
data listed in Tables 1 amd 2 are summaries of the important informa 
tion esi ec aatct ani sneratnrs streams were examined. The "Pool Grade" column in Table 1 
ditions according to quality. Pool Grade A repre- 
represents a classification of pool con Se SeeE Sacle hee palabra? | 
ents stream sections consisting of 50 per cent 0 
hel ter for fishes by reason of depth, boulders, overhanging banks, logs, and abundant 
tream sections consisting of 25 to 50 per cent of 
vegetation. Pool Grade B represents 5s 
eats providing cover of average to excellent quality. Pool Grade C is applied to stream 
j to excellent cover 
ctions that have less than 25 per cent of pools providing average ry 
of a higher percentage of total stream area in pools. of poor quality. The pool classifica— 
tion is based primarily from the amount of cover, but depth of the water is important, for 
provided in direct, ratio to depth and turbidity, 
the ditions are equal, shelter is 
faba witncmater Tishes, the ideal situation is a stream consisting of 50 to 80 per cent 
or more of pools, with depths of one and one-half meters or more. 
on is listed because of the importance of riffles as a 
habitat for insects, crustacea, and other groups of organisms which provide an important 
portion of the fish foods. The quantity of organisms found in the different types of bottom 
is usually highest in silt (organic debris and soil) and decreases in the following order; 
rubble (rocks 7.5 to 30 centimeters in diameter), boulders (30 centimeters or larger 
diameter), bedrock (solid rock) and sand (rock particles less than 0.25 centimeter ) 
The riffle compositi 
Bottom fauna was collected with a square-foot bottom sampler in a number of 
streams with different types of riffle bottoms. Samples taken from riffles consisting 
predominantly of rubble, gravel, and boulders usually averaged more than two grams per 
square foot (an area 30.48 centimeters square), while those taken from riffles with large 
amounts of sand interspersed with rubble and gravel averaged about one gram. Samples taken 
from streams with sandy bottom averaged less than one gram per square foot. The shrinp 
(Palaemon carcinus) and the crab (Potamocarcinus temalensis) occur in nearly all streams. 
As these forms were not easily taken in the bottom sampler, but were observed with a light 
at night to occur in moderate numbers, it may be assumed that the bottom fauna is repre- 
sented in considerably greater quantity than could be measured. Because of the amount of 
time utilized in taking bottom samples and measuring the organisms, and the knowledge that 
the results were not representative, only a limited number of streams were sampled for the 
bottom fauna. Except in the slow flowing coastal streams, where stream bottoms consist 
almost wholly of sand, bottom food organisms are adequate to be classified as rich. In 
addition to the fauna of the stream bottoms, fishes also feed upon smaller fish, terrestrial 
insects, frogs, toads, and other organisms that live in the stream or fall into it. Since 
the waters are warm throughout the year, many of the fishes such as the live-bearers, 
Poeciliidae, reproduce the year around. The other animals that fish feed upon have no 
dermaut season as in colder climates. Consequently, the continuous growing season and ade- 
quate supply of food should make for an abundance of fishes, unless other unfavorable factors 
limit production. 
The Pacific coastal plain has approximately one meter of rainfall annually. Rain- 
fall on the lower mountain slopes of the Pacific drainage is two meters, and three or four 
meters on the higher mountain slopes. Much of the north slope has no more than one meter, 
and some sections in the Motagua Valley have considerably less. Parts of Vera-Paz, the | 
Polochic and Sarstun drainages, and the north coastal areas have precipitation ranging from 
two to as much as five meters. With some localized exceptions, most of the rain falls be- 
tween May 15 and November 15 each year. The abundance of rainfall beginning in May and 
terminating in November, with its resulting erosion and silting, followed by the long dry 
season, limits the stream areas in which the fishery resources can be developed profitably. 
During the dry season, most of the small highland streams and some of the large ones as well 
as many of the smaller streams of the southern lowlands, become dry or reduced to small flows. 
Soon after the rainy season begins, the streams became a chocolate brow color as 
a result of the heavy load of silt. As the rainy reason continues, the streams clear in 
some degree, but remain turbid, for the most part, throughout the rainy reason. Near the 
2/ Instructions for conducting stream and lake surveys by H. S. Davis, fishery Circular 
No. 26. U.S. Department of Commerce, Bureau of Fisheries, Washington, D. C. | 
102 
