Ocean color data for Sardinella lemuru management in Bali Strait Jonson Lumban Gaol 1, B. P. Pasaribu 1, K. Mahapatra 2, Y. Okada and T. Osawa 3 1 Department of Marine Science and Technology Bogor Agriculture University, Indonesia 2. Shcool of Marine Science and Technology, Tokai University, Shimizu Shizuoka, Japan 3 Center for Remote Sensing and Ocean Science (CreSOS), Kampus Udayana, Bali, Indonesia.
Introduction The Bali Strait an important area for oily sardine fisheries The productive sardine in this area are sustained through enhanced biological production during seasonal coastal upwelling. Indian Ocean Bali Strait BALI Bali Strait Sardinella lemuru
70-90% fish production from Bali Strait is Sardinella Lemuru. Average of unnual production is 20,000 ton/year. There are 15-20 units fish meal processing industry, Sardinella as a raw material. (Buhary, 2008) The fishing boats are made of wood, purseseiners are of 20-30 GT One day fishing
Status of the Sardinella Lemuru fishery Following the adoption of purseseine fishing in 1974, the catch of lemuru has increased significantly, in line with the increased number of vessels. However, the catch has shown a marked fluctuation. The first peak was reported in 1983 with a total catch of 48,000 t, then declined to an all-time low of 4,661 t in 1986, then it slowly increased and reached a peak of 61,600 t in 1991 and 1997/98 The environmental mechanism behind the process is still not clear (Gofar et al, 2000). (FAO, 2005)
Indonesian waters variability influence by: Monsoon, ENSO and IOD SST Chl-a Wind direction during southeast monsoon & Northwest (Qu et al., 2005)
Inter-annual variability Dipole Mode (+) JAMSTEC During IOD (+) Upwelling more intense around South Java, Bali & West Sumatra Sea (Saji et al, 1999) How impact of IOD mode on Fisheries? upwelling
The Objectives: The study is aimed at understanding the variability of chlorophyll-a phytoplankton concentration derived satellite in Bali Strait and assessing their impact on Sardinella lemuru production.
Data Sources: (1) Monthly average of Chl-a concentration (SeaWiFS) from GIOVANNI (1997-2010). (2) Monthly catch of Sardinella lemuru from statistic data of local fisheries agency. Data Analyses: Statistics cross correlation
Results
Variability of Ch-a concentration di Bali Strait 1) Annual Monsoon 2) Inter-annual IOD (+)
Spatial Distributions of Ch-a concentration on November in Bali Strait (1997-2008) Nov_1997 Nov_2006 Nov_2008
Annual Variability : Wirtky, 1962, Susanto et al, 2002, etc) Southeast monsoon Upwelling Inter-annual variability : (Susanto et al, 2002, Iskandar et al., 2009, etc) Blooming Phytoplankton during IOD positive Phase (Iskandar, et al, 2009)
Unnual variability of Chl-a & impact on Sardinella lemuru Usually, the Chl-a concentration reaches the highest in August- October related to upwelling southeast monsoon. Sardinellla lemuru is Zooplankton and phytoplankton feeder April Jun Aug Chl-a (mg/m 3 ) Seasonal Upwelling Seasonal Upwelling Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Life cycles of Sardinella in Bali Strait (Wudianto, 2000) Spawning >15 cm Growing of Larva (7.5-10.5 cm) Fishing Season (11.5-12.5 cm)
Sardinella lemuru sustained through enhanced biological production during seasonal coastal upwelling.
Chl-a concenration impact on Sardinella lemuru production IOD 1997/98 IOD 2006/07 El Nino Significant correlation between Chl-a and Oily Sardine (max corr. time lag 3 months) Chl-a (mg/m3 7 6 5 4 3 2 1 0 S JM S J M S J M S JM S JM S J M S J M S JM S JM S J M S 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 (Source: Giovanni)
Match or Mismatch Hypotesis (Chusing, 1990; Durant et al., 2007) time Good Year Poor Year (Durant et al., 2007)
In 2010 the productions of Serdinella was low Local News Paper
Problems: Good Year : Although fish production is high during IOD (+) phase (> 100%) but the fishermen suffered the prices was lowest. Poor Year : Production is low Problems for Fish processing industy in this area. The time series Chl-a concentration derived from satellite data can be used as an indicator to predict the abundance of Sardinella lemuru in Bali Strait, to assist fishermen in fisheries management.
Summary Usually, in Bali Strait the Chl-a concentration is higher on July to October related to upwelling during southeast monsoon, but in 1997/98 and 2006 the Chl-a concentration was the highest until November related to IOD (+) phase. The relationship between chl-a concentration and Sardinella lemuru production is significantly positive. This correlation is maximal when Chl-a concentration leads sardine production by 3 months. The increase in the abundance of sardine in Bali Strait can be predicted from the trend of chl-a concentration 3 months earlier. If the anomaly is positive, the next 3 months is expected to see an abundance of sardine. Therefore, appropriate management is needed such as adjusting the number of vessels for fishing so that fish production will not be excessive, keeping some excess production for further fish processing, or distributing the excess fish to other areas. In contrast, during a negative anomaly of chl-a concentration can be expected to decline so that necessary to arrange sa suppy for other region.
Thank you very much
Acknowledgment NASA GSCF and GIOVANNI for ocean color remote sensing data Fisheries Agency for Fish catch data APN