Home Agriculture  Growing mussels can be profitable and environment-friendly

 Growing mussels can be profitable and environment-friendly


Text and Photos by Henrylito D. Tacio

It’s called tahong in Tagalog and amahong in Bisaya.  In English parlance, it’s mussel, the common name used for members of several families of bivalve molluscs from saltwater and freshwater habitats.

Mussels have been eaten by human beings since time immemorial.  About 17 species are edible and those you buy in the markets are green mussels (called in the science world as Perna viridis).  Those are farmed while the brown mussels (Modiolus metcalfei) are exclusively gathered from natural beds.

Mussels are prepared differently, according to Wikipedia.  In Belgium, the Netherlands and France, mussels are consumed with French fries or bread.  In Italy, mussels are mixed with other seafood; they are often consumed, sometimes with white wine, herbs and served with the remaining water and some lemon.

In Ireland, mussels are boiled and seasoned with vinegar, and the boiling water is used as a supplementary hot drink.  In New Zealand, they are served in a chilli or garlic-based vinaigrette, processed into fritters and fried, or used as the base for a chowder.

In Brazil, it is common to see mussels being cooked and served with olive oil, usually accompanied by onion, garlic and other herbs.  In India, mussels are either prepared with drumsticks, breadfruit or other vegetables, or filled with rice and coconut paste with spices and served hot.

In the Philippines, fresh mussels are cooked in ginger broth.  Vegetables such as spinach or hot pepper leaves along with long green pepper are also used to make tinolang tahong, as it is called.

France has been culturing mussels since 1235 but in the Philippines, mussel culture only started in1962.  “Mussels were initially considered as a fouling organism by oyster growers,” Simeone M. Aypa wrote in a paper published by the UN Food and Agriculture Organization (FAO).   “The impetus for mussel culture in Manila Bay came about when oyster growers, attempting to collect oyster spats in less silty offshore waters, instead obtained exceptionally heavy and almost pure mussel seedlings.”

Since then, mussel culture has gone a long, long way.  “Mussel farming does not require highly sophisticated techniques compared to other aquaculture technologies,” Aypa wrote.  “Even unskilled laborers, men, women, and minors can be employed in the preparation of spat collectors as well as harvesting.  Locally available materials can be used.  The mussel harvest can be marketed locally and with good prospects for export.”

As stated earlier, only green mussels are farmed in the country.  The brown mussels are not suitable for farming because they are not known to attach to ropes or bamboo poles, but only to living adults growing in dense mats on muddy bottoms.

Mussel farms are mainly found in Bacoor and Manila Bays in Luzon as well as in Sapian Bay in West Visayas, Maqueda Bay in East Visayas and in a number of bays and inlets along the northern coast of Panay Island. 

“This bivalve species reaches sexual maturity within the first year and spawns with the rising of seawater temperature,” Aypa wrote.  “In the Philippines, mussels spawns year-round, however, the peak period of spawning and setting is in April and May and again in September to October.  Eggs and sperms are shed separately and fertilization occurs in the water.”

According to Aypa, green mussels have two relatively distinct phases in their life-cycle.  “A free swimming planktonic or larval stage and a sessile adult stage.  The free swimming larvae remain planktonic for 7-15 days, depending on the water temperature, food supply and availability of settling materials.

“At about 2-5 weeks old, the larvae seek a suitable substrate to settle on and final metamorphosis takes place, changing its internal organ structure to the adult form.  The young spat then grow rapidly and within 4-8 weeks, after settlement they measure 3-4 millimeters in shell length,” Aypa wrote

The mussel industry is an important component of the aquaculture sector in the country.  Due to its popularity in recent years, mussel farming now provides additional income and livelihood to fisherfolk in many coastal areas. 

As it requires little capital, fisherfolk can readily raise mussels.

There are many ways of growing mussels but Filipino marine scientists are recommending the use of the longline system of mussel growing.

