Catch-and-Release Fishing

By Erik Williams and Malia Schwartz

Every recreational angler in every part of the country must at one time or another release fish. Minimum size regulations require many anglers to release sub-legal-sized fish or "shorts." Rivers, lakes, and reservoirs are areas where catch and release are particularly important. The increasing popularity of recreational fishing has led to the problem of too many people, too few fish. In some areas, only catch-and-release fishing is allowed. The increase in recreational anglers is not just limited to inland fisheries. Marine recreational angling is having a great impact on certain fish stocks as well. One of the primary means of allowing all these anglers to continue fishing and maintain healthy fish stocks is catch and release. Catch and release, whether it is voluntary or required, must be done properly if it is to succeed in having the fish survive. This fact sheet should help anglers to release fish properly to increase the likelihood that the released fish will survive.

Why Catch and Release?

With the cost of a typical fishing trip, the uncertainties of success, and the appeal of a fish dinner, why should anglers want to adopt the practice of catch and release? Aside from certain regulations, such as bag limits or size limits, there are a number of good reasons for releasing a portion of the catch alive.

First, catch and release offers a sensible way to extend the fishing trip after a reasonable or legal catch limit has been reached. If the trip involves a guide or charter service, catch and release can prolong an enjoyable recreational opportunity, giving anglers more value for their money.

Second, several recent studies have suggested that as anglers gain expertise in a particular fishery or fishing technique, they often develop an interest in "limiting their kill instead of killing their limit."

Why Do Hooked Fish Die?

Fish that are caught and released may die for several reasons, but the two primary causes are stress and wounding. Stress results from the fish fighting after being hooked. Internally, the physical exertion causes an oxygen deficit in the tissues, forcing the muscles to function anaerobically (without oxygen). This causes lactic acid to build up in the muscle tissue, and then to diffuse into the blood. Lactic acid acts as an acid in the blood, causing the pH of the blood to drop. Even slight changes in pH can cause major disruptions of the metabolic processes, ultimately killing the fish. If the fish is quickly released, its blood pH usually returns to normal and the fish will be unaffected. Some fish, after a long tow, may appear to live once released, but the imbalance in the blood chemistry may kill them as late as three days after being caught. In most cases, the means of preventing this type of mortality is to not keep the fish in action for a long period of time, unless the intent is to keep it.

The other primary cause of mortality is wounding by the hook. Injuries caused by hooks can range from very minor to lethal. The degree of injury is dependent on the location of the hook wound. Higher mortalities will occur in fish that are hooked in the gill or stomach areas, while lower mortalities occur in fish that are hooked in the lip, jaw, or cheek areas. Baited hooks are more likely to result in a gill or stomach hooking that artificial lures. Treble hooks, for obvious reasons, will result in more puncture wounds and subsequently higher mortalities. Barbless hooks facilitate release and decrease "out-of-water" time, but for reasons yet unclear, may not significantly reduce mortality, especially when used with bait.

There are other kinds of physiological stress that can lead to higher mortalities in released fish. Fish may not be able to adjust to changes in pressure or to higher surface water temperatures. Also, when a fish is handled or comes in contact with dry surfaces, such as landing nets or dry hands, its mucous layers – commonly called slime layers – may be partially removed, presenting an opportunity for bacteria or pathogens to invade the skin.

Burping and Puncturing

When certain fish are brought up from depths greater than 40 feet too quickly, their swim bladders, which normally control buoyancy, can overinflate from rapid depressurization. Burping is a technique used on a fish with an overinflated swim bladder. The fish is massaged in the belly region in an attempt to release the excess air in the swim bladder. Puncturing involves using a needle or ice pick to poke a hole in the fish’s exposed swim bladder. Both of these techniques are currently being advocated in other parts of the country. However, if the procedure is not carried out correctly, more damage than good may be done to the fish.

The success of burping depends on the species of fish. Some fish, such as largemouth bass, perch, striped bass, cod, hake, and black sea bass, do not have a connection from their gut to their swim bladder. If a fish’s gut is not connected to its swim bladder, then burping is impossible. Puncturing is a very controversial technique. To date, there is no evidence that puncturing will increase a fish’s chance of survival.

The best advice for releasing fish with overinflated swim bladders is to let them go as quickly as possible.

NEVER ATTEMPT TO BURP OR PUNCTURE A FISH WITHOUT KNOWING WHAT TO DO!

