Fur seals and sea lions and its relationship with Peruvian anchovy abundance during 1979-2000

Abstract

This paper presents data on the importance of the Peruvian anchovy in the diet of fur seals and sea lions between 1996 and 1999 along the Peruvian coast. We use graphs and non parametric statistics to analyse the relationships between the abundance of seals and the biomass of anchovy, or the anchovy's landings since 1984. Using the acoustic biomass of anchovy we observe similar trends, with recovery in the seals and anchovy populations between 1984 and the early 90', high levels of anchovy biomass and numbers of seals between 1993 and 1997, a dramatic decrease during 1997 and 1998 and a delayed recovery between 1999 and 2000. Very similar relationships are found comparing seal population to anchovy landings. No significant correlation was found between the biomass or landings of anchovy and the abundance of fur seals (r_SPEARMAN 0,43; 0,14) nor the abundance of sea lionsand the same was found using abundance of sea lionsS (r_SPEARMAN 0,26; 0,6), but we found high levels of significance between the number of fur seal pups and the biomass of anchovy since 1984 (r_SPEARMAN= 0,943; p =0,01). Our results show that there is posible a relationship between the abundance of anchovy and the sea lion and fur seal populations, in contrast from what was reported by Muck and Fuentes (1987) for the years 1952 to 1984.