The Philippines is located in the tropics and the weather and climate prevailing in any particular place in the country is due to its geographical location and the different wind systems that prevail in the locality during the different times of the year.
When we speak of weather, it refers to the condition of the atmosphere at a particular time. Weather is thought of in terms of temperature, humidity, precipitation, cloudiness, brightness, visibility and wind on a certain day or hour. All these climatic elements are closely associated with each other and determine to a large extent the final outcome of fishpond production.
On the other hand, when we speak of climate, we simply refer to the long term records of weather such as long term average conditions of weather elements, the greatest amount of rainfall or sunshine as the case may be.
The prevailing wind systems in the Philippines are as follows:
Northeast (NE) monsoon - from November to February
Southwest (SW) monsoon - from July to September
Trade winds - winds in the tropics. They generally come from the east. The trade winds prevail during the rest of the year whenever NE monsoons are weak.
The typhoon season is usually from the month of July to November. Most often typhoons touch the islands between the southern tip of Samar and Northern Luzon. Approximately 15 per cent of typhoons strike areas south of Samar. The least frequently visited is Southern Mindanao. Northern Luzon is visited by approximately 35 per cent of typhoons, Central Luzon by 20 per cent while Southern Luzon and the Central and Northern Islands by approximately 30 per cent. Climate in the Philippines has been described in terms of the characteristics of the distribution of rainfall received in a locality during the different months of the year. There are four climatic types in the Philippines based on rainfall distribution. It will be noted that most differences in climatic types from North to South are due to mountain barriers which are high enough to cause variations in rainfall distribution. The different climatic types are as follows:
Type I - There are two pronounced seasons: dry, from November to April; wet, during the rest of the year. The localities of this type are protected from the Northwest (NW) monsoon; some are protected from the trade winds by mountain ranges. However, the controlling factor is topography in those areas open only to the Southwest (SW) monsoon and cyclonic storms.
| Average temperature : 27.0°C | |
| Average rainfall : 100.58 in. | |
| Geographic coverage | Exposure to Typhoons (per cent) |
| Ilocos Norte | 32 |
| Ilocos Sur | 32 |
| Mt. Province (Western part) | 32 |
| Abra | 32 |
| La Union | 32 |
| Pangasinan | 32 |
| Tarlac | 16 |
| Nueva Ecija | 16 |
| Zambales | 16 |
| Pampanga | 16 |
| Bulacan | 16 |
| Bataan | 16 |
| Manila | 16 |
| Rizal | 16 |
| Laguna | 16 |
| Cavite | 16 |
| Batangas | 16 |
| Mindoro Occidental | 19 |
| Antique | 19 b; 7 c |
| Iloilo | 19 b; 7 c |
| Negros Occidental (western, central and southern parts) | 7 |
Type II - There is no dry season with a very pronounced maximum rain period from November to January. These regions are along or very near the eastern coast which are sheltered neither from the NE monsoon and the trade winds nor from cyclonic storms.
| Average temperature : 26.8°C | |
| Average rainfall : 129.08 in. | |
| Geographic Coverage | Exposure to Typhoons (per cent) |
| Quezon (a great portion of eastern part) | 16 |
| Camarines Norte (eastern and northern parts) | 16 |
| Camarines Sur (eastern and northern parts) | 19 |
| Albay (eastern part) | 19 |
| Catanduanes | 16 |
| Sorsogon | 19 |
| Samar | 19 |
| Leyte del Norte (eastern part) | 19 |
| Leyte del Sur (eastern part) | 7 |
| Surigao del Norte | 7 |
| Surigao del Sur | 7 |
| Agusan del Sur | 7 |
| Davao (eastern part) | 1 |
Type III - Seasons are not very pronounced; relatively dry from November to April and wet during the rest of the year. The maximum rain periods are not very pronounced, with the short dry season lasting only from one to three months. These localities are only partly sheltered from the northeast monsoon and trade winds and open to the Southwest monsoon or at least to frequent cyclonic storms.
