Species Spotlight: Vaquita

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.

Vaquita (Phocoena sinus)

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.

Northern-most area of the Gulf of California, where vaquitas can be found

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.

A school of grunts (family: Haemulidae), a favourite meal of vaquitas

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.

Statue of vaquita mother and calf at San Juan de Aragón Zoo, Mexico City

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.

Fish caught in a gillnet

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.

My sketch of a vaquita (photographs are hard to come by)

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.

Aquatic News: September 2019

I plan to start each month with a breakdown of all the news and breakthroughs in marine science (and probably a little freshwater too) from the previous month. This month we have a newly confirmed whale species, an improved estimate of the size of a megalodon, success in the growth of lab-bred corals, and new seagrass and kelp initiatives to combat climate change.

Seagrass restoration off Wales

Seagrass meadow

In a project launched by Sky Ocean Rescue, WWF, Swansea University, and Pembrokeshire Coastal Forum, 2 hectares (4.9 acres) of seagrass are to be restored in Dale Bay off the coast of Pembrokeshire. Around one million seeds will be planted in what is the UK's biggest seagrass restoration.

The seeds were gathered from existing seagrass meadows along the UK coastline. They were secured in hessian bags, which are both durable and eco-friendly, made from natural fibres that are 100% biodegradable. These will be planted this winter with the goal of restoring the meadow to its previous state.

Seagrass acts as a nursery for several marine species but, over the last 100 years, 92% of UK seagrass meadows have been lost. Seagrass meadows are also responsible for 11% of the ocean's carbon absorption, despite only covering 0.1% of the seafloor, and they capture carbon at a rate 35 times quicker than a rainforest.

It is hoped that this project will be the beginning of a larger scale seagrass restoration across the UK in a bid to help tackle climate change.

Further reading

New species of beaked whale off Japan

Previously unidentified beaked whales

The black Baird's beaked whale, which can be found off the coast of Japan, has been discovered to be a new species. These elusive whales have evaded researchers until recent years, but analysis of a dead specimen that washed up has finally confirmed that it is a species separate from other beaked whales.

Beaked whales are difficult to study as they prefer deep water of up to 3,000 m (9,850 ft). Up until now, it was thought that there was only one species in the North Pacific, the Baird's beaked whale (Berardius bairdii), which is a slate grey in colour.

This newly confirmed species is the black Baird's beaked whale (Berardius minimus). It is darker in colour, has a shorter beak, and is more spindle shaped than the known Berardius species. The biggest difference, however, is its size. The black Baird's beaked whale is around 6 m (20 ft) in length, while its grey counterpart is around 10 m (33 ft).

Further research will hopefully shed some light on this species and improve our understanding of its behaviour and ecology.

Further reading

Latest estimate of Megalodon's size

Megalodon tooth

Otodus megalodon, more commonly known as megalodon or the megatooth shark, has an infamous reputation as a prehistoric giant that once terrorised the oceans. The shark lived around 15 to 3.6 million years ago and it was previously thought that it reached sizes of about 25 to 30 m (80 to 100 ft).

However, new research suggests that the maximum size for the species would have been roughly 15 m (50 ft). Dr Kenshu Shimada, professor of paleobiology at DePaul University in Chicago and research associate at Sternberg Museum in Kansas, reanalysed previously published data showing the relationship between tooth size and body size in the great white shark (Carcharodon carcharias), the closest living analogue of megalodon. He compared this data to megalodon tooth sizes from museum collections.

The largest megalodon tooth at the Chicago Field Museum of Natural History measures 16.2 cm (6.4 inches). Dr Shimada has calculated that a tooth of this size would have come from an individual 14.2 to 15.3 m (47 to 50 ft) in length. Meanwhile, the largest teeth found so far could have come from individuals who were around 18 m (59 ft) in length.

The research suggests that individuals larger than 15 m would have been extremely rare. This improved understanding of megalodon's size will provide a better insight into the shark's behaviour and metabolism, as well as new insights into the marine ecosystem as a whole during that period in Earth's history.

Further reading

Threatened coral successfully bred in a lab

Pillar coral

Researchers at Florida Aquarium in Tampa have announced the first successful sexual reproduction of Atlantic coral in a laboratory setting. Corals are able to reproduce both asexually and sexually, but the method used by the researchers could help save the pillar coral (Dendrogyra cylindrus), which is native to the western Atlantic and is threatened with extinction.

