Hydrographic conditions driving sardine and anchovy populations in a land-locked sea
ČIKEŠ KEČ, V.
The aim of this paper is to establish a relationship between long-term variability in sardine and anchovy populations in the Adriatic Sea and ocean dynamics and processes that occur over interannual and decadal timescales in the Adriatic-Ionian basin. Basis for such analysis are annual time series of sardine and anchovy landings and recruits at age 0 and annual time series of environmental parameters observed at a representative Adriatic station between 1975 and 2010. Pearson correlations and robust Dynamic Factor Analysis (DFA) were applied to quantify the connections between fisheries and environmental parameters. Variations and trends in fisheries series were best explained by changes in near-bottom temperature and salinity, being an appropriate proxy for tracking changes in water masses' dynamics and hydrographic conditions in the basin. It seems that a prolonged period of decreasing sardine population was characterized by low oxygen availability and environmental conditions in the deep Adriatic waters, triggered by an extraordinary basin-wide event called the Eastern Mediterranean Transient. A collapse in anchovy population has been observed after an exceptional cooling event followed by dense water formation.
long-term environmental data, anchovy and sardine populations, ocean dynamics, interannual and decadal variability, synchrony