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Sonar and Marine Mammals

What is LFAS?

YLFAS is an acronym for Low Frequency Active Sonar. It is a means of navigating and detecting other vessels underwater through the emission and reception of loud, low frequency sounds. Currently, LFAS is being used and tested by the United States Navy to detect enemy submarines as part of Anti-Submarine Warfare. Over the past decade the use of LFAS has become a major international controversy. It has been proven that under certain conditions, LFAS can be harmful to marine mammals.

Why does the Navy need LFAS?

The United States Navy believes that LFAS sonar is a necessity for national security. In the past, passive sonar, which is able to detect objects underwater without emitting signals, proved effective enough to give the US Navy ample time to respond to enemy submarines. However, as warfare technology continued to improve, enemy vessels became increasingly difficult to detect using conventional means. With the use of LFAS, naval ships are able to radiate sound signals and receive responses from objects at great distances, allowing them plenty of time to respond to an attack.

How is LFAS harmful to whales?

The introduction of loud and persistent noises to the marine environment could cause damage to marine animals in many capacities. Cetaceans (whales and dolphins) in particular rely heavily on sound. Displacing these animals from their habitats and compromising their use of sound can have detrimental effects on their migrating, feeding, and mating behaviors. In addition, due to the intensity of the sound from LFAS, risk of physical damage to hearing and other organs in cetaceans is increased.

Many scientists worldwide have found cases of decompression sickness, or the "bends", in marine mammals exposed to military sonar. Scientists examining bodies of beached whales and dolphins have speculated that the sonar signals could interfere with the diving behavior of some whales and cause them to accelerate to the surface at a faster rate than usual, resulting in nitrogen poisoning and gaseous bubbles forming inside the animal.

A mass stranding in the Bahamas in mid-March 2000 was speculated to be the result of U.S. Navy sonar testing. Sixteen whales were stranded, resulting in the death of six beaked whales. The corpses of five of these whales were examined, and all were found to have hemorrhaging near the ears. After extensive investigation, it was concluded and documented that the Navy's use of the sonar in question was "the most plausible source of this acoustic or impulse trauma". (U.S. Dept. of Commerce/U.S. Navy, December 2001)

Does LFAS break the law?

Recognizing the potential harm that LFAS could cause to cetaceans, sea turtles and other marine animals, the United States Navy requested authorization from the National Marine Fisheries Service (NMFS) under the US Marine Mammal Protection Act (MMPA). After a detailed review, NOAA Fisheries granted the U.S. Navy authorization for an incidental take, or harassment, of small numbers of marine mammals for a five year period while operating LFAS. The NMFS has stated that the "implementation of a monitoring and mitigation program&ensures that the takings will have no more than a negligible impact on affected marine mammal species and stocks."

What needs to be done?

To determine the effects of LFAS, the U.S. Navy has done research on four different species of baleen whales known to have the excellent low frequency hearing. By playing LFAS signals and recording whale behaviors, they found LFAS can be operated safely and effectively, under special measures. The U.S. Navy states that based on the "best available scientific information" the risk of injury to marine mammals is confined to a small area in close proximity to a vessel using LFAS.

Despite these efforts, environmentalists and many non-profit organizations feel there is a need for further research and are not convinced that the negative impact on marine mammals is negligible. The Navy has not conducted research on any toothed whales or dolphins, some of which may be more sensitive to the types of frequencies they utilize. This is concerning since many of these species, like beaked whales, are often the victims of decompression sickness and sonar-related strandings.

There have been numerous articles written and web pages dedicated to this global and highly controversial issue. To read more about LFAS and marine mammals visit the following links:

• Department of the U.S. Navy
• LFAS and marine mammals in the news
• NOAA Fisheries
• WDCS

This Months Special Topic is Sponsored by: Yankee Fleet Whale Watch and The Center for Oceanic Research and Education

Into the Deep

The Diving Adaptations of Whales

When the ancestors of modern whales entered the sea 50 million years ago they faced a considerably different environment from their previous home on land. Their prey now lived where they could not breathe, at depths where sunlight doesn't penetrate and temperatures drop dramatically. They had to adjust to moving in water, diving to incredible depths while going long periods with out air, and avoiding the dangers of nitrogen poisoning that could be fatal. As these animals evolved into the whales we know and study today, they developed several physiological adaptations that allow them to survive and flourish in the vast ocean habitat. Just a few of these adaptations are discussed below.

