Introductory Chapter: Marine Mammals of the World

1. Introduction

1.1 Definition

Marine mammals are, in short, catalytic species. Thus, knowledge of areas that are important for them will facilitate the balancing of human uses of the ocean with the imperative of conserving marine biodiversity.

Marine mammals are highly consumed animals of marine creatures production at the different levels specially utmost trophic type from initial production as sea-cows or sirenians, are an order of fully aquatic, herbivorous mammals) to predatory fish and some other types of marine mammals, such as the polar bear, some whales, and dolphins.

2. Role of marine mammals in ecosystems

Because of their large body size and abundance, they are thought to own a serious influence on the structure and performance of some marine communities.

In marine ecosystems, marine mammals play an important role in balancing and regulating the dynamics of production in the ecosystems as the following:

1. They provide a context to regulate and to judge the potential influence of their predation on prey populations.

2. They regulate and balance the structure of marine populations.

3. They impact or influence the variation in prey populations that harvesting by humans.

4. They regulate the dynamics of marine mammals [1] during environmental changes.

3. Threats due to human activities

Human activities represent a big threat to words marine mammals. These activities comprise “Bycatch” in marine media, collision with vessels, reduction of prey resources, and climatic changes on the planet. The danger of water pollution, excessive hunting or fish harvesting, diseases, and habitat destroying or degradation and loss.

For the following reasons, marine mammals represent a complex problem and challenges for conservation:

1. Lacking data concerning marine mammal bycatch.

2. Lacking data concerning marine mammal species-specific data.

3. Lacking marine studies and research.

Bycatch could be a complex, global issue that threatens the sustainability and resiliency of our fishing communities, economies, and ocean ecosystems. Bycatch of protected species, like sea turtles and marine mammals, remains a big threat to recovering dwindling populations [2, 3].

Global data on marine mammal bycatch is mostly lacking, particularly species-specific data. For these reasons, marine mammals present an array of issues and challenges for conservation and management.

Bycatch could be a complex, global issue that threatens the sustainability and resiliency of our fishing communities, economies, and ocean ecosystems. Bycatch of protected species, like sea turtles and marine mammals, remains a big threat to recovering dwindling populations.

4. Marine mammals in the world

Marine mammals are a diverse group of species that include:

1. Cetaceans

2. Pinnipeds

3. Sirenians

4. Sea otters

5. Polar bears

4.1 Cetaceans

Cetaceans are a cosmopolitan and diverse clade of aquatic mammals; they include whales, dolphins, and porpoises. They are flesh-eating (carnivorous) and most of them are found in the oceans.

Cetaceans are differed in size and weight, the length ranged from 1 m in Maui’s dolphin to 29.9 m as in blue whale, and the weight ranged from 50 kg to 173,000 kg.

4.1.1 Whales

• There are now 15 species (Figure 1) and around 89 extant species [3].

Figure 1.

Types of whales in the world.

4.1.2 Dolphins

• Families Delphinidae (the oceanic dolphins) (Figure 2) [2]

• Platanistidae and Iniidae (River dolphins)

• New World:

  • Bottlenose dolphin

  • Common dolphin

  • La Plata dolphin (disambiguation) dolphin,

Figure 2.

Types of dolphins in the world.

40 species of dolphins within the Delphinidae, 6 are commonly called whales, including the killer and also the pilot whales.

Most dolphins are small, measuring 3 meters (10 feet) long, and have spindle-shaped bodies, beaklike snouts (rostrums), and easy needlelike teeth. a number of these cetaceans are occasionally called porpoises.

4.2 Pinnipeds

The pinnipeds are a group of 33 species of aquatic fin-footed mammals composing three families (Figure 3) [4]:

• Verity seals (family Phocidae),

• The fur seals and sea lions (family Otariidae),

• The walrus (family Odobenidae).

  Pinnipeds live in some inland or tropical freshwater systems and rich marine environments.

Figure 3.

The pinnipeds are a bunch of 33 species of aquatic fin-footed mammals composing three families.

4.3 Sirenians

The Sirenia (Figure 4) commonly spoken as sea-cows or sirenians are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters [4].

Figure 4.

The Sirenia commonly spoken as sea-cows or sirenians.

4.4 Sea otters

The sea otters are the littlest marine mammals; they live in the Pacific Ocean (From the coasts of the northern and eastern). The weight of adult sea otters ranged from 14 to 45 kg) (Figure 5).

Figure 5.

The sea otter.

4.5 Polar bears

The polar bears (Ursus maritimus) [5] live within the polar circle, encompassing the ocean. They are highly carnivorous animals and the largest extant land carnivore [6, 7]. Adult polar bear weights from 350 to 700 kg (Figure 6).

Figure 6.

The polar bear (Ursus maritimus).

5. Marine conservation

5.1 Why marine conservation is important?

1. Sustaining healthy marine mammal populations is very important in maintaining balance in marine food webs and helping to stay marine ecosystems functioning as they ought to. Additionally, nutrient recycling (reusing nutrients for other styles of ocean production) plays an outsized role all told ocean ecosystems.

2. A healthy ocean regulates climate and reduce temperature change impacts. Ocean currents distribute heat across the world, regulating temperature and weather. The ocean also absorbs over 90% of the warmth and approximately 30% of CO₂ emissions produced by human activities.

3. As a number of the highest predators of the oceans, marine mammals play a crucial role within the organic phenomenon and help ensure balance within the ocean’s ecosystem [7, 8, 9].

5.2 How can we protect marine mammals?

• To help in the protection of marine mammals and other protected species the following responsibilities should be taken:

• Eliminate chemicals and Xinobiotics waste.

• Take role and responsibility to combat water pollution.

• Forbidding waste materials (Agriculture and industrial) into marine and water resources.

• Avoid excessive fish hunting.

• We are requiring the authorities to minimize bycatch in fisheries to make sure our fisheries are sustainable and guarded species are given the most effective chance to recover.

• Global leader in marine mammal conservation and sustainable fisheries, with U.S. fisheries abiding by a number of the world’s most robust conservation practices, including measures to cut back marine mammal bycatch—a global threat to several populations of marine mammals.

• Global foundations and the Governorates marine Mammals Protection in response to increasing concerns among scientists and therefore the public that significant declines in some species of marine mammals were caused by human activities. The global and the national policy to:

• Encourage the public to forestall marine mammal species

• Encourage the public to forestall population stocks from declining beyond the purpose where they ceased

Unfortunately:

1. The basic information remains poorly known for many species, and not only for those considered Data Deficient, but new technologies are getting down to provide new and better data on both the biology of marine mammals and also the ecology of the oceans.

2. Many marine mammals are still unknown to most of the people and will be forever.

3. Many of those rare species are still unknown to most of the people and will be forever.

Therefore, our aim emphasizes the importance of understanding the essential biology and ecology of marine mammals to assess the correlates and causes of extinction and to implement science-based conservation (Figure 7).

Figure 7.

Drawings are by Sharyn N. Davidson. TM Cox, et al., understanding the impacts of anthropogenic sound on beaked whales. J Cetacean Res Manage 7, 177–187 (2006) [10].