A kind of hanging method, it is different from the stake method, the traditional way of culturing the young mussels (spats) in bamboo stakes or poles. 

“In this method, the bamboo poles act as a wall or barrier to the runoff from the uplands resulting in siltation,” explained Rodolfo De Guzman, of the Science and Technology Information Institute (STII) of the Department of Science and Technology (DOST). “In time, the accumulated silt makes the waters shallow and is no longer suitable for mussel culture.”

In the longline method, the young mussels are literally hanging on the line that is submerged in the water.  This is the reason why it is sometimes called sampayan, the Filipino term for clothesline.

“The cost of the longline is much lower than the stake method that uses bamboo, which is more expensive,” De Guzman wrote.

The longline culture system is already practiced in New Zealand but the local counterpart is a cheaper version.  It was modified by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (PCAARRD), a DOST line agency.

Aside from being inexpensive, the longline method is easy to manage and maintain.  The spats are collected from the wild using spat collectors made of coconut husks, which are generally thrown away. 

Here’s how it is done: The collected young mussels are placed in onion bags and then hung in 50-meter longlines with recycled plastic containers that serve as floats.  All the fisherfolk need to do is regularly clean the longline of unwanted materials which come from the water and attach themselves to the lines.

After four to six months, the mussels are ready for harvest.

“Based on research, the longline method is a viable economic enterprise with a return on investment rate of as high as 87% and a short payback period of just one year to recoup investment,” De Guzman wrote.

As most materials used are recycled, the longline method is considered environment-friendly.  In addition, it is also climate resilient as “it is not easily destroyed during typhoons and other natural calamities.”

During typhoon advisories, fisherfolk are advised to fill the plastic containers with seawater so that “the longline can be lowered, thus preventing it from being damaged by big waves or strong winds,” said Dr. Carlos Baylon, a professor at the University of the Philippines-Iloilo, who was the project leader of the Pinoy Longline Mussel Farming System.

Another way is to untie the longline from the concrete anchor and move to a sheltered area until the typhoon has passed through the culture site, Dr. Baylon added.

The longline method can also be employed in deeper waters.  Unlike the stake method, it won’t cause sedimentation and most importantly, it reduces damage to the coastal environment.  With all these advantages, the longline method is described as “a sustainable enterprise.”

Despite this, production of mussels is still not as vibrant compared to other aquaculture initiatives.  Part of the problem is the insufficient and unstable seed stock.  Spat supply is affected by both human activities and nature.

“The mussel industry in the Philippines is still dependent on collection of wild spats,” Dr. Baylon was quoted by Hatchery International.  “The supply from the wild should be supported by production from the hatchery.”

In 2014, the UP-Visayas launched the Mussel Hatchery and Nursery Program with funding support from DOST. 

Based on study, the hatchery-produced green mussel spats that were transported to different culture sites as far as 1,250 kilometers away from the site “attained high survival of up to 100 percent.”

Nutritionists say mussels contain protein, carbohydrate and fiber.  It is an excellent source of selenium and vitamin B12.  It is also a good source of zinc and folate.

People who love to eat mussels must ensure that the mussels they are cooking are alive before being cooked.  The enzymes mussels produce quickly break down the meat and make them unpalatable or poisonous after dying or uncooked.  Some mussels might contain toxins, the Medline Plus Encyclopedia warns.

“A simple criterion is that live mussels, when in the air, will shut tightly when disturbed,” the ABC Science pointed out. “Open, unresponsive mussels are dead, and must be discarded.  Unusually heavy, wild-caught, closed mussels may be discarded as they may contain only mud or sand.  A thorough rinse in water and removal of  ‘the beard’ is suggested.”

In addition, don’t eat mussels that are harvested in areas where there is red tide.  It is caused by dinoflagellates and their toxins are harmless to mussels.  But if the mussels are eaten by humans, the concentrated toxins can cause serious illness like paralytic shellfish poisoning. – ###

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