Grey reef sharks
Project Leaders: Tova Bornovski, Dr Mark Meekan, Novot Bornovski
Background
Tova Bornovski
Dive tourism is a major part of the economy on the Micronesian island of Palau, and much of its underwater reputation lies with its abundant number of sharks, particularly grey-reef sharks (Carcharhinus amblyrhynchos).
Although the Palauan government has taken a lead in shark conservation by banning shark finning, as the value of shark meat and fins rises, illegal, unregulated and unreported (IUU) fishing as well as by-catch continues to grow as a problem, representing an increasing hazard to the sharks and the economics of Micronesia.
SOSF recognises that the only way to address and manage this developing situation is by gaining an understanding of the biological systems underlining grey reef shark biology, as strictly enforced conservation measures, such as the banning of shark finning in one region, will be of little value if sharks then migrate to other areas where they are targeted by unregulated fishing.
Preliminary tagging of Palauan grey reef sharks has already shown that they are resident in small areas of the reef for many months, though at certain times of the year they appear to undergo large scale migrations. Furthermore, observations by dive tourism operators show that resident sharks are occasionally joined by groups of transient females, many of whom have fresh scarring from mating bouts, again suggesting that the sharks are likely to undergo wide ranging seasonal migrations.
Although the Palauan government has taken a lead in shark conservation by banning shark finning, as the value of shark meat and fins rises, illegal, unregulated and unreported (IUU) fishing as well as by-catch continues to grow as a problem, representing an increasing hazard to the sharks and the economics of Micronesia.
SOSF recognises that the only way to address and manage this developing situation is by gaining an understanding of the biological systems underlining grey reef shark biology, as strictly enforced conservation measures, such as the banning of shark finning in one region, will be of little value if sharks then migrate to other areas where they are targeted by unregulated fishing.
Preliminary tagging of Palauan grey reef sharks has already shown that they are resident in small areas of the reef for many months, though at certain times of the year they appear to undergo large scale migrations. Furthermore, observations by dive tourism operators show that resident sharks are occasionally joined by groups of transient females, many of whom have fresh scarring from mating bouts, again suggesting that the sharks are likely to undergo wide ranging seasonal migrations.
In the field
Building on these observations, Tova, Mark & Novot are undertaking a study into the migratory and population dynamics of grey reef sharks right across Palau. The project aims to use a combination of satellite and sonar tagging, photo-identification and community monitoring to assess population densities, trends in population size and movement patterns.
Both acoustic and satellite tags are going to be used to track local and longer range shark movements, while photo identifications will be used to create a database of individuals. The community monitoring will be comprised of data sheets being given to ecotourism dive operators and community groups to be completed at the end of every dive. These sheets will record the species, number and size of sharks seen by dive masters and instructors. As a result of such a large dive tourism industry and the variety of sites covered, the community monitoring has the potential to provide an extremely potent data stream for analysis. This engagement with local dive operators and the wider community is also vital in terms of raising wider awareness about both the vulnerability and the value of reef sharks.
Both acoustic and satellite tags are going to be used to track local and longer range shark movements, while photo identifications will be used to create a database of individuals. The community monitoring will be comprised of data sheets being given to ecotourism dive operators and community groups to be completed at the end of every dive. These sheets will record the species, number and size of sharks seen by dive masters and instructors. As a result of such a large dive tourism industry and the variety of sites covered, the community monitoring has the potential to provide an extremely potent data stream for analysis. This engagement with local dive operators and the wider community is also vital in terms of raising wider awareness about both the vulnerability and the value of reef sharks.
Aims & objectives
The research primarily aims to determine residency and migratory patterns in the grey reef sharks around Palau. In turn, this data will be used to produce management recommendations for consideration by the Palauan as well as other Micronesian governments, while simultaneously developing a community based monitoring network of shark abundances at a multi-regional scale, including Palau, Uap, Pohnpei, Kosrae, Chuuk, Guam and the Philippines.
Project Update: 2008
As part of our scientific research program, the Micronesian Shark Foundation has been collaborating with tour operators to collect shark count data for the past 2 years. Information we collect includes the numbers of sharks sighted and their behavior patterns, location, species, gender and size. We also record other factors such as water temperature, visibility and number of divers underwater.
This daily data will be invaluable for our research into the migratory patterns of gray reef sharks in Palau as it will help us to determine the optimal month to tag sharks. Through this program we can also identify anomalies in sightings and behavior and relate this to climatic and oceanographic phenomena. Recent examples are observations of female sharks with mating scars in August. Typically, the mating season for these animals occurs from February-March. The activity in August was correlated with abnormally low water temperatures, when water conditions were similar to those during the mating season. At present, the link between oceanographic conditions and the shark mating season remains speculative, however the value of the sighting data set will increase through time, and with it our insight into the lives of these keystone reef species. By sharing our results and engaging the dive tourism community across Micronesia in this work, we hope to broaden our understanding of reef sharks and raise awareness of their value to the ecosystem and to human communities throughout the region.
This daily data will be invaluable for our research into the migratory patterns of gray reef sharks in Palau as it will help us to determine the optimal month to tag sharks. Through this program we can also identify anomalies in sightings and behavior and relate this to climatic and oceanographic phenomena. Recent examples are observations of female sharks with mating scars in August. Typically, the mating season for these animals occurs from February-March. The activity in August was correlated with abnormally low water temperatures, when water conditions were similar to those during the mating season. At present, the link between oceanographic conditions and the shark mating season remains speculative, however the value of the sighting data set will increase through time, and with it our insight into the lives of these keystone reef species. By sharing our results and engaging the dive tourism community across Micronesia in this work, we hope to broaden our understanding of reef sharks and raise awareness of their value to the ecosystem and to human communities throughout the region.