Analysis of Impacts of Shallow Water 2D and 3D Seismic Survey and Exploration Drilling on Marine Mammals and Marine Turtles in the Rovuma Area 1, Mozambique, proposed by AMA1

Prepared by: Almeida Guissamulo

Marine Biologist Marine Mammal Specialist UEM – Natural History Museum. Maputo. Mozambique.

Report prepared for Impacto – Projectos e Estudos Ambientais

1 Contents

1. Introduction...... 4 2. Project Area...... 4 5 4. Species of marine mammals existing in the Project area...... 5 4.1 Baleen whales (true whales)...... 5 4.2 Sperm whales...... 6 4.3 Killer whales ...... 8 4.4 Short-finned pilot whale ...... 8 4.5 Melon-headed dolphin ...... 8 4.6 False killer whale ...... 8 4.7 Cuvier’s beaked whale ( Ziphius cavirostris )...... 9 4.8 Blainville’s beaked whale ( Mesoplodon densirostris ) ...... 9 4.9 Longman’s beaked whale (Indopacetus pacificus )...... 9 4.10 Risso’s dolphin ( Grampus griseus )...... 9 4.11 Rough-toothed dolphin ( Steno bredanensis )...... 9 4.12 Long snouted spinner dolphin (Stenella longirostris )...... 10 4.13 Spotted dolphin ( Stenella attenuata )...... 10 4.14 Striped dolphin (Stenella coeruleoalba) ...... 10 4.15 Fraser’s dolphin ( Lagenodelphis hosei )...... 10 4.16 Bottlenose dolphin ( Tursiops sp.)...... 11 4.17 Indo-Pacific humpback dolphin ( Sousa plumbea or S. chinensis ) ...... 12 4.18 Long-Beaked Common Dolphins(Delphinus capensis) ...... 13 4.19 Dugong (Dugong dugon) ...... 13 4.20 Sea turtles ...... 14 5. Description of the 2D and 3D seismic exploration activity, and the potential impacts on marine mammals and sea turtles...... 17 5.1. 2D and 3D seismic exploration ...... 17 5.1.1. 2D Survey ...... 17 5.1.2. 3D Survey ...... 17

5.2. Discussion of the potential impacts of the 2D and 3D seismic exploration on cetaceans, sirenians and sea turtles...... 18 5.2.1. The behavior of sound in the marine environment...... 18 5.2.2. Effects of the seismic survey on cetaceans, dugongs and sea turtles ....19 5.2.3. Zones of sound influence on animals, from the sound source; ...... 20 5.2.4. List of the effects of the increased level of sound on wild life...... 21 5.2.5. Sound emissions, audio frequency and sound susceptibility of marine mammals and sea turtles...... 22 5.3. Responses of marine mammals to the influence of seismic exploration...... 24 5.3.1. Marine mammals...... 24 5.3.2. Marine turtles ...... 27 5.4. List of impacts of seismic exploration on marine mammals and sea turtles...... 28 5.5. Mitigation measures to avoid or minimise the potential impacts of seismic exploration in shallow waters...... 29 6. References...... 32

2 List of figures

Figure 1. Map of all the sightings of marine mammals and sea turtles observed in the exploration area up to 17.04.2008 ...... 7 Figure 2. The bottlenose dolphin (Tursiops aduncus) at Ponta do Ouro. Photo by Angie Gulland ...... 11 Figure 3. Humpback dolphin (Photo: Almeida Guissamulo) ...... 12 Figure 4. Journey of the turtle Cláudia ...... 16 Figure 5. Zones of influence of seismic exploration shots for toothed cetaceans and dugongs... 21 Figure 6. Zones of influence of the seismic exploration shots for whales...... 21

List of tables

Table 1. Marine mammals species of in the Mozambique Channel [(*) species whose presence was confirmed in the area by Peddemors et al. 1997 and Kizka et al. 2006; (** ) Occurrence confirmed in the exploration area and nearby (Other sources: CSA Internacional 2007, Marques da Silva et al., 2007); Occurrence confirmed in the Comoros (Kizka et al 2006)]...... 14

Table 2. Intensity of sound and pressure (dB re 1 micro Pascal) at one metre from the source (data taken from the document of APPEA, which adapted it from Swam et al 1994 and Ketten 1998)...... 18

Table 3. Levels of frequency of audio sound of various marine mammals and marine turtles (Source: Western Australian Department of Industry and Resources)...... 23

Table 4. Hearing frequency amplitude of 3 species of sea turtles. In parentheses, the best hearing frequencies are indicated (Source: Ketten & Bartol, 2006)...... 24

Table 5. Results of the Acoustic Modeling. *...... 29

Table 6. Table analysing potential impacts on marine mammals and sea turtles...... 32

3 1. INTRODUCTION

The knowledge of species of marine mammals in the Mozambique Channel dates back to the 18th century, during the period of the exploitation of cetaceans, and is based mainly on records from whaling ships (Wray & Martin 1983). After this period, no detailed study was undertaken, until 1979, when a brief survey was made of species on the Mozambican coast by scientists on board the R/F Fridjoft Nansen (Saetre & Paula and Silva 1979) which explored the entire Mozambican coast. Some whale and dolphin species were reported. More recently, in 1991 and in 2003, 2 cruises were held along the Mozambican coast, but both were limited to the southern and central regions (the first as far as Quelimane, and the second as far as Mozambique Island (Findlay et al, 1993 and Findlay et al. 2004). However, based on various information gathered sporadically on the waters of the Mozambique Channel (in both Mozambique and Madagascar), Peddemors et al. (1997) compiled the list of cetaceans (whales and dolphins) that occur in the Mozambique Channel (de Boer et al. 2003).

A study in the Comoros Archipelago lists the species of cetaceans that may also occur in the coastal waters of northern Mozambique, given the geographical proximity and the mobility of these species (Kiska e t al. 2006). Furthermore, in 2007, an aerial reconnaissance of marine mammals and sea turtles undertaken on the continental shelf (from the coast up to 200 metres in depth), resulted in observations of 3 species of marine mammals – Sousa chinensis near the coast, Tursiops aduncus in the eastern part of the islands and an enormous school of the genus Stenella , near Tecomaji island. The acoustic and visual monitoring undertaken as part of the seismic exploration done in Rovuma Area 1 by the company AMA1, in 2007 and up until April 2008, showed the occurrence of dolphins (species unidentified), pilot whales ( Globicephala melas ), sperm whales ( Physester macracephalus ) and humpback whales ( Megaptera novaeangliae )

Five species of sea turtles occur in Mozambican waters, but they have different nesting areas (Hugues 1971). The knowledge of nesting sites on the northern coast of Mozambique is sparse, but one should note the studies undertaken in Vamizi, where the green turtle ( Chelonia mydas ) and the hawkshead turtle ( Eretmochelys imbricata ) nest (Hill & Garnier 2003).

2. PROJECT AREA

The area where the seismic exploration will take place covers the coastal waters between the mainland and the eastern shore of the islands of the Quirimbas Archipelago, where the depths are mostly less than 200m. However, in some places, where abysses occur between some islands, the depth will exceed 200m. The average depth between the islands of the archipelago and the mainland is mostly less than 20m, although there are some exceptions such as the access channels to Mocimboa da Praia and Palma. In general the sea bed is sandy and rocky. The predominant habitats are banks of seagrass in the bays of Olumbi, Palma and Mocimboa da Praia.There are some scattered rocky banks between the islands and the mainland, some of which have been colonized by corals and seaweed. The waters around the islands are mostly dominated by rocky and coral reefs, which are often isolated.

4 The main objective of this project is to undertake 2D and 3D seismic exploration in the coastal waters of Rovuma Area 1 to determine drilling sites. The drilling will be used to determine whether the prospects identified contain commercial quantities of hydrocarbons. The exploratory drilling is a temporary activity and leaves no structure on the surface of the ocean after the end of drilling operations.

