Good news seems to be rare these days, and good news about the environment even rarer.

But in January this year, after fifty years on the endangered species list, the US Fish and Wildlife Service (FWS) proposed to remove the manatee as its numbers in Florida have increased 400% in the past 25 years. And just this month, the FWS proposed to delist the Greater Yellowstone grizzly population as the number of bears has increased from 136 in 1975 to about 700 today.

The encouraging stories are not limited to such famous animals. You would not have seen any headlines, but over the past 15 years, dozens of handsome sea creatures such as the monkfish, lingcod, and something called the gag grouper have rebounded from depleted numbers, along with certain stocks of more familiar menu items such as coho salmon, haddock, snow crab, and swordfish.

How did all of this happen?

The answer is regulation – of two kinds.

The first kind was human regulation. We gave these animals a chance by regulating their hunting or fishing through the Endangered Species Act [1973], the Marine Mammal Protection Act [1972], and the Magnuson-Stevens Fishery Conservation and Management Act [1976].

The second kind of regulation is biological. As a rule, nature is remarkably resilient and productive. And I do mean rule. The ability of species to rebound from very low numbers reflects a fundamental biological rule about how populations are regulated in nature. When populations are small and resources abundant, populations can multiply at near maximal rates.

Populations grow when the birth rate exceeds the death rate, so when human-caused mortality is restricted or eliminated, the rebound can be impressive.

For example, when the American side of the Georges Bank fishery was closed in 1994 due to overfishing, haddock and yellow flounder numbers tripled and quintupled in just five years, while large scallops increased 15-fold.

The closure of fisheries and the regulation of catch limits are usually unpopular and understandably so. But we ignore biological rules and resist such regulation at our peril.  The United States commercial and recreational fisheries contribute $200 billion to the economy and support 1.7 million jobs. While overfishing of some stocks continues, and others remain to be rebuilt, the US is arguably a global leader in the sustainable management of fisheries.

Elsewhere, where regulation is absent or ineffective, the situation is increasingly dire. Across the globe, more than 2.6 billion people rely on the ocean as their primary source of protein.  But it is estimated that over the past century, as the global population has more than tripled, the total mass of the large predatory fish that we like to catch and eat – tuna, cod, etc. - has declined by two-thirds. That’s one-tenth as much large fish per person.

That is an average decline; regionally and locally, things can be much worse. Despite the European Commission’s adoption of the Mediterranean Fisheries Regulation in 2006, fish stocks in the Mediterranean have continued dwindling and 96% of stocks are currently overexploited. These facts are undisputed, but getting the 28-nation bloc to row their boats in the same direction has been difficult. At a February meeting in Sicily, the crisis prompted a series of organizations to issue a joint plea for “immediate emergency and recovery measures.”

There is now justified concern that some stocks may be depleted past the point of no return. That threat is more than just the vanishing of individual species, but the breakdown of ecosystems. Another general rule of Nature is that species are parts of extended food webs. Species interact and can both directly and indirectly regulate the abundance of other species. Changes in one population can have cascading effects both up and down the food chain.  

While we sometimes summon enough concern to do something about protecting edible, commercial animals, or lovable creatures like manatees, what do we do when the important animals are neither so desirable nor lovable?

This is the plight of sharks across the oceans. Sharks have been top predators for over 400 million years, but their numbers have been decimated in the past half-century by the combination of shark-finning and industrial fishing for other species (by-catch). About one-quarter of all species are now threatened with extinction. Because sharks are among the largest and most-wide-ranging predators, their demise has effects on all parts of the ocean – from shallow coastal waters to the bottom of the sea.

The consequences of the steep declines in sharks on commercial or other species are not well understood. But we do know that, as a rule, such apex predators can have strong, so-called “top-down” effects on not just their prey, but their prey’s prey and so on, all the way down to the level of vegetation.

In light of these potentially far-ranging effects, some regulations have been adopted to thwart the practice of shark-finning, such as the US Shark Conservation Act [2010], and shark fishing has been outlawed in more than a dozen countries. In 2014, a coalition of 120 United Nations member countries moved to place 21 species of sharks and rays including, for example, three species of hammerheads, under the highest level of international protection. Whether these or other measures will halt the decline remains to be seen. A new global shark census has been launched in order to better understand how many sharks there are and where.

In this political season, we are hearing a lot of about curtailing government regulation. But a recent PEW poll found that three-quarters of Americans believe that government should play a major role in protecting the environment.

In nature, regulation is not a dirty word, it is an inescapable fact of life.

So, too, for the 7.4 billion people who depend on her.

Sean B. Carroll is vice president for science education at the Howard Hughes Medical Institute, the Allan Wilson Professor of Molecular Biology and Genetics at the University of Wisconsin–Madison, and author of THE SERENGETI RULES: The Quest to Discover How Life Works and Why It Matters.