MARINE DEBRIS IN NORTHERN TERRITORY WATERS 2004

Transcription

1 MARINE DEBRIS IN NORTHERN TERRITORY WATERS 2004 WWF-Australia March 2006

2 WWF-Australia. All Rights Reserved. ISBN: Author: Damian White WWF-Australia Head Office GPO Box 528 Sydney, NSW, Australia 2001 Tel: Fax: wwf.org.au Published March 2006 by WWF-Australia. Any reproduction in full or in part of this publication must mention the title and credit the above-mentioned publisher as the copyright owner. First published 2006 For bibliographic purposes, this report should be cited as White, D 2006 Marine Debris in Northern Territory Waters 2004: WWF Australia, WWF-Australia, Sydney. The opinions expressed in this publication are those of the author and do not necessarily reflect the views of WWF. Printed by Image Offset on FSC-certified paper. Cover image: WWF-Australia Anindilyakwa Land Council vehicle heavily loaded with Thai sorting trays and foreign gillnets, Six Mile Beach survey, For copies of this report, please contact WWF-Australia at publications@wwf.org.au or call World Wide Fund for Nature ABN: WWF-Australia 2

3 Table of Contents 1. EXECUTIVE SUMMARY 4 2. INTRODUCTION 5 3. SURVEY METHODS Beach surveys Net Kit reports 8 4. RESULTS Marine debris surveys 9 General debris 11 Derelict nets Net Kit reports DISCUSSION REFERENCES Personal communications APPENDICES 24 Appendix 1. Acknowledgements 24 IMCRA ZONE COBOURG 24 Cobourg Peninsula (Garig Gunak Barlu National Park) 24 IMCRA ZONE ARNHEM-WESSEL 24 Elcho Island 24 IMCRA ZONE GROOTE 24 Cape Arnhem (Dhimurru Indigenous Protected Area) 24 Groote Eylandt 24 IMCRA ZONE PELLEW 25 Bing Bong 25 IMCRA ZONE WEST CAPE YORK 25 Mapoon 25 Stranding reports 25 Appendix 2. Survey locations 26 Appendix 3. Pictorial marine debris survey sheets 27 Appendix 4. Origins of general debris survey sheet 34 Appendix 5. Fishing net survey sheet 35 RUBBISH ON OUR SHORES AND AT SEA 36 Appendix 6. European Article Numbers (EAN International 2004) 37 Appendix 7. Net Kit data sheet 38 WWF-Australia 3

4 1. Executive Summary The contamination of northern Australia s marine environment by manmade materials, known collectively as marine debris, is an ongoing concern to all groups utilising, researching and managing the coastlines and waters of northern Australia. In order to determine the extent of the problem WWF-Australia and partner groups have monitored selected sites on the Northern Territory coastline since 2000, while instances of wildlife entangled in marine debris at sea have been recorded by interested individuals since the release of the WWF Net Kit in This work has been performed in a concerted effort to determine the quantities, composition and origins of the debris found on the shorelines and in the waters of northern Australia and its effects on the marine species that inhabit it. In 2004, thirteen sites covering 28.6 kilometres of beach was surveyed for the presence of marine debris. In total, 57,635 items > 9cm 2 were collected or 2,015 items/kilometre. All sites monitored were found to have accumulated quantities of debris, however, sites on either side of the northern Gulf of Carpentaria, Cape Arnhem, Groote Eylandt and Mapoon were found to have accumulated significantly greater quantities of debris. The most frequently recorded items were plastic bottles, bottle tops, lengths of rope, rubber footwear and fishing floats. All items collected were examined for information which might be used to identify the sources of this debris. Results from this examination identified that 87% of all items originated from foreign sources. The sector found to be most responsible for this debris were marine industries such as fishing and cargo shipping. Marine debris has been listed as a Key Threatening Process in Australian waters due to its ability to harm vertebrate species by either ingestion or entanglement and is listed in the Australian Recovery Plan for Marine Turtles as one of the threats to the recovery of marine turtle populations in Australian waters. Harm to vertebrate species by ingestion of synthetic items is yet to be thoroughly investigated in northern Australia and it is the entanglement of marine species in derelict fishing nets that is considered to be of most concern. A total of 406 derelict fishing nets were collected from monitoring sites, weighing a total of kilograms, 36% of all debris by weight. The origin of these nets was overwhelmingly foreign, 98%. Foreign fishing nets were also found to be responsible for all recorded wildlife stranding events, five marine turtles and 42 fish on monitoring sites and a further 40 marine turtles and 31 fish and sharks reported to WWF as Net Kit reports. All six marine turtle species found in Australian waters are listed as threatened under Australian environmental legislation and four of the six - the olive ridley, hawksbill, green and flatback turtles - are regularly found entangled in derelict fishing nets. The species most often recorded or reported to WWF were juvenile hawksbill turtles (58%) and sub-adult and adult olive ridley turtles (17%). The quantities of marine debris recorded on northern Australian beaches originating from foreign vessels and the numbers of threatened species being caught in derelict nets by this sector confirm that foreign vessels fishing to the north of Australia are the sector which requires targeted solutions urgently. WWF-Australia 4