3. SPECIES OF MARINE MAMMALS EXISTING IN THE PROJECT AREA

According to Peddemors et al. (1997), at least eighteen species of marine mammals have been recorded in the Mozambique Channel, twelve of which probably occur in the project area (Table 1). Peddemors et al. (1997) compiled this list based on observation from cruises undertaken on the Mozambican coast in 1991, as well as on other observations obtained during cruises carried out in the Mozambique Channel and on the southeast and southwest coast of Madagascar in 1994. A list of marine mammals that occur in the central Mozambique Channel produced by Kizka et al (2006) has been added.

3.1. Baleen whales (true whales)

Two species of fin whales occur on the coast of Mozambique, namely the humpback and minke whales. The humpback whale occurs in the waters of the Mozambique Channel during the southern winter, where it travels for purposes of mating and procreation. Findlay et al (1994, 2004), who conducted two cruises on one part of the Mozambican coast in 1991 and 2003, confirmed that more females with newborn calves predominate in the northern part of Mozambique than the southern part. The whale numbers were estimated at 1954 animals in 1991 and close to 6,000 whales in 2003. In the region between Vamizi and Rongue islands, in the Quirimbas Archipelago, humpback whales occur between June and November. These are mostly females with new-born calves, which makes clear the importance of this region as a breeding site (Isabel Silva, Biologist of Maluane, Lda, 2006). These whales with calves do not tolerate the approach of sports fishing motor boats. During the seismic exploration undertaken in January 2008, for the AMA1 Deep water 3D seismic program, teams of Marine Mammal Observers noted some humpback whales in the project area. These observations are unusual as they occurred outside of the migration period of these whales and therefore require better research of species identification for their certainty, knowledge of original stock and group age structure, and amount of whale population staying in the area outside the migration season.

Despite their distribution close to the coast, humpback whales may cross very deep areas, heading towards the Comoro Islands and Mayotte or to Madagascar. The whales, which move along the coast of Mozambique may often cross the Mozambique Channel at various locations, in order to reach the islands in the middle of the Mozambique Channel or even the Island of Madagascar, which are their mating sites (Best et al. 1998). Often, sounds of solitary individuals making these crossings have been recorded (Best et al. 1998).

The minke whale, which occurs in two forms in the Indian Ocean, is not very well-known but is also found in the waters of the continental shelf of the Mozambique Channel. It normally rests in areas with depths varying between 20 and 50m. It was observed once

5 in Bazaruto Bay (September 1992). Despite being not very well-known, it is considered the most common whale and engages in solitary behaviour. During the southern summer, it occurs in the Antarctic circumpolar region and in winter it migrates to the region situated between the latitudes of 7ºS and 35ºS. Although it feeds on krill, it also consumes schools of pelagic fishes. Its social structure is complex, with divisions by age, sex and reproductive stage.

3.2. Sperm whales

The sperm whales in the Indian Ocean consist of three species, namely the sperm whale (Physester macrocephalus), the pygmy sperm whale (Kogia breviceps) and the dwarf sperm whale (Kogia simu). Generally, these species inhabit the deep areas of the continental shelf and of the continental slope. They possess the spermcetti organ in the head, which gives them the ability to dive to extraordinary depths (up to several hundred metres).

The Physester macrocephalus sperm whale was the target for hunting in the Indian Ocean in the XVIII and XIX centuries, which considerably reduced its population. The males exhibit wide migratory movements out to very high (circumpolar) latitudes while the females, who have a cohesive social structure, tend to remain in certain areas, close to undersea slopes and abysses. They can stay immersed for up to forty minutes, and normally stay on the surface for periods of ten minutes in the interval between dives. Visual and acoustic observations undertaken in January 2008 during seismic exploration of area 1 of the Rovuma basin confirmed the occurrence of the sperm whale in waters between 500 and 1,000 meters deep, near Vamizi island, and near an underwater abyss.

The pygmy sperm whale and the dwarf sperm whale differ slightly in the form of the fin and in the size and number of teeth. Their adult size is 2.7 and 3.2 m, respectively. Normally they are solitary or occur in groups reaching six and ten animals. They tend to stay for long periods on the surface of the sea, but have the ability to dive to great depths. Their migratory movement is unknown, as is their abundance. They inhabit the deep waters of the continental shelf and slope.

6

Locations of Shutdowns for Turtles

Locations of Sperm and humpback

Location of Pilot Whale

Map of all Marine Mammal and Turtle Sightings and Detections, up to 17.04.08.

Green Dots refer to Turtle sightings Blue Dots refer to visual sightings and acoustic detections of Dolphin species Red Dot refers to confirmed Pilot whale sightings Black Triangles refer to Whale visual sightings and acoustic detections. So far no whales have been acoustically detected.

Figure 1. Map of all the sightings of marine mammals and sea turtles observed in the exploration area up to 17.04.2008

7 3.3. Killer whales

Two species of killer whales occur in the Mozambique Channel: the killer whale (Orcinus orca) and the pygmy killer whale (Feresa attenuata) . Their distribution and numbers in the Mozambique Channel and in the project area are not very well-known. The killer whale (Orcinus orca) tends to inhabit the circumpolar regions, but during the winter they tend to wander, which means they do not display a distinct migratory movement. They feed off a variety of prey, including other whales, dolphins, sea turtles and fishes..

The pygmy killer whale (Feresa attenuata) can reach 2.6 m, with a pan-tropical distribution, inhabits ocean waters and forms groups of about fifty animals. Its distribution in the Mozambique Channel is unknown, but the species is considered rare and does not undertake any migratory movement.

3.4. Short-finned pilot whale

The short-finned pilot whale (Globicephala macrorhynchus), which can reach up to 7 m in size, inhabits tropical waters and occurs in groups of fifteen to fifty animals. In the southern hemisphere. Mating occurs in May and births in July – August. Its diet is dominated by squid. Its status is considered good and the species is abundant, although the numbers are unknown. It does not have a migratory nature, although it wanders. During the seismic exploration for the AMA 1 Deepwater 3D program, the teams of Marine Mammal Observers observed the short-finned pilot whale in waters about 1,000 meters deep, in front of the Bay of Mocímboa da Praia, in January 2008.

3.5. Melon-headed dolphin

The melon-headed whale (dolphin) (Peponocephala electra) has a broad distribution in the tropical seas and oceans, but not going beyond the latitudes of 20°S and 20°N, inhabiting sites where the shelf is narrow and next to the continental slope. It is an extremely gregarious species, with groups of hundreds of animals being reached. It feeds on prey (fishes, squid and crustaceans), which inhabit great depths (1500 m). Its status is not considered vulnerable, although its numbers are not known. It does not have a migratory nature, but its occurrence in temperate waters may be associated with the warm currents.

3.6. False killer whale

The false killer whale (Pseudorca crassidens) has a broad distribution, and is gregarious (groups normally of ten to twenty individuals) in the coastal regions, up to depths of 1,000 m. It feeds on various animals, including other cetaceans, but normally it occurs on the continental slope and prefers cephalopods (squid). Its numbers on the Mozambican coast are unknown. No migratory character is known.

8 3.7. Cuvier’s beaked whale ( Ziphius cavirostris )

This species, the length of which can reach 7 m, inhabits the cold deep ocean waters of the tropical and temperate regions, in locations with a sharp depth gradient (in abysses). Normally they are solitary or occur in groups of up to seven animals. They feed on squid, fish and some deep-water ocean crustaceans. Their number is unknown, but it is known that the species is very vulnerable to certain types of sound emission (ASOC, 2005).