Catch-and-Release Guidelines

These guidelines provide basic information on the most beneficial catch-and-release methods for most small- to medium-sized freshwater and marine fish:

1. If you plan to fish with artificial lures, such as plugs and spoons, consider replacing treble hooks with single hooks. Single hooks are quicker and easier to remove, especially when dealing with such predatory fish as bluefish and northern pike. Consider pinching the barb on your hooks, since this will make releasing the fish much easier.
2. Plan your release strategy. Decide whether to keep or release any fish prior to angling or at least before removing the fish from the water. Familiarize yourself with any regulations in effect for the species targeted, and gather any items that will facilitate handling and releasing the fish.
3. When a fish is hooked, use a steady, deliberate retrieval technique. This can reduce the amount of stress a hooked fish undergoes when pulled up from the depths too quickly, or when physically exhausted from an overly slow retrieve.
4. Once you have decided on releasing the fish, avoid netting or even removing it from the water if possible. Use needle-nosed pliers to pry the hook from the fish while it is still in the water. Fish that can be lifted by the leader – the short length of line used to attach the end of the fishing line to the lure or hook – can easily be released over the rail using a "dehooker." These devices, whether homemade or purchased, are gaining in popularity in the bluefish industry – to avoid the fish’s nasty teeth – and are useful for releasing a number of other species. A dehooker may simply be a metal rod with a handle at one end and a small upturned hook at the other end. If live bait or a lure is deeply embedded in the fish’s gullet, cut the leader close to the fish’s mouth and let the fish keep the hook. Studies have shown that fish can get rid of the hook up to 120 days later.
5. When landing the fish, it is important to minimize out-of-water time and any fish contact with surrounding surfaces or objects.

• Avoid using landing nets if possible. If a landing net must be used, one with a neoprene bag rather than natural twine should be used. Neoprene removes less of the fish’s mucous coat.

• Do not use a gaff!

• Keep hands moistened. This helps prevent removal of the fish’s natural protective mucous layer, and reduces the chance of subsequent infections in the fish’s skin.

• Minimize handling, particularly of the gills and soft underbelly. Gently prevent the fish from battering itself on surrounding hard surfaces. Place the fish on an old piece of foam cushion and place a wet rag or gloved hand over the fish’s eye. These two actions can do much to subdue even unruly tuna and bluefish.

1. Return the fish to the water headfirst. In most cases, it is best to point the fish’s head straight down and allow the fish to plunge down into the water.

Sources:

Klauber, A. 1992. Catch & Release. In: Nor’easter: Magazine of the Northeast Sea Grant Programs. Fall/Winter 1992.

Malchoff, M.H., M.P. Voiland, and D.B. MacNeill. 1992. Guidelines to Increase Survival of Recreational Sport Fish. Cornell Cooperative Extension Fact Sheet.

Swordfish

By : Malia Schwartz, Deborah Grossman-Garber, and Henry Milliken

The swordfish (Xiphias gladius Linnaeus 1758), also called the broadbill, is the only member of the family Xiphiidae. As its name implies, this magnificent fish is characterized by an upper jaw that extends to form a flat, sharp-edged "sword." Swordfish are impressive jumpers and powerful fighters—thrilling for anglers and boaters alike.

Physical Characteristics

The swordfish has a stout, fairly rounded body and large eyes. The first dorsal fin (rising from the back of the fish) is tall and crescent-shaped. The second dorsal fin is quite separate from the first and very small. Both are soft-rayed—having thin, bony rods that extend from the base of the fin and support the fin membrane. The anal fins approximate the shape of the dorsal fins, but are noticeably smaller. Ventral fins, found on the underside of fish, are absent. There is a strong, longitudinal keel, or ridge, on either side of the caudal peduncle (the base of the tail where the tail fins project from), which leads to a broad, crescent-shaped tail. Adult swordfish have neither teeth nor scales.

The swordfish snout elongates into a true sword shape. Measuring at least one-third the length of the body, it is long, flat, pointed, and very sharp. The lower jaw is much smaller, though just as pointed, ending in a very wide mouth.

The bodies of swordfish fry (recently hatched fish larvae) are quite different form those of the adults. Their upper and lower jaws are equally prolonged; bodies are long, thin, and snakelike; they are covered with rough, spiny scales and plates; tails are rounded; and they have just one long dorsal and anal fin.

Swordfish coloration varies greatly among individuals. The dorsal side can range from dark brown to grayish-blue. This dark shading can extend anywhere from halfway down the side to almost the full extent of the body. The remaining area of the skin is tinged silvery white.

In Northeast waters, only the spearfish bears any resemblance to the swordfish. It is distinguished from the swordfish by its rounded sword, small teeth, a long, continuous dorsal fin, and ventral fins.

Size

Swordfish are very large fish. Today, the average fish caught in the commercial fishery weighs between 90 and 150 kilograms (1 kilogram equals 2.2 pounds). While fish over 200 kg are unusual, the largest recorded in the North Atlantic ocean weighed 550 kg. The largest fish to be caught on a tackle weighed 274 kg. These larger fish measure approximately 4.5 meters in length (1 meter equals 3.3 feet)—with a 3 meter body and a 5 meter sword.

