What mono gill nets are and how they catch fish

A mono gill net is a single-wall net made from monofilament — a single strand of synthetic material, usually nylon — knotted into a mesh. Fish swim into the net, and their gills catch on the knots as they try to back out. The monofilament is nearly invisible in water, which makes these nets efficient at catching fish that rely on sight to avoid obstacles.

Mono nets differ from multifilament nets (made of twisted or braided fibers) because the single strand is thinner and harder for fish to detect. This invisibility is why they're effective, but it's also why they're restricted or banned in many waters — they can catch fish indiscriminately, including species you're not targeting and fish too small to keep.

The mesh size determines what species the net will catch. A 2-inch mesh catches larger fish; a half-inch mesh catches baitfish and juveniles. Commercial fisheries use specific mesh sizes matched to their target species and regulated by law. Recreational use of gill nets is illegal in most states, with limited exceptions for specific regions or tribal fishing rights.

Key Takeaways

  • Mono gill nets are made from single-strand monofilament that is nearly invisible underwater, making them highly effective at catching fish but also prone to catching non-target species.
  • Mesh size directly controls what fish the net catches, and regulations specify legal mesh sizes for each fishery and target species.
  • Most states prohibit recreational gill net use entirely; commercial use is limited to licensed operations in designated waters.
  • Mono nets can cause high bycatch rates and harm to non-target fish, which is why many fisheries have moved to more selective gear or banned them outright.
  • Where mono gill nets are still used commercially, they are subject to strict regulations on soak time, location, and seasonal closure periods.

Where mono gill nets are legal and regulated

Commercial fisheries in coastal states and the Great Lakes still use mono gill nets under strict licensing and seasonal rules. In the Atlantic, gillnetting for striped bass, shad, and herring occurs in designated zones during open seasons. The Pacific coast uses them for salmon, halibut, and groundfish, though many areas have shifted to other methods or reduced gillnet effort over the past two decades.

The Great Lakes allow gillnetting for lake trout, whitefish, and other species in specific zones, with mesh size and soak time limits set by state and tribal agreements. Each state and tribe sets its own rules: Michigan, Wisconsin, Minnesota, and New York all have different regulations for where, when, and how long nets can remain in the water.

Recreational use is banned in nearly all states. A few exceptions exist — some states allow hand-thrown cast nets (which are not gill nets) for baitfish, and tribal nations may have separate rights to traditional gillnetting. Check your state's fishing regulations before assuming any gill net use is legal in your area.

Mesh size and what it catches

Mesh size is measured as the distance between knots on opposite sides of the opening. A 2-inch mesh (the distance across the square opening) is designed to catch fish with heads larger than 2 inches — typically adult fish of harvestable size. A 1.5-inch mesh catches smaller fish; a half-inch mesh catches baitfish and juveniles.

Regulations specify legal mesh sizes for each species and fishery. A striped bass gillnet in the Atlantic might be required to use 5-inch mesh to avoid catching shad and herring; a lake trout net in the Great Lakes might use 2.5-inch mesh. These rules exist to reduce bycatch — fish caught but not the intended target — which can include endangered species, juveniles, and fish with no commercial value.

Undersized mesh is illegal in commercial fisheries and is one of the most common violations. Fishermen sometimes use smaller mesh to increase catch volume, but this practice damages fish populations by removing juveniles before they can reproduce and by catching protected species.

Bycatch and environmental concerns

Mono gill nets catch whatever swims into them, not just the target species. A net set for striped bass may also catch shad, herring, eels, and occasionally marine mammals or sea turtles. Many of these bycatch fish die in the net, even if they're released. This indiscriminate catch is the primary reason gillnetting is restricted or banned in many regions.

The invisibility of monofilament makes the problem worse. Fish that would avoid a more visible net swim directly into mono nets, increasing both target catch and bycatch. In some fisheries, bycatch rates exceed 50 percent of the total catch — meaning more than half the fish killed are not the species being targeted.