3.8. Blainville’s beaked whale ( Mesoplodon densirostris )

This species, which may reach a maximum length of 4.5 m, is widely distributed in tropical and warm temperate waters. There is no evidence of them being migratory, and they occur in locations the depths of which ranges from 500 to 1,500 m, and in abysses. They occur in groups of 3 to 5 animals; they may dive for up to 22 minutes and are sensitive to acoustic trauma (ASOC, 2005.

3.9. Longman’s beaked whale (Indopacetus pacificus )

This is a very little known species. The adults grow up to 6 to 9 meters long. The coloring is variable, but dominated by grayish brown tones. The melon organ is well developed and can be white. The beak is relatively long, as is the dorsal fin, which is hooked, and is located on the posterior part of the body. Behind the blowhole the head is a black/dark grey color. There is just one pair of well developed teeth in adult males. The teeth are inclined forward at the tip of the jaw. The beak has an “abnormal” lateral swelling half way along its length. They occur in cohesive groups of 5 to 20 animals, and sometimes these groups reach a hundred individuals. They expose the beak and the melon above the surface when traveling rapidly. Their blow is low and bushy. Their dives last for 18-25 minutes. They are sometimes seen with short-finned pilot whales and bottlenose dolphins. They occur in tropical ocean waters. They feed on deep sea fish, squid and possibly crustaceans and echinoderms (starfish and sea urchins) from the sea bed. Little is known about their breeding.

3.10. Risso’s dolphin ( Grampus griseus )

This dolphin, which does not reach more than 4m in size, normally has a spotted body. It occurs in the tropical and temperate regions and inhabits very narrow niches on a seasonal basis, with temperatures that vary between 10° and 28° C, on the steep continental slopes where the depth reaches 300 m. It has no defined migration patterns and feeds on various kinds of cephalopods, mainly at night. They are considered to be abundant in the world.

3.11. Rough-toothed dolphin ( Steno bredanensis )

This species occurs in ocean waters of the tropical regions and rarely close to the mainland. However, it may occur close to the islands, the coast of which is situated near

9 the continental slope. It forms groups of 10 to 20 individuals, undertakes deep dives and can stay submerged for 15 minutes. It feeds on fish and cephalopods. It is considered a common and widely distributed species. Peddemors et al (1997) report this species in the centre of the Mozambique Channel

3.12. Long snouted spinner dolphin ( Stenella longirostris )

This species inhabits the coastal tropical and subtropical waters, and is most abundant between the tropics, where the water is deeper than 50 m. Its migratory character is not known and it forms enormous groups in the ocean regions. They reproduce at any time of the year, although they have a reproductive peak, which varies between the different regions. Normally this species rests during the day, off the islands situated near the marine boundary of the continental shelf, and feeds at night on meso-pelagic prey, which rise to the surface. It is an amply abundant species, which causes no concern for conservation. A group of more than 200 dolphins of this species was seen in the Quirimbas Archipelago, on the open sea, on the edge of the continental shelf across from the town of Palma (CSA International, 2007). They are not migratory.

3.13. Spotted dolphin ( Stenella attenuata )

This species occurs in the tropical and warm temperate oceans, between the latitudes of 40º N and 40º S, inhabiting local coastal waters and in some parts of the world it changes location on a seasonal basis, within a diameter of 200 to 300 nautical miles. It is a gregarious species, forming schools of hundreds to thousands of individuals, containing various social units of 20 individuals of a given age range or reproductive state. It reproduces at any time of the year, with various seasonal peaks. It feeds on small pelagic fish, cephalopods and crustaceans. The global population is estimated at around three million individuals, and it runs no risk of extinction.

3.14. Striped dolphin (Stenella coeruleoalba)

This species is cosmopolitan, occurring in tropical and warm temperate ocean waters. Peddemors et al (1997) observed only one group of individuals of this species off the Mozambican coast in 1991. They travel in schools which can exceed 100 individuals, with their diet being varied, including pelagic fish and cephalopods. It is a species that is very abundant.

3.15. Fraser’s dolphin ( Lagenodelphis hosei )

This species has a cosmopolitan distribution in tropical deep ocean waters between latitudes 30º S and 20º N. It feeds on pelagic fish, cephalopods and prawns up to depth of 200-500 m, using echolocation. This dolphin is 1 meter long at birth, and reaches 2.75 meters and a weight of 200 kg in adult life. The body is robust, the melon is not well developed, the dorsal fin, the pectoral fins and the beak are characteristically small. The coloring on the upper part of the body is grey-blue to grey-brown. A dirty cream colored

10 line runs along the flanks from the beak, above the eye, to the anus. There is a dark stripe under this line. They swim rapidly in large groups of between 100 and 1,000 animals, normally leaping above the surface. The status of the species is not well- known. Apparently they breed in the spring and autumn.

3.16. Bottlenose dolphin ( Tursiops sp.)

This species possesses two forms: a coastal form, the size of which is normally less than 2.5 m, inhabiting the coastal waters out to sites where the depth is no more than 30 m (T. aduncus) and another ocean going form (T . truncatus), whose adult size is larger than 2.5 m, which occurs in waters more than 50 m deep, on the continental shelf.

Figure 2. The bottlenose dolphin (Tursiops aduncus) at Ponta do Ouro. Photo by Angie Gulland

Dolphins of the . T. aduncus species occur in groups, with an observed average in Maputo Bay of 27 animals (Guissamulo 2006). During the survey undertaken in the waters of the continental shelf of the Quirimbas Archipelago, few groups of these dolphins were noted and the average size of the group was 8.5 animals (CSA International, 2007). A larger number occurred in open waters close to the islands with reefs. Generally speaking, they were relatively rare in relation to other sites in the South of Mozambique.

Little is known about the oceanic form (T. truncatus), beyond the fact of it having a more robust body. On the east coast of South Africa, this species exhibits migratory movement following the migration of the sardines from the coast of Cape Town out to the coast of Natal Province, during the month of June – July, which is to say, in the winter (Peddemors and Cockcroft, 1993). In 2006 there were beachings of the oceanic form of these dolphins in Zanzibar (around 600 dolphins) (Narriman Jidawi, personal communication 2006) and in 2007 on the Island of Bazaruto 46 dolphins ran ashore (Cockcroft and Guissamulo, 2007), with the causes of these beachings being unknown.

11 However, the group appeared to be dominated by juvenile males, but contained some adult females. A lot of these dolphins were found with empty stomachs or filled with the remains of the digestion of fish and cephalopods.

3.17. Indo-Pacific humpback dolphin ( Sousa plumbea or S. chinensis )

This species, classified as vulnerable due to its occurrence in places with intense human activity and to the degradation of the habitat. It is not migratory and inhabits the coastal waters associated with the mangroves and rocky or coral reefs, at a depth that rarely exceeds 20 m. Its distribution is known within the project area, where it was normally found in the waters between the islands of the Quirimbas Archipelago and the coast of the mainland, with the groups varying from one to ten individuals and the average being four animals (CSA International, 2007). Given its occurrence in shallow waters, it is less susceptible to the action of seismic surveying. It doesn’t normally display seasonal movements (Guissamulo and Cockcroft 2004; Karczmarski 2000).

In tropical waters this species apparently tends to occur in smaller areas than in the temperate regions (coast of South Africa) where there are seasonal variations of temperature and of prey availability. The groups observed in Maputo Bay were extremely large in relation to those reported in other areas of its distribution (Guissamulo and Cockcroft, 2004). Peddemors et al. 1997 observed this species near the main rivers. It should be noted that these observations occurred at greater depths than those inhabited by this species, due to limitations of the vessel in which the cruise was undertaken. Also, its expansion into distant areas was due to the extension of its habitat next to the large riverine systems.

