THE MAUGEAN SKATE
Zearaja maugeana
Maugean Skates are Tasmania’s largest endemic fish
growing up to 750 mm from tip of snout to end of tail. They are listed as one of the State’s most ‘endangered’ marine species which means that there aren’t many of them left in the world and they face a very high risk of extinction.
This ancient skate been described as a relict species that has a Gondwanan lineage possibly dating back to the Cretaceous period (145 to 66 million years ago), a time before fish had bones. Their closest cousins live in New Zealand (NZ Rough Skate – Zearaja nasuta) and in South America (Yellownose Skate – Zearaja chilensis), both landmasses to which Tasmania was once connected.
They are adapted to living in dark conditions as the strong tannin layer in Macquarie Harbour blocks out much of the light. They share many features with deep ocean skates even though they are generally found in relatively shallow water.
Image: Male Maugean Skate – Copyright Neville Barrett
A benthic species
which means they are mainly bottom dwellers and have adapted to living on the sea floor. They have a flat body and large wing-like pectoral fins attached to their head.
Image: Female Maugean Skate – Copyright Jane Ruckert
A benthic species
which means they are mainly bottom dwellers and have adapted to living on the sea floor. They have a flat body and large wing-like pectoral fins attached to their head.
Image: Female Maugean Skate – Copyright Jane Ruckert
They are very well-camouflaged creatures
often resting on or lying concealed within the sediments.
This makes them challenging to see and difficult to photograph, especially given that they generally found at a depth where light levels are very low or there is total darkness.
Only limited images of these skates have ever been captured in the wild, further adding to their mystique.
Image: Male Maugean Skate – Copyright Neville Barrett
Only one place left in the world
The last known population is restricted to Macquarie Harbour on Tasmania’s West Coast. They are classified as a micro-endemic species which means they have a very restricted range.
There are 400 species of skates known worldwide but these are the only ones that live exclusively in brackish estuarine waters. This ability to tolerate a wide range of salinities is a unique characteristic of the Maugean Skate.
Researchers have been studying these intriguing fish since they were first known to science in 1988, however, there is still a lot to learn about the species
Image: Bonnet Island Lighthouse, Macquarie Harbour – Copyright David Moreno
Only one place left in the world
The last known population is restricted to Macquarie Harbour on Tasmania’s West Coast. They are classified as a micro-endemic species which means they have a very restricted range.
There are 400 species of skates known worldwide but these are the only ones that live exclusively in brackish estuarine waters. This ability to tolerate a wide range of salinities is a unique characteristic of the Maugean Skate.
Researchers have been studying these intriguing fish since they were first known to science in 1988, however, there is still a lot to learn about the species.
Image: Bonnet Island Lighthouse, Macquarie Harbour – Copyright David Moreno
Distribution of the Endangered Maugean Skate. Source: CSIRO Rays of the World 2016 p.362
Skates are cartilaginous fish and are closely related to sharks and rays. Their skeletons are built of cartilage rather than bone.
Superficial calcification is more apparent where the skeleton needs to be strongest and endures more pressure or force for example the jaws, cranium, shoulder and girdle.
Image: Xray Immature Male– Copyright CSIRO Australian National Fish Collection
Skates are cartilaginous fish and are closely related to sharks and rays. Their skeletons are built of cartilage rather than bone.
Superficial calcification is more apparent where the skeleton needs to be strongest and endures more pressure or force for example the jaws, cranium, shoulder and girdle.
Image: Xray Immature Male– Copyright CSIRO Australian National Fish Collection
Skates are egg-laying fishes
Female skates do not mature until they are between 4-6 years old and only have a relatively short life span, approximately 10 years.
They lay small clutches of eggs which generally sink towards the bottom and are then subject to the water movements in Macquarie Harbour. Each egg is protected by a rough leathery egg case made mostly from collagen which is a golden-green colour. This helps them blend into the surrounding muddy sediments and cloudy water, making them more difficult for predators to find. The distinctive shape of each egg case and the arrangement of the filamentous horns on each corner is unique to each species of skate and you may find them washed up on the beach.
Seawater exchange occurs through slits in the egg case and the respiratory channels open after 15 weeks. The embryos are nourished by a yolk and the hatchlings push themselves out of their egg cases using their tails when they are suitably developed after 31 weeks.
