Changes in the Peruvian hake distribution área: effect of fishery and El Niño event

Abstract

Wosnitza-Mendo C, Ballón M, Benites C, Guevara-Carrasco R. 2009.- Changes in the Peruvian hake distribution
area: effect of fishery and El Niño event. Bol Inst Mar Perú 24(1-2):29-38.- The distribution and size of Peruvian hake
(Merluccius gayi peruanus) off the Peruvian coast exhibit two patterns: (a) Distribution is determined by changes in the
Cromwell Current due to seasonal (winter/summer) and inter-annual El Niño’s effects; (b) Hake sizes are related to latitude,
with larger individuals found to the north and smaller ones to the south. From the start of the heavy trawl fishery in 1973,
Peruvian hake suffered reduction in biomass and changes in distribution and population structure. In this study, we use
survey data since the 1970s as well as length frequency and biological data from fleets acting at different latitudes and
collected by the Peruvian Marine Research Institute (IMARPE) in Paita (5°S), Chimbote (9°S) and Callao (12°S). The survey
data distribution of adult hake during different periods, and a separate treatment of the length measurements from the
different ports, allowed us to reconstruct size distributions over time for the three landing areas. We show that during the
1970s, large hake with mean length of more than 40 cm (age 4+) were present as far south as Callao. The former presence
of large hake in that area shows the direct effect of combined trawl and purse-seine fisheries on hake biomass and on the
range of hake distribution. Possible indirect short and long-term effects on hake due to changes in the anchovy biomass and
distribution and/or environmental long term changes are discussed.