process of implementing the conservation plan and setting aside protective marine zones [Walley 2004]. For conservation planning in the Kilwa coastal region, a thorough discussion of details between the local people and the government is necessary.

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AJAMES no.26-1 2010 238 ABSTRACT NAKAMURA Ryo Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania

The objectives of this paper are (1) to show how the people of Kilwa Island, located off the southern Swahili Coast, Tanzania, make use of mangrove resources by direct use and environmental use; and (2) to consider how a harmonious coexistence between humans and the natural environment might be achieved and sustained in this maritime society with otherwise limited living space and resources. The multiple roles of the mangrove resources as materials, occupational spaces, and a medium for the formation of regional societies on Kilwa Island are clarified from the perspectives of direct and environmental uses. Kilwa Island, once an influential Islamic kingdom, is now home to a small village. It is surrounded by two distinct seas: an inland sea with mangroves and the open sea fringed with coral reefs. Its maritime environments can be divided into three ecological sea zones. Ecozone 1 is the inland sea covered with mangroves. Ecozone 2 is the open sea that is fringed with coral reefs, and Ecozone 3 is the intermediate region between ecozones 1 and 2. Ecozone 1 is the most satisfactory place to live on Kilwa Island, and historically, its shallow seas enabled the inhabitants of the former Kilwa Kingdom to defend themselves against enemies from across the Indian Ocean. People on Kilwa Island have long lived close to the mangrove inland sea. Seven kinds of direct use (house-building materials, boat-building materials, fishing-gear materials, firewood, medicine, fodder, and toys) and five kinds of environmental use (fishing grounds, sea transportation routes, salt panning, beekeeping grounds, wind and wave breaks) are discussed in this paper. The relationship between direct and environmental uses is delicately balanced because immoderate mangrove pole logging destroys the environment, but prohibition of logging on conservation grounds leads to difficulties in the lives of the local people. Although the balance is tenuous, the mangrove environments in the Kilwa coastal region have not been destroyed by the local people’s daily use. This may be due to the low population density of the southern coastal regions, including Kilwa (12 people/km²), and the stagnant economic conditions of the region. Another key factor in the sustainable use of mangrove resources is that local people understand the importance of mangroves and possess valuable local knowledge about them; therefore, they treat mangroves with care.

239 Direct and Environmental Uses of Mangrove Resources on Kilwa Island, Southern Swahili Coast, Tanzania (Nakamura) The local community in the Kilwa coastal region has developed through the use of sea routes in the mangrove inland sea. Based on shared values of Islam and relationships of reciprocity, exchange of products and information, and mutual help between relatives and friends, a regional society has been established since, and possibly even before, the Kilwa Kingdom era. Mangrove resources provide countless benefits to members of the Swahili maritime society, whose living space and natural resources are limited. To ensure a sustainable future, consideration must be given to the historical meaning of mangroves on the Swahili Coast and the appropriate management and use of mangrove resources to cope with increasing human pressure on the maritime environment. Project Researcher, Research Institute for Humanity and Nature (RIHN) 総合地球環境学研究所プロジェクト研究員

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