The oceans and seas are filled with a stunning variety of creatures that are unlike anything you will see on land. Every individual species is interesting in its own way and I intend to highlight what makes each one stand out with my Species Spotlight. In this instance, we'll be looking at the vaquita (Phocoena sinus), a magnificent marine mammal and one of the world's most endangered animals.
Description
The vaquita, meaning "little cow," is a species of porpoise and, as such, belongs to the family Phocoenidae. It is the smallest of all the cetaceans, measuring an average of just 1.37 m (4.5 ft) in length. On top of that, they are not particularly heavy, weighing just 54 kg (120 lb), which is a similar weight as your average 12-year-old human.
They are easily distinguishable from dolphins and other porpoises by the iconic dark markings around their eyes and mouth. The rest of their body is grey, dark on the back and fading to white on the underside. This is a typical example of countershading, allowing the vaquita to blend in with their surroundings both from above and below. They have a smaller skull and shorter rostrum (or beak) than other porpoises, which gives their face a very distinct appearance.
Habitat
The vaquita is the only porpoise species that is found in warm waters, though they are able to tolerate significant changes in temperature. They live in shallow lagoons in the northern section of the Gulf of California, the marginal sea that separates the Baja California Peninsula from mainland Mexico.
They rarely venture any deeper than 30 m (100 ft) but their general depth range is between 11 and 50 m (36 to 160 ft). They are not often found in the open sea and generally stick to the coastline, between 11 and 25 km (6.8 and 16 miles) from the shore. They prefer murkier water as it has a high nutrient content, which attracts more prey.
Diet
Vaquitas are non-selective predators. They forage around the lagoons within their natural habitat and will eat fish, crustaceans, octopus, and squid. They're really not picky; though, based on the stomach contents of deceased individuals that have been recovered, some of their favourite prey items appear to be grunts, croakers, and sea trout.
Vaquitas hunt alone, searching along relatively shallow waters within the lagoons. Like many other cetaceans, they use echolocation, emitting high-pitched sounds that bounce off their surroundings and allow them to navigate. It is thought that they may also use this echolocation to locate their prey, following distinctive sounds to find a particular fish with astounding accuracy.
Reproduction
Vaquitas are less social than other porpoises and are typically solitary animals. Or, at least, they are until the mating season hits in late spring or early summer. During that time, they come together and can become quite competitive when it comes to finding a partner.
The females are larger than the males, with the former being around 1.41 m (4.6 ft) in length and the latter 1.35 m (4.4 ft). In terms of their life cycle, vaquitas are estimated to live for about 20 years and mature between the ages of 3 and 6, at which point they are able to reproduce.
The gestation period of a vaquita is between 10 and 11 months, so they usually calf in March. The calf will typically weigh around 8 kg (17 lb) at birth and measure just 71 to 78 cm (28 to 31 inches) in length. They are nursed for around 6 to 8 months until they are able to fend for themselves and, at that point, will begin to live independently. The amount of time between calves, when the female is able to reproduce again, is usually around 1 to 2 years.
Biggest Threats
The vaquita is currently the most endangered cetacean in the world and has been listed as critically endangered on the IUCN Red List of Threatened Species since 1996. In 2018, it was believed that there were only between 6 and 22 of the porpoises left. The latest estimate, from July 2019, has concluded that there are now only 9 vaquita porpoises remaining.
The biggest threat to the species comes from illegal gillnet fishing of totoaba (Totoaba macdonaldi), where the vaquita is often caught and killed as accidental bycatch. A gillnet ban was put in place in 2015 but it made no difference and the vaquita population continued to decline at a rate of almost 50% each year.
Poaching is also a major concern, with fishermen going out at night to avoid the consequences of illegally catching protected species. It is believed that some fishermen even kill vaquitas deliberately as they are seen as competition in hunting for fish. It is difficult to estimate the extent to which these issues have impacted the vaquita population but they have, without a doubt, contributed to the species' decline.
It has now become necessary to implement a captive breeding programme and protective housing for vaquitas in order to save the species. However, their ability to survive and reproduce in captivity is uncertain and, so far, all attempts have failed. Unfortunately, it may already be too late for this little porpoise.
To end on a brighter note, the remaining vaquita do appear healthy and are able to breed. But, to ensure these beautiful and fascinating creatures are able to survive (and, better yet, thrive), we must seriously intensify our efforts to protect them and their habitat, and to crack down on illegal fishing activities.
Comments