Is the Cold Weather Putting the Chill on Taiwan Fish Stocks?

If you are an angler in Taiwan, you are probably counting the days until the Lunar New Year holiday for a chance at some uninterrupted fishing. Cold wet weather has no doubt put a damper on the angling plans of some this winter. So, if you’re like me, you are hoping for a slightly warmer, somewhat sunnier holiday week. You may also be wondering just what to expect when you do finally arrive at water’s edge.Unusually cold weather in Florida was blamed for killing large numbers of Tilapia and Peacock bass. Can Taiwan expect the same? Photo by Scott Wheeler, The Ledger.

Unusually cold temperatures prevailed throughout the northern hemisphere this winter and subtropical Taiwan hasn’t been spared. Even on the southern end of the island, usually immune to the seasonal chill, has seen temperatures drop into the single digits (Celsius). What impact the falling mercury will have on local fish stocks has yet to be determined, but everyone from anglers to fish farmers are getting nervous.

Not all local game fish and aquaculture species are sensitive to sharp fluctuations in temperature. Most native fish as well as some imports from temperate regions (largemouth bass and rainbow trout) should do OK. However, those species introduced from warmer climes could face mass die-offs. Tilapia, an important food fish and the backbone of the local aquaculture industry is probably the most at risk. The species stops feeding and reproducing as temperatures near 10˚ Celsius and begins dieing after that point. Mass weather-related kills of tilapia have already been reported in the U.S. state of Florida and in Haiti this month.

Another cichlid, the peacock bass, is also at risk. The prized South American game fish was introduced to Taiwan through exotic aquarium market and has become established several southern Taiwan ponds and lakes. Like its cousin the Tilapia, it is also extremely sensitive to drops in water temperature.

Freshwater fish are not the only one’s potentially affected. Milkfish, another important aquaculture species, is farmed in cement ponds filled with seawater. A mass kill could be economically devastating for farmers because domesticated milkfish take eight to ten years to reach sexual maturity.

For now, there is not much to do but wait and see. As of today, the mercury was up a bit, rising as high as 19˚ C during the day. However, it is expected to dip down to 7˚ C at night this weekend in Taoyuan, the heart of north Taiwan’s fish farming industry.



Species Profile: Tilapia

A fly rod is a great way to pursue this widespread cichlid, but you have to get up early. Photo: Michael Rupert HayesFamily: Cichlidae

Scientific names: (three primary species in Taiwan, though most “wild” specimens are hybrids. Oreochromis mossambicus, Oreochromis niloticus, Oreochromis aureus, Tilapia zillii

Common names: (respectively) Mozambique tilapia, Nile tilapia, blue tilapia, red-bellied tilapia

Habitat: Slow moving rivers and canals, ponds, lakes and swamps. Can tolerate low oxygen levels and high pollution.  Prefers areas of heavy aquatic vegetation, its main food source.  Prefers warm water and is sensitive to drops in temperature.

Size range: Large specimens can reach 40-60 cm, depending on species. Individuals under 1 kg. are more common. Typically, tilapia size is determined by competition for food. Larger population concentrations result in smaller fish.

Angling tactics: Most local anglers fish with prepared baits or worms. Flies can be productive depending on time of day. Large specimens have been known to strike top-water lures when spawning/brooding.

Love them or hate them, tilapia are one of the most commonly pursued freshwater fishes in Taiwan. This is mostly due to their ubiquitous nature and ability to flourish nearly everywhere warm fresh water can be found. Urban rivers, canals, farm ponds and swamps are all likely places to find tilapia. Their prevalence leads some “serious” anglers to turn their noses up at this fascinating import that has played a key role in the island’s aquaculture industry.

Widespread though they may be, tilapia can be fun and challenging to catch, particularly on artificials. They are omnivores, but vegetation makes up the largest part of their diet.  Many anglers swear by prepared baits, corn or bread. Worms can also work. Before dawn and just around dusk, tilapia will often begin feeding on insects and this is the best time to get out the fly rod.  

Tilapia are generally considered good eating and have a mild flavor, but be mindful of the water quality in the area you are fishing. Most tilapia sold commercially or in local restaurants are farm-raised.

Tilapia are rapid breeders (individuals spawn several times a year), invasive and can push out more sensitive native species, so catch-and-release is not necessary and in some cases may even be discouraged.

Tilapia fight hard once hooked and are a particularly fun fish to catch on light tackle. Their ease in locating makes them an excellent choice for introducing young anglers to the passtime.

Further reading:

Taiwan Tilapia-- The Fish That Became a National Treasure