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- TL;DR Summary
- Small stickleback fish can reduce the population of larger predators by eating the predator's young.
Cycles of predator-prey population size changes have been described where the predator eats so many of its primary prey that the reduced prey population can no longer support the predator population. In these conditions, the predator population crashes, which allows the prey population to recover, and the cycle continues.
Another kind of predator prey interaction is described in a news article in Science, here.
The research article is here.
The research is based upon 13,000 fish surveys from 1979 to 2017.
In the Baltic Sea, sticklebacks (~3-4 inches long) can live in sea water as well as freshwater.
Freshwater dwelling pike and perch can move out toward the sea as long as outflowing freshwater dilutes the sea water enough for them to survive.
Once the sticklebacks numbers increased, the sticklebacks become major predators on the juvenile perch and pike, thus reducing their numbers below what they might normally have been.
Among other things, they are proposing to stock bays with juvenile pike and perch too big for stickleback to eat.
Another kind of predator prey interaction is described in a news article in Science, here.
The research article is here.
The research is based upon 13,000 fish surveys from 1979 to 2017.
In the Baltic Sea, sticklebacks (~3-4 inches long) can live in sea water as well as freshwater.
Freshwater dwelling pike and perch can move out toward the sea as long as outflowing freshwater dilutes the sea water enough for them to survive.
Instead, complex ecological factors appear to have first worked against pike and perch: Beginning in the 1990s, gray seals became more common, thanks to better water quality and an end to bounty hunting. The seals, along with cormorants, began to eat more pike and perch. Meanwhile, sticklebacks were thriving in the rapidly warming seas. And overfishing of cod, the top predator, and large herring translated into fewer predators on sticklebacks.
Once the sticklebacks numbers increased, the sticklebacks become major predators on the juvenile perch and pike, thus reducing their numbers below what they might normally have been.
The work “clearly shows that the [disappearance] of larger predators can cause cascading effects all the way down to algae, and that these changes can unfold over vast spatial scales like falling dominoes,” says Boris Worm, a marine biologist at Dalhousie University. Worm worked in the Baltic Sea as a Ph.D. student, and he mourns the change, calling it “a slow-motion disaster through the Baltic Sea.”
Among other things, they are proposing to stock bays with juvenile pike and perch too big for stickleback to eat.