Tag Archive | dolphins in danger

Dolphins in Danger: Vaquita


The vaquita, or the Gulf of California porpoise is the most endagnered species of porpoise in the world. (Photo by Thomas A. Jefferson).

The vanquita (Phocoena sinus) is the smallest species of porpoise in the entire world. Although the vaquita resembles the common harbor porpoise, they have longer pectoral fins, a tall, triangular, dolphin-like dorsal fin, little or no beak, and are evenly grey on the back and lighter on the sides with no sharp demarcation between the colors.  Males may grow around 4.9 feet long with females being larger at around 4.11 feet long while animals of both genders may weight around 120 pounds.  Fossil records tell us that this endagnered porpoise evolved from an ancestral population of harbor porpoises that moved northward into the Gulf of California region during the beginning of the last Ice Age around 1 million years ago.

 

The vaquita can only be found in the Gulf of California. (photo is public domain).

As the only species of porpoise to be found in warm waters of the eastern Pacific, the vaquita in found only exclusively in the northwestern corner of the Gulf of California. From confrimed observations, they have been known to only swim in water that is less than 130 feet deep within 25 miles offshore. Although they are found at open sea, they are generally found in shallow areas that are less than 6 feet deep at low tide, including straits and sea bays. Fossil records tell us that this endagnered porpoise evolved from an ancestral population of South American Burmeister’s porpoises that moved northward into the Gulf of California region  during the beginning of the last Ice Age around 1 million years ago.

The vaquita is usually sighted either alone or in small pods that are up to seven animals.

Vaquitas are normally solitary animals that can sometimes be seen in pods of up to 2-7 animals although reports of them living in pods of 10 have been reported. However, unlike most other cetacean species, they do not apporach vesasels and are generally undemonstrative at the surface, only emerging briefly. Yet because of this behavior, vaquitas can be effectively surveyed only when conditions are ideal of calm winds and good lighting. Because theyare so elusive by nature, the vaquita is very diffcult to observe.

Although little is known about the life cycle of the vaquita, their gestation period is around 11 months.

Little is known about the breeding cycle of the vaquita but researchers tell us that it’s similar to that of the harbor porpoise in most respects. If so, then their gestation period is likely around 11 months and they may sexually mature at around three to six years of age. From what researchers know, most calves are born in late winter and early apring (February-April), with a peak in late March and early April. During her 22-year lifespan, a female vaquita may have one calf every two years.

The vaquita is endangered due to fishery conflicts and accidental byctach.

While there are no records of the vaquita ever  being subjected to whaling, they have victimized bu commercial fisheries since the 1920’s. The large-mesh gillnets that are used to catch large fish such as tuna and totoabas have proven to be fatal to the vanquitas as it has to other cetacean species. As a result, the entire population has rapidly declined by around 8% each year as these nets continue to kill more porpoises than are born. In the 1970’s, the Mexican government banned commercial totobas fisheries , but illegal fishing still continues along with gillnetting for sharks and rays. It’s estimated that around 245 vaquitas are left in the entire world. If prompt progress is not made by the Mexican government to better protect them, researchers believe that the vaquita may become the second cetacean species to become extinct during a human lifetime in the next few years.

What can be done to save the vaquita?

1. Tell your friends, family, and social networking followers about the plight of the vaquita.

2. Don’t buy seafood products that came from fisheries that use gillnets.

3. Support tourism in Mexico

4. Write a letter to Congress or even the Mexican Embassy and ask them to support Mexican action to protect the vaquita.

5. Support wildlife conservation.

 

 

 

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Dolphins in Danger: The Maui’s Dolphin


A pod of Maui Dolphins

A pod of Maui Dolphins (Also known as the "Northern Hector's Dolphin) off the coast of New Zealand

The Maui’s Dolphin (Cephalorhynchus hectori maui) is one of the world’s rarest and smallest cetaceans on Earth. It can only be found exclusively in the shallow coastal waters of New Zealand. One full grown animal may measure in at about 1.4 meters and weight in at around 50 kilograms. In fact, these animals are no bigger than a small human child. Maui Dolphins are easily distinguished by their black facial markings, short stocky bodies, and their mouse ear-shaped dorsal fins.

Maui's Dolphins tend to swim closer to shore unlike the Hector's Dolphin, which lives usually 9 to 27 kilometers from shore.

Identified as a subspecies of the Hector’s dolphin in 2002, Maui’s Dolphins are found in shallow coastal waters off New Zealand’s North Island along it’s western shores. The majority of the sightings of these animals have mainly been between Manuka Harbor and Raglan Harbor, North Island, NZ. Maui’s tend to swim close to the shore line, making them more at risk of becoming entangled in fishing nets. During the Southern Winter months (June-September), the dolphins are distributed between the shoreline and 7.5 kilometers offshore while in the summer months (December-March), they are usually seen much closer to the shore.

Maui's Dolphins live in small pods that range in size from two to eight animals.

Maui’s Dolphins live in small pods that range in size from two to eight animals. Pod membership is usually fluid because pod mates mix freely from other pods.These animals are well known for their playful and acrobatic behaviors such as blowing bubbles, playing with seaweed, or surfing the waves. However, they do spend most of their time foraging for food underwater. They have been known for taking short dives for up to 90 seconds. During that time, the animals may be finding or catching fish and squid by using echolocation in mid-water.  However, they have been sighted feeding near the surface of the water.

Maui's Dolphin Mother and Calf

Females do not breed until they are at least 7-9 years of age. Although the gestation period for these animals in not known, calves are said to be born around the southern spring and early southern summer, from November to mid-February. Calves will stay with their mother for up to two years and begin to feed on fish for the first time when they are at least six months old. Over the course of her 20-year lifespan, a mother Maui dolphin may give birth to only four calves, but that is not enough to keep a dangerously low population of only 100 dolphins growing beyond %2 due to the ever increasing deaths by human impact.

This Maui's Dolphin is one of many dolphins that die due to entanglement.

Because they live close to shore, Maui’s dolphins are at great risk of dying by entanglement and boat strikes. Deaths by entanglement in both recreational and commercial gill and trawl nets have been recognized by both New Zealand’s Ministry of Fisheries and the New Zealand Department of Conservation as the biggest threat the animals face. What happens is the dolphins would be detecting their prey using echolocation when the fish passes the nets, the dolphins simply, just get to close to them because these fishing nets are not picked up by the echolocation and thus, the dolphin may try to swim through it as a way to find prey before getting themselves entangled. Once entangled, they cannot release themselves from the nets, and thus, they drown within a matter of minutes.

There area a number of efforts being done to protect Maui's and other dolphin species in New Zealand.

There area a number of efforts being done to protect Maui's and other dolphin species in New Zealand.

What is being done to protect both the Hector’s and Maui’s Dolphins?…….

  1. Long term radio tag surveys are helping researchers understand their daily migration patterns and harbor uses
  2. Researchers have conducted the relationship between boats, human swimmers, and dolphins to determine the long term impact it has on animals.
  3. New Zealand’s Department of Conservation has encouraged the public to call their dolphin sighting hotline if they site either a dead or live dolphin.
  4. Educating the public about the plight of these endangered dolphins
Let’s hope with all the efforts being made to help protect New Zealand’s Maui’s dolphins, the population will make a comeback and be around for generations to come. Till then, all we can do is hope and do our part in saving them.