Environmental groups and fishery managers have pushed for alternatives: hook-and-line fishing, trap nets, and seine nets are more selective and reduce bycatch. Many commercial fisheries have transitioned away from gillnets over the past 20 years, either voluntarily or through regulation. Where gillnets remain legal, soak time limits (how long the net can stay in the water) and seasonal closures are used to reduce bycatch.

Soak time and seasonal restrictions

Soak time is how long a gill net can remain submerged before it must be checked or removed. Shorter soak times reduce bycatch and allow fishermen to remove dead fish more quickly. Regulations vary widely: some fisheries allow 24-hour soak times; others limit nets to 12 hours or require daily checks.

Seasonal closures prevent gillnetting during spawning periods when fish congregate and are most vulnerable. Spring and fall closures are common in freshwater systems. Coastal fisheries often have seasonal windows tied to migration patterns — striped bass gillnetting in the Atlantic is typically open in spring and fall but closed in summer and winter.

These restrictions are enforced by state fish and wildlife agencies and tribal authorities. Violations — fishing outside the season, exceeding soak time, or using illegal mesh — result in fines, gear confiscation, and loss of fishing privileges.

Mono nets versus multifilament and other gill net types

Multifilament gill nets are made from twisted or braided fibers and are more visible in water. Fish can sometimes detect and avoid them, making them less efficient but also reducing bycatch in some cases. They are more durable and easier to repair than mono nets, but they're heavier and more labor-intensive to handle.

Tarred nets (treated with tar or other coatings) are darker and more visible, which further reduces bycatch but also reduces target catch. Some fisheries require tarred nets specifically to make them easier for fish to see and avoid.

Mono nets remain popular in commercial fisheries because they are lightweight, durable, and highly effective. However, their efficiency at catching fish — including non-target species — is why they face increasing restrictions and why many regions have banned them in favor of more selective gear.

How to find regulations for your state or region

Each state's fish and wildlife agency publishes its own gill net regulations, usually in the annual fishing guide or on the agency website. Search for "[your state] gill net regulations" or "[your state] commercial fishing rules" to find the official document. These guides list legal mesh sizes, soak times, seasons, and zones for each species and fishery.

If you're in a coastal state, check both your state's marine fisheries division and the Atlantic States Marine Fisheries Commission (ASMFC) or Pacific Fishery Management Council, depending on your coast. These regional bodies coordinate rules across multiple states and manage shared fish stocks.

For Great Lakes fishing, contact the state where you plan to fish — Michigan, Wisconsin, Minnesota, New York, Ohio, Indiana, or Illinois — or the relevant tribal authority if you're fishing in tribal waters. Tribal nations have their own gillnetting rights and regulations separate from state rules.

Frequently Asked Questions

Can I use a mono gill net recreationally?

No. Recreational gill net use is illegal in nearly all states, including monofilament nets. A few states allow cast nets (hand-thrown nets for baitfish), which are not gill nets. Check your state's fishing guide to confirm what's legal in your area.

Why are mono gill nets banned in so many places?

Monofilament is nearly invisible to fish, so nets catch high numbers of non-target species and juveniles. This bycatch damages fish populations and can harm protected species. Many regions have banned or severely restricted gillnetting to protect fish stocks and shift to more selective fishing methods.

What's the difference between a mono gill net and a cast net?

A cast net is thrown by hand and sinks quickly, trapping fish in a small area. It's typically used for baitfish and is legal recreationally in many states. A gill net is set and left to soak, catching fish by their gills. Cast nets are much smaller and more selective; gill nets are industrial-scale gear.

How do fishermen know what mesh size to use?

State and federal regulations specify legal mesh sizes for each species and fishery. A commercial fisherman receives this information in their license materials and the annual fishing guide. Using the wrong mesh size is a violation and can result in fines and gear confiscation.

Are mono gill nets still used commercially?

Yes, but in fewer places than historically. Commercial fisheries in coastal states and the Great Lakes still use them under strict licensing, mesh size, soak time, and seasonal rules. Many regions have transitioned to more selective gear like hook-and-line or trap nets over the past 20 years.