Bycatch

By Kathleen Castro and Erik Williams

What is it?

Bycatch describes living creatures that are caught unintentionally by fishing gear. Unlike target species—animals specifically targeted for capture—bycatch is unwanted and often unused. Sometimes bycatch may be kept or sold; for example, and angler who catches a legal-sized bluefish while fishing for striped bass may keep the catch to eat at home or to sell, if he has a proper license. Other times, bycatch cannot be used—for example, if it is undersized or a protected species—and must be thrown back. This returned bycatch is called discard.

The problem

Everyone who fishes, whether for a living or recreation, catches bycatch. Unwanted bycatch is usually thrown back into the water; however, handling and exposure sometimes injure the bycatch, which may die after being discarded. Although this discard may serve as food for other species when it is thrown back, it is not recruited into, and does not become a part of, the reproducing population. As a result, discard not only affects the current population, but influences the species’ opportunity to replenish itself.

The National Marine Fisheries Service (NMFS), the government agency that manages fisheries, has called bycatch "the problem of the 1990s." Although the extent of the problem has not been satisfactorily determined, three areas of particular concern have been identified by NMFS:

• User conflicts, which happen when one fishery discards fish that are important to another;
• Laws, under which animals caught as bycatch are protected by the Endangered Species Act or the Marine Mammal Protection Act;
• Public regard, through which the public can affect fishing revenues by voicing opinions about the wastefulness of bycatch.

Bycatch in the Northeast

One of the main reasons bycatch is a problem in many fisheries is that different species of animals are found together: this is called a multispecies fishery. It is possible to catch any mix of whiting, flounders, hake, squid, cod, butterfish, or other species on a given day in a given place. Since these fishes attain different sizes when fully grown, it is hard to target only one of them in their shared habitat. However, efforts to adapt fishing gear to specific target species have resulted in more selective fishing. Appropriately, such gear is termed "selective."

Gear problems

Hook and line, and long-line:
Since most fish will bite a hook, it is hard to be selective with this gear. But anglers and commercial fishermen both can make their hooks more selective by using knowledge of fish behavior—for example, choosing bait, jigs, lures, and hook sizes known to catch their target species.

Traps:
In the Northeast, traps are used for catching lobsters, crabs, whelk, and some finfish. Because traps can attract both nonlegal and nuisance bycatch, they may be constructed in different sizes and shapes to be more selective to the behavior of the target species. Lobster traps must include escape vents to allow for the release of smaller, sublegal animals.

Gill net:
An important fishery in the Northeast and throughout the world, gill net fishing uses a panel of webbing, usually made of clear, monofilament line, that can be set at any depth. Fish can’t see the net, so they swim right into it and are caught. Gill net bycatch includes animals that are too large to pass through the webbing.

Bottom trawl:
This is the single most important fishing method in the Northeast, yet it produces the most noticeable bycatch problem. An bottom trawl is a funnel-shaped net that is dragged on the bottom of the sea. Much of the bycatch in an bottom trawl might not survive because it is damaged in the net, brought up from the depths too quickly, or thrown back too late.

Solutions

Fishermen and scientists have been working for many years to resolve the inefficiency and wastefulness of bycatch. One early response to the problem was the inclusion of escape vents and variably spaced laths, or slats, in traps to allow escape of nontarget species. More recently, educational programs for recreational anglers in catch-and-release fishing have helped minimize harm to fish. And the introduction of the Turtle Excluder Device (TED) in the southern shrimp fishery, and the similarly designed Fish Excluder device—the Nordmore Grate—in the Gulf of Maine fishery, has helped assure the release of nontarget animals from shrimp trawls. Other promising areas of research include the use of sound devices attached to gill nets to ward off dolphins and whales, and new designs of bottom trawls that take into account fish behavior.

