Fishermen grapple with three invasive species
By Yolanda Sotelo
DAGUPAN CITY – Fishery stakeholders in Pangasinan are grappling with and are at a loss on how to deal with the threat of three invasive species that are taking over their farms and a river – blue mussels, black chin tilapia and janitor fish.
In Binmaley, Freddie Quinto, 43, has to sail daily to oyster beds he and his wife Lune operate in Gayaman River. He painstakingly removes, manually, the tiny blue mussels that envelope each oyster clinging on the ropes.
“We have to remove the mussels when they are tiny because they grow fast and suffocate the oysters to death,” Quinto says. Those “saved” don’t grow big and look shrivelled because they can’t get enough nutrients.
The oyster farmers have no idea on how the blue mussels got into the rivers of Binmaley and Dagupan City. They mussels have rapidly proliferated and have overpowered the areas known for delectable oysters.
Many oyster farmers stopped production because of what they call the blue mussel menace.
Quinto’s wife Lune said when they started farming oysters years ago, the river was clear of blue mussels and the harvest was good. But when the new kind of mussels was “introduced,” the harvest was cut in half.
Maggie Arenas, 38, also an oyster farmer, said a dasig (20-foot long bamboo) that used to produce 10-12 sacks of oysters, produces only five sacks now.
“Worse, oyster farming has become labor intensive because we have to remove the blue mussels that cling on the oysters before we can sell them,” she said.
Lune said they allow other persons to harvest the unwanted seashells in their oyster beds for free.
The harvesters sell the blue mussels at almost giveaway price of P10 per kilo, she said.
Oyster farmer and vendor Lydia Solano, 63, has a bunch of blue mussels, which she removed from her oysters, in a corner along the highway of Lucao district where she vends.
“Nobody wants them. They are a menace to us,” she said, although she said she tried cooking the blue musssels for her family and “it tasted okay.”
But if its a consolation, the low oyster production has pushed the oyster prices up – from P250 to P500 per sack.
In Bolinao, there must be somebody who introduced the blue mussel in the aquaculture areas in 2014 and dislodged the green mussels that abundantly grow there.
But the blue mussel did not thrive and after some months, they were gone, Jesem Gabatin, Bolinao’ fishery and agriculture management council head.
He said it could be because the species could not thrive in high salinity water. When they were gone, the green mussels returned.
Black chin tilapia
Another invasive species that lodged in the fishpond areas of Dagupan and Binmaley is the black chin tilapia (Sarotherodon melanotheron), locally known as mulmol.
The species that earlier wreaked havoc in Bataan, Pampanga and Bulacan, was first observed in Pangasinan aquaculture areas in 2014, but multiplied fast in 2015.
The tilapia species was named gloria in Pampanga because of a “mole” in the chin, and mulmol in Pangasinan also because of the mole. Former President Gloria Arroyo has a mole in the chin.
“The species fight for food, dissolved oxygen and space with the bangus in the ponds. They grow and multiply fast and they are voracious eaters. They compete with the bangus for feeds and they eat the fingerlings,” Paul Fabia, whose family operates fishponds, said.
Fabia said last year, he stocked a two-hectare nursery pond with 500,000 fingerlings. After four months, the stock was down to 200,000.
“The pond was ‘infested’ with mulmol which devoured the fingerlings. They also have big appetite for prawns and vannamei, ” Fabia rued.
Bangus grower Phil Perez said a banyera (tub that carries 25 kilos) of mulmol is sold at P150, “and no one wants to buy.”
The amount could hardly cover the additional cost for feeds, Milan de Guzman said. In 2015, he has to add 50 bags of commercial feeds for his 2.5 hectare bangus pond because the mulmol are “insatiable.”
“But at P15-P25 per kilo, the sale of mulmol can’t cover the expenses for additional feeds,” he said.
The fishfarmers tried drying their ponds and using teaseeds to get rid of the unwanted tilapia. But once the water enters and even when they put nets at the water’s entrance, the mulmol are back.
Fabia theorized that birds could be instrumental in bringing the tilapia into the ponds, as they could drop the fish while flying above the ponds.
In Rosales town, the bank of Lagasit River in Rizal village is eroding because of janitor fish that burrow into the riverside.
Residents claimed that many trees along the river tumbled down because the banks weakened and eroded because of the janitor fish that were once sold as aquarium pets.
“There are no more carps that used to flourish in the river, and when their gill nets yield aquarium fish, there are no carps,” the residents said. The biggest janitor fish caught in the river was two feet long.
One resident broiled the undesirable fish, but found it unpalatable and bony.
Bureau of Fisheries and Aquatic Resources Ilocos Regional Director Nestor Domenden said there are no records at all on who brought the unwanted species into the country.
“We will continue digging further on who introduced them and find a way to punish them because of the negative impacts of the species not only to the aquaculture industry but to the environment,” he said.
“But while all deliberate or undeliberate introduction of any species in the country negatively impacted on the aquaculture, there could be potentials of the new species for economic value,” he said.
“Nandiyan na eh (they are there), so we just have to find their economic value,” he added.
For instance, the blue mussels may not be acceptable to the consumers right now, but they are edible and some consumers even find them better tasting than the green mussels.
“The blue mussels could also be processed like into bagoong,” he said.
The black chin tilapia on the other hand, is also safe for human consumption, although it has less flesh, tastes bland as compared to other tilapia species, and is bony.
They could be used as feeds of high-value species like seabass and talakitok, or processed into food for animals like dogs and cats, Domenden said.
The janitor fish’ flesh meantime, could also be used as ingredient for animal feeds, while its hide could be processed into wallets or bags.
“Maybe we could design a tanning machine for the janitor fish’ hide which has nice design,” he added.
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