Figure 3. Humpback dolphin (Photo: Almeida Guissamulo)

12 3.18. Long-Beaked Common Dolphins(Delphinus capensis)

In spite of Peddemors et al (1997) not having observed this species in the Mozambique Channel, it occurs in Mozambican waters. A school of these dolphins was observed in May 2003 in the area separating the Islands of Vamizi and Rongui (Guissamulo. personal observation) travelling at high speed alongside a passenger and cargo transport vessel, with some members remaining beside this vessel for a period of three minutes. The site where it was observed consisted of deep waters (between 200 and 600 m), in one of the abysses situated between these islands. Proof of the occurrence of this species in Mozambique also comes from the collection of two crania, one found in the Bay of Sofala and the second in Maputo Bay.

This species is considered oceanic and in South Africa it carries out migratory movements associated with the migration of the sardine (Peddemors et al. 1997). However, it is not known whether the species is migratory in Mozambique. On the other hand, its status is unknown. It feeds mainly on schools of pelagic fish. Reproduction occurs in summer.

The map of marine mammal observations obtained during seismic exploration in area 1 of the Rovuma Basin indicates observations of dolphin species. However, it does not identify the species observed. In any case, this map shown that dolphin species are widely distributed in the exploration area.

3.19. Dugong (Dugong dugon)

The dugong is a herbivorous sirenian which feeds on seagrasses and is classified as vulnerable on the east coast of Africa, due to its extremely low density (WWF Eame 2004). Its distribution in Mozambique was initially described by Hughes (1971), who indicated its occurrence on the coast between Maputo Bay and the Save River and in the area between Angoche and Pemba Bay. This author suggested that the dugongs should likewise occur on the north coast of Mozambique, in the Quirimbas Archipelago. Hughes (1971) indicated that in general the dugongs were relatively common on the coast, even though they were rare to the south of Inhambane. In that time, frequent catches of these animals were already reported in the non-industrial fisheries spread throughout the country (Hughes 1971).

The ecological value of this species is high, due to its important role in the dynamic of seagrasses. However, it is one of the marine species with priority for conservation, due to its monophyletic character and its extreme vulnerability to disturbance factors. The Mozambican coast possesses one of the possible viable populations of dugongs on the east coast of Africa (WWF EAME, 2004).

Although the species has historically been reported as occurring in the area between the islands of the Bazaruto Archipelago and the mainland, in the area between the Island of Macaloe and the Island of Sencar (WWF EAME, 2004), aerial reconnaissance undertaken in March 2004 over the whole Quirimbas Archipelago in the waters of the continental shelf, was not able to observe any dugongs. This implies that the species is very rare in the area. On the other hand, it is unlikely that the dugongs occur beyond the

13 waters of the continental shelf, despite these animals being capable of crossing extremely deep areas.

Table 1. Marine mammals species of in the Mozambique Channel [(*) species whose presence was confirmed in the area by Peddemors et al. 1997 and Kizka et al. 2006; (** ) Occurrence confirmed in the exploration area and nearby (Other sources: CSA International 2007, Marques da Silva et al., 2007); Occurrence confirmed in the Comoros (Kizka et al 2006)].

Period of Reproduction Common name Species Period of occurrence Residence Seasonal June - June – Humpback whale Megaptera novaeangliae* November November Balaenoptera acutorostrata Seasonal June - June – Minke whale November November Dolphin Delphinus delphis/capensis* Unknown All year Pygmy killer whale Feresa attenuata All year All year Short-finned pilot All year All year Globicephala macrorhynchus* whale Risso’s dolphin Grampus griseus* All year All year Pygmy sperm All year All year Kogia breviceps whale Blainville’s beaked All year All year Mesoplodon densirostris whale Killer whale Orcinus orca Seasonal/ Melon-headed All year Peponocephala electra* whale All year/males All year Sperm whale Physeter macrocephalus are migratory False killer whale Pseudorca crassidens* All year All year Indian humpback All year All year Sousa plumbea* dolphin Pantropical All year All year Stenella attenuata* spotted dolphin Striped dolphin Stenella coeruleoalba* All year All year Long-snouted All year All year Stenella longirostris* spinner dolphin Rough-toothed All year All year Steno bredanensis* dolphin Bottlenose dolphin Tursiops truncatus* All year All year Cuvier’s beaked All year All year Ziphius cavirostris whale Dugong Dugong dugon Unknown All year

3.20. Sea turtles

Five species of sea turtles inhabit Mozambican coastal waters, namely the green turtle (Chelonia mydas), the leatherback turtle (Dermochelys coriacea) , the loggerhead turtle (Caretta caretta) , the Olive Ridley turtle (Lepidochelys olivacea) and the hawksbill turtle (Eretmochelys imbricata) (Hugues 1971). All of these species are listed as threatened by

14 the IUCN Red List, with the leatherback turtle and the hawksbill turtle considered critically threatened.

Recent studies undertaken by the Maluane Group Ltd. in conjunction with the London Zoological Society on the coast of Cabo Delgado Province, on the islands of Vamizi and Rongue as well as Macaloe Island, indicate that only two species of turtles nest in the area, namely the green turtle and the hawksbill turtle (Hill and Garnier, 2003). The turtles nest mainly on the sandy beaches of the islands, with the nesting periods being different from those observed in the southern and central regions of Mozambique. In these areas, the turtles nest throughout the year, but in Vamizi Island nesting peaks in January and August. In Macaloe Island the turtles have their nesting peak between November and May, with the reasons for this variation being unknown.

The distribution of the sea turtles in the waters of the continental shelf of the Quirimbas Archipelago was recently documented by CSA International (2007) as being scattered over the whole Archipelago. The turtles were four times more abundant in the waters of the Quirimbas National Park than in the northern part of this Archipelago, outside the Park. The largest groups of turtles outside of the park were observed in the deep waters situated around Macaloe and Medjumbe Islands. During the seismic exploration for the AMA1 Deepwater seismic program, the teams of Marine Mammal Observers, from January to March 2008. noted some turtles in the area in front of Suafo island.

A green turtle which received a satellite positioning device in April 2007 on Vamizi Island, where it had nested, has already travelled a distance of more than 3,000 km, crossing the coastal waters of Tanzania and reached the Kenyan coast. Its course was undertaken along the coast and often in waters less than 1,000 m. deep (see Figure 1 obtained from the site: http://www.zsl.org/field-conservation/marine-and- freshwater/turtle-tracking,615,AR.html ). The greater part of the journey was undertaken in the first twenty days.

15

Figure 4. Journey of the turtle Cláudia

16 4. DESCRIPTION OF THE 2D AND 3D SEISMIC EXPLORATION ACTIVITY, AND THE POTENTIAL IMPACTS ON MARINE MAMMALS AND SEA TURTLES.

4.1. 2D and 3D seismic exploration

2D and 3D seismic exploration and the drilling of wills will take place within the limits of area 1 in waters that are not deeper than 200 m (Figure 1), but the exact location of the wells will only be determined after the results from the analysis of the seismic exploration which is under way.

4.1.1. 2D Survey

The 2D seismic exploration in shallow coastal waters will be undertaken along a grid of lines that have not yet been defined were not of the knowledge of the consultant (the Author of thisDocument), in order to determine the likely area of hydrocarbon accumulations. It will be done through a recording technique known as “shallow water streamer”. The boat carrying the sonar source operates alongside the shallow keeled boat which does the recording.

The equipment will consist of the following: a) A seismic sonar source of compressed air coupled to a boat. b) a single cable (e.g., 1 - 2 km long) containing several hydrophones that serve as receivers of the seismic sound produced by the seismic source and reflected from the sea floor. c) a recording system and related equipment to place the seismic source and hydrophones in their appropriate positions and monitor them once in position d) a tail buoy equipped with a radar reflector and flashing light, which is attached to the end of the streamer for navigational purposes and to warn passing vessels.