Body Shape

Modern whales have lost all unnecessary appendages that would cause drag in the water and slow them down while traveling in water. They have only remnants of their hind limbs, which were their means for locomotion on land. In place of legs, extensions of fibrous elastic tissue form the flukes of a powerful tail. External ears are also lost, while the genitalia are tucked inside for streamlining. Their thick mammalian hair does little for warmth in water and reduces drag so all but a few sensory hairs are lost leaving smooth skin. The density and buoyancy properties of water do away with the size limitations and the need support structures in air. The immense body size of modern whales provides a very small surface area to volume ratio which allows them to slip through the water more easily. Telescoping of the skull move the nostrils far back on a whale's head, making breathing at the surface while swimming much more efficient. The combination of these adaptations provide a sleek shape that reduces drag and allows modern whales to travel faster and better through the water.

Blubber Layer

All whales have a thick layer of blubber that surrounds their bodies. This layer of fat that lies just below their skin has three main purposes. The first is another adaptation to reduce drag. The whale's skin and blubber are not firmly attached together, allowing the blubber to shift and change form, further reducing drag while swimming. Blubber also provides very valuable insulation, important to the survival of warm blooded mammals in cold water. Diving to depths where the water temperature is just above freezing, this very thick layer of fat prevents heat loss and conserves energy. The third use is for energy storage. The blubber is made up of high-energy lipids that provide a large enough food store to take care of the whale's energetic needs during their yearly migration and fasting period.

Respiratory and Circulatory System

Because a whale's dive may last up to an hour and take them thousands of feet below the surface, they must take enough oxygen with them in order to survive. While whales have proportionally smaller lungs than other mammals, they can exchange up to 90% of their long volume with each breath, compared to only 15% for humans. They have larger and many more red blood cells than other mammals, which allows them to store much more oxygen and makes their blood appear almost black in color. They also have up to ten times more myoglobin, the protein that stores oxygen in the muscles, than terrestrial mammals which allows their muscles to work much more efficiently. During a deep dive, oxygen is further conserved by a slowed heart rate and controlled blood flow. Oxygenated blood is directed only to vital organs such as the heart and brain while on a deep dive. To counteract the effects of nitrogen poisoning, sometimes called the "bends", any extra air remaining in the lungs is forced into the trachea during a dive, where nitrogen gas and other gasses are not absorbed into the blood. All these adaptations allow the whales to dive deeply without the danger of running out of oxygen.

The Sperm Whales

While all whales have the special adaptations described above, Sperm Whales, the champion divers of the sea, have a few special features that allow them to dive to depths of up to 10,000 feet and stay submerged for up to two hours at a time. The first is their breathing pattern. Sperm whales will return after their dives and float on the surface while they take a breath every ten to twenty seconds. After recharging for up to an hour, they will dive again. The second is its very unique Spermaceti organ that is found only in the head of the Sperm Whale. This organ is composed of layers of muscle sandwiched between layers of oil filled connective tissues. In adult Sperm Whales, this organ can hold up to four tons of oil. The organ is surrounded by blood vessels and nasal passages and scientists believe that the whale changes the temperature of the oil by altering the flow of blood and water around the Spermaceti. If the oil is surrounded by cold water from the nasal passage, it cools and becomes denser, allowing the whale to sink. If it is exposed to warm blood flow, the oil becomes more buoyant, allowing the whale to rise to the surface. This is how these whales dive to such incredible depths while they pursue their prey, the Giant Squid.

Red Tide and other Bio-Toxins

Phytoplankton forms the base of the marine food chain and almost all life in the ocean is directly or indirectly dependent on it. Consequently, biotoxins work their way up the marine food web causing illness in fish, seabirds, marine mammals and humans. At right is a basic description of a basic marine food chain.

Red tide is a common name for a phenomenon where phytoplankton or unicellular algae grow rapidly or "bloom" forming dense, visible patches near the surface of the water. Certain phytoplankton species contain reddish pigments and the blooms give the water a reddish color.

THE FACTS...