Image: Maugean Skate Egg Case – Copyright David Moreno
Baby skate
Baby animals are almost always endearing and young skates are no exception.
In this photo, you can clearly see the eyes, gills, abdominal cavity and pelvic fins which they use like ‘legs’ to propel themselves in the water.
Image: Baby Maugean Skate – Copyright David Moreno
Unlike many other baby animals, skates do not have a special name. When they hatch they look like miniature adults and they are simply known as ‘baby skates’.
Image: Baby Maugean Skate – Copyright David Moreno
Although skates have formidable-looking thorny tails, their thorns are not venomous and do not a pose a major threat to humans.
Both sexes have regular rows of tail thorns, arranged in three rows in males and five rows in females.
Both sexes also have orbital thorns arranged in a half-circle around the upper half of their eye.
Males also have a set of small thorns below their eye (malar thorns) and several irregular rows of small thorns near the tip of each the wing (alar thorns).
Image: Adult male middle of tail – Copy right CSIRO Australian National Fish Collection
How the Maugean Skate got its unusual name
The scientific name is Zearaja maugeana.
Like many animals, this skate actually has a few common names.
The first skate was discovered by scientists in Bathurst Harbour and was initially known as the ‘Port Davey Skate’. Another population was later found in Macquarie Harbour, so a new common name was required.
The species was not officially described until 2007 and the species name ‘maugeana’ was used to draw a link with the Australian marine and coastal biogeographic region, the Maugean Province (see map). Its common name, the Maugean Skate, follows this theme.
West Coast locals know it as the ‘Spiky Skate’ in reference to the tail thorns.
Pointy snouts
Skates use their long pointy and sensitive snouts to bury their quadrangular shaped bodies and hide in the soft mud on the seabed. The underside of their snout is covered with tiny electro-sensory organs (ampullae of lorenzini) which they use to find their prey such as the Common Shore Crab.
Behind each eye are large respiratory openings called spiracles. These actively pump oxygenated water into the mouth with gas exchange occurring as the water passes over the gills. The spiracles allow skates to bury themselves in the sediments to hide and wait for prey and breathe without the aid of exposed gills. There are five pairs of gill clefts on the underside of their bodies.
Image:Maugean Skate – Copyright Neville Barrett
Pointy snouts
Skates use their long pointy and sensitive snouts to bury their quadrangular shaped bodies and hide in the soft mud on the seabed. The underside of their snout is covered with tiny electro-sensory organs (ampullae of lorenzini) which they use to find their prey such as the Common Shore Crab.
Behind each eye are large respiratory openings called spiracles. These actively pump oxygenated water into the mouth with gas exchange occurring as the water passes over the gills. The spiracles allow skates to bury themselves in the sediments to hide and wait for prey and breathe without the aid of exposed gills. There are five pairs of gill clefts on the underside of their bodies.
Image:Maugean Skate – Copyright Neville Barrett
Moving skates
Only a few intrepid divers who have braved the murky waters have had the special privilege to catch a rare sighting of these fascinating animals moving in their natural habitat.
Maugean Skates often ‘walk’ slowly across the seabed using their anterior or front pair of pelvic fins like a pair of ‘legs’.
To increase speed they can alter the way that they undulate their fins to accelerate water faster.
Image: Maugean Skate in motion – Copyright Jane Ruckert
Moving skates
Only a few intrepid divers who have braved the murky waters have had the special privilege to catch a rare sighting of these fascinating animals moving in their natural habitat.
Maugean Skates often ‘walk’ slowly across the seabed using their anterior or front pair of pelvic fins like a pair of ‘legs’.
To increase speed they can alter the way that they undulate their fins to accelerate water faster.
Image: Maugean Skate in motion – Copyright Jane Ruckert
Raising awareness of this endangered species
The long angular snout distinguishes it from the Common Thornback Skate which is the other skate that may be found in Macquarie Harbour.
If you inadvertently catch one whilst fishing then it is better for both you and the skate if you handle it using the long pointy snout and not the tail.
All skates in Macquarie Harbour are now protected and they must all be returned to the water unharmed without delay.
In addition to fishing impacts, Maugean Skates are also threatened by habitat changes that have occurred in Macquarie Harbour.
This project is supported through funding from the Australian Government