4.1.2. 3D Survey

The 3D seismic survey makes it possible to obtain geological information from below the sea-bed between the lines of the seismic survey. To this end, rectangular grids of deep cables or individual receivers, which are recording equipment, are placed on the surface of the sea bed. The distance between them is 100m to 500m. Another boat carries the sonar source of compressed air and operates independently of the recording boat. The sound waves sent to the sea bed are reflected to the surface and caught by the hydrophones of the deep cables or the individual receivers. While the cables immediately collect the sound reflected to the ship, the individual receivers store the data in their memories and the data are transmitted when they are recovered.

17

4.2. Discussion of the potential impacts of the 2D and 3D seismic exploration on cetaceans, dugongs and sea turtles

4.2.1. . The behavior of sound in the marine environment

This chapter is based on the descriptions of APPEA - Australian Petroleum Production & Exploration Association and on information no. 012/2003 of IBAMA – the Brazilian Institute on the Environment and Renewable Natural Resources. These institutions have ordered studies on the effect of seismic exploration in their respective countries. One of the best known studies is that of MacCauley et al (2003), but Engel et al (2000) lists other authors who assessed the effect of seismic exploration on cetaceans.

There are many natural sound sources in the marine environment. The wind, the waves, fish, whales, etc, all contribute to high levels of sound in the environment. Natural events such as underwater volcanic eruptions, earthquakes and lightning strikes, can also produce short duration, acute and intense sounds. Table 2 shows the frequency and intensity of sound sources. On the other hand, sounds of human origin include those caused by the movement of ships, seismic exploration, and echo-sound (in shipping, fisheries, the military) as well as building and demolition work. These sounds may be propagated over long distances in the marine environment, because the pressure and the velocity of particles is very different between water and air for the same sound intensity. The intensity of sound declines as it travels away from the source. The highest intensity occurs very close to the sound source, but it falls drastically with distance from the source.

Table 2. Intensity of sound and pressure (dB re 1 micro Pascal) at one metre from the source (data taken from the document of APPEA, which adapted it from Swam et al 1994 and Ketten 1998)

Source Intensity of sound ( dB) Frequency Undersea earthquake 272 50 Hz Undersea volcanic eruption 255 or + Variable Lightning strike on the 250 Variable surface of the sea Acoustic source of seismic 230 – 255 < 200 Hz exploration Pulses of sperm whales Up to 235 db 100 – 30,000 Hz Pulses of bottlenose Up to 229 Up to 120,000 Hz dolphins Sound of ship (near the 200 10 – 100 Hz hull) Leap of whale 200 20 Hz Song of blue whale 190 12 – 400 Hz Marine ambient sound 80- 120 Variable

18 The emission of horizontal energy from the sound source is the most crucial when considering sound transmission over long distances. During the seismic exploration, the sound emitting apparatus, namely the compressed air sources, are arranged specifically so that the sound waves are directed at the sea bed; therefore, most of the energy is propagated downwards and not horizontally (APPEA publication 2006). So the intensity of the sound measured directly below the seismic source is not an appropriate way of measuring the potential horizontal transmission of the sound. The signal transmitted by the water can be propagated for some tens of kilometers.The acoustic energy from the seismic exploration sources in waters less than 50m deep diminishes very rapidly with horizontal distance from the source. On the contrary, there is a slight increase in the horizontal transmission of the sound in seismic exploration in deep water..

Measurements of sound taken in sea turtle habitats with intense human activity, notably at Long Island, in the United States, showed that during the day, especially on holidays, the maximum pressure of sound reached 110 dB and declined to 80 dB with the reduction in human activity (Samuel et al. 2005). , which indicates that continual exposure to high sound intensities such as these can affect the behavior and ecology of the sea turtles (Samuel et al . 2005).

4.2.2. Effects of the seismic survey on cetaceans, dugongs and sea turtles

An experimental study of the effect of marine seismic acquisition on marine fauna, conducted by McCauley et al (2000) between March 1996 and October 1999, is the main basis of the analysis of this project’s impact on cetaceans, dugongs and sea turtles. This study, which has been quoted by other literature (Le Provost & Meaney, 2002, e IBAMA 2003), analyzed various aspects of the seismic operation and its effect on the behavior and even on the health of some types of fauna.

The UNICPOLOS (2005) stressed that to understand the acoustic noise effect on marine mammals, it should be remembered that these animals evaluate their environment mainly through the sound that is more effectively transmitted in water, sometimes across many kilometers, while light/vision is useful only for short distances. These marine organisms need to listen to the sounds of their prey and of their predators, to use the sound for their orientation or to select an adequate habitat, to produce sounds for mating purposes and to communicate among group members. The insertion of strange sounds of industrial origin resulting from the traffic of petroleum industry vessels and of vessels’ high intensity echo sounders, do interfere with these animals.

Well drilling activity produces intermittent low frequency noise (10 Hz to 10 kHz at an intensity of 190 Decibels at the source), which results from the action of the drill and the propulsion system of the vessels. Further acoustic disturbance may be caused by the physical presence of boats and aircraft. The most studied cases of the disturbance/effects of drilling on marine mammals concerned the whale Balaena misticetus. It was found that the sound disturbance caused by drilling wells caused a change in its migration route, as it avoided the source of the noise (NOAA 2007),

Maritime and air traffic (of helicopters) to and from the drilling platforms cause not only acoustic disturbance, but also visual disturbance for marine mammals (NOAA 2007)

19 The effect of the noise on marine mammals can vary greatly, and may be categorized as followed:

• The noise may be very weak in intensity (below prevailing levels in the environment) which is not detected by the animal. • The noise may be audible, but not strong enough to provoke a behavioural reaction. • The noise may cause reaction of varying characteristics and relevance to the well being of the marine mammal. Its responses may vary from temporary alert, to actions of active distancing, such as abandoning the area, at least until the noise stops. • Under repeated exposure, the marine mammal may show reduced reaction to the noise (tolerance) or the effects of the disturbance may persist, Persistent disturbance is more likely when the characteristics of the sounds are very variable, and infrequent, and when their occurrence is unpredictable. They are then associated to cases that the marine mammals perceive as threats. • All sounds of human origin that are strong enough to be heard have the potential for reducing (masking) the ability of the marine mammal to listen to natural sounds of a similar frequency, including calls of other animals of the same species and other underwater sounds. • If the mammals remain in the area because it is important for feeding, reproduction or some other reason, even when there is chronic exposure to the noise, it is possible that psychological stress, induced by the noise, may occur. This in turn may have negative effects on the well being or reproduction of the animals involved.

Very intense sounds may cause temporary and permanent reductions in hearing sensitivity. Some sounds received may greatly exceed the thresholds of audition, and may cause permanent hearing incapacity. Furthermore, intense acoustic events or explosions may cause trauma to the tissues associated with the vital hearing organ, the production of sound, breathing and other functions. These traumas may include slight or serious haemorrhages.

4.2.3. Zones of sound influence on animals, from the sound source;

There are four zones of sound influence with effect on the marine fauna in relation to the distance from the source and to the decay of the sound.

(i) In the region nearest to the source, the animal is exposed to discomfort and to the possibility of physical and physiological damage;

(ii) At a rather greater distance, the avoidance zone, the sound interference can disturb or hinder the use of sound communication, orientation, feeding and protection;

(iii) Still further away, the influence of the sound is minor. However, it still causes alterations in the behavior of the animals, who seek to avoiding the sound (response or reaction zone);

20 (iv) In more distant areas, the sound pulse is still audible; however, its effects are limited by the environmental noise level (audibility zone).

