Detection of pelagic habitat hotspots for skipjack tuna in the Gulf of Bone-Flores Sea, southwestern Coral Triangle tuna, Indonesia

Abstract

Using remote sensing of sea surface temperature (SST), sea surface height anomaly (SSHA) and chlorophyll-a (Chl-a) together with catch data, we investigated the detection and persistence of important pelagic habitat hotspots for skipjack tuna in the Gulf of Bone-Flores Sea, Indonesia. We analyzed the data for the period between the northwest and southeast monsoon 2007–2011. A pelagic hotspot index was constructed from a model of multi-spectrum satellite-based oceanographic data in relation to skipjack fishing performance. Results showed that skipjack catch per unit efforts (CPUEs) increased significantly in areas of highest pelagic hotspot indices. The distribution and dynamics of habitat hotspots were detected by the synoptic measurements of SST, SSHA and Chl-a ranging from 29.5° to 31.5°C, from 2.5 to 12.5 cm and from 0.15 to 0.35 mg m-3, respectively. Total area of hotspots consistently peaked in May. Validation of skipjack CPUE predicted by our model against observed data from 2012 was highly significant. The key pelagic habitat corresponded with the Chl-a front, which could be related to the areas of relatively high prey abundance (enhanced feeding opportunity) for skipjack. We found that the area and persistence of the potential skipjack habitat hotspots for the 5 years were clearly identified by the 0.2 mg m-3 Chl-a isopleth, suggesting that the Chl-a front provides a key oceanographic indicator for global understanding on skipjack tuna habitat hotspots in the western tropical Pacific Ocean, especially within Coral Triangle tuna.

Catch per Unit Effort Dynamic of Yellowfin Tuna Related to Sea Surface Temperature and Chlorophyll in Southern Indonesia

“…Meanwhile, chl a data can also be used as a valuable indicator of water mass boundaries and may identify upwelling that can influence tuna distribution within a region [14,15]. Chl a concentrations over 0.20 mg•m −3 , indicate high phytoplankton abundance for tuna prey, such as small pelagic fishery resources [16,17].…”

The Effect of Oceanographic Factors on Skipjack Tuna Fad vs Free School Catch in the Bone Bay, Indonesia: An Important Step Toward Fishing Management

“…A combined satellite remote sensing (SRS) and geographic information system (GIS) provides a powerful tool to detect potentially skipjack tuna habitat. The skipjack habitat has been proved to correspond with several oceanographic factors such as surface temperature, salinity, and thermal fronts and Chl-a (Andrade, 2003;Mugo et al, 2010;Zainuddin et al, 2017).…”

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“…Adanya pergerakan massa air secara musiman dan tahunan yang telah mempengaruhi kondisi oseanografi, mengungkapkan faktanya bahwa pergerakan massa air ini mempengaruhi pola migrasi pergerakan ikan-ikan migratory (high migratory species) (Safruddin dkk, 2014;Zainuddin et al, 2017;Hidayat et al, 2019;Safruddin et al, 2019).…”