As these examples attest, much progress has been made in reducing bycatch. With continued interest and concern, progress will continue, particularly in the following avenues:

Research and Development:
Ongoing research into fish behavior, application of new knowledge to the development and modification of fishing gear, and continued efforts to pinpoint specific bycatch problems should generate practical solutions to this important issue.

Education:
The availability of current information about the actual impacts of bycatch, and the progress being made in controlling the problem, should help clarify the issues and encourage cooperation in developing solutions. Conferences and other forums for public discussion enhance prospects for solutions.

Cooperation:
Cooperation among the public, the government, academia, environmentalists, and the fishing industry is essential if any proposed bycatch solution is to be effective. Such cooperation has a head start in the collaboration of fishermen, NMFS, and New Hampshire Sea Grant on the use of "pingers"—small acoustical devices—to warn harbor porpoises away from gill nets. In this, as in other responses to bycatch issues, the goal is the same for everyone—fish for the future.

Web site:

FAO Fisheries (Includes State of World’s Fisheries and Aquaculture)

Book:

Petruny-Parker, M.E., K.M. Castro, M.L. Schwartz, L.G. Skrobe, and B. Somers (eds.) 2003. Proceedings of the new England Bycatch Workshops. Rhode Island Sea Grant, Narragansett, R.I. 52pp. pdf.

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.

WHALES

By Tony Corey

They are the largest animals on the planet. They are mammals but they are completely aquatic, feeding, mating, calving, and suckling their young in the water. They are thousands of years old and ubiquitous throughout the world, but they remain elusive and mysterious.

Whales are among the oldest, most diverse group of marine mammals, dating back 40 to 50 million years, according to fossil evidence. They share with dolphins and porpoises the taxonomic order cetacea. Within this order, they fall into two suborders, according to their feeding habits: mysticeti and odontoceti. Mysticetes are baleen whales, which feed by filtering animal plankton and small schooling fish from the water through bristlelike baleen plates growing from the upper jaw. Odontocetes are toothed whales, whose conical teeth grasp prey consisting primarily of squid and fish.

Defined in large part by their size, whales exhibit considerable variation among species. The blue whale, the largest animal ever to exist, can grow to 90 ft (27 m) and 125 tons. At the other end of the range, the dwarf sperm whale may be only 7 to 9 ft (2.5 m) and just over 600 pounds (280 kg).

Huge size suits these creatures to life in the ocean. With their massive bulk supported by water, they take maximum advantage of evolutionary adaptations for specialized swimming. With body shape streamlined to reduce drag, limbs tapered into powerful flippers, and horizontally flattened tails, or flukes, propelling them, they can sustain speeds up to 25 mph. Moving through the water at different depths, they may stay submerged anywhere from one minute to two hours.

Their respiratory systems are specially adapted for diving. Highly efficient lungs allow exchange of 80 to 90 percent of air with each breath. The additional capacity to draw on oxygen reserves chemically stored in blood and muscles and to work muscles anaerobically (without oxygen) permits maximum locomotion during long dives. As whales surface, they forcefully expel moist air through a blowhole on top of the head. The blowhole differs from one species to another—single, divided, off-center—and the blow itself can be distinctive enough for identification. The Northern right whale, for example, has a divided blowhole and a unique V-shaped blow; the sperm whale has a blow that angles forward at 45 degrees; and the blue whale exhibits a tall, dense blow that can shoot up to 30 feet (9 m).

Along with the blow, the dorsal fin can characterize a specific whale species. Triangular to falcate (sickle-shaped) in shape and varied in size from the low hump of the sperm whale to the 6-foot fin of the male killer whale, the dorsal fin helps stabilize the animal as it swims. The right whale, alone among the North Atlantic baleen whales, has no dorsal fin.

Environment and society

As mammals living in the cold ocean waters, whales have evolved adaptations for maintaining body temperature and water/salt balance. Their immense bodies present a small surface-to-volume ratio that combines with the insulation of a subcutaneous blubber layer to conserve heat. Blubber also provides a reservoir of freshwater which, along with water ingested in food and inspired air, maintains the mammals' freshwater balance against a saltwater environment. In addition, they excrete excess salt via their kidneys.

