Scripps and NOAA Study Suggests Key Factor in California Anchovy Population Shifts

Scripps and NOAA Study Suggests Key Factor in California Anchovy Population ShiftsSource: Scripps Institution of Oceanography
Kamal Jenkins
Published on December 06, 2023

A new research study conducted by scientists from the Scripps Institution of Oceanography and the NOAA Fisheries Service could usher in a wave of understanding regarding the erratic population swings of California's northern anchovy, a critical fish in the Pacific marine ecosystem. According to an article published in Nature Communications on December 5 and sourced from Scripps, researchers point to the length of food chains supporting anchovy larvae as a significant factor influencing these fluctuations.

The investigation unveiled a strong correlation between shorter food chains and subsequent spikes in anchovy numbers. On the flip side, longer food chains seemed to foretell a downfall in population. The variances in population have been known to last over a decade, impacting not just the fish but also the birds and marine mammals that rely on them for food. Anchovies form a crucial link in the food web for numerous marine animals along the California coast, such as sea lions, various species of whales, and even the state's profitable tuna fisheries.

Rasmus Swalethorp, Scripps associate project scientist and lead author of the study, explained, "It's analogous to the energy loss that occurs when electricity goes from the power plant to our homes—the longer the distance, the more energy gets lost along the way," in a statement obtained by Scripps. Swalethorp suggested that the shorter and thus more energy-efficient food chains help more anchovy larvae to survive, which can proliferate into a boom in the anchovy population in subsequent years.

The study's findings, which analyzed 45 years of data on anchovy larvae collected by the comprehensive CalCOFI monitoring program, could eventually be instrumental in anchovy fishery management and conservation methods. However, the research team has underscored the need for further exploration into these ecological dynamics before implementing new management strategies. The aforementioned program is a cooperative effort involving Scripps, NOAA, and the California Department of Fish and Wildlife, making it a leading and longstanding effort in ocean monitoring.

The implications of such a discovery span beyond the Golden State's waters, raising questions about how larval food chain lengths might affect fish populations worldwide, including the world's largest single-species fishery, the Peruvian anchoveta. While the current study ended in 2005, Swalethorp expressed interest in extending this research to present numbers, potentially contrasting the findings with recent anchovy population surges off the California coast.