5 2. Introduction The contamination of northern Australia s marine environment by manmade materials, known collectively as marine debris, is an ongoing concern to all groups utilising, researching and managing this relatively pristine region of the country. Concerns about the harmful effects of marine debris in Australian waters have lead to marine debris being: listed in the Recovery Plan for Marine Turtles in Australia (Environment Australia 2003) as a threat to the recovery of marine turtles in Australia, and accepted as a Key Threatening Process (Injury and Fatality Caused by the Ingestion and Entanglement of Marine Life in Marine Debris) under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999). The scale of the problem in northern Australian waters first became apparent in the 1980s when Aboriginal communities in the Northern Territory and northern Queensland became concerned about the quantity of debris being washed ashore on their traditional lands, bringing with it stranded marine wildlife. However, it was not until the 1990s when Aboriginal communities, industry, state, territory and Commonwealth government agencies and non-government organisations began to actively remove and record the fishing nets and other debris on beaches in northern Australia; and after 2000 that significant funding became available to support larger projects such as the Carpentaria Ghost Nets Programme, which aims to support and fund groups wishing to remove and record marine debris in the Gulf of Carpentaria. On the Queensland side of the Gulf of Carpentaria, several groups became aware of the increasing quantities of marine debris being washed ashore each year and took it upon themselves to remove this debris. In the 1990s, Aboriginal communities and commercial fishers began removing derelict nets without recording their activities. One of the first groups to record its activities was Carpentaria Contracting, a private company operating out of Weipa, which began removing derelict nets from the northern Gulf beaches in 1993 (Hugh Edwards pers. comm. 2004). Further groups also became involved in marine debris removal when in 1998 the Mapoon Rangers and the Queensland Environmental Protection Agency began examining and removing derelict nets and recording stranded wildlife in the Mapoon region (Lawry Booth and Cecil Woodley pers. comm. 2004). A further Aboriginal group, the Napranum Rangers (Weipa), began removing and recording derelict fishing nets on beaches north of Weipa in 2002 (Richard Barklay pers. comm. 2004). In the Northern Territory, two Aboriginal groups, the Dhimurru Land Management Aboriginal Corporation (Dhimurru) in Nhulunbuy and Anindilyakwa Land Council (ALC) on Groote Eylandt began to address the issue of marine debris on their traditional lands. The ongoing Dhimurru Turtle Recovery Program was launched in 1996 after the Dhimurru Rangers and Northern Territory Parks and Wildlife Commission had examined Cape Arnhem in 1996 and found the area was indeed being inundated by derelict fishing nets and other marine debris. Each year participants in the program monitor a stretch of coastline partly contained within the Dhimurru Indigenous Protected Area (Dhimurru IPA), rescuing turtles stranded in derelict fishing nets, recording biological information about the turtles and sampling the nets responsible (Roeger et al. 2004). Their continued work and promotion of these activities in various media have successfully maintained the profile of the issue in Australia and influenced other groups in the region. At about the same time as Dhimurru was developing its Turtle Recovery Program, the ALC on Groote Eylandt was raising concerns with the Australian Fisheries Management Authority and Northern Prawn Fishery Management Advisory Committee about the amount of fishing debris washing ashore on the island. It was assumed by the ALC, at the time, that this debris originated from the Northern Prawn Trawl Fishery (NPF), as these were the vessels observed WWF-Australia 5

6 fishing the waters around Groote Eylandt. Their lobbying was successful and lead to a clean up and survey of accessible beaches in (Sloan et al. 1998). Results from this survey demonstrated that the NPF was partially responsible, as 35% of nets were attributed to the NPF. However, the remaining 65% was found to originate from foreign vessels and all observed wildlife strandings were caused by foreign nets. Unfortunately the survey was not repeated. In 1999, the WWF Marine Debris Program was established, after WWF responded to concerns raised by the Yolŋu people of north east Arnhem Land about the impact of marine debris on their beaches and marine turtle resources. The site of the first marine debris survey was Cape Arnhem in 2000 (Kiessling & Hamilton 2001). The initial survey performed by Dhimurru, Conservation Volunteers Australia (CVA) and WWF proved to be successful and was subsequently expanded to include a network of permanent sites at Groote Eylandt with the ALC, in the Borroloola area with the Lianthawirriyarra Sea Rangers, on Elcho Island with the Gumurr Marthakal Rangers, on Cobourg Peninsula with Parks and Wildlife Commission of the Northern Territory and CVA, and at Mapoon in northern Queensland with the Mapoon Rangers. To complement the surveys performed each year, WWF also undertakes a number of other research related activities. One of these activities is supporting other groups and individuals recording derelict nets and stranded wildlife found at sea or in areas where marine debris surveys are not currently performed. WWF has been recording stranding events in northern Australian waters since commencing the marine debris program in 1999 and provides support to the Dhimurru Turtle Recovery Program in the Dhimurru IPA. However, it was not until the release of The Net Kit in 2002 (Hamilton et al. 2002) that a tool became available to gather wildlife stranding information and derelict net reports in a standardised format. Since the initial release of The Net Kit, the number of nets and wildlife stranding events reported has grown and continues to grow as increasing numbers of groups utilise this resource. By examining marine debris in a structured, consistent manner, WWF and partner groups Dhimurru, ALC, Marthakal Homelands Resource Centre, Lianthawirriyarra Sea Rangers, Mapoon Rangers and CVA hope to use this information to inform others of the situation in northern Australia, formulate practical solutions to the problem of marine debris and ultimately reduce the quantity of debris entering northern Australian waters. WWF-Australia 6

