Tag Archives: Chris Rattray

Comparative Count of Dugongs


Mission: Comparative Count of Dugongs
Date: 4 September 2008
Requesting organisation:
Paul Dutton
Location: Mozambique’s Bazaruto National Park
Chris Rattray and Etienne Oosthuizen

Surveying Bazaruto National Park’s Elusive Mermaids by Paul Dutton
Chris Rattray in ZSCTW, flying in seach of Dugong

The Dugong Survey Team:  from the left Dr Almeida Guissamulo, Paul Dutton, Etienne Oosthuizen and Chris Rattray

The Bateleurs supported a count of Mozambique’s Dugongs in February this year, when the exercise yielded alarming reports of decreasing numbers of these gentle sea creatures.  In September a comparative count was conducted, and this is the short report  prepared by Paul Dutton, a Bateleurs pilot and ecologist.  The flying for this mission was performed by volunteer pilots Chris Rattray and Etienne Oosthuizen.

Surveying Bazaruto National Park’s Elusive Mermaids  :  3-7 September 2008, by Paul Dutton

“This was my sixth aerial survey, since 1990, of Dugong that occur in the sheltered marine grass environment of the Mozambique’s Bazaruto National Park.  I had just graduated with an MSc degree in coastal management and as luck would have it I found Dr John Hanks sitting at the Africa Desk of WWF (International) in Glande, Switzerland and he offered me a contract to formulate a Master Plan for the Bazaruto Archipelago. This opened up an opportunity for me to test the veracity of my MSc dissertation “Traditional Fisheries and Conservation Ethics” whilst gathering a plethora of data required for formulating the Master Plan. However, it was not long after I had pitched my tent on the northern shore of the main island of Bazaruto that my attention was drawn to the presence of the mythical Sirenia or Dugongs that grazed the sea grass meadows throughout the archipelago. To promote the conservation of an ecosystem one needs a flagship species – like the tiger that symbolizes India’s jungle, or the white rhino that assured iMfolozi Game Reserve’s future. The Dugong, because of its rarity and important ecological niche as a bulk grazer of marine grass, fitted into this role.



Chris Rattray in ZSCTW, flying in seach of Dugong

Dr Almeida Guissamulo, a young graduate of the Mondlane University in Mozambique, and cetacean specialist Dr Vic Cockcroft, accompanied the first aerial survey in 1990 when Dugong were of mixed sexual and age aggregations and were widespread throughout the Archipelago.  An estimate of between 150 and 180 animals was based upon a 25% survey sample.

Since then population estimates have  followed a roller coaster ride of discrepancies in terms of numbers and distribution. It became apparent that small sample numbers were being extrapolated in relation to our original study when in fact the introduction of gill nets for shark harvesting had caused  numerous “accidental” drownings in previously occupied habitats.

Counting a small number of widely distributed animals that can submerge for up to 8 minutes played a major part in the variance in numbers. For example, the survey carried out in February this year accounted for less than 20 animals – all but one occurring close to the islands of Benguerra, Magaruque and miniscule Bangue. Perfect weather on one of the days of the September survey, with the sea clean and mirror calm, resulted in an additional 45 being found close to Santa Carolina.  This elevates the population estimate to at least 56 animals, including 6 sub adults and 5 juveniles in 33 localities.

On this occasion flight transects 2 km apart and covering 130 km starting from the Save River Estuary and moving southwards through the national park were flown over a period of 5 days.  This produced as near as possible a total figure rather than a statistically generated estimate.  A total distance of  3781 km over a period 30 hours was flown by the two aircraft, providing an indication of the intensity of the current survey.

A total of at least 420 Humpback and Bottlenose Dolphins,and 6 Humpback whales were encountered on the survey transects.

We were fortunate to have Dr Almeida Guissamulo design and guide this recent survey which I believe is a definitive estimate of the current status of the Dugong.  It will enable initiation of the  long term management of the Dugong whose current distribution still places them in the precarious situation of being the proverbial “eggs in just two disparate baskets”.

Our beloved squadron leader Nora Kreher and board members of The Bateleurs – Flying for the Environment in Africa once again showed their commitment to caring for our beleaguered natural environment by funding and fielding two of its proficient member pilots, Chris Rattray and Etienne Oosthuizen, who flew their C182 and Kitfox7 aircraft with utmost precision over Bazaruto National Park’s azure clear water. Sunday Times photographer Darryl Hammond worked hard to capture images of Dugong underwater on known feeding grounds. On one occasion Darryl and I had two Dugongs within a few meters of our dive boat but when we slipped overboard in our scuba gear all we saw was  blue water – and no sign of the mythical Mermaid! 

