Old, Fat, and Fertile Fish Are Essential to Fishery Survival

You may be familiar with the idea that the young are the legacy and backbone of any community, leaving the old to grow fat and retire without a care in the world. It would be nice to think that this romantic concept applies to animal populations too. However, researchers are arguing that this is just not the case. Fisheries are extremely dependent on their old, slow, but still fertile females to keep populations up.

Researchers actually call these exceptionally important fish "big, old, fat, fertile, female fish," or BOFFFFs for short. Once you get over the fact that experts are actually using such an insanely long acronym in a serious manner, you're likely to wonder, "wait, so why do they need old fish?"

According to Mark Hixon of the University of Hawai'i at Mānoa, it all comes down to something called "size and age truncation."

"Information on many different kinds of freshwater and marine fish tell the same story," he said in a statement. "The loss of big fish decreases the productivity and stability of fishery stocks."

According to the researcher, it has long been known that the bigger the female, the more eggs she can produce in one breeding season. For example, in Hawai'i, a 27-inch bluefish produces 84 times more eggs than one half its size. That's a massive difference in reproductive potential.

And, according to Hixon, fish don't age like humans, they just grow and grow.

Additionally, "larger fish can produce better quality eggs that hatch into young that grow and survive better than young from smaller females," he said.

Instead of youngsters being the legacy of a fishery, it's up to these less productive fish to try to find new times and places to spawn and grow into BOFFFFs themselves, added co-author Darren Johnson.

"[This] increases the odds that some young will find favorable environments in an unpredictable ocean," he explained.

These results and others were detailed in special issue of the ICES Journal of Marine Science dedicated to the memory of Johan Hjort, a Norwegian fisheries scientist who was one of the first scientists to identify some of these unusual and incredibly important factors of fish population change.