APhytoplankton are microscopic organisms that use the sun's energy to photosynthesize Red tides are commonly caused by types of phytoplankton known as dinoflagellates and diatoms. The water may appear red, brown, pink, violet, orange, yellow or green depending on the color of the phytoplankton. Some species of phytoplankton produce biotoxins. Biotoxins are naturally occurring toxins. At low levels these toxins are harmless but during a red tide bloom the toxins reach high levels that are dangerous to both marine life and humans.

How Biotoxins Affect People

The most common way for people to be affected by biotoxins associated with red tides is to eat seafood, namely shellfish that have been affected by red tides. Shellfish are filter feeders, meaning that they filter plankton out of the water column during feeding. The biotoxins present in the plankton are then stored in the shellfish's bodies. When people eat the contaminated shellfish the toxins can affect the gastrointestinal and/or nervous systems.

The red tide that is currently affecting New England is caused by the dinoflagellate Alexandrium. Alexandrium species produce a biotoxin known as saxitoxin, which is responsible for Paralytic Shellfish Poisoning (PSP).

How Biotoxins Affect Whales

Whales don't eat shellfish, but they do feed on very large amounts of plankton and small schooling fish that feed on plankton. Whales are thought to be particularly susceptible to biotoxins for two reasons. 1) During a dive the blood is concentrated in the heart and brain and away from the liver and kidney where the toxins could be excreted. 2) Even a slight period of disorientation, caused by the toxin affecting the nervous system, can be enough to keep a whale from surfacing for a breath, causing it to drown.

In 1988, brevetoxin, produced by the dinoflagellate Gymnodinium brevis, was thought to be the cause of the deaths of several hundred atlantic bottlenose dolphins. In 1983 and 1996 this same toxin was responsible for the deaths of 37 and 155 manatees in the Gulf of Mexico. A different biotoxin was thought to be responsible for the deaths of 14 humpback whales off the coast of Cape Cod back in 1978.

For more information on red tides and shellfish bans you can visit the following websites:

• Massachusetts Division of Marine Fisheries
• Woods Hole Oceanographic Institute
• National Oceanic and Atmos pheric Administration

Social Life of Whales

Cetaceans can be divided into two groups: the Baleen Whales and the Toothed Whales. Having baleen vs. teeth is one of the main characteristics that distinguishes the two groups, but they differ in many other ways as well. Socially, they are very different.

A social group of whales is called a pod, which is defined as a coherent long-term social unit, averaging seven or more animals per group. While Baleen whales travel alone or in small pods, the toothed whales travel in large, sometimes stable pods. Mothers and calves form very close bonds, with the calves remaining with their mothers for up to six years. Often times, other animals within a pod will even help raise each others young. They frequently hunt their prey in groups, migrate together, and share care of their young.

Toothed Whales

Dolphins have been shown to be highly intelligent, very social, and communicate largely through sound. It has been suggested that dolphins develop a social hierarchy within a group, with dominance displayed by jaw-smacking, tail slapping, biting and chasing others.

Dolphins are extremely vocal. They can emit two main types of sounds: clicks and whistles. The clicks are used to detect other objects in the sea, called echolocation. The whistles may communicate an emotional state, such as alarm or excitement and differ from the clicks in terms of the sound tones. Research has also concluded that dolphins may have signature whistles, which they use to call and recognize each other.

Some studies show that dolphins can develop a preference for each other, and recognize each other even after a long separation. Surprisingly, males often form bonds that can be very strong and long-lasting. They come together in cooperative behavior, such as pairing up to gain better access to females. During courtship, dolphins engage in head-butting and tooth-scratching. Dolphins have been observed frequently stroking each other with their flippers

Dolphins can also form super-pods or aggregations, which are much larger groups with up to several hundred dolphins. Groups like this may form for feeding, mating, migration, or simply social stimulation.

Baleen Whales

In this hemisphere, all baleen whales are thought to make an annual migration to and from a Northern feeding ground and a southern mating and calving ground. The behaviors seen at the two locations are very different, so it is important to treat them separately. As a representative baleen whale we will look in depth at the social behavior of the well studied Humpback Whale.