7 3. Survey Methods 3.1. Beach surveys The WWF marine debris surveys were consistent with survey methods suggested by Ribic et al. (1992) and surveys performed previously by WWF and partner organisations. The survey method used by WWF estimates the quantity, composition and where possible the origin of debris items on site at the time of the survey. They are performed annually and all items collected are removed from the site. Survey teams, which consist of Indigenous Sea Rangers, local community volunteers, CVA and WWF volunteers, are briefed prior to the survey taking place and each participant is provided with a survey manual. The survey technique requires that all anthropogenic (human produced) marine debris other than fragments smaller than the top of a plastic bottle top (9 cm 2 ) be collected from the area of beach between the water s edge and the base of the primary sand dune (Figure 1). Teams are instructed to form a line at right angles to the water s edge and walk the survey sites maintaining their relative position to the other members of the team. Most items are collected in large bags carried by collection teams and larger items dragged down the beach to below the high tide mark for collection by support vehicles. Once the debris has been collected from the monitoring sites, it is emptied into a pile and sorted in an arc around the pile, according to debris types pictured on the general debris data sheet (Appendix 3). Figure 1. Seaward and landward limits of marine debris survey Frequently recorded plastic, rubber, metal, glass, paper and cloth items are all illustrated and space is provided at the end of each category for items that are less frequently encountered (Appendix 3). There are three methods of examining the items themselves to identify the sector or country of origin. While the debris is being sorted, the country of origin is recorded using any information still present, such as barcodes (EAN International 2004; Appendix 6), the manufacturer s name, their address and logos (Appendix 4). Items are then classified according to sector; terrestrial, marine or other after Ribic (1998) (Table 1). Other refers to items that could originate from either terrestrial or marine sources. WWF-Australia 7

8 Table 1. Categories of debris items, after Ribic (1998) and Wace (1995), for marine industries such as fishing, terrestrial sources such as landfill and beach litter and common items which could have originated from either. Marine Terrestrial Common items Aerosol cans Aluminum cans Coloured plastic bottles Baskets and buckets Baby care items Glass bottles Cigarette lighters (including disposable nappies, Tooth and hairbrushes Fishing line milk bottles and milk formula Clear plastic bottles and Fishing nets spoons) plastic bottle tops Foam cups Cardboard drink cartons Foam insulation Children s toys Foam packaging Cloth and clothing Fodder bags Food wrappers Fuel pumps Footwear (rubber thongs) Gloves Medical waste Hard hats Paper and cardboard Ice bags Shopping bags Light globes/tubes Six pack rings Lures Steel food tins Net floats and buoys Oil bottles Pallet wrappers Potable water filters, Ropes Scrubbing brushes Steel drums Strapping bands The third element of the marine debris survey method is the recording and identification of fishing nets. Fishing nets are recorded on a separate recording sheet (Appendix 5). Space is provided for recording the sample number, length, depth, weight and the WWF Net Kit code (Hamilton et al. 2002). A sample of each net is retained for comparison with the net archive maintained by WWF in Darwin. Upon completion of each survey day, all debris items are removed from the beach and deposited at the local community landfill site Net Kit reports Participating individuals and groups are asked to record derelict fishing nets and stranded wildlife, using the Net Kit as a reference to assist in completing the data sheets. They are also asked to provide a minimum sample of eight intact meshes with the returned data sheet and a photo for verification, if possible. The data sheet is broken into three sections and space is provided for the recording of: the contributors details, location information and date when the net was found; the net s details including length and drop in metres; and stranded wildlife using pages of The Net Kit. When a Net Kit report is received, the accompanying net samples are identified against the archive and entered into the database. They are then stored according to entry number and with their original data sheets and any other accompanying materials and fouling organisms. WWF-Australia 8

9 Objectives Prior to WWF becoming involved in marine debris surveys in 2000, most surveys undertaken in the Northern Territory were one-off events. The series of surveys undertaken by WWF and partner groups have the following objectives: Assist coastal communities in understanding and addressing a complex regional problem On ground research to help understand o volume, o composition, o source and o impact of marine debris in northern Australian waters Provide consistent monitoring information over time Assist in the development of targeted strategies to reduce the problem at its sources Generate public awareness of the issue. 4. Results 4.1. Marine debris surveys The 2004 marine debris surveys took place in five IMCRA zones (Table 2), four in the Northern Territory and one in northern Queensland. A total of 13 sites were assessed for the presence of debris items and all were found to be contaminated. A total of 57,635 items (>9cm 2 ) weighing a total of 4,804.2 kg were collected for the 28.6 km of monitoring sites. Figure 2. The 2004 survey locations represented by a yellow triangle and corresponding IMCRA Zones highlighted in shades of blue. WWF-Australia 9

10 To compare the monitoring results spatially the Interim Marine and Coastal Regionalisation for Australia version 3.3 (IMCRA) was used and survey results reported according to the IMCRA Zone in which they fell (Figure 2). The IMCRA meso-scale regionalisation is an ecosystem-based classification of Australia s marine and coastal environments and was developed to provide groups with a regional framework for planning sustainable resource development and biodiversity conservation (Interim Marine and Coastal Regionalisation for Australia Technical Group 1998). The 2004 marine debris surveys took place in five IMCRA Zones; Cobourg, Arnhem-Wessel, Groote and Pellew in the Northern Territory and West Cape York in Queensland. A total of 13 sites were assessed for the presence of debris items and six communities were trained in survey techniques while participating actively in the surveys themselves (Appendix 2). A total of 57,635 items or 2,015 items/km of survey site was collected from the 28.6 km surveyed in These items weighed in at 4,804.2 kg or 168 kg/km (Table 2). Contamination levels varied greatly between IMCRA Zones. Sites in the Gulf of Carpentaria generally received substantially greater quantities than Cobourg and Arnhem-Wessel, which are outside the Gulf of Carpentaria. The exception to these results is the site in Pellew, which is within the Gulf but sheltered from prevailing winds and currents by the Sir Edward Pellew Islands (Figure 2). The most heavily contaminated site was Six Mile Beach on Groote Eylandt, which contained 6,287 items or kg/km of survey site. However, the IMCRA Zone with the greatest quantity of debris per kilometre was West Cape York, which contained 3,769 items/km of beach surveyed (Table 2). The most numerous items on all sites were those made of plastic and rubber. Common plastic items were lengths of rope, plastic water and shampoo bottles and plastic bottle tops. Quantities of plastic debris per kilometre ranged from 55 items/km in Cobourg to 2158 items/km in West Cape York or about 56% over all. Rubber items were almost entirely composed of rubber thongs (also known as flip flops), which ranged from between 3.5 items/km in Cobourg and Pellew, to 113 items/km in the Groote IMCRA Zone and 1038 items/km in West Cape York or about 26.7% over all (Table 2). The other categories of metal, glass, paper and cloth were minor components of the debris collected, with the exceptions of the West Cape York sites where metal items (168 items/km) and glass (397 items/km) were also common (Figure 2). Table 2. Total number and weight of debris items collected from survey site in 2004 Total/ IMCRA ZONE km Plastic Rubber Metal Glass Paper Cloth Total Cobourg n/km wt/km Arnhem-Wessel n/km wt/km Groote n/km wt/km Pellew n/km wt/km West Cape York* n/km wt/km * The Mapoon Rangers had removed most of the large nets prior to the survey taking place. Therefore, the results presented here are an underestimation of the total plastic items number and weight for this IMCRA zone. WWF-Australia 10

