Overfishing: The main cause of fish loss

In Photo: A diver swims with a school of sardines in Dauis, Bohol. The area is now a tourist attraction, and is part of a dive site after conservationists, volunteers, the local government unit and residents of Tangnan, Dauis, have agreed to protect the area.

Story & photo Stephanie Tumampos

Our fish population is declining…And this drastic decline isn’t because of climate change yet.”

Thus, said Dr. Vincent Hilomen, project manager of Marine Key Biodiversity Areas of the Department of Environment and Natural Resources (DENR)-Biodiversity Management Bureau.

Managing the Philippines marine resources is a tough challenge as the country is in the center of the coral triangle and marine biodiversity. While the country is the apex of such resources, the Philippines is also a large hotspot for biodiversity.

“This means there are many problems in our country concerning biodiversity, and we need to take care of it,” Hilomen said during the Visayas Regional Scientific Meeting spearheaded by the Department of Science and Technology and the National Academy of Sciences and Technology held in Cebu City last week.

The country’s fisheries resources is depleting because of overexploitation.

“We need to catch the right size of fish,” Hilomen said in an interview with the BusinessMirror.

Effect of climate change

Earlier studies showed smaller fishes have shorter lives. But recent researches showed smaller fishes and bigger fishes have the same long life. This means a fish grows fast, but the accumulation of biomass is slow.

“If you have to catch a fish and remove too much biomass, the ability to replenish in the long run is dimished,” Hilomen explained to the BusinessMirror.

This means the rate the fish is removed is higher than the rate at which the natural population can be replenished because of exploitation.

“And it can be exacerbated more due to the effects of climate change,” he said.

Usually, fishes reproduce in time when food is available. If the water temperature changes, fishes are confused if they will have to spawn or reproduce when their food is not ready yet.

He said a study on the ocean color was held in areas in the country where there were upwelling, or an area where nutrients from the sediments are brought up because of water movement.

The nutrients include nitrogen, phosphorus and potassium (NPK). An abundance of these nutrients favors growth of plankton. But fishes don’t eat plankton, since they are too small for their mouths to eat. Hence, zooplankton eat the plankton before the small fishes eat the zooplankton, and the bigger fishes eat the smaller fishes, and so on.

In Hilomen’s study, when they wait for three weeks to about a month, an upwelling area the fish population in the area would grow.

“This is their food chain. I think these resources [NPK] are inexhaustible,” Hilomen said. Plankton quickly grew, and in just days, their number increases. “They can double [the number], since they can both do sexual and asexual reproduction because they are single-celled animals.”

Still, the main problem is “we are overfishing our resources”.


As an archipelago, the world’s second largest, the Philippines is at an advantage with 2.2 million square kilometres of marine-water area, including its exclusive economic zone, according to the Bureau of Fisheries and Aquatic Resources.

This advantage gives the Philippines an abundance of marine resources, and puts the country in one of the top major fish-producing nations in the world.

Yet, in a 2008 to 2012 study of 12 major fishing grounds in the country conducted by Hilomen’s team, it was found out that eight of these areas were overfished, and the rest are at a brink of being overfished.

“Sogod Bay is one of these sites that’s overfished,” Hilomen told the BusinessMirror. “The Visayas and Mindanao are the most overfished areas in the country.”

Hilomen lamented on how the fishermen have exploited the Philippine seas. He said fishermen should catch only mature fishes.

“The idea is to allow the fish to spawn before you catch it,” Hilomen said. But even if the fishes haven’t spawned yet, they already catch it. “So who would spawn later on?”

Hilomen also cited the size of mesh of nets used for fishing. Fishermen are required by law to use a size 16 mesh. “What they do is they stack up two to three nets with this mesh size, which makes it [mesh size] smaller.”

Resiliency and action

In a five-year data simulation of how water current moves fish eggs, eggs laid by fishes in the West Philippine Sea (South China Sea) are moved inwards to the Philippines and circulated around the islands. “If this area [reefs in the South China Sea] is destroyed, these resources will be gone,” Hilomen showed to the BusinessMirror.

Hilomen recommended the fishes and their habitat must be protected from pollutants. “Plastic is one source of pollutant, and siltation is another,” he said.

He also recommend alternative livelihood, although he said not all areas have the opportunity for it.

He said in areas where there are very good attractions, these areas can be developed for tourism purposes by training the fishermen on how to handle tourists. Models of this kind of alternative livelihood are in Anilao and is being replicated in Palawan, he said.

A drastic measure is the imposition of a moratorium, where the fishing grounds are closed for the development of marine protected areas (MPA).

A MPA is only 15 percent of the fishing grounds. It is an area used by the fishes to grow. “You allow stocks there to accumulate biomass.” Fishermen have 85 percent as fishing grounds.

In an MPA, coral reefs, seagrass and mangrove must be all present. “The fish that you want to eat use these three habitats in each stage of their life cycle, and if you remove one, you compromise the growth of these fishes.”

On climate change, he said adaptation through education should be pushed. “We can only do adaptive measures,” Hilomen said. “Right after, we can improve resiliency.”

The country’s rich biodiversity gives so much for the people. Steps for action are already included in the Philippine Development Plan under the Philippine Biodiversity Strategic Action Plan, Hilomen said. “Our resources, if not protected, can cripple the world in terms of marine resources. Therefore, there is a need for us to protect them.”

Image credits: Stephanie Tumampos


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