Find Out What the Research Discovered on the Existence and Behavior of Dolphins in Kiluan Bay.

Four Dolphins shows a mix of behavior : lobtailing and traveling.

Kiluan Bay is a bay basin located in Semangka Bay, Tanggamus Regency, Lampung Province. Precisely located on the east coast of Semangka Bay which is in the south of Sumatra Island and directly adjacent to the Sunda Strait. It has an area of around 10 km² and is part of the Kiluan Negeri Village, Kelumbayan District, Tanggamus Regency. Geographically, this bay is located between 05°45'54” South Latitude – 05°48'00” South Latitude and 105°05'06” East Longitude – 105°07'05” East Longitude (Siahainenia 2008).

Kiluan Bay has a depth between 5 – 400 meters above sea level and is relatively calm waters, has a humid tropical climate that is influenced by humid sea breezes and monsoons from the Indian Ocean. The population of Teluk Kiluan was 1,118 people in 2010 with 414 families. Kiluan Bay has a diverse population from several ethnic groups such as Lampung, Sundanese, Javanese, Balinese, to Bugis. The inhabitants of Teluk Kiluan have a main livelihood in farming and farming (Hudisaputra 2011). 

Based on research conducted by Siahainenia (2008), Kiluan Bay is one of the migration sites for cetaceans, especially the bottlenose dolphin (Tursiops truncatus) and the long-beaked dolphin (Stenella longirostris). Currently, all types of cetaceans based on the IUCN are included in the Critically Endangered list. Based on Law Number 5 of 1990 concerning Conservation of Biological Natural Resources and Ecosystems, and Government Regulation Number 7 of 1999 concerning Preservation of Wild Plants and Animals, dolphins are protected marine mammals (Siahainenia and Isnaniah 2013). 

This study was intended to determine the species, behavior, and distribution of dolphins in the waters of Kiluan Bay, Lampung.The Data collected on the species and distribution of dolphins was carried out on 31 May – 2 June 2015 in the waters of Kiluan Bay and Kiluan Island, Kiluan Negeri Village, Kelumbayan District, Tanggamus Regency, Lampung Province. Observations were made on seven transects.a straight line or narrow section through an object or natural feature or across the earth's surface, along which observations are made or measurements taken.

The method used to observe the presence of dolphins is the roaming method to record the number of species and observe the behavior of dolphins along the 7 transects  designed prior to the observation. The behavior of dolphins are including:

• Bow riding : the movement of dolphins follows the ship's movement
• Aerial : Dolphins jump high, somersault, turn and spin in the air
• Spy Shopping :Dolphins move their heads out of the water
• Breaching: the movement of the whale jumps and drops its body backwards
• Lobtailing :the movement of lifting the tail out of the water surface and hitting it to the wate
• Feeding :activities carried out when looking for food, marked by fish schooling near dolphins
• Avoiding: the movement to avoid ship
  
• Traveling :move in a certain direction, then dive together, then reappear to the surface of the water, and chase fish in groups;

Having observed for 3 days with a total time of 4 hours 43 minutes, the survey found two types of dolphins. The species identified were the Bottlenose dolphin (Tursiops truncatus) and the Spinner dolphin (Stenella longirostris). Research conducted by Siahainenia and Isnaniah (2013) showed that the dolphins identified in the waters of Kilaun Bay were Tursiops truncatus and Stenella longirostris. 

Bottlenose dolphin is an animal that does not attack so it can be easily and safely enjoyed by its attractions. Identification The Bottlenose dolphin is characterized by its relatively short body with a short snout. The dorsal fin is high and ends slightly bent like a sickle and emerges from the middle of the back. Color varies from light gray to black on the back, fading to white (sometimes with a pinkish tinge) on the belly. Group sizes are generally less than 20 individuals, but are sometimes seen in groups of up to hundreds of individuals on the high seas and in association with other types of cetaceans (Jefferson et al. 1993). According to Shane et al. (1986) generally these dolphins are found in small groups of 2-15 individuals.

Spinner dolphin (Stenella longirostris) is identified by the characteristics of frequent aerials movements, having a long and slender beak, an erect dorsal fin, a long and slender body, a sloping forehead and a long and pointed tail. According to Jefferson et al. (1993), Spinner dolphin has 3 color patterns, including dark gray, light gray on the sides, and white (grey and white) on the belly. Spinner dolphin is the name for the habit it performs, which is to jump out of the water and spin up to 7 times before falling back into the water. Herd sizes range from less than 50 to thousands. Usually associated with the Pantropical Spotted dolphin (Stenella attenuata) which is common in the eastern Pacific.

When observing dolphins, the observed behaviors were traveling, bow riding, aerials, and feeding. The dolphin's behavior on the first day was traveling, namely the dolphins moved towards Semangka Bay, while on the second day the behavior of traveling is visible and the movement of dolphins was to the southeast. The behavior on transect 5, namely at the same location, two types of dolphins were seen traveling and feeding. This can be seen from the collection of dolphins swimming at the same location and swimming around the location to catch prey. 

In addition, dolphins perform aerials movements that are seen when dolphins jump into the air and there are some who do bow riding, namely swimming next to the ship. Observations on transect 7 (third day) showed the movement of dolphins avoiding the ship (avoidance) and dolphins were seen looking for food. Observations on the transect were carried out after the rain, so that the conditions of the waters were wavy and the dolphins swam towards the open sea.

Based on research conducted for three days in the waters of Kiluan Bay, the types of dolphins found consisted of bottlenose dolphin (Tursiops truncatus) and long-beaked dolphin (Stenella longirostris) with a total of 501 individuals. . The dolphins found were found on transect 2, transect 4, transect 5, and transect 7. The movement of dolphins observed in the morning showed the behavior of dolphins looking for food and taking advantage of tidal currents. Dolphins move to the southeast in the morning and start moving towards Watermelon Bay in the afternoon. The distribution of dolphins found is at a depth of 150-250 meters with a movement towards the open sea.

 

Source :"Jenis dan Distribusi Lumba Lumba di Perairan Teluk" oleh Kiluan Tri Nur Sujatmiko and Aulia Rahmania Putri,  Dep. Ilmu dan Teknologi Kelautan,Fak. Perikanan dan Ilmu Kelautan, IPB.