11 General debris Marine debris other than fishing nets (general debris) was identified as originating from several nations. In the local region, debris from Australia and Asian nations (Indonesia, China, Singapore, Japan, Taiwan, South Korea, Philippines, Thailand, Malaysia, Vietnam) were found to be the most common, while debris from other regions (India, Dubai, France, Germany and USA) were also recorded. In particular, debris items from five nations made up about 95% of all identified debris collected. In order of relative significance, they were Indonesia (33.5%), China (29.1%), Singapore (15.1%), Australia (12.9%) and Thailand (5%) (Table 3). The proportion of debris from Australia, Asia and other regions varied between IMCRA Zones. Asian nations contributed the majority of debris items in the Gulf of Carpentaria, with the exception of Pellew, while sites outside the Gulf contained proportionally more items originating from Australia (Table 3). Table 3. Relative proportion of identified item (other than fishing nets) found on monitoring sites. IMCRA Zones Cobourg Arnhem- Wessel Groote Pellew West Cape York All sites Country origin % % % % % % Australia Indonesia China Singapore* Japan Taiwan South Korea Philippines Thailand Malaysia Vietnam India Dubai Other Examination of general debris items showed that the majority of items originated from sources outside Australia, although Cobourg, Arnhem-Wessel and Pellew sites contained proportionally more general debris items from Australian sources. The majority of items originating from Australian sources found at Cobourg and Pellew were aluminium beer cans. While at Arnhem-Wessel the major Australian component was food packaging and steel food tins. The most common general debris items from foreign sources were rubber footwear (both adult and children s), plastic water bottles, shampoo bottles, skin care products and motor oil containers. In addition to the rubber and plastic items found on all sites, West Cape York also had many tins of peanut soup from China and glass Red Bull bottles from Thailand. The allocation of whole debris items to predetermined categories of marine, terrestrial or common (Table 4) resulted in about 25.6% of all items being allocated to marine, 4.8% to terrestrial and the majority, 69.7%, to common. WWF-Australia 11

12 Table 4. Results of assigning debris items to marine, terrestrial and common categories (Table 1) 2004 IMCRA zones Cobourg Arnhem- Wessel Groote Pellew West Cape York Marine % % % % % Nets Net floats and buoys Lures Fishing line Baskets and buckets Ropes Strapping bands Ice bags Pallet wrappers Salt bags Oil bottles Foam insulation Foam packaging Hard hats Cigarette lighters Scrubbing brushes Gloves Steel drums Aerosol cans Light globes/tubes Other (potable water filters, fuel pumps) Total marine Terrestrial Shopping bags Food wrappers Baby care items Aluminum cans Steel food tins six pack rings Cloth Cardboard drink cartons Paper and cardboard Other (toys, balls Medical Total terrestrial Common items Colored plastic bottles Clear plastic bottles Foam cups Footwear Plastic bottle tops Tooth and hair brushes Glass bottles Other Total common WWF-Australia 12

13 Derelict nets A total of 406 derelict fishing nets were collected from the 28.6 km of monitoring sites in 2004, weighing a total of kg. The two IMCRA Zones most affected by derelict fishing nets were Groote and West Cape York, on either side of the Gulf of Carpentaria (Table 5). West Cape York contained 27.5 nets/km, while Groote contained about 17.9 derelict nets/km. This was despite most of the large nets having been removed from the West Cape York survey sites by the Mapoon Rangers prior to the survey taking place. Commercial fishing nets of foreign origin were about 98% of all nets collected. A total of 398 foreign nets were collected, 270 were fragments <10m 2 in area, 96 were between 10 m 2 and 100 m 2 and 32 >100 m 2. There were eight nets of Australian origin collected during all surveys. Seven originated from commercial fishing vessels and all were less than 10 m 2, while one net found on Gitan Beach in the Arnhem-Wessel IMCRA Zone was >10 m 2 and originated from the local community (Table 5). The largest net recorded was found on Araru Point in the Cobourg Zone. The net was a piece of discarded trawl netting that measured 78 metres by 30 metres and weighed 181 kilograms. This net, although tied in a bundle before being discarded, had managed to ghost fish and contained the bones of an unidentified marine turtle. A total of 47 animals were recorded stranded in fishing nets on the 28.6 kilometres of sites surveyed, two juvenile hawksbill turtles (Eretmochelys imbricata), two unidentified turtles, 33 catfish (Arius sp.), 8 triggerfish (Balistidae) and one shark (Carcharhinus sp.) (Table 5). A further three turtles were found dead on survey sites in the Groote IMCRA Zone, without evidence of being stranded in fishing nets or other debris. These were a juvenile hawksbill and a juvenile olive ridley turtle (Lepidochelys olivacea) found on the Cape Arnhem survey site, and a juvenile green turtle (Chelonia mydas) on Six Mile Beach. Table 5. Area, number and origins of nets collected during the 2004 marine debris surveys. IMCRA Zone Cobourg Arnhem- Wessel Groote Pellew West Cape York* Stranded wildlife found in net Net Size Class (M 2 ) n/km n/km n/km n/km n/km Turtles Fish Australian nets Total Foreign nets Total Total n/km Total wt/km * The Mapoon sites had most large nets and stranded wildlife removed prior to the survey taking place. Therefore the figure presented is an underestimation. Non-commercial fishing net WWF-Australia 13

