Unraveling the stories of sardines and anchovies in Dumanquillas Bay

If fish could talk we could know all about the oceans and their lives. Finding out what life is like underneath the water is no simple task but anchovy and sardine populations are starting to decline in Dumanquillas Bay and a plan is needed to protect them. We need to figure out what is wrong and what we can do in order to make their lives a bit better.

But how can the fish tell their story?

The story begins here. Fresh fish are being unloaded to be processed by local fishermen

The bay under pressure

Known as the richest fishing ground in western Mindanao, Dumanquillas Bay along the southern edge of the Zamboanga Peninsula in the southern Philippines was declared a national protected area on August 10, 1999 by the Department of Environment and Natural Resources (DENR). The protected area, officially known as the Dumanquillas Bay Protected Landscape and Seascape (DBPLS), is still currently facing pressure from rampant overfishing and destructive fishing practices, according to DENR.

Dumanquillas Bay and its surrounding communities have long been experiencing the effects of overfishing where the local markets are so saturated with fish that fishermen have lost income due to cheap prices. Fishermen can increase the value of their catch by processing the fish but overfishing has also caused a decrease in the number of adult fish they catch and one has limited options with what can be done with small baby sardines and anchovies.

Cropped Fish Market
A saturated market. Dried fish being sold at local markets are sold for cheap due to too much fish

Science to the rescue!

So what is there to do for the people of Dumanquillas Bay when harvests are starting to show signs of overfishing? Stock assessment for fisheries management !

The bay is the site of a CTI-Southeast Asia organized stock assessment of sardines and anchovies. This study is being done in coordination with local government units and Zamboanga State College of Marine Sciences and Technology.

But what is a stock assessment? How does that information lead to sustainable fisheries and bigger incomes for fishermen in Dumanquillas Bay?

Here is some basic information on what a stock assessment is and why it’s important for DBPLS.

  1. What is a stock assessment?

The questions we are really asking when it comes to stock assessments are, “How much fish are there? Are there enough fish in the sea to spawn and replenish the harvested fish?   How often do they spawn?  Have the fish in the sea lived to maturity?”

Stock assessments look at dozens or hundreds of samples over one year  to get a clear picture of what life is like for the fish that live in Dumanquillas Bay.

Stock assessments look at dozens or hundreds of samples over one year to get a clear picture of what life is like for the fish that live in Dumanquillas Bay.  Measuring the length of numerous fish over a period of time will allow us to see how the fish has grown and how often they spawn (analyzed using a computer software).

Coupled with a study on spawning activity, which involves opening up and examining a fish, will add to our understanding of the stock.  It is like reading the story about how the stock of fish has lived and grown. The size of the gonads (sexual organ), presence of eggs, and the size of a fish can tell us whether or not it lived a full healthy life where it was able to reproduce.
We analyze the data to look for patterns and trends in how the fish lived; this will allow us to get a better picture about the life cycle of the fish in the bay and how they use the bay. For example, if a certain part of the bay yielded smaller fish on average over a long period of time, it tells us that it might be a spawning area or it is heavily overfished and that area needs some form of protection.

  1. Why do we need stock assessments?
Fishermen Harvest
A delicate balance. Data is needed to find out how much fish the communities can harvest without harming the ecosystem

Effective ordinances need to be built from good information. Similar to how communities tell their stories to government agencies during consultations about new laws; stock assessments reveal the stories about the life cycles of the fish. This can allow the government agencies to consider one of the most important groups of all in Dumanquillas Bay– the fish themselves.

Baseline data gathered from the stock assessment study will allow local governments to create new fishing regulations that take into account the needs of both the community and the ecosystem.

An example of a possible law is a fishing ban where the fish are allowed to have some time to grow and spawn, life cycle data will allow us to see at what point during the year they tend to reproduce and lay their eggs.

  1. So why is CTI-Southeast Asia focusing on DBPLS?

DBPLS is part of the Sulu-Sulawesi Marine Ecoregion (SSME), a large region which is located in the heart of the Coral Triangle and spans the countries of Philippines, Indonesia, and Malaysia. Despite the protection offered under the National Integrated Protected Areas System (NIPAS), there is a lack of support from the national government to implement the law in Dumanquillas Bay.

After the stock assessment is done, CTI – Southeast Asia is hoping to create a sustainable Ecosystems Approach to Fisheries Management (EAFM) zone within Dumanquillas Bay. This would be part of the overall plan to protect critical fisheries within the Coral Triangle to protect the environment and the communities that depend on them.

  1. What do we need to look for in a stock assessment study?

Like a story that is missing a plot, Dumanquillas Bay lacks solid information. To find out the stories of the fish we need to create reference points – meaning we need to define what will be the baseline data for the Dumanquillas Bay.

This will be based on the local data we acquired and what we know about the marine resources that we want to use sustainably. While there are a lot of reference points that can help us, we will focus on the terms that are most relevant to our stock assessment in Dumanquillas Bay.

Fishing mortality rate. This is the rate at which fish in the ecosystem are being harvested by fishermen.

Optimum Yield. This is the preferred upper limit when harvesting fish. This takes into account society’s needs and the fish stock’s needs and finds a middle ground to satisfy both.

  1. How do you process a fish specimen?

The length, weight, gender, and the age of the fish specimen are taken. The information on the length and weight of the fish over a period of time will provide us information on the growth of the fish. The information on the gender and age of the fish will provide us information on the how often, when, and how long the fish spawns.


An important tool

It is often said by scientists that we know less about what’s underneath the water than what we know about space, stock assessments are an important tool in unraveling the story about our seas and in the fight against overfishing. The stock assessment is estimated to finish by the end of the year and we hope to learn the story of Dumanquillas Bay.

Pressure on marine resources has been increasing not only within the Coral Triangle, but globally as well. Dumanquillas Bay is just one of the many fishing zones that are being overfished but we hope the research activity we are conducting will be the first step in a properly managed fishery in the bay.


Written by Panji Brotoisworo with inputs from Dr. Annadel Cabanban, Regional EAFM Specialist  of Coral Triangle Initiative – Southeast Asia (RETA 7813)


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