Who is the Short-tailed stingray?
is a rarely found beast of a fish, and likeliest the heaviest true freshwater species of South America; at 220kg fully grown, it’s nearest rivals are (at 200kg) and catfish (at some 150kg). The disc of the Short-tailed stingray can reach 1.5m in diameter, and yet this fish has still been historically caught for aquarium keeping.
While it faces many threats including overfishing and habitat destruction, it is also susceptible to dams, which have severely restricted its natural range.
The commotion caught the attention of flocks of Large-billed terns, Phaetusa simplex. These expert fishers, appearing in the Pantanal only in the wet season, wheeled above the river before plunging down to grab the unfortunate Astyanax at the surface. They didn’t enter the water, but instead dexterously snapped up the small fish with their long bills.
Such feeding phenomena carried on regularly through each day of our trip. Wherever one group of predators began to attack, the others joined in. The frequency of such events and the volume of fish involved attested to the importance of an angling closed-season and to the health of the river. This was the period when all fish needed to feed as much as possible, to support their breeding activity and to last through the leaner months of the long dry season (May-December).
As the evening drew in, Tiagão proudly presented a large catfish which had taken the bait intended for the stingray. It was a Zungaro jahu. We took photos and measurements before easing it back in to the shallows. As darkness fell, myself and another team member attempted to use a small dragnet to trap fish against the bank, ourselves waist-deep in water. However, the density of the mosquitoes forced us inside within ten minutes. We couldn’t even hear each other talk over their hum.
The ash lagoon
The following day, I went out on the boat with Heriberto and we snorkelled through several temporary lagoons hoping to film and photograph smaller species. The area had been ravaged by fire in November and the substrate was just ash. Here and there were a few
lilies but almost no fish. The lagoons usually act as refuges for fish; feeding, breeding and escaping predators in the main river channel, but the charred bottom meant there was no food for even aquatic invertebrates and small fish, and so the entire food chain was unsupported.
Where the lagoon drained into the main river, we found shoals of juvenile Piraputanga, Dourado and Curimba, patrolling and feeding in the current, and I had the chance to fish from the boat and caught several medium-sized Dourado. In the evening we caught several more catfish from the bank; Pimelodus argenteus, Pinirampus pinirampu, and Pterodoras granulosus, all whiskers, spines and croaks.
The hunt’s end
On our final day, we had to concede defeat regarding the stingray.
Several members of the team who had been fishing for over 20 years said they’d only ever seen one or two, so we should not take the failure too hard. As we loaded up the boats by the shore, we noticed some animal prints in the mud at the water’s edge. Jaguar prints. While we had slept in our bunks, a big cat had been prowling about by the deck, perhaps drawn by the smell of fish (and our cooking).
We were picked up by another two members of the Environmental Police who showed us photos of two jaguars, lounging on the deck, taken a few months before. It was good to know that, despite our supposed dominance of the planet, at least in this bit of the world we were truly in non-human territory.
The journey back was slow. Regardless of the failure of our main mission, we were animated about what we’d seen and experienced and I reflected that I am truly, incredibly lucky to be able to visit such wild locations, even if I didn’t get to see the biggest stingray that South America has to offer.