14 4.2. Net Kit reports During the 2004 calendar year, WWF received completed data sheets, photos and net samples detailing 138 individual derelict fishing nets, found both at sea and onshore (Figure 3). When the nets were compared with the WWF net archive, 129 were identified as foreign and nine of Australian origin. No stranded marine wildlife were reported in the nets originating from Australian commercial fisheries, but 40 stranded marine turtles and 31 fish and sharks were found in foreign fishing nets (Table 6). The species reported were 30 juvenile hawksbill turtles, five sub-adult/adult olive ridley turtles, two juvenile green turtles, one juvenile flatback (Natator depressus) and two turtles which were not identified due to their late stages of decomposition. Fish and shark species reported stranded in derelict fishing nets were 14 common dolphin fish (Coryphaena hippurus), nine rainbow runners (Elegatis bipunnulata), five catfish, one triple tail (Lobotes sirinamensis), one triggerfish and one shark. Figure 3. Locations of derelict nets on the Australian continental shelf during the 2004 calendar year. Reported nets and standings from the Pulu Keeling National Park (Sunda Provice (b)) are not depicted. In addition to the stranded wildlife, a commercial fishing vessel was also reported stranded in a foreign gillnet. The Samantha J, a NPF trawl vessel, picked up a Taiwanese gillnet (Net Kit Code GR24) around its propeller shaft and spent the next four days stranded at sea (Alan Watt, pers. comm. 2004). WWF-Australia 14

15 Table 6. Net Kit reports received during the 2004 calender year. IMCRA zone in which the net was found, size, class of nets and number of marine wildlife stranding events are shown. Origin IMCRA zones Stranded wildlife Net Size Class (m 2 ) Anson- Beagle Arafura Arnhem- Wessel Cobourg Oceanic Shoals Pellew Sunda Province (b) Tiwi Torres Strait Turtles Fish Australian nets Foreign nets * * 27 Total * One net contained an estimated 20 juvenile hawksbill turtles in the first five metres of an estimated 150 metres of derelict netting. The rest of the net was not inspected, due to the stench of dead animals, and was sunk using an anchor chain. WWF-Australia 15

16 5. Discussion The Arafura and Timor seas and their coastlines are often assumed to be in a relatively pristine condition. This assumption appears to be based on the area s relatively small population when compared to other parts of Indonesia and Australia. However, surveys in the region (Sloan et al. 1998; Kiessling and Hamilton 2001, 2003; White 2003, 2005) have found that quantities of marine debris accumulating on beaches in northern Australia, each year, are alarming. Particularly when compared with the results of other surveys in Australia. Cary et al. (1987) reported 17 kg km -1, Edwards et al. (1992) 50.5 kg km -1, Wace (1994) 12.4 kg km -1 and Edyvane et al. (2003) 15 kg km -1. These figures are far less than the Groote and West Cape York IMCRA Zones with 200 kg km -1 and 439 kg km -1 respectively and less than most other monitoring sites surveyed during 2004 (Table 2). Two methods of gathering information are used each year to monitor marine debris both onshore and at sea. Aboriginal Sea Rangers and community volunteers, CVA, Northern Territory Parks and Wildlife staff and WWF monitor permanent survey sites each year, recording all items > 9 cm 2, while the WWF Net Kit is used by volunteers to gather information at sea and on land. These two methods, although able to provide a substantial amount of data, have limitations. Items on survey sites < 9 cm 2 are not recorded and items that have either sunk due to bio-fouling or become snagged underwater remain essentially invisible to the survey techniques currently employed. Therefore, the results presented in this report can provide only an indication of the total quantities of marine debris affecting northern Australian waters. Non-fishing items found on monitoring sites contained barcodes and other identifying information from Australia, 12 Asian nations and other nations such as France, Germany and the USA. Items from Indonesia, China, Singapore and Thailand were the most frequent with >80% of all identified debris having been purchased in these countries. Items of Australian origin were about 13% of all general debris items collected (Table 3). Items from Indonesia indicate that vessels are taking on supplies in Indonesia and dumping their waste at sea and/or originating from coastal landfill sites in the region. Items from China, Singapore and Thailand indicate that some vessels active in the region either originate from or had restocked in these countries recently. The categorisation of debris items into terrestrial, marine or common items (Table 4) indicate that marine activities are contributing the majority of debris on all sites (Table 4). However, as the majority of items were categorised as common, further work on assigning items to categories is required. The categorisation of rubber thongs, plastic water bottles and their lids as common items compounded this problem, as these three groups are also the most common items recorded on monitoring sites in northern Australia. Rubber thongs are worn on fishing vessels but are also everyday footwear in the tropics. They were eventually assigned to common due to 5-7% of rubber thongs being children s sizes and the sheer numbers found (100s/km Groote IMCRA Zone and 1000s/km Western Cape York) ruled out the fishing industry as being solely responsible. Plastic bottles and plastic lids were also assigned to common, although about 25% had barcodes from Singapore, China and Taiwan, indicating that they had come from shipping and possibly fishing vessels that had recently visited these countries. However, as the majority of bottles found were degraded and crushed and storing water onboard vessels in 600 ml and 1 L bottles is extremely inefficient in terms of space, they could also have come from landfill sites in the region. WWF-Australia 16

