Philippine Journal of Science Vol. 145 No. 3, September 2016 higher latitudes (Cushing & Dickson 1976; Portner & Peck 2010). So far, studies on the effects of El Niño on fishes focus mainly on small and large pelagic fishes. The spread of warm water towards EEP deepens the thermocline and results to reduced productivity of upwelling. During 1972/1973 El Niño, one of the results was the devastation of anchovy fishery in Peru, one of the largest fishery in the world, due to reduction of nutrients (Cushing 1981; Bakun & Broad 2003). The distribution, spawning, and recruitment of northern anchovy off California was also negatively affected during the 1982/1983 El Niño event (Fiedler et al. 1986). This event also suppressed the upwelling in the ECP that resulted to a decrease in yellowfin tuna (Thunnus albacares) catches (Miller 2007). In 1997, the stocks of small pelagic fishes decreased again in the EEP particularly on the anchovy fishery (FAO 2000). In the EWP, the spread of warm pool of water extends the distribution of tuna species. Lehodey et al. (1997) observed an eastward movement of the tagged skipjack tunas released in the EWP to the ECP during the 19911992 El Niño. Although the migration of skipjack tunas were mainly driven by temperature, the inhibition of equatorial upwelling concurrent with the spread of warm pool of EWP also drove these species as the water displaced eastward (Lehodey et al. 1997; Lehodey 2001). Bigeye tuna (Thunnus obesus) also extended to the east during El Niño years (Yukinawa, et al., 1988). In the Philippines, tuna catch drastically decreased up to 58% particularly in regions 2 and 9 with region 2 being unable to recover after the 1997 event (Vera & Hipolito 2006). Prolonged and recurring El Niño increases the effort of finding suitable fishing grounds and leads to decreased tuna harvest being landed in the Philippines. This happened to Taiwan mackerel purse seine fishery which experienced a sharp decrease in harvest by 47.75% during the 1997/1998 El Niño and had estimated loss of US $6.22 million by 1998 (Sun et al. 2006). However, temperature alone cannot explain the abundance and distribution of fishes but also involves their feeding habitat. As discussed above, primary productivity in the Philippines is increased during El Niño years in some parts of the country. Villanoy et al. (2011) noted that sardine fishery in Zamboanga Peninsula had the highest landed catch during some El Niño years (2003, 2005, 2007) as compared during some non- El Niño years. El Niño enhanced the upwelling that is beneficial to pelagic plankton-feeding species such as sardines and supported the municipal fishery of Zamboanga. Although high productivity means greater food source in relation to the amount of phytoplankton present, this could also lead to the occurrence of blooms for some Damatac II & Santos: Possible Effects of El Niño on Some Philippine Marine Fisheries Resources algal species. Algal blooms not only affect shellfishes but may also trigger fish kills due to oxygen depletion. This poses threat to mariculture such as farms of milkfish, the main aquaculture product of the country. On January to February 2002, a massive fish kill of milkfish happened in Bolinao, Pangasinan simultaneous with the occurrence of dinoflagellate Prorocentrum minimum bloom (Azanza et al. 2005). Aquaculture areas like Bolinao are usually eutrophic, such that even in the absence of El Niño the water is already prone to algal blooms. Still, oceanographic conditions during El Niño create favorable conditions for algal growth and further contribute to the conditions set up by eutrophic waters. Yin et al. (1999) revealed that El Niño was responsible for the occurrence of several red tides in Hong Kong from 1997 to 1998, which resulted to an estimated loss of US $32 million from fish kills. The conditions brought by El Niño helped in the outbreak of red tides along the eutrophic coast of China (Yin et al. 1999). Moreover, reduced rainfall and drought caused by El Niño do not help to replenish the aquaculture areas with cleaner waters, thus, may further contribute to eutrophication. Martins et al. (2001) pointed out that the input of freshwater in a eutrophic water is a major factor that controls the incidence of algal blooms. Therefore, El Niño may further contribute to the induction algal bloom in many aquaculture farms of the country. El Niño also seems to affect the transport of larvae and juveniles. The partitioning of NEC into Kuroshio and Mindanao currents also influences the oceanographic processes and determines the north-south fish differences and larval dispersal off coast the country (Alino & Gomez 1993; Qiu & Chen 2012). One example is the Japanese eel (Anguilla japonica), that is transported through the NEC in the northern part of the EWP and is, thus, one of the commodities found in Northern Luzon. Kim et al. (2007) showed through their larval transport model that eel larvae were transported more to the Mindanao current than the supposed route Kuroshio Current during El Niño years. There is no data on the eel catch in Luzon, however, time series catch in Taiwan showed that El Niño coincides to the years of low eel production (Han et al. 2009). Reduced precipitation during El Niño causes relatively higher salinity and drought in the EWP. Euryhaline species such as most species of Tilapia (Oreochromis spp.) may not be affected by the phenomenon but other species strongly dependent on salinity may have negative effects to increased salinity. Portunid crabs (Scylla serrata) are known to be influenced by salinity changes and prefer lower salinity (Williams & Hill 1982; Bonine et al. 2008). Meynecke et al. (2012) reported that portunid crab production is higher during La Nina when rainfall rate is higher. Drought, on the other hand, limits the environment of many aquaculture farms shortening the culture periods 287