The coverage of each of these zones varies in accordance with the physical environmental characteristics and the respective species

Figure 5. Zones of influence of seismic exploration shots for toothed cetaceans and dugongs

Figure 6. Zones of influence of the seismic exploration shots for whales

4.2.4. List of the effects of the increased level of sound on wild life

The effect of the increased sound level n the oceans can have direct impacts, with the potential to cause physical or physiological damage, or indirect impacts which may interfere in basic activities such as feeding and reproduction. The direct effects may be:

i. Physical effects

- Damage to the body tissues and organs (lungs, bladder)

21 - Damage to the tissue and structure related to the sense of hearing - Permanent and temporary alterations in the hearing threshold (reduction of hearing capacity)

ii. Sensor effects

Masking of sounds that are essential for the survival of the animal (communication signs, echo-location, search for prey, and perception of the approach of threats).

iii. Effects on Behaviour

Interference with standard behavior, such as avoiding certain areas as well as diving and breathing standards

iv. Chronic effects

Stress capable of compromising the animal’s ability to survive, or the appearance of diseases.

v. Indirect effects

Reduction of the availability of prey, reduction in food supply, restriction of feeding and breeding areas.

4.2.5. Sound emissions, audio frequency and sound susceptibility of marine mammals and sea turtles.

Marine Mammals

The seismic acquisition produces low frequency sounds, generally lower than 200 Hz. The majority of the odontocete cetaceans (dolphins and toothed whales) have their highest sensitivity to sound at the ultrasonic frequencies (i.e.>20000 Hz), although some species have shown sensitivity of 1000 to 20000 Hz. It has not yet been demonstrated that the odontocetes are sensitive to frequencies of below 500 Hz or that they show any exceptional response to these levels of frequency (APPEA, 2006).

Dolphins, besides producing echolocation sound pulses and intense pulses, also produce sounds of modulated frequency, generally with a harmonic structure described as like a whistle. These sounds have frequencies that vary between 7 and 10 KHz and last for about a second, but may continue for up to 2-3 seconds (Berta and Summich, 1999). These sounds serve as a mean to disseminate the identity of individuals and maybe to communicate other kinds of information to other group members. Sociable dolphins whistle/vocalize more frequently.

No baleen whale has been directly subject to testing of its audio capacity, but it is known that their vocalizations are of a much lower frequency than those of the odontocetes,

22 which means they rarely exceed 10000 Hz. Models that allow for the prediction of superior audio ranges of the whales may reach up to 30000 Hz. Various species of whales can hear low infrasonic frequencies such as 10-15 Hz (APPEA, 2006). The humpback whales are the most vocalizing whales, in their breeding areas. The sounds are emitted by the adult males and normally repeated every 15 minutes. The sound is composed of “themes”, “phrases” and “sub-phrases”, with frequencies below 1,5 kHz. These sounds can be used to transmit sex, age, and location, availability to mate and to compete with other males. These sounds also serve to demarcate underwater territories (Berta & Summich, 1999).

Dugongs transmit short sounds of modulated frequency in the range of 3 to 18 kHz and they are transmitted from the frontal part of the head. Such sounds are transmitted by the dugongs when they feed themselves or when patrolling their territories (Berta & Summich, 1999). In Australia and in many locations where their distribution is extensive, there is evidence that dugongs avoid areas with heavy maritime traffic (Marsh et al , 2005). However, although there have been naval exercises involving detonation of projectiles in one of the areas where dugongs occur in Australia, there is no record up to the moment, of mortality among these animals. On the other hand, some specialized seismic acquisitions that transmit sounds in the frequency range of 500 to 1000 Hz, can interfere with the audio systems of the dugongs, affecting their physiology and behavior. However, the impact of seismic acquisition on dugongs has never been studied (Marsh et al , 2005).

Table 3. Levels of frequency of audio sound of various marine mammals and marine turtles (Source: Western Australian Department of Industry and Resources).

Type of animals Frequency of Better listening Level of overlap Migratory audible sounds frequency with seismic character emissions Baleen whales 12 Hz up to 8 10 – 100 KHz High Yes and sperm KHz, whales Dolphins, pilot 75-125 KHz up 1 KHz Small whales and to 105-150 beaked whales KHz Dugongs 1-2 KHz Small Turtles 100 – 700 Hz High Seismic 10 – 300 Hz emission

Sea turtles

Five species of sea turtle occur in the waters of northern Mozambique (Hugues 1971, Hill & Garnier 2003). Studies of hearing levels of turtles are rare, and have only been done for the green turtle ( Chelonia mydas ) and the loggerhead turtle ( Caretta caretta ). New born and juvenile individuals of these species hear in a broad range of frequencies (100- 800 Hz), but this declines in the adults (100-500 Hz) (Ketten & Bartol, 2006).

23 Table 5 shows the amplitude of frequencies heard and the levels of hearing by age of the 2 species. No data on hearing were found for the other species of sea turtles, namely the leatherback turtle ( Dermochelys coriacea), the Olive Ridley turtle (Lepidochelys olivacea) and the hawksbill turtle ( Eretmochelys imbricata) . However, it was noted in this study that another species (which does not occur in Mozambican coastal waters) Lepidochelys kempi (from the Atlantic Ocean) possessed a lower sound perception frequency amplitude (Ketten & Bartol 2006).

Table 4. Hearing frequency amplitude of 3 species of sea turtles. In parentheses, the best hearing frequencies are indicated (Source: Ketten & Bartol, 2006).

Specie Newly born Juvenile Sub-adult T. bighead ( C. caretta ) 100-900 Hz 100 – 700 Hz 100 – 400 Hz (500-600 Hz) T. green ( Chelonia mydas ) 100 – 800 Hz No data 100 – 500 Hz (600-700 Hz) (100-200 Hz) Lepidochelys kempi No data 100 – 500 Hz No data (100-200 Hz)

These studies show that the seismic exploration partially overlaps with the hearing frequencies of some species of sea turtles.

4.3. Responses of marine mammals to the influence of seismic exploration

4.3.1. Marine mammals

Baleen whales

McCauley et al. (2000) made tests of the proximity of seismic acquisition vessels in operation on humpback whales in the northeast coast of Australia. This place is one of the known areas of humpback whale mating and procreation during winter. In this season, the whales were migrating south, while the seismic acquisition vessel was following its course on an east-west route. Sixteen (16) proximity experiences were made during which the humpback whales were observed for a one-hour period. Afterwards the seismic acquisition vessel containing the seismic sound source went closer and they were followed during another one hour period. In these observations, behavior was recorded one hour before and one hour after the exposure.

The experiences showed the following:

i) The groups of whales which contained females, and the females with newly born calves tended not to go near the acquisition vessel, maintaining an average distance of 1.3 Km from the source of acoustic transmission, with the escape maneuvers seen at distances between 1.2 and 4.4 Km. The whales´ escape was verified with sound intensities of 140dB re 1µPa rms, the maintenance of the minimum distance in relation to

24 the sound of 140dB re 1 1 µPa rms and the reaction of the whales to the noise of the acquisition started to be observed at the sound intensity of 112dB sound re 1 µPa rms (McCauley et al . 2000).

ii) Some adult males came temporarily closer to the acquisition vessel and they quickly swam away, possibly because the sound characteristics are identical to those of a whale in acrobatic jumps (breaching). This suggests a behavior of recognition of rivals/competitors. On these occasions the whales experience levels of sound exposure of 179dB re 1 µPa rms. . iii) While during transit the whales keep at a distance of 1.3 Km from the seismic acquisition source, in the key habitats (of resting or breeding) the whales tend to initiate their flight at a distance of 7-12 Km from the seismic acquisition source. Continuous movement of these animals can reduce the resting and feeding time for the newly born calves and that can cause serious consequences for the population of whales.