17 To remove some of the subjectiveness of assigning items to categories and to allow for a portion of items to be assigned to either marine or terrestrial categories, further observations about the condition of the items is required. An example of how this could be achieved is provided in Whiting (1998), where a portion of the items in a category are assigned to different sectors. The combination of using barcodes and other information and the allocation of debris items to terrestrial (4.8%), marine (25.6%) and common (69.7%), indicates that it is the marine industry that is primarily responsible for debris items found on northern Australian beaches. This is in contrast to most of the world s oceans where an estimated 5% of marine debris items originate from marine activities (O Hara et al. 1988). The general debris items originating from vessels visiting the Arafura Sea, such as plastic bottles and rubber thongs, are a threat to marine life because they can be mistaken for food items and ingested (Carr 1987). In other parts of the world the presence of synthetic debris in turtle stomachs is well documented (Derriaik 2002). Marine turtle species are known to be vulnerable to marine debris, particularly during their juvenile stages, as they scavenge and seek shelter in drift lines where currents and winds cause floating objects to converge (Carr 1987, Witherington 1994). In Florida USA, examination of the diet of juvenile loggerhead turtles showed that 34% of animals examined had ingested plastic and synthetic fibres (Witherington 1994). The effect of ingesting plastic and other synthetic materials is known to reduce the fitness of animals. Effects include: reducing lipid destabilisation (Schulman and Lutz 1992), blocking gastric enzyme secretion, diminishing feeding stimulus and causing blockages in the intestine (Derraik 2002), lowering steroid hormone levels which causes a delay in ovulation and reproductive failure (Derraik 2002), as well as causing marine turtles to become buoyant so that they have difficulty feeding and escaping predators or avoiding boat strikes (Lutcavage et al. 1996). After the 2002 survey, samples of debris were taken to the Northern Territory Museum and Art Gallery in an attempt to determine what caused the bite marks commonly observed in plastic bottles, bags and rubber thongs. The animal species thought to be responsible for the bite marks were marine turtles and puffer fish (Lapocephlaus sp.). However, the species of turtle responsible for the bite marks could not be determined (White 2003). During the 2003 surveys, the number of items that contained bite marks was recorded. It was found that 23% of all coloured plastic bottles and 15% of all rubber thongs contained bite marks. Other items that also contained bite marks were plastic motor oil bottles, plastic bags and plastic bottle tops (White 2003). The link between bite marks in plastic items and turtle deaths was established in 1995 when a juvenile flatback turtle was found to have died due to the ingestion of part of a woven sack (Chatto et al. 1995), but no further incidents have been confirmed in the Northern Territory. However, marine turtles are known to ingest plastic bags and other marine debris (Schulman and Lutz 1992, Derraik 2002) and there are a high number of animals found to have ingested synthetic materials in other parts of the world, suggesting that more research into this possible source of turtle mortality is required in northern Australia. WWF-Australia 17

18 While there is little information presently available about the threat that ingested debris poses to marine turtles, the destructiveness of derelict fishing nets is becoming increasingly well documented. Derelict fishing nets are a major pollutant on monitoring sites in terms of bulk and weight, contributing about 36% of the total weight of debris. The total contribution of Australian fishing nets was about 2% of all nets collected (<1% by weight) and there were no wildlife standings associated with pieces of Australian fishing net. This is in stark contrast to the 98% of nets which were from foreign vessels and responsible for all of the wildlife standings recorded during marine debris surveys (Table 5) and reported by volunteers using the WWF Net Kit (Table 6). The first report of a stranding event in Northern Territory waters was by Chatto et al. (1995), when two adult olive ridley turtles, one juvenile green turtle and a juvenile hawksbill were found caught in a single length of derelict fishing net. Northern Australian waters are home to six of the world s seven marine turtle species - flatback, green, hawksbill, olive ridley, leatherback (Dermochelys coriacea) and loggerhead turtles (Caretta caretta) (Limpus 1998). All six are listed as threatened under Australian legislation (EPBC Act 1999) and all except the leatherback and loggerhead have been reported stranded in derelict nets in northern Australia. Other species also found caught in derelict netting in northern Australia are dolphin fish, rainbow runners, catfish, triple tail, triggerfish, marlin (Makaira indica), sharks, dolphins (Tursiops sp.), juvenile crocodiles (Marianna Akaczonek pers. comm. 2004) and birds (Sloan et al.1998). Reports of wildlife standings received by WWF since the release to The Net Kit in 2002 (Hamilton et al. 2002) come from a wide geographical area, with local areas possible having differing proportions of species caught in derelict nets. However, the marine turtle species most often reported, in order of relative frequency are juvenile hawksbill turtles (58%), subadult/adult olive ridley turtles (17%), juvenile green turtles (13%), sub-adult flatback turtles (1%), with about 10.5% of species remaining unidentified, due to late stages of decomposition. Olive ridley turtles are thought to lead a primarily pelagic existence (Plotkin et al. 1993) and feed in benthic habitats over 100 metres deep. Juvenile hawksbill turtles with a curved carapace length of < 35cm are also pelagic and yet to switch to the benthic phase of their life cycle (Limpus 1992). Both olive ridley and juvenile hawksbill turtles are commonly observed in Northern Territory waters at depths of over 100 meters (Luke Miller and Ben Slater, pers. comm. 2003). Internationally, both the olive ridley and hawksbill turtles are considered to be Threatened. Hawksbill turtles are considered to be Critically Endangered while the olive ridley turtle is listed as Endangered, according to the 2004 IUCN Red List of Threatened Species (Baillie et al. 2004). Under Australian legislation, it is the olive ridley turtle that has the highest conservation status and is listed as Endangered, while the hawksbill is listed as Vulnerable (EPBC Act 1999). Marine debris is possibly the greatest source of anthropogenic mortality of post hatching hawksbill and olive ridley turtles. However, the true effect of mortality caused by marine debris is difficult to determine when no population estimates are currently available for Northern Territory populations of both species. The reason for marine turtles, dolphin fish, rainbow runners, triple tail, triggerfish and sharks being frequently reported in derelict fishing nets, is probably due to their behaviour. Many animals find food in the open ocean by scavenging in drift lines, where currents and winds converge, focussing on floating food items and larger objects which provide shelter. Large objects at sea are often known as FADs (Fish Attracting Devices or Fish Aggregating Devices) and used commonly by recreational and commercial fishers alike. Juvenile turtles are known to shelter under floating objects (Arenas and Hill 1991), a fact confirmed by commercial fishers in the Timor Sea who regularly observe hawksbill and olive ridley turtles WWF-Australia 18

