Posts Tagged ‘blackwater’

Fish of the Week: Catfish – Sorubim

September 26, 2011
Sorubim

Sorubim

Our “Fish of the Week” is Catfish – Sorubim, which is a beautiful species sporting an elegant pattern of hieroglyphic black markings on a silver grey background dorsally and stark white ventrally. The common name sorubim is used for several similarly shaped species in the genus. Body markings, typical habitat and maximum size differ. P. tigrinum is commonly encountered by anglers in Amazon lowland, highland and Guyana shield fisheries.

The Sorubim is distinguished by its flattened head, elongate body and large terminal mouth. Its silvery gray upper body with heiroglyphic markings dorsally, and tiger stripes laterally, also set it apart. Sorubim’s fin markings continue from the body, evolving into spots toward margins. The silver gray on its dorsum changes abruptly to white on its ventral sides, as well as its abdomen. Specimens up to one meter in length and more than 100 pounds have been reported. The genus contains eight recognised species, and although all are similarly elongate, many are uniquely marked and have separate ranges. Common names include Barred Shovelnose (English); sorubim, suribim, cachara (local); and Bagre rayado.

This catfish can be found in Brazil, Peru, Guyana, Ecuador, Bolivia, Suriname, Columbia, Venezuela and Argentina, particularly in the Amazon, Orinoco, Essequibo, Corantijn and Parana drainages and river basins. They usually occupy lotic (moving water) environments in blackwater river systems. Primarily feeding on fishes, P. fasciatumis are readily encountered with cut bait on shallow sandbars in river channels. Although mostly an evening and nocturnal feeder, anglers are often surprised by large sorubim attacking artificial lures in open water at any time of day. The current IGFA record is 35 pounds, 10 ounces.

In addition to being a great angler’s target, the barred sorubim is a pleasant adjunct to any fishery. Its habit of attacking artificial lures and then fighting like whiskered tuna, makes it endearing to peacock bass anglers and catfishermen alike. In most high gradient fisheries sorubim can be targeted by anglers at evening time. They tend to congregate and forage at the edges of shallow beaches with nearby drop-offs to deeper water. Small live bait or pieces of cut bait are equally effective when cast onto the beach and allowed to drift naturally to the nearby drop-off. An effective rig consists of a 10/0 to 14/0 circle hook (or smaller J hook) with a wire leader and relatively light sinker (approx. 1 oz.), enough to keep it down while still allowing the current to slowly carry it. The take is usually quite forceful. Once hooked, sorubim will fight in open water with strong runs and surprising stamina.

Pintado

Pintado

Pintado – Psuedoplatystoma corruscans – up to 1.5 meter
This larger catfish is found outside the Amazon in the Pantanal and the Sao Francisco and Parana river basins
(Illustration from “Peixes do Pantanal” – Embrapa – poster)

Pintado

Pintado

Acute Angling – Official Website
Tackle-Box.net
Facebook
Twitter
LinkedIn
YouTube
Photos

Advertisements

Peacock Bass Science and Conservation – Peacock Bass pH Tolerance

September 16, 2011
The more anglers know about their quarry, the better they are able to successfully pursue it and manage its conservation. The giant peacock bass (Cichla temensis) roams a blackwater environment that is so significantly different from that of temperate zone freshwater sportfish, that it is worthwhile for peacock bass anglers visiting the Amazon to gain an understanding of the peacock’s home waters. The following article attempts to provide some insights via a research project assessing fishes’ acid tolerance in blackwater environments Throughout North America, Europe and Asia, pollution has caused serious damage to aquatic ecosystems. One of the worst culprits is acid rain. Resulting mostly from sulfur emitted by power plant smokestacks, this toxic acidification has been shown to cause massive fish kills and a serious loss of biodiversity in our lakes, rivers and streams.
On the other hand, in the Amazon basin, highly acidic “blackwater” regions exist that support a huge diversity of fishes in spite of being far more acidic than even our most damaged waters. In fact, this is the preferred home of the giant peacock bass. The most powerful freshwater gamefish in the world, lives in water with enough acid content to kill most species! The obvious question you might ask is, “How is this possible?” Many researchers have asked the same question. The answer may lie in the tea-colored material that gives blackwater its name.

