Linking lampuki (dolphin fish) catches to environmental and satellite data

Abstract

The Mediterranean Sea supports numerous small-scale fisheries and habitats, which is essential for economies, cultural heritage, and food security. The Lampuki (Coryphaena hippurus) fishery, which uses conventional fish aggregating devices (FADs), is one of the most iconic in Malta. However, recent catch decreases raise questions with regards to fishing pressures, climate change, and environmental variability. This study investigates whether environmental variability, particularly sea temperature, chlorophyll-a (chl-a) concentration, and current speed, acts as a primary driver of Lampuki catch fluctuations in Maltese waters, we test the hypothesis that changes in sea temperature, chl-a concentrations, and current speed alter Lampuki distribution and abundance, leading to corresponding changes in catch rates in Maltese waters. Fishery records from 2019 to 2024 were integrated with satellite-derived and modelled environmental data from the Copernicus Marine Service across depth layers (1 to 1000m). Catch weight was analysed at the General Fisheries Commission for the Mediterranean (GFCM) subarea level and catch per area (CPA) was calculated to enable comparison among regions of varying sizes. Environmental variables included temperature, salinity, oxygen, currents, and chla. The Pearson correlation was then used to assess the relationship between these variables and catch variability. The findings demonstrated a considerable drop in catches over the past few seasons in all geographic sub-areas (GSAs), with reductions of ~69% from 2019 to 2024. Temperature exhibited the strongest positive correlation with catches (r = 0.34 - 0.59 across GSAs), whereas chlorophyll-a consistently showed negative correlations (r = -0.32 to -0.57). Current speed displayed weaker and spatially inconsistent relationships. These findings show the importance of integrating real-time environmental monitoring to understand environmental drivers and any occurring fluctuations. The results give a scientific basis for adaptive management, e.g., refining FAD deployment strategies and monitoring Lampuki availability with the ever-changing oceanic conditions.