Figure 4 illustrates the distribution of all fish as observed with the acoustic integration system. The unit of fish abundance is 0.1 m2per 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.
Nicaragua.
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 75 m. This community contains small pelagics, mainly anchovies and clupeids, and various bottom fish, predominantly gerrids and lutjanids (snappers). Good concentrations were found in two small areas in the central and southern part of the region.
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 Fonseca.
As in previous survey fish was found all over the shallow gulf that could be surveyed by the vessel, but in low concentrations only. The main part of the fish observed was anchovies, clupeids and various bottom fish, predominantly croakers and catfishes.
El Salvador.
The distribution pattern of the pelagics, recorded by the echosounder is similar to that observed off Nicaragua. Fairly good concentrations were found in two small areas in the central and northern part of the region. These consisted of anchovies and clupeids mainly. Barracudas and sharks may also have contributed to these recordings.