Such evolutionary progress would seem to give these leviathans free reign of the oceans, but like other marine animals, whales delineate their habitat primarily by food and reproductive needs. Many Atlantic whale species migrate north in spring to feed in productive New England waters. But for breeding and calving they seek out warm waters farther south. Females typically bear one calf every two to three years after gestation periods of 10-14 months, with lactation continuing for a few months to a year. Some species produce young less frequently: The sperm whale may go six years between births. Depending on species, these long-lived creatures may live 40, 70, even 90 years.

For the most part, whales are social creatures, swimming in pods made up of two or three to more than 50 (killer whales) or even 100 (pilot whales) individuals. Some species, including the minke whale, are often solitary, but most species form aggregations of varying sizes for feeding. Female-calf pairs also tend to aggregate in the protective waters of nursery areas.

The human factor

Their sociability sometimes gets these creatures in trouble. Mass strandings, according to one theory, stem from the social cohesion that causes a whole group of whales to follow when one—distracted by illness, disruption of its "sonar," or interference with its ability to navigate by the earth's magnetic field—heads into the beach.

More positive social behaviors earn whales particularly fond attention among humans. Their use of sound, or echolocation, both to locate prey and to communicate, becomes "singing" for human purposes. Songs of the humpback whale, for example, are available as recordings for relaxation tapes and other "musical" uses.

Whales' acrobatic behaviors also engage humans through whale watches and marine life exhibits. Breaching (leaping into the air), bowriding (swimming in the wave made by a moving boat, often at the bow), lobtailing (forcefully slapping the water with the tail), and spyhopping (poking the head vertically out of the water) are common behaviors among many species. The killer whale, also called orca, is especially acrobatic and therefore very popular in marine life attractions.

These benign human associations with whales cap a history of much more aggressive interactions. Even 1,000 years ago, humans hunted whales in the North Atlantic, according to Robert Kenney, University of Rhode Island marine biologist and right whale expert. The Basques, the world's first commercial whalers, were hunting whales from their settlements in Labrador by 1530. By the time the Yankee whaling industry got under way, the Northern right whale was commercially extinct. Today, the right whale is the most endangered species in the world, numbering fewer than 300 individuals in the western North Atlantic.

No longer widely hunted for food, oil, or whalebone, whales are nonetheless susceptible to injury from humans. Entanglement in fishing gear is a hazard that now draws stringent management intervention, with regulations ranging from gear modifications to fishing area closures. More deadly, though, are ship strikes that account for a significant number of whale deaths. Solving this problem requires international initiative and cooperation because of the international nature of marine commerce and the economic disruption of rerouting shipping traffic.

Many whale species are now federally protected, with a number of initiatives in effect to minimize harmful whale-human interactions. Breakaway fishing gear, 500-yard buffer areas, early warning systems to alert commercial and military vessels about whale sightings, disentanglement response teams, and ongoing public education efforts help keep these marine mammals protected in reality as well as in regulatory status.

The Marine Food Web

by Tony Corey with Dave Beutel

Big fish eat little fish; that’s how the food cycle works. Of course, there’s more to it than that. A whirlwind spiral up the marine food chain goes like this: Phytoplankton—microscopic plants drifting in the water—feed the copepods and other grazers that feed the small menhaden and crustaceans that feed the stripers and bluefish that feed the tunas and swordfish that feed us.

Taking it a little more slowly and stopping at each trophic level (feeding level), we start with the primary producers. Single-celled plants, microscopically small phytoplankton floating in the upper layers of the ocean, use the sun’s energy to photosynthesize chemical compounds, such as carbohydrates. These carbohydrates can be eaten for energy, and these plants—mostly diatoms and algae—are the foundation of the ocean’s entire biological community.

