
wf 
Zacapa, and Gualan probably it is less than half that amount. Selow Gual4n, the amount of 
precipitation increases rapidly toward the coast, and averages near 293 centimeters in the 
lower reaches of the drainages, with approximately 240 centimeters falling in the months of 
June nee i inclusive. The two forks that form the main stream in the vicinity of 
Santo Tomas have a combined flow of approximately 0.7 to 0.84 cubic meter (25 to 30 cubic 
feet) per second. Below the forks, additional tributaries join the river, forming a 
turbulent mountain stream with an average fall of about eight meters per kilometer. In the 
region of Concua, about 60 kilometers below Santo Tomas, the stream averages 23 meters in 
width, and had an estimated flow of 11.3 cubic meters (400 cubic feet) per second at the 
time observations were made. The gradient at Concua was estimated at 4 to 5 meters per 
kilometer. In this region, it has eroded a mountain valley more than 1,300 meters in depth. 
Near the mouth of the tributary, Rfo Agua Calienta and about 30 kilometers below 
Concua, the gradient becomes less, and the sea dechags of pool area is ieee cased above the 
approximate equal percentage of pools and riffles at Concua. The bottom changes fron 
predominately boulders, sand, and rubble to sand and gravel; the clear water of greenish- 
blue color becomes slightly turbid due to shifting sand. Below Gual&n the stream has many 
oxbows, a width of 75 meters, shallow pools of one to one and one-half meters, and a con- 
tinuous flow over sandy bottoms devoid of aquatic vegetation. Near Tenedores, approximately 
60 kilometers from its mouth, the stream is about 100 meters wide. At the time observa- 
tions were made, it had an estimated flow of 16.9 cubic meters (600 cubic feet) per second. 
The stream averages about one foot in depth, and has few pools. The sandy bottam supports 
little aquatic vegetation, except occasional small beds of Gramineae along the shore margin. 
In many places, the banks are undercut, and are shaded by overhanging vegetation. The 
stream was not observed below Tenedores, but well-informed natives told us that its char- 
-acter changes little except near its mouth, where there is a swampy shoreline, deeper water, 
slow current, and a considerable amount of aquatic vegetation. 
The stream contains three species of characins (Characinidae), six species of 
Poeciliidae, six or seven mojarras (Cichlidae), and 15 or more other species. 
Spawning areas for smallmouth bass (Micropterus dolomieu) and largemouth bass 
(M. salmoides) are considered to be excellent above Agua Caliente. Below this point, spawn- 
ing areas are available for largemouth bass, and the entire stream is suitable for channel 
catfish (Ictalurus lacustris punctatus). For the best utilization of habitat, smallmouth 
bass should be stocked above Rio Agua Caliente and largemouth bass below. Channel catfish 
are recommended for the entire stream. 
Tributaries of the Rfo Motagua.--There are a number of excellent tributaries 
entering the Motagua, but most of these were examined only at one or two points. Bxcept 
the lower five kilometers of Rio Grande Rio Zacapa at Zacapa, these are mountain streams 
with boulders, rubble, and gravel, containing pools of average to excellent quality. 
Tributaries were examined as follows: South fork of Rio Motagua at Chichicastengo, Rios 
Belejeya, Chol, Las Vacas, Purgatorio, Platanos, Agua Caliente, Morazan, Tato, Chimalapa, 
Riachenlo, Viejo or Sunsapote, El Hondo, Grande (Rfo Zacapa) at Zacapa, and Xuteque. Except 
in the upper reaches, where the streams are relatively small, most of the tributary waters 
have gradients within the normal limits for smallmouth bass. 
For the best utilization of habitat, it is believed that the smallmouth bass 
(Micropterus dolomieu) and the channel catfish, (Ictalurus lacustris punctatus) should be 
introduced if these species prove to be successful in the trial plants elsewhere. 
nfo Polochic 
| This drainage arises in the vicinity of Tactic, Tamahu, and Purulha at altitudes 
of 1,200 to 1,500 meters. It has many characteristics of a rainforest in that the drainage 
is well covered by abundant tropical vegetation. Rainfall records taken at Tres Aguas at 
an altitude of 250 meters are suggestive of the average for the watershed, although precipi- 
tation is undoubtedly greater at higher altitudes. The records (Sapper, 1899) show an 
anmal precipitation of 5,617 millimeters, with 125 to 215 millimeters falling monthly during 
the first four months of the year, 400 in May, 950 to 1,075 monthly during June, July and 
August, 675 in September, 490 in October, 260 in November, and 160 in December. Livingston, 
on the Gulf of Honduras at the lower end of the drainage, has an average yearly rainfall of 
5,230 millimeters. 
105 