| Average temperature : 27.2°C | |
| Average rainfall : 77.26 in. | |
| Geographic Coverage | Exposure to Typhoons (per cent) |
| Cagayan (western part) | 32 |
| Isabela (western part) | 32 |
| Mt. Province (eastern part) | 32 |
| Nueva Vizcaya (western part) | 32 |
| Quezon (small portions of southern part) | 16 |
| Romblon | 18 |
| Masbate | 19 |
| Aklan | 19 |
| Capiz | 19 |
| Negros Occidental (northern part) | 7 |
| Negros Oriental | 7 |
| Cebu (central and southern parts) | 7 |
| Bohol (northern parts) | 7 |
| Palawan (eastern part) | 7 |
| Misamis Oriental | 7 |
| Bukidnon (northern part) | 7 |
| Zamboanga del Norte (southern part) | 1 |
| Zamboanga del Sur (southern part) | 1 |
Type IV - Rainfall is more or less evenly distributed throughout the year.
| Average temperature : 26.8°C | |
| Average rainfall : 101.84 in. | |
| Geographic Coverage | Exposure to Typhoons (per cent) |
| Batanes | 25 |
| Cagayan (eastern part) | 33 |
| Isabela (eastern part) | 32 |
| Nueva Vizcaya (eastern part) | 32 |
| Quezon (northern part, a small portion | |
| of eastern part, and southwestern part) | 32 b; 16 d |
| Camarines Norte (southern & western parts) | 16 ; 19 e |
| Camarines Sur (southern & western parts) | 16 |
| Albay (western part) | 16 |
| Marinduque | 19 |
| Mindoro Oriental | 19 |
| Leyte del Norte (western part) | 19 |
| Leyte del Sur (western part) | 7 |
| Cebu (northern part) | 7 |
| Zamboanga del Norte (northern part) | 7 |
| Zamboanga del Sur (northern part) | 1 |
| Misamis Occidental | 7 |
| Bukidnon (southern part) | 1 |
| Lanao del Norte | 7 |
| Lanao del Sur | 1 |
| Cotabato | 1 |
| Davao (western part) | 1 |
| Basilan | 1 |
| Sulu | 1 |
Legend:
a - per cent of typhoons to which province is exposed
b - northern part
c - southwestern part
d - southern part
e - small portion of eastern part
The weather exerts much influence on the pond conditions; when it rains, salinity decreases. The amount of change depends on the surface of the pond. A small compartment will change more than a bigger one of the same depth because dike area in a small pond is relatively greater in proportion to the surface area of the pond. Rain or flood waters bring into the pond nutrients, silt and other material. Strong winds cause wave formation and action which would tear algae or lab-lab from their growing surfaces and blow them to the sides of the pond where they die and decompose. Strong waves cause the stirring of the bottoms when water is shallow, thereby increasing turbidity. Turbidity is harmful to aquatic animals and inhibits photosynthesis. Strong waves also destroy and wash away the pond dike by constant wave action. The stirring effect of winds, however, help in oxygenating pond water.
An area where rainfall patterns are distinct, not prone to typhoon and flood, coastal waters not rough, and where strong currents do not prevail, is an ideal place for fishponds. To much rain will cause very low salinity. Floods are likely to occur which can destroy the pond. Strong waves generated by winds will endanger the perimeter dikes and entail great expense in the construction and maintenance of dikes. The same problem will arise with swift current moving along the coast. Sedimentation or sluice gates and water supply canals is likely to happen. Strong winds will generate wave action in the ponds which will tear away the algae or lab-lab growth from the pond bottom. Flood waters, which are usually turbid due to suspended particles carried away from land by rain to streams and rivers, will cause turbidity in the pond. The construction of flood control dikes and canals will entail more expenses.
The BFAR statistics shows that Type I weather has an average production of 900 kg/ha/yr of bangus. The average production of Type II weather is 600 kg/ha/yr while both Types III and IV weather have an average of 700 kg/ha/yr. The stocking rate per cropping is assumed 3–4 marketable size bangus per kilogram.
On the other hand, statistics shows that Type I weather has an average production of 600 kg/ha/yr while Types II, III and IV weather have both 250 kg/ha/yr with the same stocking rate per cropping and assumption as mentioned in existing areas. Production statistics show that weather exerts influence on pond productivity. Pond management should be modified to adjust to climatic conditions to maximize production of fish food to attain good production.
