Sardines, anchovies, other fast-growing fish vulnerable to dramatic population plunges

August 5, 2015, Rutgers University
Malin Pinsky, assistant professor of ecology and evolution in the School of Environmental and Biological Sciences at Rutgers University. Credit: Shonda Foster

A Rutgers marine biologist studying the rise and fall of fish populations worldwide recently made a counterintuitive discovery: ocean species that grow quickly and reproduce frequently, such as sardines, anchovies and flounder, are more likely to experience dramatic plunges in population than larger, slower growing fish such as sharks or tuna.

Why is this counterintuitive? Because for life on land, the situation is in stark contrast.

"Rabbits are doing pretty well compared to rhinos," said Malin Pinsky, assistant professor of ecology and evolution in the School of Environmental and Biological Sciences. "Mice thrive while lions, tigers and elephants are endangered."

After studying population changes in 154 species of fish worldwide over 60 years, Pinsky was surprised to see marine equivalents of rabbits and mice collapsing to low levels - still shy of extinction but serious enough to disrupt ocean food chains or fishing-based societies.

In his research, published this week in the journal Proceedings of the Royal Society B, Pinsky sought an answer to this riddle. In nearly all of the cases, overfishing was the culprit.

Climate variations or natural boom-and-bust cycles contribute to population fluctuation in small fast-growing fish," he noted, "but when they are not overfished, our data showed that their populations didn't have any more tendency to collapse than other fish."

For example, this effect is apparent in off the coast of southern California, whose populations have fluctuated naturally for thousands of years. But these fluctuations are not enough to explain why so many fast-growing fish species have collapsed in recent decades - meaning a drop to less than 10 percent of historical levels. With the advent of efficient fishing vessels and techniques after World War II, population collapses started to occur much more frequently in sardines and anchovies, which are valued for pet food and fish oil.

"Overfishing is a problem throughout the world and across all species, including slow-growing fish like sharks, many of which are in serious trouble," said Pinsky. "But it turns out that fishery collapses are three times more likely in the opposite kinds of species - those that grow quickly."

Combining climate variability with high levels of fishing greatly increases the risk of collapse, Pinsky says.

"If environmental factors are driving the population down, previously sustainable levels of fishing might suddenly drive a collapse," he said. "The proper response would be to quickly change fishing practices, but every political or bureaucratic process has some lag."

Pinsky will examine this further with summer flounder, a popular east coast sport , as populations drop off the coast of the Carolinas in response to warmer waters and increase off the Mid-Atlantic States.

Pinsky's analysis relied on data from fisheries management agencies worldwide, and used mathematical analyses developed by collaborator David Byler in operations research and financial engineering at Princeton University. The work is important, he notes, because species declines can affect the viability of sea life higher in the food chain and human societies that rely on fishing to supply food and economic support.

Explore further: 'Small fry' fish just as vulnerable to population plunges as sharks or tuna

More information: Fishing, fast growth, and climate variability increase the risk of collapse, Proceedings of the Royal Society B, rspb.royalsocietypublishing.or … .1098/rspb.2015.1053

Related Stories

Fishing amplifies forage fish collapses

April 6, 2015

A new study shows for the first time that fishing likely worsens population collapses in species of forage fish, including herring, anchovies and sardines. Some of the largest fisheries in the world target these species, ...

Two-thirds drop in large fish numbers in 100 years

January 16, 2015

Overfishing has significantly reduced the populations of larger species of marine fish. In fact, stocks of large fish have declined by two-thirds in one century. These findings come from an international research team who ...

West Coast sardine season called off amid population decline

April 13, 2015

Fisheries managers have decided to call off the West Coast sardine fishing season that starts in July because of rapidly dwindling numbers, hoping to save an iconic industry from the kind of collapse that hit in the 1940s ...

Harvesting of small fish species should be cut: study

July 22, 2011

( -- New research on the fishing of small fish species near the bottom of their food chains suggests harvesting at levels previously thought to be sustainable could have devastating effects on some marine ecosystems. ...

Recommended for you

Nanoscale Lamb wave-driven motors in nonliquid environments

March 19, 2019

Light driven movement is challenging in nonliquid environments as micro-sized objects can experience strong dry adhesion to contact surfaces and resist movement. In a recent study, Jinsheng Lu and co-workers at the College ...

OSIRIS-REx reveals asteroid Bennu has big surprises

March 19, 2019

A NASA spacecraft that will return a sample of a near-Earth asteroid named Bennu to Earth in 2023 made the first-ever close-up observations of particle plumes erupting from an asteroid's surface. Bennu also revealed itself ...

The powerful meteor that no one saw (except satellites)

March 19, 2019

At precisely 11:48 am on December 18, 2018, a large space rock heading straight for Earth at a speed of 19 miles per second exploded into a vast ball of fire as it entered the atmosphere, 15.9 miles above the Bering Sea.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.