Coral reefs are important as they support a wide variety of sea life and are often areas of high biodiversity. They also help to protect inland waterways. This is why breakthroughs such as this that could help protect or restore corals are so important.

While other countries have reported similar results from lab trials, this is the first example of such a success in the US. The research team collaborated with Horniman Museum and Gardens, who have already successfully induced spawning in Pacific corals.

By creating the right condition in the lab, this could be a real turning point for coral restoration. The team plans to use this method to spawn new coral colonies and help repopulate Florida's struggling reefs. Laboratory spawning certainly has the potential to make a huge difference to the current restoration efforts.

Further reading

Campaign to save kelp forests off Sussex

Kelp forest

The Help Our Kelp campaign by Sussex Wildlife Trust and the Inshore Fisheries and Conservation Authority (IFCA) has been launched to save kelp forests, which are an extremely important marine habitat.

Kelp forests are among the most biodiverse habitats on Earth. On top of that, kelp can absorb around 600 million tonnes of carbon a year, making it vital in reducing the impact of climate change. However, seafloor pollution and damage from fishing activities threatens these habitats.

This latest initiative will introduce an inshore trawler exclusion zone to protect Sussex's kelp forests and give them a chance to regenerate. They previously stretched along 40 km (25 miles) of the West Sussex coastline but, over the last 40 years, have diminished to almost nothing.

Restoring these kelp forests will bring back vital nursery and feeding grounds for many fish species. This, in turn, will bring back fish populations that have left the area, allowing several species to finally recover and thrive.

Further reading

Where the Oceans Came From

More than 70% of the Earth is covered by water and 96.5% of this is contained in our oceans, which equates to around 1.35 billion km³. Water in its liquid form is so plentiful on our planet but so scarce in the rest of the solar system that it leaves many people wondering where all that water came from. To answer that question, you'll first need a brief history of how our planet was formed.

In the early days of our solar system, the newly-formed Sun began to pull objects into orbit around it. Gas molecules and dust particles fused to form larger objects and, by around 4.5 billion years ago, roughly 65% of planet Earth had been assembled.

But the process was not without problems. Around 4.53 billion years ago, Earth was struck by an object the size of Mars. The energy from this collision melted the planet's upper layers, eventually melting it right to the core.

And the violence continued. The Earth was repeatedly struck during a period known as the Late Heavy Bombardment between 4.1 and 3.8 billion years ago. One possible explanation for the presence of water on Earth is that it arrived during this time, brought by icy comets and asteroids from the outer solar system.

However, for oceans, ponds, and other bodies of water to have formed at this time, there would need to be a solid surface for them to sit on, suggesting the Earth's crust was already in place. Also, for there to be liquid water, there would have to be a thick atmosphere in order to prevent the water from boiling off in the heat.

Recent evidence contradicts the comet theory of the oceans' origin. Ancient volcanic basalt rocks from Baffin Island, in the Canadian Arctic, contain inclusions (material trapped inside a mineral during its formation) formed in the Earth's mantle around 4.5 billion years ago. These inclusions contain hydrogen molecules from water of the same age.

Quartz containing inclusions

The amount of deuterium, a hydrogen isotope, in these inclusions is low, which could rule out meteorites as the source of the water since these usually have high amounts of deuterium. This suggests that water initially came from the cloud from which the Sun and planets originally condensed. In this scenario, water would have clung tightly to the coalescing dust particles during Earth's formation.

Our planet also has more water than we would expect beneath its surface. It's possible that some of this water migrated upwards to the surface to form the oceans. It is estimated that there is three times the volume of all the oceans put together way down in the mantle, in the internal reservoir. And there could be more reservoirs of water even deeper.

So, there's no definitive answer for where the oceans came from but, instead, there are several theories, each with supporting evidence.

Regardless of how they were formed, there is no doubt that our oceans are important. They are able to regulate the planet's temperature, storing heat on a large scale. They also absorb carbon and CO2 in large amounts, removing it from the atmosphere and locking it away; particularly important in the fight against climate change.

So, as you can see, healthier oceans and seas will lead to an overall healthier planet. It's probably for the best that we look after them.