Feeding Grounds

In General, Baleen whales do not form stable pods like dolphins and other toothed whales. On the feeding grounds, humpback whales generally form fluid groups, with the only stable associations between mothers and calves. Other associations seem to form mainly for cooperative feeding, a behavior humpbacks are well known for. They use a feeding strategy called bubble-net feeding, in which an animal deploys a series of bubbles from its blowhole, surrounding a school of fish. The bubbles serve to concentrate the school and improve feeding efficiency. Research has shown that during cooperative feeding there appears to be a division of labor, with certain whales continuously leading the group and deploying the nets. As a focus of COREs research, we look for possible dominance hierarchies among cooperative feeding humpbacks and other social groups. The feeding appears well organized with each whale maintaining the same position in the feeding formation. It is likely that the feeding is intricately choreographed and directed by older individuals, which use specific sounds to initiate their cooperative lunge-feeding behavior.

Breeding/Calving Grounds

The winter months are spent in warmer southern waters. The humpbacks of the North Atlantic migrate to the Caribbean where females give birth to their young and males work hard to compete for mating access to females. Males are the only sex to sing the famous song of the humpback whale, which is believed to 'advertise' the fitness (size and power) of a male. The songs are still poorly understood, but it is thought that it is used to attract a mate and notify other whales of their presence and location. Songs can last for about 20 minutes and make up larger units called themes which can be repeated for up to 22 hours! Generally, the song of each male on a breeding ground is the same and evolves or changes slightly each year.

During this competitive season males will also join battles in competitive groups, where they engage in physical combat for proximity to a female, who is usually positioned in the middle of the group. While mating has never been observed, it is believed that the female chooses one male to mate with each season and the pair is together for only a few days.

Also on the breeding grounds, mother-calf pairs are frequently accompanied by a third whale called the escort Escorts have since been found to be males. Multiple escorts may accompany a female whale, often engaging in intense male-male aggression. A mother-calf pair can be seen with many different escorts, each for a short period of time, while the same males are often seen associated with different mother-calf pairs. The social matrix can then be described as fluid, with the escorts prospecting among multiple females, possibly for detection of receptivity to mating.

Acoustics

Hearing

The ears of all cetaceans are thought to be non-functional, because they lack an external ear and do not attach to the tympanic membrane, or ear drum. The ear canal of toothed whales (odontocetes) is very narrow and plugged with a dense wax. The ear canal of baleen whales (mysticetes) is capped at the external end by a similar wax. If cetaceans do not have functional ears, how do they hear?

Sound Production

Most marine mammals produce sound by passing air from their nasal sacs across ligaments in the pharynx which makes a vibration. Mysticetes produce low frequency sounds to communicate with other whales. Their low frequency vocalizations can travel hundreds of kilometers in the ocean. In contrast to the baleen whales, odontocetes echolocate, they produce the high intensity sound clicks within their nasal passages and transmit it to the water by passing it through the melon. The melon, composed of fats, works with the slope of the head and rostrum to focus the sound beam. The high intensity sound beam reflects off items in the water, producing an echo which the odontocete uses to "see" in its environment. Thus echolocation works in the same way that sonar works.

Marine Mammals and Noise

Sound, or acoustics, is very important for all marine mammals. In addition to echolocation, cetaceans produce sound for communication and listen for sound to sense their surrounding environment. Because sound is so crucial to cetaceans, many biologists are concerned with how noise pollution affects them. Noises from boats, underwater drilling, even earthquakes produce loud sounds that may potentially harm cetaceans.

Active Sonar

One of the most debated sources of noise pollution is active sonar. Used by the military worldwide, active sonar is a relatively new technology that uses loud sounds and their echoes to detect submarines. Active sonar produces sounds at a level of 240 decibels (as loud as a rocket launch) underwater. The intense sound allows the Navy to detect enemy submarines at long ranges, which gives them hours to react. In contrast, our old submarine sonar system gave us only minutes to react. While obviously crucial to our national security, this active sonar poses a threat to cetaceans. During many of the initial testing periods, mass strandings and deaths of many species of whales and dolphins occurred. Many of these cetaceans exhibited ear hemorrhaging, which scientists believe was caused by the active sonar. However, other studies show different results. In a study conducted by several prominent marine biologists, grey, blue, and fin whales only slightly altered their course away from the active sonar sounds. Also, singing Humpback Whales only briefly paused their singing when in the presence of active sonar. While the extent to which cetaceans are disturbed by the sonar is under much debate, most scientists agree that the cetaceans are noticing the sonar sounds and subsequently altering their behavior. Because this new technology is very crucial to our military, it is important that we continue to learn as much as possible about the effects it has on our marine life.

