Evaluating the role of large jellyfish and forage fishes as energy pathways, and their interplay with fisheries, in the Northern Humboldt Current System

GRAHAM, WILLIAM M.; ACHA, MARCELO; DECKER, MARY BETH; LEAF, ROBERT; BRODEUR, RICHARD D.; QUIÑONES, JAVIER; ALEKSA, KATRINA T.; ROBINSON, KELLY L.; TAM, JORGE; MIANZAN, HERMES W.; UYE, SHIN-ICHI; HERNANDEZ, FRANK J.; RUZICKA, JAMES J.; CHIAVERANO, LUCIANO M.

PROGRESS IN OCEANOGRAPHY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2018 vol. 164 p. 28 - 36

0079-6611

Large jellyfish are important consumers of plankton, fish eggs and fish larvae in heavily fished ecosystemsworldwide; yet they are seldom included in fisheries production models. Here we developed a trophic networkmodel with 41 functional groups using ECOPATH re-expressed in a donor-driven, end-to-end format to directlyevaluate the efficiency of large jellyfish and forage fish at transferring energy to higher trophic levels, as well asthe ecosystem-wide effects of varying jellyfish and forage fish consumption rates and fishing rates, in theNorthern Humboldt Current system (NHCS) off of Peru. Large jellyfish were an energy-loss pathway for hightrophic-level consumers, while forage fish channelized the production of lower trophic levels directly intoproduction of top-level consumers. A simulated jellyfish bloom resulted in a decline in productivity of allfunctional groups, including forage fish (12%), with the exception of sea turtles. A modeled increase in foragefish consumption rate by 50% resulted in a decrease in large jellyfish productivity (29%). A simulated increase of40% in forage fish harvest enhanced jellyfish productivity (24%), while closure of all fisheries caused a declinein large jellyfish productivity (26%) and productivity increases in upper level consumers. These outcomes notonly suggest that jellyfish blooms and fisheries have important effects on the structure of the NHCS, but they alsosupport the hypothesis that forage fishing provides a competitive release for large jellyfish. We recommendincluding jellyfish as a functional group in future ecosystem modeling efforts, including ecosystem-based approachesto fishery management of coastal ecosystems worldwide.