Evaluating the Role of Large Jellyfish and Forage Fishes as Energy Pathways, And Their Interplay with Fisheries, In the Northern Humboldt Current System

This 2018 study suggests that competition between forage fish and jellyfish may have important effects on the ecosystem in the waters off Peru and Chile, especially for top predators and the anchoveta fishery, the world’s largest. Jellyfish are known to compete for food with forage fish—small-bodied schooling fish of which anchoveta are an example. Jellyfish also eat the eggs and larvae of many forage fish, including anchovies.

The researchers used an ecosystem model to estimate the effect of changing jellyfish abundance in the Humboldt Current. They found that a jellyfish “bloom” reduced the productivity of forage fish by 12 percent. This also reduced the productivity of many predators, by roughly 10 percent, and it reduced the overall productivity of fisheries by 13 percent. Although a 13-percent decrease may seem modest, the Peruvian anchoveta fishery is one of the largest in the world, so that would translate to a potential decline of 845,000 metric tons of fish. The impacts could be greater for a larger, short-term jellyfish blooms, but the model was not set up to examine such scenarios.

These findings suggest managers wishing to maintain the abundance of forage fish—as well as predators such as marine mammals, seabirds, and larger fish—may need to reduce harvest rates in years when jellyfish are abundant. The authors recommend including jellyfish in future efforts to understand ecosystems through modeling.

Click here for the full paper: https://www.sciencedirect.com/science/article/pii/S0079661117303312

Chiaverano, L. M., Robinson, K. L., Tam, J., Ruzicka, J. J., Quiñones, J., Aleksa, K. T., Hernandez, F. J., Brodeur, R. D., Leaf, R., Uye, S., Decker, M. B., Acha, M., Mianzan, H. W., & Graham, W. M. (2018). Evaluating the role of large jellyfish and forage fishes as energy pathways, and their interplay with fisheries, in the Northern Humboldt Current System. Progress in Oceanography, 164, 28-36. https://doi.org/10.1016/j.pocean.2018.04.009.