Blackwater is formed when wet, oxygen-poor soils permit the slow decay of matter from vascular plant material. Runoff delivers a constant supply of this mixture of dissolved organic matter (mostly made up of tannic and humic acids). Not only does this material deliver blackwater’s characteristic coloration, but scientists have found convincing evidence that it actually protects fishes against the poisonous effects of acidic environments.

Acid water causes fishes to lose their body salts. Freshwater species have a biological pumping system in the cells of their gills that keeps the salt in their bodies from leaking out into the salt-free freshwater that surrounds them. Acid conditions attack these cells and cause them to stop working. The material in blackwater, however, appears to provide a protective effect for these cells, enabling them to continue to work normally. The peacock’s own ecosystem may be what protects it from environmental toxicity that kills fish elsewhere.

The Amazon is a giant enigma, with thousands of interlocking puzzles waiting to be solved. We haven’t even begun to understand how they fit together. Here is just one more reason why it must be protected at all costs. With more study, we might learn how to use Amazon-based knowledge to protect fishes in each of our various backyards. Perhaps we’ll find that reducing the constant deforestation in our countryside might put more of these blackwater materials into our waters and help slow the rate of environmental degradation and fish loss.

Note – The following unpublished paper is the result of an experiment performed on non-Amazon fishes, with an eye toward understanding more about the nature of Amazon Blackwater systems. The reference materials cited in this paper can provide additional information regarding this subject matter from peer-reviewed sources.

Laboratory Analysis of the Effects of Blackwater on Low pH Tolerance in Fishes

PAUL REISS; Rutgers University, Graduate Program in Ecology and Evolution, New Brunswick, NJ, 08901, USA
Rutgers University Marine Field Station, Tuckerton, NJ

Abstract

The unusually high level of fish biodiversity found in acidic “blackwater” systems in the Amazon basin suggests that the humic and fulvic acids in blackwater may provide some form of protection against the toxic effects of low pH, or that fishes endemic to this environment may be more tolerant of those effects. These ideas were tested by two experiments in a laboratory study. In the first experiment, seven fish species from three water types were subjected to a treatment regime of reduced pH to compare the species’ tolerance to pH toxicity. Species examined included: Enneacanthus obesus, Micropterus salmoides and Aphredoderus sayanus from blackwater; Fundulus heteroclitus, Menidia menidia and Cyprinodon variegatus from brackish water and Lepomis macrochirus from clear freshwater. The results demonstrated markedly different resistance to mortality in low pH among the species, as measured by the cumulative concentration of excess H+ ion over time. For example, Enneacanthus was able to tolerate almost three times as much exposure as Lepomis, a member of the same family, and over eight times the exposure of Cyprinodon, a brackish water fish. The results also demonstrated that fishes from blackwater are more resistant to low pH toxicity, as a group, than fishes from other source waters.

In a second experiment, the effect of water type on tolerance to low pH was measured among a subset of species selected from the first experiment, i.e., Fundulus heteroclitus, Cyprinodon variegatus and Lepomis macrochirus. Resistance to mortality ranged from 20% to 100% greater in both blackwater and brackish water than in clear freshwater for each species. These results indicate that there are effects inherent in both blackwater and brackish water that protect fishes against low pH and which are lacking in clear freshwater. The study examines the physiological aspects of pH toxicity in various water types, considers differences in innate or acquired tolerance to low pH among species and analyzes the relevance of ecosystem management strategies in relation to the toxic effects of acidification.

To read the full report, please click here.

Acute Angling – Official Website
Tackle-Box.net
Facebook
Twitter
LinkedIn
YouTube
Photos

Photo – Steve Brody With A Big Peacock

August 23, 2011

Steve Brody shows off a trophy peacock caught in the black water lagoons of the Rio Unini on our Fly-in Safari Camp trip.

Steve Brody with Peacock Bass

Steve Brody with Peacock Bass

Acute Angling – Official Website
Tackle-Box.net
Facebook
Twitter
LinkedIn
YouTube
Photos

Photo – Jeff Berzon With a Big Peacock Bass

August 12, 2011

Jeff Berzon became a peacock bass fanatic after his successful week on the black water lagoons of the Rio Unini on our Fly-in Safari Camp trip.