The Dugong Trust contributed to the team’s lodgings at the Bazaruto Lodge where managing director Louis Erasmus accommodated the team at a generously reduced rate. Other tourist entrepreneurs namely Gonfishen and the Islands of  Benguerra, Indigo Bay and Santa Carolina all helped in various ways to make this survey a pleasant and successful mission. I took a back seat on this, probably my last air survey of Dugong after 18 years.”

Selous-Niassa Wildlife Protection Corridor Project


Mission: Pre-feasibility Study of the Ruvuma Ecological Reserve
Date: 14 August 2008
Requesting organisation: Selous-Niassa Wildlife Protection Corridor Project
Location: Ruvuma Ecological Reserve, Zambia
Pilot: Chris Rattray

The Selous-Niassa Survey, by Wayne Lotter


The Bateleurs was contacted by Wayne Lotter, Natural Resources Manager and International Team Leader of the Selous-Niassa Wildlife Protection Corridor Project, who asked us to provide aerial assistance for a pre-feasibility study of the Ruvuma Ecological Reserve.

The Selous-Niassa Wildlife Protection Corridor Project will link the Selous Game Reserve in Tanzania with the Niassa Game Reserve in Mocambique. The total area is vast, encompassing over 8 million ha, and it includes the biggest Wild dog and the biggest elephant (80 000) populations in Africa.  The project is largely community-based and is being implemented in partnership with the Tanzanian government.

Bateleurs pilot Chris Rattray volunteered for this complex mission and flew his Cessna 182 to Zambia to participate in the pre-feasibility exercise regarding the inclusion of the Ruvuma Ecological reserve.  We have included here some extracts from the detailed report submitted by Wayne – the full report is available on request.


The Selous-Niassa Survey, by Wayne Lotter

ruvuma2_14082008Bateleurs pilot Chris Rattray (left) and Wayne Lotter crossing the Ruvuma river.

“On 8 August 2008 an aerial survey was conducted in order to assess the status quo of the proposed Ruvuma Ecological Reserve area in terms of its integrity, potential and the extent of which it is continuous (intact and natural) or interrupted. A pilot with his Cessna 182 was kindly made available by The Bateleurs.

The survey team comprised Eberhard Halla,Community & Environmental Officer, Tunduru District Council; Wayne Lotter, International Team Leader, Selous-Niassa Wildlife Protection Corridor Project; Krissie Clark, ecologist; and Chris Rattray, Bateleurs pilot.

Four transects were flown over the proposed Ruvuma Ecological Reserve area (Figure 3). The land cover and land use on either side of the plane within a 2 nautical mile band on the transect line was noted at regular intervals by the survey team.

In order to investigate the viability of establishing of the proposed Ruvuma Ecological Reserve, and to determine whether the proposed sub-contracting of services to undertake a more in depth feasibility study is really required, a preliminary assessment and aerial survey was conducted to assess:

* the status quo of the area;
* the ecological integrity of the area; and
* the suitability of formalising the area as a WMA.

This report highlights the finding of the preliminary assessment and aerial survey.”



Chris’s aircraft had to be refuelled with petrol as there as no avgas to be found – anywhere.

“It is recommended that the following be considered by the major stakeholders of the SNWPC:

* Not to carry out the detailed, primarily biological diversity, survey of the target area as outlined in the May 2005 Feasibility Assessment and in the February 2008 SNWPC Project Operational Plan.
* To conduct a study on the feasibility of establishing the area as a WMA, or including it as a part of one of the planned WMAs in the south eastern area of the SNWPC. The conservation protection of this area would help link the SNWPC ecologically with a larger section of the Niassa National Reserve and with the Mwambesi Forest Reserve and possibly further to the Eastern Selous-Niassa Corridor which is being established by WWF Tanzania.
* Should the establishment of the area as a WMA not prove viable, to then investigate the possibility of including as much of the area as possible as a proclaimed extension to the existing Mwambesi Forest Reserve.

The proposed WMA feasibility study should be conducted as soon as possible, while the Selous – Niassa Wildlife Protection Corridor Project is still in full swing and is in a position to possibly support recommendations emanating from the study.”

