Salmon and other fish predators rely on 'no guts, no glory' survival tactic

Sep 15, 2011
Bluegill forage on snails in Florida. Credit: Jonathan Armstrong

The phrase "no guts, no glory" doesn't just apply to athletes who are striving to excel.

Salmon and other predators take the adage literally, by having up to three times the "gut" capacity they need on a daily basis just so they can "glory" when prey is abundant, University of Washington researchers have discovered.

It's a previously unrecognized survival tactic that might apply to other top predators, such as , lions and bears, according to Jonathan Armstrong, a UW doctoral student in aquatic and fishery sciences and lead author of a letter published recently in the journal Nature.

"The we examined have the guts to consume two- to three-times the amount of food that they regularly encounter. This much excess capacity suggests predator-prey encounters are far patchier – or random – than assumed in biology and that binge-feeding enables predators to survive despite regular periods of famine," Armstrong said. Co-author on the paper is Daniel Schindler, UW professor of aquatic and fishery sciences.

This is a gray snapper school in Florida waters. Credit: Jonathan Armstrong

"Guts are really expensive organs in terms of metabolism," Armstrong said. For instance, maintaining a gut can require 30 to 40 percent of the blood pumped by an animal's heart.

Some animals have some capacity to grow or shrink their guts in response to changing conditions. For example, the digestive organs of birds that are about to migrate expand so they can eat more and fatten up. This is followed by a period when their guts atrophy and then, freed of the baggage of heavy guts, the birds take off.

That and results from lab studies led some scientists to assume that predators eliminate excess digestive capacity to save energy in times of famine. But the UW findings show that many fish species maintain a huge gut, which enables them to capitalize on unpredictable pulses of food.

"For predator fish, the world is a slot machine – sometimes they stumble upon small meals and other times they hit the jackpot. It's just not as predictable as some have thought," Armstrong said.

"Unlike some other animals, fish can't just hoard their food behind a rock in the stream and eat it later. They need to binge during the good times so that they can grow and build energy reserves to survive the bad times."

Armstrong and Schindler hope that their results can help with ecological models used in conservation and management.

"Ecosystem models typically assume relatively constant interactions between predator and prey but our results suggest such interactions are extremely patchy. We're excited to see if including this ecological realism might improve the predictions of these models."

Explore further: Danish museum discovers unique gift from Charles Darwin

More information: Nature: www.nature.com/nature/journal/… ull/nature10240.html

Related Stories

Predatory fish have large guts to help them through famine

Jul 08, 2011

(PhysOrg.com) -- A new study by scientists in the US has solved the mystery of why predatory fish have a far greater digestive capacity than they actually need. The study suggests the reason is that the extra-large ...

Predators do more than kill prey

Jan 17, 2008

The direct effect predators have on their prey is to kill them. The evolutionary changes that can result from this direct effect include prey that are younger at maturity and that produce more offspring.

Fish can be picky eaters

Jul 19, 2010

(PhysOrg.com) -- We all know how fussy kids can be about their food, but now new research suggests they're not the only ones.

Recommended for you

Danish museum discovers unique gift from Charles Darwin

13 hours ago

The Natural History Museum of Denmark recently discovered a unique gift from one of the greatest-ever scientists. In 1854, Charles Darwin – father of the theory of evolution – sent a gift to his Danish ...

Top ten reptiles and amphibians benefitting from zoos

15 hours ago

A frog that does not croak, the largest living lizard, and a tortoise that can live up to 100 years are just some of the species staving off extinction thanks to the help of zoos, according to a new report.

User comments : 0