Jeff Berzon With a Big Peacock Bass

Jeff Berzon With a Big Peacock Bass

Acute Angling – Official Website
Tackle-Box.net
Facebook
Twitter
LinkedIn
YouTube
Photos

Fish of the Week: Peacock Bass – Cichla temensis

August 8, 2011
Cichla temensis

Cichla temensis

Our “Fish of the Week” is Peacock Bass – Cichla temensis, which is the largest member of the peacock bass genus. This top level predator is considered by many to be the most powerful freshwater gamefish in the world, as evidenced by its current IGFA record of 27 pounds.

Cichla temensis, in its bright spawning color phase, is called “assu” in Brazil or “three-bar” in English. They become heavier and deeper bodied in this form due to prespawn changes and matured gonads. In the “paca” form, Cichla temensis displays a darker color pattern and a more hydrodynamic shape.

Cichla temensis identification is made somewhat complex by the species’ morphological variability. Specimens are encountered in two very distinct color and pattern phases, with an array of intermediate stages corresponding to their degree of reproductive readiness. The spawning pattern transformation process is gradual – the bars darken, colors brighten and the white speckles disappear. The brilliantly colored acu (pronounced ‘assu’) is in reproductively active condition. The Paca morph has white or yellow dots (3) arranged in four distinct longitudinal rows. Both morphs have 3 distinct dark bars (2) along the sides of the body and a distinct black stripe or speckled markings from the eye to the end of the opercular bone (cheek or gill cover) (1), no ocelli on the sides or at the base of the second dorsal.

Cichla temensis

Cichla temensis

Temensis is the most elongate of the Cichla species, with a body depth generally around 25 percent of its standard length (length measured to the base of the tail). It has the smallest relative scale size of the genus, generally having from 100 to 125 scales along its lateral line.

The species has three distinct, entire bars from dorsal peak to below lateral line, almost to the abdomen. It also has a distinctive postorbital band (or series of connected blotches on operculum [cheek]). In paca form, they sport four horizontal rows of light colored speckles. Its colors are extremely variable. Juveniles can grow up to about 300 cm (12 inches), while adults can grow from 300 mm up to about one meter (39 inches). Its depth to length ratio is approximately 25 percent and it has about 110 lateral line scales. Similar species include Cichla pinima and Cichla vazzoleri.

Cichla temensis

Cichla temensis

Cichla temensis’ violent behavior and awesome tackle-busting power is the primary attraction that brings avid sport fishermen to the Amazon. Its known range include the countries of Venezuela, Columbia and Brazil. Within these countries, you’ll find Cichla temensis in the Rio Negro, Orinoco, Madeira and Branco basins, with some limited populations noted in several rivers draining into the Solimoes and Amazon. Temensis primarily occupies lentic (slow or still water) environments in lagoons, backwaters and shoreline pockets. However, they will readily enter faster waters to feed and when water levels leave most lentic habitat dry. They are mostly restricted to blackwater systems. Common names for this peacock include three-barred peacock, speckled peacock, tucunare, acu, paca and giant peacock.

A primarily piscivorous (fish-eating) predator, C. temensis will behave as both a pursuit feeder and an opportunistic feeder. Their determined and aggressive fry-guarding behavior makes large acu readily accessible to sharp-eyed anglers. Cichla temensis is the premier peacock bass species pursued by trophy anglers. Its sheer size, violent attacks and general overall aggressiveness have made it the most highly regarded of all freshwater sportfish. It has spurred volumes of literature and endless variations of tactics and techniques. See our ‘Peacock Bass Primer‘ for a thorough introductory guide to catching this species in its native, pulsative river environments.

 

Acute Angling – Official Website
Facebook
Twitter
LinkedIn
YouTube
Photos

Fish of the Week – Redtail Catfish (Pirarara)

June 14, 2011
Our “Fish of the Week” is redtail catfish, also known as pirarara in Brazil. One of the most ubiquitous of the giant cats, it appears to have very few habitat limitations, just as happily living in acidic, blackwater lowlands streams as it is in alkaline highlands rivers. They can be found in all parts of clear (blue) water, blackwater and whitewater (sediment carrying) rivers, including small tributary streams.
Redtail Catfish

Redtail Catfish

Their unique markings and bright coloration makes them very easy to identify – their bright tail is an instant giveaway. Their dark upper body contrasts sharply with a cream to white segment below the lateral line posteriorly. The mix of contrasting colors highlighted with red makes this catfish one of the most striking of the big cats. Its body color is dark olive to shiny black, its abdomen white and lower fins red. Its dorsal fin and adipose fin are fringed with red.

