Fish-a-Plenty if You Control Who Get's Fed

Imagine you have a pond of fish and you feed them the same amount of food every day. Suddenly you're tasked with making these fish more plentiful, or at least larger, without affecting how much they are fed. This may sound like a problem that can be solved only with a biblical miracle, but a team of researchers has managed pull it off, and without using chemicals, hormones, or other modern "cheats."

It turns out, all you need to make bigger fish is more control over who eats what. That's at least according to a study recently published in the journal Nature Communications, which details how researchers at Umeå University doubled the biomass of a fish biomass population, and only by controlling when and how much of a limited food supply was channeled to juvenile and adult fish, respectively.

What exactly do I mean by that? Well, traditional ecological theory says that if a population is to grow in size or mass, it will understandably need more food, or at least a richer nutritional source. However, studies of the human body have long found that there are other factors that contribute to weight gain - the healthy kind, or otherwise.

In this new study, the researchers managed to increase the biomass of a least killifish (Heterandria formosa) population without improving food sources. They managed this after determining that different sized killifish effectively use food for growth in different ways.

For instance, the researchers knew that smaller killifish more efficiently use food for growth, meaning that already large killifish are the ones actually lagging behind.

Therefore, "switching from an equal distribution of food between small and large individuals to a distribution where the less efficient large individuals received two thirds of the food doubled the fish biomass," it was explained in a recent release.

Feeding more to the largest of a population may not make a ton of sense, but if you think of it in terms of potential, it actually pays to keep filling the deeper bucket, so to speak - if the smaller bucket can be filled with less. In this way, both fish demographics continue to grow. It's a strategy that could have major implications for fisheries around the world - resources which are increasingly helping to supplement the globe's otherwise insatiable hunger for fish.

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