Whale sharks, Mexico
Project Leader: Dení Ramírez
Background
Dení Ramírez, has been studying whale sharks (Rhincodon typus) in the Sea of Cortez (Gulf of California) since 2002. So little is known about the sharks in her study area that the research she is conducting is vital to understanding their feeding zones, population structures and genetic diversity in order to better protect them. Obtaining DNA samples, taking photographic IDs and tracking and observing whale sharks to obtain sex ratios and sizes has allowed Dení to begin the process of defining the population.
In the field
Deni Ramirez
In the Sea of Cortez, juvenile whale sharks are known to feed in different areas, and preliminary results using photo identification have shown that some whale sharks move from one feeding area to another; what has not been established is what causes these movements in the first place.
Using telemetry tags on juveniles at the end of the season in the different areas is helping to determine whether the whale sharks migrate between plankton blooms that are known to occur throughout the season. As these feeding areas also support dolphins, fish, manta rays and other shark species, the presence of whale sharks is a good indicator of biodiversity – and that a region requires special protection and conservation. Whale shark tourism has recently expanded in these locations, making it more economical to exploit whale sharks for tourism, rather than for consumption, but also meaning that population monitoring is more vital than ever.
This study will now employ the use of satellite archival pop-up tags to record the swimming profile and dispersal movements of pregnant female whale sharks from the south of the Gulf of California. The plan is to attach three tags to sharks from El Bajo and three to Gorda Banks, two critical habitats lacking managementwhere pregnant females aggregate. With the integration of these areas a greater regional management program in the Gulf of California can be created for a wider network of protection for whale sharks and their habitats. These tags gather continuous information on shark location, depth and water temperature for a period of up to one year.
Using telemetry tags on juveniles at the end of the season in the different areas is helping to determine whether the whale sharks migrate between plankton blooms that are known to occur throughout the season. As these feeding areas also support dolphins, fish, manta rays and other shark species, the presence of whale sharks is a good indicator of biodiversity – and that a region requires special protection and conservation. Whale shark tourism has recently expanded in these locations, making it more economical to exploit whale sharks for tourism, rather than for consumption, but also meaning that population monitoring is more vital than ever.
This study will now employ the use of satellite archival pop-up tags to record the swimming profile and dispersal movements of pregnant female whale sharks from the south of the Gulf of California. The plan is to attach three tags to sharks from El Bajo and three to Gorda Banks, two critical habitats lacking managementwhere pregnant females aggregate. With the integration of these areas a greater regional management program in the Gulf of California can be created for a wider network of protection for whale sharks and their habitats. These tags gather continuous information on shark location, depth and water temperature for a period of up to one year.
Aims & objectives
The aim of the project is to tag pregnant female whale sharks in the south of the Gulf of California in order to record their swimming profile and movements. This information will help in the Mexican whale shark management program, and the conservation strategies.
Specific objective 1: To determine migratory paths of the pregnant females from the South of the Gulf of California. Every year pregnant females aggregate in the area and there no re sight records of these females, which suggest that they migrate to another areas. Previous studies using telemetry tags showed that at least two of the three pregnant females tagged at Gorda Banks eventually migrated away from the Gulf of California. Determining the migratory path will help in conservation strategies of this shark. For example, do we need local or international conservation strategies?
Specific objective 2: To provide information to the Mexican government to enable them to develop conservation and management plans for this shark, and include the pregnant female areas in the management program.
Specific objective 3: To continue the monitoring of whale sharks in the Gulf of California.
A study begun in 2005 with the Centro de Investigaciones Biologicas del Noroeste has already shown that 2 whale shark populations, those in the Caribbean and those in the Gulf of California, are genetically different. As a consequence, SOSF went on to fund further genetic studies on a global scale, with Dení having already examined whale shark genetic material from Mexico (Pacific and Atlantic coasts), the Philippines and Mozambique. Plans to add genetic information from populations in Australia, Dijibuti, Galapagos, Taiwan and elsewhere are currently being discussed; this would allow the establishment of migration patterns for populations, which would have obvious implications for whale shark conservation policies.
Specific objective 1: To determine migratory paths of the pregnant females from the South of the Gulf of California. Every year pregnant females aggregate in the area and there no re sight records of these females, which suggest that they migrate to another areas. Previous studies using telemetry tags showed that at least two of the three pregnant females tagged at Gorda Banks eventually migrated away from the Gulf of California. Determining the migratory path will help in conservation strategies of this shark. For example, do we need local or international conservation strategies?
Specific objective 2: To provide information to the Mexican government to enable them to develop conservation and management plans for this shark, and include the pregnant female areas in the management program.
Specific objective 3: To continue the monitoring of whale sharks in the Gulf of California.
A study begun in 2005 with the Centro de Investigaciones Biologicas del Noroeste has already shown that 2 whale shark populations, those in the Caribbean and those in the Gulf of California, are genetically different. As a consequence, SOSF went on to fund further genetic studies on a global scale, with Dení having already examined whale shark genetic material from Mexico (Pacific and Atlantic coasts), the Philippines and Mozambique. Plans to add genetic information from populations in Australia, Dijibuti, Galapagos, Taiwan and elsewhere are currently being discussed; this would allow the establishment of migration patterns for populations, which would have obvious implications for whale shark conservation policies.
Project Update 2009
A tag attached to one of the whale sharks Deni is studying
On the 16th of December Deni attached a powered telemetry tag on a 7 metre male whale shark in Bahía de La Paz named Flavio (a resident La Paz shark since 2004). After 20 days the tag detached as its constant-depth trigger had been activated after a 4 day period. The initial data from Flavio appeared to be good and is undergoing analysis at the moment. It is hoped the data provided will allow Deni to compare day and night activities over the entire 20 day period.
Deni also deployed 2 additional tags on the 17th of January, 2009, with one going on Flavio and the other on a 4.5 metre male named Tango. The intention is to see if 2 known male sharks of different sizes who both return to La Paz year after year, will have similar movements. The tags are expected to remain on the whale sharks for 9 months.
The tags will continuously record information on location, depth, and temperature for the entire period, helping Deni and her team formulate a whale shark management program. The project continues to work closely with the Mexican authorities to develop an official program for non-extractable uses of the whale shark, with ecotourism opportunities as the most obvious example.
Deni also deployed 2 additional tags on the 17th of January, 2009, with one going on Flavio and the other on a 4.5 metre male named Tango. The intention is to see if 2 known male sharks of different sizes who both return to La Paz year after year, will have similar movements. The tags are expected to remain on the whale sharks for 9 months.
The tags will continuously record information on location, depth, and temperature for the entire period, helping Deni and her team formulate a whale shark management program. The project continues to work closely with the Mexican authorities to develop an official program for non-extractable uses of the whale shark, with ecotourism opportunities as the most obvious example.
Project Update: 2008
Through the deployment of archival tags (MK9) and telemetry tags (PAT tags), Deni continues to record the swimming behavior and dispersal movement of Whale sharks around Bahia de la Paz (BLP) and Bahia de los Angele (BLA). The current plan is to acoustically tag one male and one female whale shark in BLP and the same in BLA, with a further satellite PAT tag deployed in each area.
The tags will continually gather information on location, depth and temperature for up to one year which will help to formulate a management program. The project continues to work closely with the Mexican authorities to generate the official management program for the non-extractable use of the whale shark, with ecotourism opportunities being the most obvious example.
The tags will continually gather information on location, depth and temperature for up to one year which will help to formulate a management program. The project continues to work closely with the Mexican authorities to generate the official management program for the non-extractable use of the whale shark, with ecotourism opportunities being the most obvious example.