How to Identify Marine Mammal Strandings

Marine mammal strandings, often referred to as beachings, are a natural phenomenon where marine mammals, such as whales, dolphins, seals, and other cetaceans, end up on the shore or coastline, typically in distress. These strandings can range from single individuals to mass strandings involving entire pods or groups of animals. Identifying and responding to these strandings is crucial for animal welfare, conservation efforts, and understanding the reasons behind such events. In this article, we will explore the key aspects of identifying marine mammal strandings, the reasons behind them, the process of assessment, and how these events can be managed.

What Are Marine Mammal Strandings?

A marine mammal stranding occurs when a marine mammal, whether alive or dead, ends up on the shore or coastline, where it cannot return to the water. The causes behind these strandings can vary significantly, from natural factors to human-related influences. While some strandings are not unusual, others can be indicators of larger environmental or ecological problems.

Marine mammal strandings can be classified into two categories:

1. Live Strandings: When a marine mammal is alive but stranded on the shore, usually in distress. These strandings often require immediate attention to provide medical help or attempt to return the animal to the sea.
2. Dead Strandings: When a marine mammal is already dead upon arrival on the shore. These strandings often provide researchers with an opportunity to perform post-mortem examinations to understand the cause of death.

Common Marine Mammals Involved in Strandings

Different species of marine mammals are involved in strandings. Some of the most commonly stranded species include:

• Cetaceans: This group includes whales, dolphins, and porpoises. Due to their size and migratory behavior, cetaceans often face a higher risk of strandings, particularly in coastal areas.
• Pinnipeds: Seals, sea lions, and walruses fall under this category. Pinnipeds are frequently found on beaches and are more likely to strand due to illness, disorientation, or environmental changes.
• Sirenians: Manatees and dugongs are rare but can strand, particularly in regions where they are found in shallow waters.

Understanding which species are involved in strandings can help researchers and responders assess the situation more effectively.

Why Do Marine Mammals Strand?

There are numerous reasons why marine mammals strand. The causes can be natural, environmental, or human-induced. Some of the most common reasons include:

1. Illness or Injury

Marine mammals, like any other animals, can suffer from illnesses or injuries that leave them unable to navigate or find their way back to the ocean. Infected wounds, infections, diseases (such as morbillivirus), and parasites can affect their health and behavior, causing them to strand. In some cases, animals that are injured may be disoriented, which leads to them swimming toward shore instead of away from it.

2. Disorientation or Navigation Errors

Marine mammals, especially those that are highly migratory, can become disoriented due to various factors, including oceanographic anomalies (like temperature changes or currents), geomagnetic anomalies, or even intense noise pollution. For example, sonar equipment used by ships and submarines can interfere with the echolocation systems of dolphins and whales, causing them to become lost or disoriented and ultimately strand.

3. Mass Strandings or Social Bonding

Certain species of whales and dolphins are known for their strong social bonds. In some cases, if one member of the pod becomes stranded, others may follow. This can result in mass strandings, where multiple animals are found stranded at the same time. Such strandings may occur when a leader of the group becomes disoriented or sick, leading the others to follow and eventually strand.

4. Environmental Factors

Natural events such as extreme weather conditions, storms, and changes in tides can also cause strandings. Strong winds or currents may drive marine mammals closer to shore, and shallow waters may make it difficult for them to return to deeper waters.

5. Human-Related Causes

Human activities can contribute to marine mammal strandings in various ways:

• Pollution: Chemical pollutants, plastics, and toxic algae blooms can harm marine mammals. They may ingest or be affected by these substances, leading to disorientation, injury, or death.
• Fishing Gear: Entanglement in fishing nets or other debris can injure marine mammals, preventing them from swimming freely and leading to strandings.
• Ship Strikes: Collisions with large vessels can cause physical harm to marine mammals, leading to strandings or deaths.
• Noise Pollution: As mentioned earlier, human activities that generate excessive noise, such as military sonar or industrial shipping, can interfere with marine mammal navigation and cause strandings.