Taking advantage of this abundant plant life, zooplankton—animal planktonic forms—drift through the water grazing on the phytoplankton. These "grazers" include copepods and larval stages of fish and benthic, or bottom-dwelling, animals that make up the second trophic level.

Zooplankton range from microscopic copepods to more substantial coelenterates, including jellyfishes, all drifting passively on the ocean currents. The larger zooplankton may be food for proportionally larger animals, such as baleen whales and other marine mammals. Still, the most abundant zooplankton are the copepods. By sheer biomass and their trophic position, copepods are the crucial link between the primary producers and the rest of the ocean food web. They make up most of the animal mass in the ocean, and they account for one-half to two-thirds of the zooplankton in Narragansett Bay.

Copepods and other plankton, both animal and plant, nourish filter-feeding organisms that strain their food directly from the water. This third trophic level includes molluscan bivalves, amphipods, and larval forms of many fish and crustaceans as well as small fish such as alewife and menhaden. These finfish are schooling fish, and they can make a significant dent in the zooplankton population. A single adult menhaden, for example, can sift 8 gallons of water a minute. If a school of perhaps 100,000 of these fish passes through an area, it can temporarily decimate planktonic life.

In the same way, a school of bluefish may eat through a school of menhaden, creating the next trophic level. Because menhaden are the food of choice for species all the way up the food ladder to apex predators, they are popular bait fish. It is bluefish, though, that feast most voraciously on the menhaden, wasting as much as they consume. The waste sinks to the bottom, where it may be eaten by bottom-dwelling carnivores, such as lobsters, or decomposed by bacteria and ultimately returned to a nutrient form usable by plants.

The bluefish, striped bass, and fluke that feed on bait fish are among the most popular recreational fishing targets in Rhode Island. Like species at successively higher trophic levels, these predators are food for every level along the way. Not only are they hunted from the water but also from the sky, plucked by ospreys, cormorants, and other sea birds. Their primary predators, though, are larger fish, the game fish that migrate from coastal to deep ocean waters in search of sustenance. Among these high-level hunters are tunas, sharks, and billfishes such as swordfish. These animals are both dominant predators in the marine environment and prey for other large animals at the apex of the food web.

At this level of predation, the hunt is cutthroat and circular. Marine apex predators are opportunistic feeders—they eat what is available. This means they may sometimes eat each other: The bluefin tuna that is such a prize for humans is also a target of toothed whales, swordfish, sharks, and even other tuna. Sharks, depending on the species, eat seals, tuna, and other sharks.

Opportunistic feeders may also eat larval forms of their own predators: Squid, for example, feed on juvenile bluefish but become the quarry for adult bluefish. At the extreme, opportunistic feeders may eat the larval forms of what they eventually become: Lobsters, for instance, are notoriously cannibalistic.

Even animals that have no immediate predators ultimately contribute nutrients to the food web. Large whales and sea turtles, while not specifically targeted for consumption, do produce waste. The waste may be either excretions from digestive processes or dead tissue. It is eventually broken down by decomposers—bacteria, primarily—in a process that releases nutrients that plants can use to start the whole cycle again.

Organisms higher up the food ladder tend to be larger in size and fewer in number than those at lower levels. This is partly a function of the many trophic steps required to meet advanced energy needs. Because the efficiency rate at each trophic level is only about 10 percent, each succeeding level supports a smaller total biomass to compensate for the 90 percent loss of food value.

So if it takes 100,000 pounds of phytoplankton to feed 10,000 pounds of copepods, and these copepods feed 1,000 pounds of silversides, and these silversides feed 100 pounds of mackerel, and these mackerel feed 10 pounds of bluefin tuna, this tuna nourishes only one pound of apex predator at the end of the chain. When all is said and done, that tuna steak on the dinner plate culminates a web of interdependencies that passes sustenance from a one-celled plant all the way up to the most complex organisms on Earth.