The SNWPC Project would like sincerely to thank The Bateleurs and in particular their pilot, Chris Rattray,  and ecologist Ms. Krissie Clark (Game Rangers Association of Africa) for their expert assistance and for the aircraft made available for conducting the preliminary aerial survey and assessment of the proposed Ruvuma Ecological Reserve, at zero charge to the project.”

Aerial Survey for Dugong


Mission: Aerial Survey for Dugong in the Bazaruto National Park
Date: 12 February 2008
Requesting organisation: Nguni Productions for 50/50
Bazaruto National Park, Mozambique
Barry de Groot, Chris Rattray and Paul Dutton

Current Account of The Aerial Survey for Dugong in the Bazaruto National Park by Paul Dutton
Dugongs then and now
Dugong Population Trends
The Dugong Survey Team

This mission for The Bateleurs is one of very few in which Paul Dutton plays the part of a passenger, and not the pilot.  In fact, for this flight he was wearing his ecologist’s hat, and following the survey he produced a wonderfully detailed scientific report, from which we present the following extract:

Current Account of The Aerial Survey for Dugong in the Bazaruto National Park by Paul Dutton

“The Mozambique coastal littoral (i.e. the zone between the high and low tide marks) is blessed with many extensive inshore marine grass habitats suitable for the herbivorous Dugong, pictured above, which used to occur from Inhaca to the Rovuma River. The introduction of large mesh gill nets in 1976, set for the harvesting of sharks, has been the principal cause of the demise of the Dugong throughout their former range.

The Bazaruto Archipelago is situated in the Inhassoro and Vilankulu districts of the Inhambane Province.  It has extensive marine grass habitats which supported a widely distributed population of Dugongs, estimated at 150 animals in 1990. Since then at least 10 aerial surveys, up to February 2008, indicate that the population is now estimated to be less than 30, with only two nucleus breeding pairs. Most of the original study area is now depleted of Dugongs because of the trappings and subsequent incidental drownings.

Mozambique’s fisheries and Port Captain authorities continue to facilitate the use of gill nets within the boundaries of the national park.  This makes a very difficult task for the conservation authority – Direcção Nacional da Áreas da Conservação (DINAC) – which is charged with controlling the continuing destruction of the Dugong.

Dugongs have a very important niche in the marine environment.  They convert the little-used marine grasses into useful nutrients for the benefit of other mariner fauna, such as fish, and the reported reduction of fish catches in the two districts could be the result of the demise of the Dugong.”

dugong2s_feb08Dugongs then and now

Dyllan Smith, cameraman for Nguni Productions and 50/50, preparing to make the most of an aerial perspective.

“From 1969 until 2003 there were several reports of Dugong sightings in the vicinity of the Bazaruto Archipelago, and until the early 1970s there were  also accounts of Dugongs in other suitable sea grass habitats near Inhaca, Inhambane, Chitenguela, and Angoche. The intensification of large mesh gill netting from 1976, coupled with the lack of law enforcement, has been the principal cause of the decline of Dugongs in Mozambique.  This decline extends, as far as is known, up to the Somalia border with Kenya.

The population of Dugongs at Inhaca, once numbering about 20, is believed to be extinct also as a result of gill netting. Small numbers of Dugongs have been reported near Lingalinga, Inhambane, but their current status is not known.  The present situation at Angoche is also unknown, and my own enquiries indicate that Dugongs are now extinct on the northern coast of Mozambique.  There are reports from further north that Dugongs are now extinct on the Tanzanian coast, with only a few isolated groups in the Lamu district of Kenya.  So it appears that Bazaruto has the last remnant population of Dugongs, now numbering about 20 animals with only two breeding pairs, the rest being lone males.  

It is illegal to kill Dugong in Mozambique and the offence carries a fine of 50 000 000 Meticais, or 16 000 Rand.  However, there were no convictions on record until 2008 when a local fisherman was arrested for having the remains of a recently killed Dugong on his property. There is anecdotal evidence that flesh from captured Dugong was served on occasions at Margaruque island, and Vilankulo’s Port Captain once prepared a special meal of Dugong flesh for ex president Chissano!  It is only recently that gill nets have been banned in the vicinity of the Bazaruto Archipelago National Park, but illegal nets are still being set, some close to where the last breeding groups of Dugong occur.

