2020-Fall Newsletter
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Fall 2020 Shark Research Institute Global Headquarters 70 Heather Lane • Princeton, NJ 08540 • USA • Phone: 609-915-5211 • www.sharks.org Sharks, Soot and Silt on the Amazon River By Dave Grant – Conservation Director “Every young man in the world is fascinated with either sharks or dinosaurs.” ...Peter Benchley Peter Benchley could have had me in mind when he wrote that line years ago, so while studying up on the Amazon before sailing up it, I collected information on one of the river’s most enigmatic inhabitants, the bull shark (Carcharhinus leucas). Known around the globe by various local names from other waters – the Zambezi, Lake Nicaragua and Rio San Juan shark–the stocky and aggressive bull, with its reputation for attacking humans, is the bad boy of coastal, warmwater elasmobranchs. I first became aware of peculiar “freshwater” sharks when hearing about the experiences in Central America of our grandfather and great-grandfather, and their exploits and commercial dealings during the Panama Canal construction and development of the region’s fruit plantations. Over the years, more reports of bull sharks piqued my curiosity: Locally, as a possible culprit in the infamous 1916 shark attacks along the New Jersey coast; and while traveling, learning of unusual catches reported in rivers as far from the sea as St. Louis, Missouri, and St. Petersburg, Russia. Over a dozen references to sharks in the Amazon River are found in the scientific literature. Some merely document a jaw in a museum or a photograph, but others are rather intriguing: 1970 – Shark jaws displayed in “Indian villages” in the region; 1969 – Shark meat marketed in Bogotá and Leticia, Columbia as “freshwater fish” and “dried catfish”; 1966 – “Sharks taken by collectors near the mouth of the Rio Negro river.” 1948 – And by far the most interesting: “Heavy fish kill following after-effects of earthquake included several sharks in Rio Ucayali.” Recently, the Amazon River has become a hot ticket for cruise companies, and equipped with a fish guide, pictures of shark teeth, a plankton net and microscope, I hitched a ride upstream from the river mouth at Belem, Brazil. Although the river is quite wide; a bar at the mouth, strong currents and a large tidal range, mean that ships must plan their transit carefully. Although we had onboard IN THIS ISSUE: two local pilots, we did Erich Ritter 4 Hawaii Expeditions 11 River ferry at Belem Interview by Emma Claisse 6 Shark Shop 12 run aground News from HQ 8 Journal Articles 13 for a day. Bookshelf 9 Our Supporters 15 Upcoming Events 10 Continued on page 2 Volume 29, No. 3 Page 6 The estuarine and tidal portion of the Amazon reaches more than 100 miles upriver, as indicated by the diatoms and copepods in plankton I collected while make short hops on small, crowded and over-worked local ferries. Typically, these were short and adventurous crossings, interspersed with frequent allisions (What the coast guardsmen call glancing blows) between other vessels jostling to dock at the crowded landings. On the stern, I’d be joined by a few to spend extended periods there. Visits to fish markets here are like perusing the pages and plates of William T. Innes’ classic Exotic Aquarium Fishes, but missing, were any signs of sharks. Instead, they hawked typical tourist fare like cheap jewelry, carvings, and sadly, mounted fishes. At most tourist stops, Zooplankton, silt and soot these offerings are so ubiquitous that we jokingly referred to them as part sample the estuarine of a Piranha-Industrial Complex–and a terrible waste of noble fishes. waters at Manaus I also approached locals along the shore. As angler and writer Dery Bennett liked to say “A fisherman knows everything there is to know…Just ask him!” and most of them immediately recognized what I was seeking and vigorously gestured downriver and out to sea to indicate where to find tubarões. Surprisingly, I had better luck finding teeth at bazaars, by searching the stashes of enthusiastic young people whom the Brazilians label “hippies” (Venezuelan expatriates and adventurers escaping the troubles back home and supporting themselves by making jewelry.). Among their hoard of artifacts being fashioned into objets d'art, they produced some teeth, but all were either from “crocodiles”, otters, pigs, or the distinctive teeth of tiger sharks; not triangular bull shark shapes I sought. The earliest scientific report about sharks near Belem is from 1897, but there have been other sightings halfway up the river in Manaus, and anecdotal reports all the way upriver to the foot of the Andes in Iquitos, Peru-over 1700 miles inland (As the macaw flies). Over two dozen marine elasmobranchs are known to enter brackish or freshwater for short