Other investigations made by McCauley et al (2000) during the seismic acquisition demonstrate that: i) In general, the seismic acquisition did not change the distribution of whales in the area, however, the whales were more abundant near the seismic acquisition vessel (at a range of 3 Km) when the seismic sound source was not transmitting sound (acoustic sound) than when the vessel was operating the seismic sound source. Therefore these observations suggest that the whales avoid seismic acquisition vessels when they are in operation. This distance of 3 Km corresponds to a sound intensity of 157-164dB re 1 µPa rms in water depths of 32m (McCauley et al . 2000).

ii) When the vessel was operating the seismic sound source, the rates of abundance of whales at distances over 3 Km from the vessel were relatively higher than when the sound sources were not operating(McCauley et al . 2000).

iii) The whales tend to spend more time on the surface near the seismic acquisition vessel when that vessel is in operation. The assumption is that the sound intensity is reduced by the cancellation of sound waves resulting from phase differences during the propagation and reflection at the interface (McCauley et al . 2000).

iv) Seismic acquisition has greater impact on whales (mainly females with calves) when in resting behavior than when they transiting an area. One study showed that in general more whales and dolphins were observed when the seismic exploration ship was present but was not conducting active seismic operations than when operating (Davidson 2000).

Odontocetes (Toothed whales and Dolphins)

In general these impacts are felt mainly on coastal species (bottlenose dolphin Tursiops aduncus and Tursiops sp., Indo-Pacific humpback dolphin Sousa plumbea , the long- snouted spinner dolphin Stenella longirostris , and the spotted dolphin Stenella attenuata ) because the habitat covered is mostly less than 50 m deep. However, on the eastern side of the islands of the Archipelago the depth gradient increases rapidly to 400 m, and

25 this attracts some ocean-going species (Risso’s dolphin, Fraser’s dolphin, sperm whales, beaked whales, pilot whales, melon-headed dolphin), which, though not migratory, frequent these places for feeding, as well as pelagic species that occur marginally in these areas (common dolphin Delphinus capensis , striped dolphin Stenella corealoalba ).

Some of these species have the capacity to remain submerged for long periods of time searching for food. A negative factor will be the absence of concrete (realistic) data about their distribution and abundance in the project area, as well as the fact that some species, particularly sperm and beaked whales are difficult to detect. The census held by CSA International in 2007 verified the occurrence of 3 species of dolphins in coastal waters: in waters less than 200 m deep: the Indo-Pacific hunchback dolphin ( Sousa plumbea ) at depths of less than 20 m, the bottlenose dolphin ( Tursiops aduncus ); and in deeper waters (20 to 200 m) dolphins of the genus Stenella sp. at the limit of the continental shelf. The Marine Mammal Observers recorded alongside the continental shelf and in ocean waters many schools of dolphins, though they did not identify the species (CSA International 2008).

There are few studies carried out on the impact of seismic acquisition on dolphins, although the effect of it is equivalent to the one on whales. Although the dolphins vocalize high frequency sounds, that do not coincide with the main low frequency output transmitted by the seismic sound sources, a part of the transmitted sound by such seismic sound sources can exceed frequencies of 200 Hz (this means that sometimes it can reach 1000 to 8000 Hz) (Cumming & Brandon, 2004). These levels of frequencies can cause disturbances and affect sperm whales, barracuda whales, killer whales, pilot whales and dolphins – that is, all the odontocetes.

In the Gulf of Mexico, where seismic acquisition has been occurring for more than 40 years, sperm whales maintain their presence in the area,. They stop vocalizing and get away from the seismic acquisition areas ( SCAR Ad Hoc Group on Marine Acoustic Technology and the Environment, 2002 ). These whales normally inhabit areas where the water depths are around 1000 meters. They feed on giant squid at depths of about 400- 600 meters and can remain submerged for more than an hour when hunting their prey.

A recently published study by the Minerals Management Services of the U.S Department of the Interior on the impact of seismic exploration through controlled experiments of sound exposure on the threatened population of sperm whales in the Gulf of Mexico showed that, of the 8 whales who had equipment for measuring the sound emissions received and which measured the direction of movement (so-called D-tag), 7 did not change their horizontal direction of movement (that is, moving away) when exposed to sound levels lower than 150 dB re 1 µPa (rms) (Jochens et al. 2008). These results were consistent with the opportunist observations made during seismic explorations. The study also stresses that there were no exposures to sound greater than 164 dB p-p re 1µPa (equivalent to 147 dB re 1 µPa (rms)) (Jochens et al. 2008).

Opportunist observations made in 2002-2004 for two hours, before and after the start of exploration, of whales that were 100, 50 and 20 nautical miles distant showed that the whales did not significantly change their direction of movement with regard to the location of the seismic exploration sound source: the time the whales stayed on the surface, as well as rates of floating also did not vary significantly (Jochens et al. 2008). However, a whale that received levels of sound emission of 164 dB @ 1 µPa remained

26 floating for 4 hours (longer than the 2 hours that whales normally rest after submerging at great depths) and reduced its foraging rate by 60% (Jochens et al. 2008).

Although no change was detected in the direction of movement of the whales exposed to sound emission, these controlled experiments on exposure to sound on sperm whales verified statistically significant changes in the swimming and foraging behaviour of the sperm whales exposed to the sounds of the seismic exploration air sources when the levels of sound reception were between 111 and 147 dB re 1 µPa (rms) ( equivalent to 131 to 164 dB peak-peak re 1 µPa) at distances of approximately 1.4 -12.6 kms from the source of sound emission (Jochens et al. 2008).

Dolphins suffer reductions in hearing sensitivity when exposed to sound pressure of 102- 191 dB re 1 µPa at frequencies of 0.4, 3, 10, 20, 30 and 75 kHz. Furthermore, beaked whales suffered brain haemorrhages when exposed to the action of low frequency sonars of the navy (SCAR ad Hoc group on marine acoustic technology and the environment, 2002). Seismic sound signal emit a wide range of sound frequency and the low frequency range emitted can cause similar effects of the low frequency sonar on marine mammalsl

No experiments have been made on the action of seismic acquisition on dugongs (Marsh et al . 2005) However, there are suspicions that the activity would cause the same effects as verified on whales. Nonetheless, despite their coastal nature (generally at less than 20 m depth, sometimes these animals do cross deeper areas).,

4.3.2. Marine turtles

The experiences carried out by McCauley et al . (2000) tested the effect of the approximation of seismic sound sources on captive green turtles and loggerhead turtles. These tests involved the exposure of 2:04 hours and another of 1:01 hours, with repeated sounds every 10 seconds. The level of sound intensity was 166 dB to 1 µPa rms. The turtles intensified their swimming speed in the periods that they were not exposed to the sound and when the levels of sound transmission from the seismic sound sources reached 175 dB to 1 µPa rms, their movement became erratic. McCauley et al (2000) suggested that this last intensity would be the one in which the turtles could attempt to flee. These levels of sound intensity may have caused temporary hearing loss in the turtles that was recovered in two weeks.

Apparently, the sea turtles start to demonstrate a startled response in relation to the seismic acquisition vessel at a distance of 2 Km and they flee from the source at 1 Km, in deep waters (McCauley et al. 2000). In shallow waters, the turtles tend to remain for a long time at the bottom of the sea, and in this case, although the horizontal sound propagation is weak, the turtles can absorb sounds reflected by the sediment through their skeleton (McCauley et al 2000).

In short, because the marine mammals and the turtles can avoid the approach of the vessels that are undertaking seismic exploration, three main types of impact can be indicated.

Auditory Trauma

27

The prolonged or repeated exposure to sufficient sound levels can induce to a Temporary Transfer of Threshold (TTL) that without time to recover, it causes a Permanent Transfer of Threshold (TPL) or permanent hearing loss. Normally, the temporary transfer of threshold can be achieved at sound reception levels of 180 dB re 1 µPa, according to the US National Marine Fisheries Service (NMFS).

