If you thought Palawan’s marine biodiversity was Insta-worthy, a place not too far south just might change your mind about all that: Tawi-Tawi. Researchers recently found that the province has more species of commercially-important coral reef fish than either Palawan or Panay, showing just how much we have yet to learn about biodiversity in the country’s southernmost region.
According to a team from the Mindanao State University-Tawi-Tawi College of Technology and Oceanography (MSU-TCTO), the University of the Philippines-Diliman, and the University of the Philippines-Mindanao, Tawi-Tawi has a total of 266 of these economically vital species, compared to Palawan’s 159 and Panay’s 139.
A dizzying abundance of fish
A walk through any of Tawi-Tawi’s many public markets (called “tabuh”) and fish warehouses (or “bodega”) can be an overwhelming experience for anyone, with all manner and kinds of fish up for sale or on display every day. Large predatory fish like lapu-lapu (grouper) and sharks are a regular sight, as well as rabbitfish, goatfish, emperors, and coral breams. Common fish are sold at the tabuh, while high-value and live reef fish are sold to the bodegas.
The researchers sampled coral reef fish sold in the tabuhs and bodegas of Bongao, Tawi-Tawi, from October 2015 to December 2018. They focused on 11 commercially important coral reef fish families and subfamilies: surgeonfish (family Acanthuridae), parrotfish (subfamiliy Scarinae, family Labridae), snapper (family Lutjanidae), grouper (subfamily Epinephelinae, family Serranidae), sweetlips (family Haemulidae), goatfish (family Mullidae), emperor (famliy Lethrinidae), triggerfish (family Balistidae), coral bream (family Nemipteridae except Nemipterus), fusilier (family Caesionidae), and rabbitfish (family Siganidae). These are considered “commercially important” because these are the fish typically sold in the markets and eaten.
All in all, the researchers photographed and identified a whopping 41,864 fish from the 11 families.
A surprising mystery
Tawi-Tawi, Palawan, and Panay are all located along the Sulu Sea, which has the highest coral reef fish diversity in the country. But why does Tawi-Tawi have more commercially important coral reef fish species compared to Palawan and Panay?
The researchers have some ideas:
First, Tawi-Tawi is in the heart of the Coral Triangle, which is the richest region in the world in terms of marine biodiversity. Within the Coral Triangle, you find the highest diversity at the center of origin, and find fewer species as you go farther away.
Second, Tawi-Tawi is part of the Sulu Archipelago, which is located at the border of the Sulu and Sulawesi Seas. This means that fish species from both seas overlap and are found in the area.
Third, Tawi-Tawi is composed of over 300 islands with reef systems. The seas between islands are deep and the currents strong, which serve to isolate the fish communities between islands. Coral reef fish also typically do not move very far away from their home reefs.
Fourth, the current in the Sulu Sea moves predominantly southwards, and so it carries fish species from the northern areas (Palawan and Panay) to southern areas (Tawi-Tawi).
And fifth, there’s less fishing pressure in Tawi-Tawi compared to Palawan and Panay. In 2016, total landed catches for Tawi-Tawi totaled just 45,857.71 metric tons, compared to Palawan’s 130,155.15 metric tons and Panay’s 90,202.79 metric tons. Bigger catch sizes mean a bigger strain on fish populations. Also, commercial fishing (fishing done with boats more than 3 gross tons in size) accounted for 42.4% of the catch in Panay and 18.5% in Palawan, but only 2.6% in Tawi-Tawi.
Point of pride
Having more species of commercially-important coral reef fish has cultural and social implications as well. “For us locals, this is a point of pride,” explains Dr. Richard Muallil, Director for the Office of Continuing Education and Extension Service (OCEANes) of MSU-TCTO and the study’s lead author. “These biodiversity-rich reefs are our national treasure and provide ecosystems services such as food, income from fisheries and tourism, and may be the source of new medicines. Healthy reefs also protect coastal communities from the severe impacts of climate change.”
He also pointed out that Tawi-Tawi and the Sulu Archipelago may turn out to be some of the most biodiverse in the world, if only more research could be conducted. “Limited studies have been done here because it’s far away from the rest of the Philippines and because of the peace and order situation. However, we have about 25% of the total coral reef area in the Philippines,” said Dr. Muallil.
The reefs in Tawi-Tawi are also in better condition compared to other reefs in the country. Large sizes of predatory fish like lapu-lapu are typically the first ones to be overfished, but Dr. Muallil and other researchers found them sold in the market. Previous studies have also shown that Tawi-Tawi’s reefs have more fish compared to other areas. While fishing is a major source of income in the province, most fishers are municipal fishers who target reef fish closer to home.
However, the reefs in Tawi-Tawi are under threat from increased fishing pressure and illegal, unreported, and unregulated (IUU) fishing. Fishing pressure is increasing because of the area’s increasing population. Illegal activities such as blast and poison fishing, as well as fishing using compressors (or “hookah”) are common, especially in reefs outside of Tawi-Tawi Bay. While coastal law enforcement has improved over time, it’s concentrated in Tawi-Tawi Bay, which is less than 5% of the total municipal waters of the province. This endangers Tawi-Tawi’s reefs and the rest of the Sulu Archipelago, which are important sources of fish larvae for other reefs in the Sulu Sea and the rest of the Coral Triangle.
“There are very few conservation groups working in Tawi-Tawi, except maybe in Tawi-Tawi Bay and in the nationally protected Turtle Islands. The government and conservation groups also need to protect remote reefs not just in Tawi-Tawi, but in the rest of the Philippines,” stressed Dr. Muallil.