How to Identify a Marine Mammal Stranding

Identifying a marine mammal stranding involves recognizing specific signs and understanding the context in which the event occurs. Whether the animal is alive or dead, early identification can be crucial for ensuring appropriate responses.

1. Observe the Species

The first step in identifying a stranding is determining which species the animal belongs to. Species identification is vital as it helps responders understand the potential risks and appropriate steps to take. For example:

• Whales: Whales are often the largest mammals to strand, and their size makes it easier to spot them from a distance.
• Dolphins and Porpoises: These animals are typically smaller than whales but may strand in large numbers.
• Seals and Sea Lions: Seals are more common to strand along shorelines, and their behavior is more terrestrial than aquatic.

Identifying the species can often be done by examining key physical characteristics such as size, body shape, dorsal fin (for cetaceans), and presence of external ear structures (for pinnipeds).

2. Check for Signs of Life

If the animal appears alive, it is crucial to assess its condition:

• Breathing: Check if the animal is breathing regularly. An active, rhythmic breath indicates life.
• Movement: If the animal is moving, even minimally, it may still be alive.
• Signs of Distress: A distressed animal may exhibit abnormal behavior, such as vocalizing or attempting to escape. It may also show signs of injury, such as wounds or bleeding.

For live strandings, immediate action should be taken to contact local marine mammal rescue organizations, as swift intervention may be needed.

3. Assess the Condition of a Dead Stranding

When an animal is already deceased, the condition of the body can provide important clues regarding the cause of death:

• Decomposition: The stage of decomposition can indicate how long the animal has been dead. Fresh carcasses may indicate a recent stranding, while more decomposed bodies may have been stranded for a longer period.
• Visible Injuries: Wounds from ship strikes, entanglement in fishing nets, or other trauma may be visible. Injuries from predation, diseases, or infections may also provide clues.
• Environmental Factors: In some cases, the body of the animal may show signs of environmental stress, such as external burns from chemical exposure or physical scars from extreme weather.

4. Evaluate the Location

The location of the stranding is also important. Marine mammals may strand on beaches, rocky shores, or estuaries. Understanding the geography and environmental conditions of the area can help experts analyze the cause of the stranding. For instance, stranding on a rocky coastline may indicate disorientation or illness, while stranding near fishing zones may suggest entanglement or pollution as the cause.

5. Take Photographs and Document Details

If you come across a marine mammal stranding, it is important to take photographs of the animal, the location, and any visible signs of injury or distress. Record any relevant details, including the time, date, and environmental conditions. These records will be helpful to marine biologists and rescue teams when assessing the situation and planning a response.

Reporting and Responding to Marine Mammal Strandings

Once a stranding has been identified, the appropriate authorities should be notified as soon as possible. Local marine mammal rescue organizations, conservation groups, or wildlife authorities are the best resources for handling strandings. They may have the necessary expertise, equipment, and knowledge to deal with the situation.

1. Live Strandings

For live strandings, it is essential to avoid attempting to return the animal to the water without proper training. Improper handling can cause additional harm. Marine mammal rescue teams typically:

• Assess the animal's condition: A veterinarian or trained responder will evaluate the health of the animal and determine if rescue or rehabilitation is feasible.
• Provide immediate care: In some cases, animals may be stabilized and transported to rehabilitation centers for care.
• Monitor: Some animals may be observed for a period to ensure they recover sufficiently before being returned to the wild.

2. Dead Strandings

For dead strandings, the primary concern is often investigating the cause of death. Authorities may perform necropsies (animal autopsies) to identify the underlying cause of death. These investigations can provide vital information about health trends, pollution levels, or environmental threats affecting marine mammal populations.

Conclusion

Identifying marine mammal strandings requires a careful understanding of the species involved, the conditions of the stranding, and the potential causes behind the event. By recognizing the signs of both live and dead strandings and responding appropriately, individuals and authorities can contribute to the welfare of marine mammal populations and better understand the ecological challenges these animals face. Continued research and conservation efforts are essential to protecting marine mammals and mitigating the causes of strandings, whether they arise from natural factors or human-related activities.

View Product