Diurnal and semidiurnal movements of two commercially important fish in a tropical bay

Abstract

Biological data collection often overlooks short-term environmental variations, potentially leading to under- or over-estimation of species abundance and ineffective conservation actions. This study investigated the complex relationship between oceanic and meteorological processes and the short-term abundance patterns of two economically important fish species in Bahía Santa Elena, a tropical bay on the north Pacific coast of Costa Rica. Using two months of continuous acoustic telemetry data from 14 Colorado (Lutjanus colorado) and 16 Pacific dog (Lutjanus novemfasciatus) snappers, we investigated temporal and spatial changes in their relative abundance patterns. A wavelet analysis revealed dominant diurnal and semidiurnal frequencies in both species. The observed semi-diurnal and diurnal periodicity in fish abundance was correlated with water level and sunlight, particularly near the mangrove in the inner bay, suggesting that both species may be using these habitats for food and shelter during periods of high tide and at night. Understanding how oceanic and meteorological conditions influence the dynamics of marine organisms in coastal environments, particularly those that are often exploited by fisheries is crucial for developing effective management and conservation approaches.