Entanglement

Cause & Effect

General degradation of coastal marine habitats is an important factor affecting whales. Accidental capture and entanglement in marine debris is the biggest threat to cetaceans worldwide. Coastal areas around Stellwagen Bank National Marine Sanctuary are heavily populated. This vast coastal watershed causes non-point source pollution from river runoff, beach use, sewage, waste disposal and fishing gear. Discarded gear which litters the oceans is not dormant, it will continue to ‘ghost fish’. Cetaceans, other marine mammals, sea turtles, seabirds and non-commercial fish get accidentally caught in actively fished or abandoned gear. They are all bycatch victims - non-target species caught in fishing gear. Entanglement in large nets can cause drowning. Smaller pieces of net can restrict body movement, cause death from infection and generally weaken health state. High risk entanglement sites on the body of a whale are: the tail, flipper bases, baleen and rostrum. If feeding is restricted it can lead to starvation.

Management

Ground fishing was the first colonial industry of America, Gloucester being one of the few historical fishing communities remaining. Management plans need to support the livelihoods of fishermen whilst developing a harmony between fisheries and ecosystems. The Atlantic Large Whale Take Reduction Plan works to reduce injury and deaths of large whales due to incidental entanglement in fishing gear. Gear and technique modifications, restrictions in designated areas and a general preservation of the marine habitat is sought.

Gear Modification

Entanglement may involve all portions of gear especially bridles, anchor and end lines. The amount of gear in the water column can be reduced. Dynamic area management means gear is moved from areas where whales are present. Seasonal management only allows use of low risk gear and designates use at certain times of the year. Weak links can be used in lines allowing breakage after a certain weight is applied. Fishermen are encouraged to maintain knot-free buoy lines to prevent snagging on whale baleen. Deterrents on gear include pingers which emit an high frequency sound to warn off cetaceans.

Universal requirements on lobster traps and anchored gill nets require gear to be hauled at least every 30 days, keeping close track of gear.

Prevention is better than disentanglement which can be dangerous, stressful to the whale and does not always result in success.

Disentanglement

Report of entanglement is the critical first step. A recent incident involved a Minke Whale just outside of Gloucester harbor. A loop of line around its flukes was heavily weighted to the bottom. The animal had assumed a vertical position in order to keep its blowholes clear for breathing. As in most cases, the initial report was from a local fisherman . This whale was eventually saved by the hard working, dedicated disentanglement team.

Assessment considers present condition as well as the likelihood of disentanglement over time. Even assessing the severity is hard when point of entanglement is normally below the surface. Improvements can be made with aerial and underwater aides as well as acoustic and heart rate evaluations of body condition.

Attaching a working line to the gear is done using a grappling or flying gaff hook. A satellite tag may be attached in order to track the whale if work cannot be completed. Successive inflatables may be used to slow the whale down as well as prevent it from diving—a technique known as kegging.

Cutting is a delicate process using a hooked knife with the cutting edge on the inside to minimize injury.

North Atlantic Right Whale

Originally named the ‘right’ whale to catch because they were easy to approach, lived close to shore, floated when dead and provided large quantities of oil, meat and whalebone. The species came very close to extinction but has been protected since 1937.

Sadly, they are showing very little signs of recovery. Recruitment of new members to any population depends on reproductive rate, survival rates of calves and age at which sexual maturity is reached. The Right Whale is a slow breeder: females have their first calves at six to twelve years and give birth only every three to four years, in contrast to one to two years for the Humpback whale.

When North Atlantic Right Whales were initially hunted to the brink of extinction, other predators that feed on the same food source flourished. Making it harder for the Right Whale to now reestablish its ecological niche due to increased competition for food. There have been 16 recorded encounters with fishing gear between 1975 and 1989 in the North Atlantic. Three whales are known to have died from entanglement. 57% of catalogued whales have scars and injuries from rope and net cuts. Entanglement cases are low because numbers are low. This makes it hard to convince parties of its importance, especially when management strategies are costly both in time and money. It also means that entanglement cases can be devastating to the population.