Dissimulation

The dissimulation or disguise of the marine animal’s communication can occur in result of the permanent action of the seismic acquisition. The seismic pulses are temporary and repeated, which reduces the probability of the communication dissimulation. In another hand, due to the big differences in the hearing amplitude of the marine mammals and turtles, its effect is considered negligible. However, the seismic impulses mimmic, in certain manner, some sounds obtained from the acrobatic jumps of the whales and this can attract the animals to the seismic pulse transmission source.

Effect on behaviour

The disturbance in behavior was observed in whales, dolphins and marine turtles. These are more frequent in the whales in their resting places or when the whales are breeding. The NMFS criteria for the disturbance in behavior are of 160 db re 1 µ Pa rms. The acoustic modeling indicates that this fact occur between 7 and 12 Km of the seismic transmission source (McCauley 2000).

4.4. List of impacts of seismic exploration on marine mammals and sea turtles

Based on the discussion above, the following impacts of seismic exploration, in the absence of any preventive or mitigation measures, may be summarised:

1. Acoustic disturbance of marine mammals and sea turtles in the seismic exploration area (limiting their communication and prey location)

2. Reduction in access to or abandonment of critical habitats by marine mammals and sea turtles

3. Alteration of the migration routes of whales and sea turtles

4. Temporary loss of hearing capacity of marine mammals and sea turtles

5. Permanent loss of hearing capacity of marine mammals and sea turtles

6. Death or injury (haemorrhages) of marine mammals and sea turtles caused by action of the seismic exploration systems

28 5. Mitigation measures to avoid or minimise the potential impacts of seismic exploration in shallow waters

The mitigation measures proposed in these studies were obtained from various sources that reviewed the impact of seismic exploration on marine mammals and sea turtles (MacCauley et al. 2000, SCAR ad Hoc Group on marine acoustic technology and the environment. 2002, Cummings & Brandon, 2004, Scripps Institute of Oceanography, 2007). In general, the measures are common for all the species dealt with in this study. It should be stressed that because of lack of data or of studies on the precise impact caused by seismic exploration, a precautionary attitude should be taken towards species where the impacts are unknown (dolphins, toothed whales, dugongs) (Ad Hoc Group on marine acoustic technology and the environment. 2002, Cummings & Brandon, 2004, Marsh et al. 2005, NOAA 2007a, 2007b).

The fact that some resident species occur in the area (and lack of knowledge about the habitats of certain species), as well as reproductive period of the species (seasonal or all year) (Table 7), does not allow us to establish appropriate timeframes for drilling the wells. However, knowledge of the impact for fin whales (July – November off the coast of Cabo Delgado) and sea turtles (nesting peaks in January and August in Vamizi, and May and December on Macaloe island) helps determine possible impact mitigation strategies.

The fact that humpback whales apparently use the waters off the northern coast of Cabo Delgado province as one of their breeding grounds indicates that the impact of seismic exploration during the whales’ migration season may disturb females with calves and affect the population (McCauley et al ., 2000). In this context, careful acquisition measures to avoid hurting the animals or irreversibly affecting their life cycles suggest the application of a conservative safety range equivalent to at least 500m be applied when these animals are in the area of during active seismic acquisition.

The results of the acoustic modeling of the potential for the temporary alteration of the hearing sensitivity (TTL) in relation to the water depth are presented in Table 5.

Table 5. Results of the Acoustic Modeling. *

Reach (m) for Frequency (m) for NMFS Criteria Modeling Water Potential TTL [(180 db re 1 µPa (rms)] Site Depth (m) (186db re 1 Modeling Alteration µPa) prediction 1 950 109 347 616 2 170 112 428 849 3 150 110 441 759 4 330 110 327 662 5 180 108 424 811 6 100 112 507 672 7 220 110 418 850 8 100 114 475 672 9 50 128 379 631

29 * This is based on a maximum range above the water line, which is a range of an angular sector of 60° centered in the axis above the water line of the water axis of the seismic cable that covers all the points in which the received level is equal or superior to the threshold value.

The measures proposed in this study were extracted from specialized studies carried out by various institutions/authors (Cummings & Brandon, 2004; Scripps Institution of Oceanography, 2007, Australian Government – Department of Environment and Water Resources 2007 , APPEA 2006, Compton 2007, McCauley et al 2000, Ad Hoc Group on marine acoustic technology and the environment. 2002, IBAMA 2003, Joint Nature Conservation Committee, 2004):

30 a) Use of minimum levels (intensity , acoustic pressure) sufficient to reach the necessary results to the acquisition b) To delay the start of the seismic acquisition whenever a whale and/or turtle are present in the safety range of 500m around the sound source, until those leave this area. c) The use of the soft start procedure (gradual increase of the acoustic transmission intensity) to allow the animals to get away of the acquisition source/vessel. This procedure should be implemented in 30 minutes-period of time. In places where sea turtles and dugongs are very abundant, these soft starts may last for about 60 minutes, to allow these slow animals to move considerably away from the seismic source .. d) To monitoring the presence of marine mammal and marine turtles (Marine Mammal Observers) on board the seismic vessel, performing a visual/acoustic observation in advance. For the acoustic observation in advance, it is recommended the use of Passive Acoustic Monitors (PAMs) of high accuracy. e) Maintain a safety strip (of at least 500 m) around the seismic exploration vessel. However, it is suggested that the exclusion area be increased (to 1 km) in the deepest zones of the exploration area, to include the initial phases of the behavioural activity of whales and sea turtles. In any case, before resuming the seismic exploration, begin once more the soft starts of acoustic emission. f) Do not begin the soft start if the safety strip has not been monitored to verify the presence of marine mammals through visual observation and the use of acoustic monitors. g) In case of a night seismic acquisition, or under foggy conditions, the PAMs - Passive Acoustic Monitors - shall be used on board the vessel, to allow for the detection of the marine mammals’ vocalizations in the vicinity. To assure that the MMOs have sufficient training for interpretation of PAM data and PAM operation. h) To avoid carrying out seismic acquisition during the humpback whales migration season (July to November), particularly during the birth and nursing of the breeds, as whales with calves use the marine waters close to the coast and near the islands. i) The safety area in the deep places close to the islands, and in places with a steep depth gradient should be increased to 1 km in order to reduce the acoustic impact on whales’ places of refuge/rest, migration corridors or places for birth and breeding. j) In the changes of exploration lines, always begin with the soft start. End the acoustic emission whenever the end of the exploration line is reached.

k) If for any reason the acoustic transmission is interrupted and not re-initiated within a time period of 5 minutes, the activity shall be initiated after 20 minutes of soft start. If a marine mammal or a marine turtle are present within a range of 1 Km or 500 m, respectively, then the procedures of observation, listening, delay and soft start shall be applied.

31 l) Special attention should be paid both to shallow waters (where the Indo-Pacific humpback dolphin may occur) and the areas where there are steep slopes near the islands, since these are habitats with a high concentration of cetaceans and turtles. Thus their demarcation may allow the Marine Mammal Observers (MMOs) to pay greater attention to the likely presence of species that are very sensitive to seismic exploration, such as Cuvier’s beaked whale and Longman’s beaked whale . m) To monitor propagation of seismic sound levels, in order to better define the exclusion areas. The acoustic monitoring should be undertaken from the site of the source of the emission (the vessel) to a maximum distance of 25 kms from the source. This is of particular relevance in the shallow waters and near the banks of the islands where there is a steep depth gradient and which are the main habitats of many species of toothed whales and sea turtles. Acoustic monitoring is a standard procedure in seismic exploration activities and makes it possible to check the real levels of sound propagation, to measure actively the exclusion radius (safety strip), because the local conditions, namely the currents, the water temperature, the topography of the sea bed, and the depth, may alter the propagation envisaged in the modelling (NOAA 2007 a, b; NSF 2008). n) To use a reduced speed and to avoid noise vessels erratic maneuvers.

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