Why whale sharks stay in Saleh Bay: what research has found so far

By Sumbawa Liveaboard Editorial Desk

Why are whale sharks found in Saleh Bay? The ISRA factsheet attributes the bay's productivity to rivers and seasonal upwelling, a likely part of the answer, and says the sharks gather at light-fishing platforms. Most identified sharks are young males, tags show limited year-round habitat elsewhere, and newborn records suggest the bay may also serve as a nursery.

What makes the bay productive?

The ISRA factsheet, from the IUCN SSC Shark Specialist Group, describes Saleh Bay as a semi-enclosed embayment in northeast Sumbawa, directly connected to the Flores Sea, with small islands, coral reefs, seagrass and mangroves. It attributes the bay's productivity to two drivers: river inputs all year, and seasonal upwellings produced by monsoon winds. A productive bay is a likely part of why large filter feeders turn up here, though that link is our inference and not the factsheet's wording.

Fishing adds a further layer. Bagan, the lift-net platforms that use light to attract small pelagic fish and sergestid shrimps, draw whale sharks, which have been seen sucking baitfish from the outside of the net. It would be easy to conclude the platforms explain everything, but local ecological knowledge recorded in the factsheet says the sharks fed on krill and small fish in the area before the bagan fishery began. Sources disagree on when that fishery and the association started, so we leave the date open.

Published sizes for the bay also need care, because each measures something different:

Who are the sharks in Saleh Bay?

Mostly young males. Konservasi Indonesia's 2025 report counts 174 individuals identified through monitoring up to 2025: 137 confirmed male, 16 female and 21 unidentified. The ISRA dataset, an earlier and smaller count of 108 individuals, found 99 percent were juveniles or sub-adults. Sighted animals averaged 512 cm in total length, give or take 112 cm. For scale, Wikipedia gives 18.8 m as the largest individual considered reliably recorded, so the sharks of Saleh Bay are a long way short of full size.

Photo-identification addresses the "stay" in this page's title. The ISRA factsheet reports 76 percent of individuals resighted across multiple years, with up to 5.12 years between observations. That shows fidelity to the area over years. It does not show that a given shark remains in the bay without leaving.

The timing evidence is contested. The factsheet records regular observations year-round between 2017 and 2022, with the largest numbers in March and April. Komodo Resort calls May to October the season and says June to August is usually the most consistent. The two claims may not measure the same thing. The Saleh Bay trip guide looks at how those seasons shape a booking.

What did satellite tags reveal?

Two findings from tagging work point in opposite directions, and both matter. A study in Frontiers in Marine Science followed 70 whale sharks tagged from 2015 to 2025 at four Indonesian sites. It found that year-round suitable habitat is limited and largely confined to a few aggregation sites, particularly Cenderawasih Bay and Saleh Bay. In other words, the bay is one of few places that remain suitable in every season.

Conservation International's summary of the same research reports whale sharks moving across 13 national boundaries, with tags averaging over 400 days and the longest lasting 990 days. So the wider population is far from resident. Those figures describe the tagged animals as a whole, not Saleh Bay's sharks alone, and it would be a mistake to read them as a local statistic.

Closer in, two tagged sharks in the ISRA factsheet foraged vertically for 39 percent of 56 tracked days; the source does not say where. Two animals make a very small sample, so read it as a note on how these sharks feed and not as a map of where.

The research is also shaping management. Mongabay reported in May 2026 that the Indonesian government is using tracking data to help establish a whale shark-based marine protected area in Saleh Bay, with zoning that considers no-take zones. We have not found a record that it has been formally gazetted, so "being established" is as far as we can go.

Is Saleh Bay a nursery?

It may be, and "may" is the authors' word. A 2025 paper in the journal Diversity reports that fishermen in eastern Saleh Bay logged five separate sightings of a small whale shark, estimated at 1.2 to 1.5 m, in August 2024. On 6 September 2024 a male neonate of about 135 to 145 cm was caught incidentally in a bagan lift net. The authors call these the first records of neonatal whale sharks in Indonesia and suggest the bay may serve as a pupping and early nursery area.

