Figure 4 illustrates the distribution of all fish as observed with the acoustic integration system. The unit of fish abundance is 0.1 m2 per nm2 acoustic reflection. Fish that occurs from 10 m below surface level down to about 0.5 m from the bottom will be observed with this system. The distribution chart shows three categories of fish concentration: 1-9 units = scattered fish; 10-49 units = slightly gathered fish; > 50 units = concentrated fish.
Guatemala
The fish distribution on the shelf as observed by the acoustic system consists of an inshore community found along the coast out to a depth of about 50 m. This community contains small pelagics, mainly carangids, anchovies and clupeids, and various bottom fish, predominantly pomadasyidae (grunts) and lutjanidae (snappers). Good concentrations were found in two small areas to the west of San Jose. In the very inshore waters at depth of abt 20 m, schools of small pelagics were occassionally observed in significant numbers at the surface above the transducer range.
High concentrations of mesopelagics were recorded over most of the slope and further off during the survey (not included in the fish distribution chart). Practically no other fish concentration could be identified from the echo traces in the offshore waters.
Golfo de Tehuantepec, Mexico.
Figure 4 shows that the distribution of pelagic fish found inshore along the Guatemalan coast continues along the Tehuantepec Gulf coast to Salina Cruz. The fish observed by the acoustic system are located close to the shore, generally at depths between 20 and 40 m. No area of high fish density was found.
The most common pelagic species were carangids, (specially bumper), mackerel and lookdown. The bottom fish were predominantly grunts and fish from the family Gerridae.
Over the offshore parts of the shelf only mesopelagic fish (Myctophids) were recorded (not included in Figure 4).