Female swordfish grow faster, live longer, and are proportionally heavier than their male counterparts. Research shows that by 1 year of age, the female is already almost 4 kg. During the next 2 years, she triples her weight of the previous year. By age 4, the female is likely to weigh 70 kg, and at age 5, 110 kg. Similar data for males and older swordfish are inconclusive.

Longevity

Swordfish reach sexual maturity at about 2 to 3 years of age, and live for at least nine years. While they may survive longer, no such documentation exists. The majority of swordfish caught in the North Atlantic sport fishery are thought to be 4 to 5 years old.

Distribution

Swordfish are pelagic fish—living within the water column rather than on the bottom or in coastal areas. They are typically found at depths of between 180 meters and 580 meters, and are found worldwide in temperate and tropical waters. They are believed to prefer waters where the surface temperature is above 15°C (58°F), although they can tolerate temperatures as low as 10°C (50°F). There seems to be some correlation between larger size and the ability to tolerate colder temperatures. Few fish under 90 kg are found in waters less than 18°C (64°F).

Swordfish are summer and fall visitors to New England waters, entering the warming Atlantic coastal waters from far offshore in the Gulf Stream around June and departing in late October. Evidence suggests that such onshore-offshore seasonal migrations are more prevalent than are migrations between the northern feeding areas off Cape Hatteras and the southern spawning grounds off Florid and the Caribbean.

Behavior

Swordfish are not schooling fish. They swim alone or in very loose aggregations, separated by as much as 10 meters from a neighboring swordfish. They are frequently found basking at the surface, airing their first dorsal fin. Boaters report this to be a beautiful sight, as is the powerful jumping for which the species is known. This jumping, also called breaching, is thought by some researchers to be an effort to dislodge pests, such as remoras or lampreys. It could also be a way of surface feeding by stunning small fish as they jump out of the water, making the fish more easily captured for food.

Swordfish feed daily, most often at night when they rise to surface and near-surface waters in search of smaller fish. They have been observed moving through schools of fish, thrashing their swords to kill or stun their prey and then quickly turning to consume their catch. In the western North Atlantic, squid is the most popular food item consumed. But fish, such as menhaden, mackerel, bluefish, silver hake, butterfish, and herring also contribute to the swordfish diet.

Swordfish are vigorous, powerful fighters. When hooked or harpooned, they have been known to dive so quickly that they have impaled their swords into the ocean bottom up to their eyes. Although there are no reports of unprovoked attacks on humans, swordfish can be very dangerous when harpooned. They have run their swords through the planking of small boats when hurt.

The adults have few natural enemies, with the exception of large sharks and sperm and killer whales. They are easily frightened by small boats, yet paradoxically, large craft are often able to draw very near without scaring them. This makes swordfish easy to harpoon.

Fisheries

Today, swordfish are caught in gill nets, with harpoons, and, most successfully, on longlines consisting of a main line, usually several miles long, which is supported in the water column by floats and from which baited hooks are suspended. In addition, swordfish are often an incidental catch in the tuna fishery.

The sport fishery normally fishes for swordfish by trolling and drift-fishing, using rod-and-reel gear. The catch rate has increased considerably since fishermen began in the mid-1970s to fish for swordfish at night using drifting baited lines.

Once almost unsalable, swordfish meat gained in popularity during World War II and continued through the early 1970s. In 1971, the U.S. and Canadian swordfish fishery was essentially terminated following U.S. Food and Drug Administration (FDA) restrictions imposed on the sale of swordfish found to have levels of mercury in the flesh higher than 0.5 parts per million (ppm).

But gradually, the U.S. fishery began to rebound. In 1979, the FDA raised the acceptable mercury level to 1.0 ppm, based, in part, on a National Marine Fisheries Service study, showing that a 1.0 ppm action level would adequately protect consumers. Finally, in 1984, the FDA switched from enforcing the mercury action level based on total mercury concentration to methyl mercury concentration. This change occurred for two reasons: (1) It was determined that methyl mercury was the toxic component of the total mercury concentration, and (2) a test specific for methyl mercury became available. Since then, both catch and fishing effort have been exceedingly high in the Atlantic Ocean, with swordfish meat commanding top prices in the marketplace.

While swordfish sold on commercial markets is closely monitored to make sure that methyl mercury levels remain below the 1.0 ppm action level, most experts urge those concerned about chemical contaminants to take certain precautions:

1. Eat a variety of different fish; don’t restrict yourself to swordfish.
2. Avoid eating excessive amounts of any single type of fish.
3. Avoid eating the internal organs of the fish—they typically contain higher contaminant concentrations than the flesh.
4. When catching your own swordfish, check and follow all applicable health advisories.
5. High-risk individuals—pregnant women, women of childbearing age, and children under age 15—should limit their consumption of swordfish. Pregnanat or nursing mothers should limit their consumption to once a month.
6. If you choose to eat a sport-caught swordfish that may contain elevated levels of contaminants, trim away fatty areas and use cooking methods like baking or broiling, to allow fats and juices to drain away.