The wider context explains why scientists paid attention. Conservation International notes that no pupping ground has been confirmed anywhere in the world, and that sightings of individuals under 1.5 m number only 33 in the scientific literature. A few small animals in one bay in one season do not settle the matter. They do give researchers a reason to keep looking, and they make travel copy calling Saleh Bay a "nursery" as settled fact premature.

How does the bay compare with other Indonesian sites?

A comparison table in Konservasi Indonesia's 2025 study lists identified individuals by site. Its data runs to about 2022 or 2023, which is why it shows 108 for Saleh Bay and not the later 174.

These are tallies of identified individuals. They may reflect how long and how hard each site has been monitored as well as how many sharks use it, so a larger number does not prove a larger population. You may also read a resort's claim of a global ranking for the bay. We found no global dataset behind it, and this table covers Indonesian sites only. What can be said with confidence is narrower: Konservasi Indonesia reports that Saleh Bay is one of Indonesia's national priority sites under the Whale Shark National Plan of Action.

What does this research mean for a traveller?

It should adjust your expectations in several practical ways:

• Expect young sharks of around five metres, not giants.
• Read "year-round" as a record of observations, not a forecast for your dates.
• Treat the platforms as one part of the picture: local knowledge recorded by ISRA has the sharks feeding in the area before the fishery began.
• Ask how your operator behaves at a bagan, because the science raises questions about that link.

On that last point, the 2025 Konservasi Indonesia report warns that the association with bagan fisheries may promote behavioural dependency, and that growing tourism, land pollution and local fishing may alter how the sharks use the habitat if not effectively managed. We take up the consequences in whether feeding whale sharks in Saleh Bay is ethical.

What other questions do readers ask about Saleh Bay whale sharks?

Are whale sharks in Saleh Bay all year?

Yes, according to the ISRA factsheet, which records regular observations year-round between 2017 and 2022. That describes past sightings. It says nothing certain about a particular morning on a particular boat.

Do the sharks only come for the fishing platforms?

No, on the local knowledge ISRA records: they fed on krill and small fish there before the lift-net fishery began. ISRA also says they commonly gather at the nets, which is where visitors meet them.

Are there adult whale sharks in Saleh Bay?

Very few have been recorded. In the ISRA dataset of 108 identified individuals, 99 percent were juveniles or sub-adults.

Has Saleh Bay been confirmed as a birthplace for whale sharks?

No. The authors of the 2024 neonate records say it may serve as a pupping and early nursery area, and no pupping ground has been confirmed anywhere in the world.

What legal protection do these sharks have in Indonesia?

Full protection. Ministerial Decree 18/KEPMEN-KP/2013 gave the species full protected status in May 2013. A separate marine protected area for Saleh Bay is still described as being established.

Which sources support this page?

• ISRA factsheet: Saleh Bay Important Shark and Ray Area
• Ekbis NTB: report on the 2024 Saleh Bay research expedition
• Konservasi Indonesia: 2025 whale shark study (PDF)
• Konservasi Indonesia: Saleh Bay whale shark 2025 report
• Wikipedia: Whale shark
• Komodo Resort: Sumbawa liveaboard page
• Frontiers in Marine Science 2026: whale shark satellite-tracking study
• Conservation International: decade-long whale shark tracking summary
• Mongabay, May 2026: satellite study and the planned protected area
• Diversity 17(12), 839: neonatal whale shark records
• Conservation International: rare newborn whale shark sightings
• Indonesian marine ministry legal database: Decree 18/KEPMEN-KP/2013

How do I reach the desk?

Source corrections and questions on this research are welcome at bd@juaraholding.com or on WhatsApp +62 811-3941-4563. Trip enquiries go to the same desk, which answers questions and makes no sighting promises.