four sampling stations were set 200-500m off limon port, costa rica, at an average depth of 20 m. from october 1996 to may 1997 horizontal subsuperficial trawls were done for 12 minutes at a speed of 1.853 km/h, with a 1 000 μm net were surveyed with. a total of 28 samples were processed and 104 physical-chemistry parameter measurements were taken. average salinity was 30.1 + 3.7 and dissolved oxygen 6.9 + 0.6 mg l-1 reflecting good aeration throughout the sampling period. this suggests good mixture and a highly dynamic hydrography. temperature showed no drastic variations (28.0 + 1.7 °c), possibly because of the constant mixing with shallow water. the highest larval counts were for november and early january and include families from reefs and estuaries (balistidae, lutjanidae) and from coastal areas (centropomidae, gerreidae, haemulidae, carangidae, engraulidae, hemirramphidae, and representative pleuronectiformes) existing in a common area.