Since 1990 systematic surveys of Dugongs within the Bazaruto area have been undertaken by various researchers using different methodologies and search intensities.  Aircraft have flown at altitudes varying from 100m to 150m, along selected transect lines with sample strip widths varying from 368 to 500 m. Low tide and calm periods were preferred for counting. The average flight time covering the study area varied from three to five hours.  Despite these varying methodologies, a useful indication of Dugong population trends has nevertheless emerged.  For the current survey a total of 14 transects 5km apart from abeam Inhassoro to Quewene Bay were flown at 80 miles/hour at an average altitude of 600ft ASL. Observations for this survey included animals recorded within an estimated 1000m on either side of the aircraft. Three observers participated in the survey.”

dugongs3_feb08Dugong Population Trends

Bateleur pilot, Barry de Groot, flying over Benguerua

“Whereas it was possible during earlier surveys to derive reasonable estimates using statistical analysis, the current sparse and unevenly distributed population makes this impractical and produces biased estimates.  For this reason the 2003 survey attempted a total count by increasing the search intensity to 35% over an extended flight time of five hours.  This total was augmented by reports of a number of individual animals from various operators in the study area.

After 18 years of survey there is little doubt that the current status of the Dugong is critical and immediate action must be taken to address the imminent extinction of the Bazaruto Archipelago Dugong. Credit must be given to the Direcção Nacional da Florestas e Fauna Bravia (DNFFB) and now Direcção Nacional da Áreas da Conservação (DINAC) for trying to prevent the use of gill nets in the proclaimed boundaries of Parque Nacional da Bazaruto, using limited means due to inadequate budgets – for example, there is no money to cover fuel costs for the patrol boat at Sitone.

It is recommended that future air surveys should concentrate effort where the last of the Dugong occur, according to the 2008 survey, and that transect lines should be established at least 1km apart to arrive at a total rather than sample count.  Also, funds should be sought to reinforce the current public conservation awareness campaign which could include posters for distribution throughout the Vilankulu and Inhassoro districts, as well as the provision of school exercise books with an image of a Dugong on the front cover and information on its usefulness on the inside cover, in both Portuguese and Xitswa.”

dugongs4_feb08The Dugong Survey Team

Standing, from the left:  Paul Dutton, Dyllan Smith, Chris Rattray, Ryan Logie and Richard Compton.  Crouching:  Nicky Troll and Barry de Groot.

Paul Dutton, Chris Rattray and Barry de Groot are Bateleur pilots.  Although a pilot, on this occasion Paul requested this mission and acted as the guide for the Dugong survey.  Dyllan, Ryan, Richard and Nicky comprised the four-person media team from Nguni Productions, contracted by 50/50.  Between them the entire team produced a very fine documentary describing the Dugong crisis which was screened by 50/50 on Monday, 17th March 2008 – with excellent coverage for The Bateleurs as well as the Dugongs.

Paul’s report, continued:
“The status of Dugongs in the entire Western Indian Ocean region, including the satellite islands, is critical.  This is due mainly to the use of gill nets set for harvesting sharks.  for their fins (Marsh, H. H 2001). The fact that there are still a few breeding groups in the Bazaruto population (estimated at 20) provides probably the last opportunity to save them from extinction.

The study area in which Dugongs occurred during the period 1990 until 1994 contained a well distributed population including a breeding nucleus of 30 animals. Recent surveys indicate these areas are now devoid of animals. The current survey shows that Dugongs are now concentrated near islands and Sanctuary.

Managing this smaller area will assist anti-poaching measures and the removal of illegal nets by all the lodges located in the Park, in collaboration with the Direcção Nacional da Areas da Conservação (DINAC).  Also, DINAC, which administers the Park, should be given the means to manage the remaining few Dugongs.

Once again, The Bateleurs – Flying for the Environment in Africa responded to an urgent call for help by sourcing the pilots and aircraft and paying for the fuel for the survey of the Bazaruto National Park’s last Dugongs.  Bateleurs pilots Chris Rattray and Barry de Groot showed their piloting skills in getting our team of seven safely to Mozambique’s Bazaruto Archipelago, and again during six hours of precision flying along survey transects to obtain a count of the highly threatened Dugongs.

The 50/50 team comprising Nicky Troll, Richard Compton, Ryan Logie and Dyllan Smith must be commended for their hard work and enthusiasm in covering the labyrinthian eco-political intrigues that characterise Bazaruto’s highly threatened Dugongs.”