A very powerful fighter, redtails are known for a sustained, line-pulling initial run and the ability to find a tangle of submerged logs at the end. Adults can grow up to 60 inches and can weigh more than 100 pounds (the IGFA world record is 113 lbs, 9 oz. caught in the Rio Negro). Found in the Amazon basin in Brazil, their seemingly endless appetite makes them easy for anglers to engage. They’re ominvores, as they feed on fish, detritus, crabs and fruit (we’ve actually caught them on pieces of watermelon!). They’ve been landed on everything anglers use, ranging from free-swimming live bait to a Wooly Bugger fly (cut bait is easiest, for practical purposes).
An entire head of a traira on a circle hook is a durable and widely accepted bait for redtails. Use an Amazon rig, configured as follows: “For Redtail Catfish, a large (14/0) circle hook haywire twisted to 12 to 18 inches of strong (120 – 220 lb. test) wire then twisted to a heavy (180 lb. test swivel. A two ounce (or heavier – as current demands) egg sinker is allowed to run freely on heavy line (50 pound or greater) braided line. This wire reinforced ‘Amazon’ rig helps keep piranha away from the actual running line and minimizes the loss of hook, line and sinker.”
Set up your road according to your preferences. Try a woodchopper rod (medium-heavy baitcaster or spinner) equipped with heavy braid (50- to 65-pound test). You’ll have fun catching these guys on light tackle – they’re very durable fish that don’t tire easily.
Several types of water are usually productive. In a river without a lot of features, a curve will often suffice. Drop the bait into the deeper, channel side. If deep pools with eddying water are available, select these types of water. Often, piranha activity on the bait is followed quickly by a take, which may summon the redtail. In any case, the traira head is a great bait even when almost entirely denuded. Let the piranha have their way and wait for your quarry. If there is a redtail there, you’ll usually meet up within 15 minutes. If not, move on.
To succeed with this tackle, you must survive the first run. Make sure your boat is ready to move upon the hookup. The “take” is usually a no-doubter – redtails grab forcefully and move on. With an open bail (or clicker on), allow line to be taken until you’re certain the fish is moving away from you and has had a chance to engulf the bait. Point the rod tip upward, engage your reel and allow the rod to be pulled downward until it points at the fish. With resistance occurring, a redtail will usually react with a screaming run, hooking himself with the circle hook in the process. This method is highly recommended because it will unfailingly result in a safe hookset in the corner of the fish’s mouth, never in its gullet or stomach.
Depending on the size of the fish and the underwater structure, anglers with light tackle can be spooled on the first run. Make sure the boat stays with the fish and you keep a reasonable reserve of line. Don’t try to stop him with a thumb or a tightened drag – you’ll probably just break him off. Let him burn off that first blast and then you can start to fight back. The key to landing a big redtail on light tackle is to get him off the bottom. If possible, get nearly over him, but offset at an angle, and work him upwards. If you can lever him into the water column, you gain the tactical and mechanical advantage and can probably land the fish quickly. If he is able to remain on the bottom, he will seek cover or structure and even though you may have survived the difficult first run, you can still lose him to an unforgiving snag. Once at the boat, redtails can be easily lifted from the water by their heavily boned pectoral fins. He’ll talk to you the entire time you take your pictures. Put him back to fight again.
If you’re record hunting or simply want to land the highest possible percentage, a heavier rig (i.e. – an Ambassador 7000 sized reel with a stiff, short and heavy Ugly Stick rod) can be used with line up to 100 lb. test. This is enough to slow down the runs and then muscle all but the biggest redtails off the bottom, the key to landing them.
John With Big Redtail

John With Big Redtail

Acute Angling – Official Website
Facebook
Twitter
YouTube
Photos