19 hiding under fishing buoys or other floating objects (Luke Miller and Ben Slater, pers. comm. 2003) (Figure 4). Without drift lines and the food and shelter provided by them, juvenile turtles would probably starve or be eaten (Carr 1987). Unfortunately, this essential habitat increasingly also contain plastic bags, bottles and fishing nets. Figure 4. A Taiwanese gillnet (GR24) ghost fishing in the Arafura Sea. Ripples on the surface of the water are caused by a stranded juvenile hawksbill turtle, while fish can also be seen dead in the net. Ben Slater One of the questions that arises from the recorded stranding events is whether all nets are dangerous or whether there are other features, such as a minimum size, that can be used to determine a net s potential threat. Unfortunately, an answer to this question is yet to be thoroughly established. Although nets with a stretched mesh size of between 7.6 cm and 15 cm have been reported most frequently to contain stranded animals, while the minimum size of net used as shelter appears to be pieces of nets >10 m 2. Of all the nets reported to WWF both through The Net Kit and marine debris surveys, the three net types most often reported are green multistrand Taiwanese gillnets (GR24), Taiwanese monofilament gillnets (WT35) and pieces of Thai trawl netting. These three net types account for more than half of all wildlife stranding events recorded to date. WWF-Australia 19

20 The information gathered in this report and appearing in previous reports by Sloan et al (1998), Alderman et al. (1999), Kiessling and Hamilton (2001, 2003), and White (2003, 2005), have all concluded that the sources of derelict fishing nets in northern Australian waters are overwhelmingly foreign fishing fleets operating to the north of Australia. It is this group which requires the bulk of attention if we are to reduce the quantity of debris and therefore numbers of marine animals injured and killed each year. There are international conventions developed to control the discharge of pollutants from shipping, the most important being the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972 (London Dumping Convention) and the International Convention for the Prevention of Pollution from Ships 1973/78 (MARPOL 73/78). Annex V of MARPOL 73/78 prohibits at sea disposal of plastics and requires that signatory states have in place reception facilities for the disposal of waste, waste logbooks on vessels, and a system of inspections and fines (IMO 2002). However, as Indonesia is yet to become a signatory to MARPOL 73/78 <imo.amsa.gov.au/public/parties/marpolv> and the dumping of plastic waste from shipping is legal in Indonesian waters; there is little reason and possibly limited opportunity for visiting vessels to improve their waste disposal practices while in the region. There is some debate about how effective the introduction of MARPOL 73/78 Annex V has been in causing changes in the waste disposal habits of the shipping and fishing industry. In Australia, the introduction of MARPOL 72/78 has been largely successful. There has been a reduction in the number of nets of Australian origin washing ashore since marine debris surveys began in the areas of the Arafura and Timor seas. One of the longest sequences of surveys (on the same site) in the region has been taking place on the eastern coastline of Groote Eylandt, beginning in During the course of the surveys the number of derelict Australian fishing nets recorded has declined from 1.9 net/km -1 (34%) in 1997, to 0% in 2004 (Table 7). This decline is also apparent at other sites monitored by WWF since The cause of this reduction is likely to be greater compliance with MARPOL Annex V, although fishing effort reduction within the commercial fishing sector is also likely to be a factor. Edyvane et al. (2003) also sites compliance with MARPOL Annex V as a factor in the reduction of fishing related marine debris on the South Australian coastline. Table 7. Comparative results from marine debris surveys performed on the eastern coastline of Groote Eylandt between 1998 and Survey year Nets/km -1 (Percentage of total) Source data (34%) Sloan et al. (1999) (7%) White (2003) White (2004) marine debris survey The reduced number of nets of Australian origin recorded at monitoring sites represents an improvement in the waste disposal practices of the Australian commercial fishing industry. Unfortunately, while the Australian sector has demonstrated that improvement is possible, waters to the north of Australia are yet to see a mechanism introduced that is capable of causing change. WWF-Australia 20

