Regulations—we hear that word more and more recently, and it means a lot of things to a lot of different people and industries. Fishing—both commercial and recreational—is no different. Fishes are a public resource that if left unregulated would not be the sustainable resource that they can be. Many fisheries do, in fact, suffer from the Tragedy of the Commons—the idea that in any shared resource individuals operate according to their own best interest, and not the common interest, which is what sustains a resource.

So we might all agree that fisheries need some type of regulation to make sure they are there next year (and tomorrow). But after that, there is no one-size-fits-all regulation, and in fact, most fisheries are subject to multiple, interacting regulations. Below follows a quick overview of basic regulatory measures.

Most fisheries at least have some type of spatial regulation, which is typically established by a natural boundary or political or jurisdictional boundary. In the US, states establish regulations on freshwaters within the state boundaries, and any coastal waters typically within 3 miles of shore.

Time is another common method of regulating fish. Sometimes seasonal openings and closures are established because fish move and may not be available 365 days a year in a given location. Other time regulations may have to do with keeping fishermen off the water during dangerous months. One common reason for seasonal regulations is to avoid capturing fish at the time of year they are spawning, so that reproductive activities can take place before harvest of adults.

Nearly every fishery has some type of gear regulation. For example, many recreational fishermen use hook and line but are not permitted to use dynamite or cyanide to kill and capture fish. In addition to types of gear that may be used, the amount of gear can also be regulated—fishermen may be able to use gill nets, but only if they are under 1,000 feet.

Size is the regulation we are often most familiar with because it determines whether or not that fish we just caught can go in our cooler or back in the ocean. Length (size) limits are typically designed to allow younger, smaller fish the chance to reproduce before harvest, although many different types of size regulations exist. Slot limits are a unique size regulation that, for example, prevents the capture of not only smaller fish, but also larger fish—you can only keep a fish that falls within the ‘slot’ (or the other way around).

In reality, all fisheries are subjected to multiple regulatory measures. For many species that undergo a stock assessment and have a total allowable catch (TAC) estimated, managers attempt to select the regulatory measures that will be least restrictive on fishers, while also recognizing the potential for negative population impacts if more fish are captured than the stock can replace. Regulatory measures are also often changing—as a fish stock becomes more or less healthy, changes in the quantity and quality of harvested fish may need to be modified.