About Whale Sharks
Biology and Ecology
The whale shark, popularly known in the Philippines as BUTANDING, is the world’s largest fish. This gentle giant is known to grow to great lengths of up to 15 t0 20 meters and can weigh up to 34 tons. It has very distinctive color markings of pale spots and stripes against a dark background (fading to a pale underside). These patterns appear to be unique to each individual and can be used for their re-identification. The head is broad and flattened with a large almost terminal mouth and its teeth are minute. There are prominent longitudinal ridges on the dorsal surface. This impressive but harmless species is unlikely to be misidentified.
As a highly migratory species, whale sharks are distributed worldwide in warm and temperate seas of the Atlantic, Pacific and Indian Oceans, mainly between latitudes 30o N and 35o S, but occasionally to 41 o N and 36.5o S. Food is an important factor for the growth, migration and abundance of whale sharks in time and space. Its presence is highly associated with blooms of planktonic organism and changes in water temperature.
The whale shark is one of only three known filter-feeding sharks, suction feeding by gulping in dense aggregations of zooplankton, or passive feeding when plankton density is lower. Prey items range in size from very fine zooplankton (1 mm diameter) to small fishes, squid and crustacea. Unlike other species of sharks, the whale shark can neither bite nor chew. Its thousand of teeth are so tiny that it can only eat small shrimps, fish and plankton by using its modified gill rakers as suction filter.
Whale sharks are ovoviviparous, which means that eggs are hatched and developed in the uterus. Whale sharks are slow growing, maturing sexually only after so many years and with long interval between pregnancies. Females have been found to produce as many as 300 embryos in her uterus, although it is thought that less than 10% of the young survive to adulthood. Upon giving birth, the mother sharks leave her young to fend for themselves. In effect, the species have low reproductive potential and low capacity for population increase. These make the species highly vulnerable to exploitation.
The ecological role of whale sharks is not yet fully understood but the links of these giants with other processes within an ecosystem have been established. Whale sharks are related to important ecological processes such as crab, fish and coral spawning. As possible indicators of plankton-rich patches, whale sharks may be using baitfish to locate their prey.
Historical Fisheries and Trade
The Philippines has a long tradition of hunting whale sharks and is historically abundant in most islands, with an artisanal subsistence fishery operated in Bohol Sea by a small number of former whaling villages. During the early 90s, there were at least 15 villages in southern Philippines involved in whale shark fishery and each was catching an average of 26 whale sharks per year, according to the joint study by WWF-Philippines and Silliman University in 1997. In the mid-90’s, increased demand for whale shark meat, skin and fins from the international market stimulated the development of a commercial targeted fishery for the species..
In the past, only five traditional hunting villages were involved, and they were hunting whale sharks manly for their meat, which was sold locally. Increasing demand for whale shark meat and fins in Southeast Asia encouraged an export market to Taiwan, as well as Japan, Hong Kong and Singapore. Fishing effort increased (new whale shark fisheries were opened up in at least 5 provinces) while catches went down (averaging between 56-100 sharks per site per year in four of the primary fishing sites years prior to 1997 to about 13 sharks per site in at least 11 sites in 1997. A fishery targeting a vulnerable species such as the whale shark clearly shows it to be unsustainable, a potentially classic “boom and bust” endeavor.
Conservation Initiatives
Whale shark, being a K-selected species as with other large sharks, is sensitive to exploitation due to low reproductive rates, long gestation periods, slow growth and late maturity. IUCN classified the species as Vulnerable based on past records of declining catches and abundance during and following targeted fisheries.
Recognizing the biological vulnerability of the species, legal protection for the species was enacted in at least 11 countries, including India and the Philippines, to prevent targeted fisheries from developing. This protection is hampered by continued demand for whale shark products (e.g., meat, fins, skin, cartilage, oil) in international trade, particularly from the Asian market. In 1998, The Philippine Government issued Fisheries Administrative Order No. 193, at the time when whale shark ecotourism in Donsol, Sorsogon was starting up and when the local population of whale shark in the Bohol Sea was declining, banning the killing and trading of whale sharks and manta rays through-out the Philippines. The LGU of Donsol also enacted a local ordinance declaring its municipal waters as whale shark sanctuary.
Ecotourism based on whale shark watching is pursued in many parts of the world as alternative to fisheries. Non-consumptive use of the species through ecotourism is seen as the most sustainable and equitable practice and is already a million-dollar industry in many countries, particularly Australia, Seychelles, Thailand, Mexico, Belize, Honduras, other Caribbean countries, East African States, and several Red Sea and Indian Ocean range states where dive tourism occurs.
Worldwide Conservation Efforts
Legal protection in state waters is still insufficient to protect stocks unless backed by regulation of the international trade demand, which now drives illegal fisheries and export. Effective regulation and monitoring of catches, landing, and shipment is needed so that resource and trade management options can be examined before the depletion has gone too far.
Thus, on the 12th Conference of Parties (CoP12) to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in Santiago, Chile on November 2002, the Philippines and India led the proposal to uplist the whale shark under Appendix II.
Although the proposal was defeated in the first voting, eighty-one countries in the final plenary agreed to mandate the regulation of the whale shark trade and to put in place measures that will ensure the survival of the species. The municipal resolution of the Local Government of Donsol, which strongly supported the Philippine proposal, was the highlight of the Philippine intervention during the debate at the conference.
Species listed in Appendix II are automatically covered by the Philippine Wildlife Conservation Act and are subject to stringent international export permit requirements. The listing for whale sharks in particular also strengthens FAO 193. The uplisting will help to ensure that exploitation of this globally threatened species is regulated and monitored, and that international trade is not detrimental to the survival of whale sharks and to the valuable ecotourism operations it supports.
Appendix II listings will also:
- Encourage international co-operation for the successful management and trade monitoring of populations of whale shark.
- Introduce population research requirements to ensure that catches do not affect the viability of populations.
- Recognize that sharks managed or protected in one country may still be highly vulnerable to unmanaged, unsustainable fisheries elsewhere in the range.
- Assist Parties in meeting the recommendations of the United Nations Food and Agriculture Organization’s International Plan of Action for the Conservation and Management of Sharks (FAO’s IPOA-Sharks).