21 6. References Alderman R., Pauza M, Bell J., Taylor R, Carter T. and Fordham D Marine Debris in Northeast Arnhem Land Northern Territory Australia. In: Entanglement of marine turtles in netting: Northeast Arnhem Land, Northern Territory, Australia. Leitch K. (ed) Dhimurru Land Management Aboriginal Corporation. Arenas P, and Hall M The association of sea turtles and other pelagic fauna with floating objects in the eastern tropical Pacific Ocean. In Salmon, M. & Wyneken J. compilers. Proc. of the Eleventh Annual Symposium on Sea Turtle Biology and Conservation. NOAA. Baillie, J.E.M., Hilton-Taylor, C. and Stuart, S.N. (Editors) IUCN Red List of Threatened Species. A Global Species Assessment. IUCN, Gland, Switzerland and Cambridge, UK. xxiv pp. Cary, J.L., Robinson, J.E. and Greg, K.A A survey of beach litter in the proposed Marmion Marine Park near Perth, Western Australian. In, Technical Series No 14 EPA WA (L. Moore, ed.). EPA, WA Perth, pp Chatto, R., M. Guinea, et al Sea turtles killed by flotsam in Northern Australia. Marine Turtle Newsletter 69, Derraik, J. G. B The pollution of the marine environment by plastic debris: a review. Marine Pollution Bulletin 44(9), EAN International 2003, Assigned EAN.UCC, < Edwards, D., Point, J., Arnold, L., Arnold, G. and Lapwood, M A survey of beach litter in Marmion Marine Park. EPA, WA, Perth. Edyvane K.S., Dalgetty A., Hone P.W., Higham J. and, Wace N.M Long-term marine litter monitoring in the remote Great Australian Bight, South Australia. Marine Pollution Bulletin 48, Environment Australia, 2003, Recovery Plan for Marine Turtles in Australia. Marine Species Section, Approvals and Wildlife Division, Environment Australia in Consultation with the Marine Turtle Recovery Team. Commonwealth of Australia, Canberra Forbes, A and Church, J 1983, Circulation in the Gulf of Carpentaria. II Residual Currents and Mean Sea Level. Australian Journal of marine and Freshwater Research. 34, Gregory R Accumulation and distribution of virgin plastic granules on New Zealand beaches. New Zealand Journal of Marine and Freshwater Research, 12, Hamilton, C., Cook, K. and White, D The Net Kit: A Fishing Net Identification Guide to Northern Australia, WWF Australian, Sydney. IMO MARPOL 73/78 Consolidated Edition International Maritime Organization, London. Kiessling, I. and C. Hamilton Marine debris at Cape Arnhem Northern Territory Australia 2000, WWF-Australia, Sydney. WWF-Australia 21

22 Lutcavage, M.E., Plotkin P., Witherington B. and Lutz P Human Impacts on Sea Turtle Survival. Pp In, Peter L. Lutz and John A. Musick (editors), The Biology of Sea Turtles, CRC Press, Boca Raton, FL. Mobson, V., Godley, B., Brodrick A. and Furness R. 1997, Marine litter on sea turtles (Chekonia Mydas and Caretta Caretta) nesting beaches in Northern Cyprus, eastern Meditaranian. Proceedings 17 th Annual Sea Turtle Symposium, Orlando Florida. Interim Marine and Coastal Regionalisation for Australia Technical Group 1998, Interim Marine and Coastal Regionalisation for Australia: and ecosystem based classification for marine and coastal environments. Version 3.3. Environment Australia, Commonwealth Department of the Environment, Canberra. Limpus, C "The hawksbill turtle, Eretmochelys imbricata, in Queensland: population structure within a southern Great Barrier Reef feeding ground." Wildlife Research. 19: Limpus, C. and Miller, J Beachwashed nets, Gulf of Carpentaria. Unpublished Report to Queensland Parks and Wildlife Service. National Oceans Office 2003, Finding Solution: Derelict Fishing Gear and Other Marine Debris in Northern Australia. O Hara, K., S. Ludicello, R. Bierce A Citizen s Guide to Plastics in the Ocean: More than a litter problem. Center for Marine Conservation. Washington. 143p. Plotkin, P.T., R.A. Bales and D.C. Owens "Migratory and reproductive behavior of Lepidochelys olivacea in the Eastern Pacific Ocean." Schroeder, B.A. Witherington and B.E. Witherington, compilers. Proc. of the Thirteenth Annual Symp. on Sea Turtle Biology and Conservation. NOAA. Department of Environment and Heritatge Recovery Plan for Marine Turtles in Australia Marine Species Section, Approvals and Wildlife Division, Department of Environment and Heritatge Canberra. Ribic, C., Dixon, T. and Vining, I Marine Debris Survey Manual. NOAA Technical Report. US Department of Commerce. Ribic, C Use of Indicator items to monitor marine debris on a New Jersey Beach from 1991 to Marine Pollution Bulletin, 36 (11), Roeger, S., Munuŋu, M. and Wise, P Entanglement of Miyapunu (Marine Turtles) in Ghost Netting: Northeast Arnhem Land, Northern Territory, Australia. Report to: Alcan Gove Pty Ltd, WWF Australia, Humane Society International and Aboriginal Benefits Trust Account. Dhimurru Land Management Aboriginal Corporation, Nhulunbuy, Northern Territory. Schulman, A. and Lutz, P. 1992, The effects of plastic ingestion on the lipid metabolisation in the green turtle (Chelonia mydas). Proceedings of the Twelfth Annual Workshop on Sea turtle Biology and Conservation. NOAA, Sloan, S., Wallner, B. and Mounsey, R Fishing Debris around Groote Eylandt in the Western Gulf of Capentaria. A report on the Groote Eylandt fishing gear debris project Australian Fisheries Management Authority, Canberra, ACT. WWF-Australia 22