periods, but the bull shark is one of the few to spend extended periods there. These may be mostly younger individuals from their robust physiology to thrive as a euryhaline species, and avoid competition, as well as predation, by larger sharks in the ocean. The main channel of the Amazon is sometimes referred to as “whitewater” because of the presence of massive amounts of silt washing down from the Andes. December is the dry season and the soot from brush fires that created striking red sunsets was also evident in the plankton samples I gathered. In spite of the load of suspended materials, the silty waters lacked much phytoplankton, but teemed with zooplankton; leading me to speculate that the aquatic food web is detritus-based this time of year. The water’s pH is mid-range and near neutral (6.5-7.3) and locals say it supports more fish than the “blackwater” tributaries like the Rio Negro River. The river mouths where these great waters meet have become popular tourist stopovers, and most tours include lingering at the interface when sailing through Meeting of great waters at the mouth of the Rio Negro Volume 29, No. 3 Page 7 them. Samples I took were silt-free and clear, but deeply stained with tannin from plant material; much like the waters of the NJ Pinelands back home. It is also acidic (pH 4.0-4.5) and indigenous people refer to the tributaries as “hungry rivers” because they support fewer fish and wildlife. Over a quarter of the Brazilian Amazon is supposed to be set aside for indigenous people, and there is a fledging tourism industry along some of the tributaries. Here, family groups have been concentrated along beaches in “villages” to entertain tourists. I have mixed feelings about visiting such places because in the Amazon region, research has shown that even simple commercialization like this can negatively impact local ecosystems and communities. Also, I travel light and never return home with any folk art, but instead have found that donating simple school items and sewing kits are welcome gifts to exchange for taking a few photographs. Although they are over-harvested and scarce, I snorkeled the blackwater at one beach, hoping to catch a glimpse of another odd freshwater elasmobranch, an Arraia–the freshwater stingray. Instead, I attracted the attention of a Boto ( Inia geoffrensis )–the fabulous pink dolphin of the Amazon. To entertain tourists, locals feed fish to these curious and formidable creatures. Three others joined us and I quickly discovered that they have little respect for personal space if they think you have fish to share; and there was a hierarchy among them that involved considerable bumping and splashing. Boto, the Amazon’s pink dolphin I have issues about interacting with wild animals that will become habituated to people, but admittedly, not so strong that I passed up the opportunity to swim with the them. They repeated some learned behaviors like spy-hopping to beg for fish; which, while entertaining, is rather intimidating when you are in the water. However, I learned later that in some places on the river, they are still butchered for catfish bait; so, things could certainly be worse for the inquisitive Botos. If we could communicate, I’m certain the dolphins would teach me much more about the river and where to find sharks; but another surprise of the trip was waiting for me when I returned home. Previously, I came across an ambiguous reference to a half-century old photograph taken near Leticia, Bolivia by notable fish collector and writer Herbert R. Axelrod; and after some effort, was able to track it down at the library of the University of Alabama. It is labeled “An Amazonian Indian holding a 60-cm, brightly colored carving of a shark…indicating that the Indians are well aware of the shark that travels far inland in South America.” Mission accomplished! Volume 29, No. 3 Page 4 Erich Ritter, Ph.D. December 30, 1958 - August 28, 2020 The shark world mourns the passing of Dr. Erich Ritter, an extraordinary scientist, the world’s leading shark behaviorist, educator and strong shark advocate. Few outside his family were aware he had a serious heart condition when he passed away in his sleep at his home in Pensacola, Florida. Erich grew up in Zollikon, Switzerland. He studied zoology at the ETH Z ürich, paleontology at the University of Z ürich, and received his Ph.D. from the University of Miami's Rosenstiel School in the field of fish behavioral ecology. Erich was the world's leading expert on shark behaviour, especially regarding shark/human interactions and as the scientific director of Sharkproject e.V., he focused shark- human relationships. In 2002 Erich had an accident in the Bahamas while filming a series for Discovery Channel’s Shark Week. A bull shark, snapping at bait, bit his calf instead.