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Shark of the week: Papuan epaulette shark — 2. July 2018

Shark of the week: Papuan epaulette shark

The last species from the genus Epaulette sharks or Hemiscyllium is the Papuan epaulette shark (Hemiscyllium hallstromi). The whole genus is a great example for plate tectonics and evolution, as shown in this great paper by Gerald Allen et. al.

comparisation of all nine hemiscyllium species
comparisation of all nine hemiscyllium species: A) H. freycineti, B) H. hallstromi, C) H. galei, D) H. trispeculare, E) H. ocellatum, F) H. michaeli, G) H. halmahera, H) H. henryi & I) H. strahani Credit: Allen et al 2016

The little (up to 30 in -77 cm- length ) Papuan epaulette shark (B in the picture) has a limited habitat in shallow tropical waters on seagrass beds and occasional rocks and coral reefs near Port Moresby, the capital of Papua New Guinea. It is considered vulnerable by the IUCN due to overfishing (mostly as bycatch) by industrial and artisanal fisheries in destructive practices like trawling and dynamite fishing, pollution by river-borne pollutants, sewerage effluent from Port Moresby and sedimentation from mining run-off, and habitat destruction by oil exploration and pipeline development.

Sources: here and here

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Shark of the week: Hooded carpetshark — 18. June 2018

Shark of the week: Hooded carpetshark

Another shark from the family bamboo shark (or longtail carpet sharks, Hemiscylliidae) living in coral reefs off Papua New Guinea (only a small region off the northern and southern coasts from the eastern part) is the Hooded carpetshark (Hemiscyllium strahani). Like all the other epaulette sharks (Hemiscyllium), its distinct features are different markings, this time large white spots and small dark spots, and an unique black mask over the head and snout (like an ‘executioner’s hood’, thus its name).

Hooded carpetshark, © Randall, John E., found on fishbase.org

This up to 31.5 in -80 cm- long walking shark is in danger due to destruction of its rather small habitat by pollution or dynamite fishing, but may be exploited in the  aquarium trade. The IUCN considers this species as vulnerable.

Sources: here, here and here

Shark of thee week: Indonesian speckled carpetshark — 11. June 2018

Shark of thee week: Indonesian speckled carpetshark

After the Epaulette shark from 1788, the next new species of the genus Hemiscyllium has been described in 1824. The Indonesian speckled carpetshark (Hemiscyllium freycineti) is another walking shark from around Indonesia and seems to live solely off western New Guinea, whereas the newly discovered Milne Bay Epaulette shark assumed the eastside (and many of the pictures). Despite being common for so long, not much is known about this reef shark of the family Longtail carpet sharks (or bamboo sharks, Hemiscylliidae), not even its length.

Hemiscyllium freycineti, Adult from reeflifesurvey.com
adult Hemiscyllium freycineti, © reeflifesurvey.com

Like all Epaulette sharks, the Indonesian speckled carpetsharks is oviparous (that means the female lays egg cases). This cute little shark is often caught for aquarium trade. Due to habitat destruction and destructive or illegal fishing practices, but above all, its newly discovered restricted distribution, it may very well be considered Vulnerable instead of only Near Threatened in the near future.

Sources: here, here and here

Shark of the week: Milne Bay epaulette shark — 14. May 2018

Shark of the week: Milne Bay epaulette shark

Epaulette sharks are cute, can walk and look all at first glance fairly similar. But if you take your time to look closer on those markings, you can find differences. Just like American marine biologist and author Scott W. Michael did, and he discovered that on some pictures and specimen of the common Indonesian speckled carpetshark the shark should not have those large and defined spots remarkably similar to the spots of a leopard. He informed his colleague Gerald Allen, and so, after genetic tests, in 2010 a new species of the genus Hemiscyllium off (the Milne Bay Province region of) eastern Papua New Guinea was named after him: the Milne Bay epaulette shark or Leopard epaulette shark (Hemiscyllium michaeli).

Milne Bay epaulette shark (Hemiscyllium michaeli) (C) Scott W. Michael 2008

Like the majority of the other 8 species of its genus of the family Hemiscylliidae (Bamboo sharks or longtail carpet sharks), the up to 27.4 in – 69.5 cm – long Milne Bay epaulette shark is considered Near Threatened due to its small home range in shallow inshore coral reef waters with problems from overheating, overfishing and destructive fishing practices like dynamite fishing. Additionally, it suffers greatly from habitat degradation due to pollution and siltation from recent gold mining in the region (cyanide poisoning, river run-off and direct dumping of waste) and from ongoing logging and palm oil plantations. Producing and using palm oil not only endangers our air, our soil, our flora and fauna, out health and our atmosphere, but our oceans, too.

Sources: here, here and here

 

shark of the week: Broadfin shark — 19. February 2018

shark of the week: Broadfin shark

Another species of requiem sharks is the Broadfin shark (Lamiopsis temminckii). Living solely in shallow waters off India, China and Southeast Asia, it suffers greatly from habitat destruction, overfishing and water pollution. The IUCN considers this species as endangered.

Breitflossenhai (Lamiopsis temminckii) aus der Erstbeschreibung von Müller & Henle
Lamiopsis temminckii by Müller & Henle – Systematische Beschreibung der Plagiostomen pl. 18, Gemeinfrei, Link

Like almost all other requiem sharks, the Broadfin shark is viviparous. 4 to 8 embryos feed at first from yolk and later via a placental connection. After about 8 month they are born at 15 to 23 in -40 to 60 cm- length. Maximal length is 5.5 ft – 1.7 m.

Sources: here and here

Shark of the week: Tawny nurse shark — 27. November 2017

Shark of the week: Tawny nurse shark

The Tawny nurse shark (Nebrius ferrugineus) is a docile shark of the family nurse sharks and lives in the Indian Ocean from the Red Sea to South Africa and India and in the western Pacific from Australia and Japan to South Sea islands. It inhabits shallow coastal waters in depths up to 230 ft – 70 m – on coral reefs. It is nocturnal and feeds from small fishes, corals, sea urchins, sea snakes, crustaceans and especially octopuses, which it sucks into its small mouth.

The female Tawny nurse shark is ovoviviparous. The embryos feed (after depleting their yolk sack) from big eggs (oophagy), they compete for food and maybe prey on weaker siblings (cannibalism) – in any case mostly only one out of 4 embryos per uterus survives. The pups are born at 16 to 31 in -40 to 80 cm- and grow up to 10 ft – 3.20 m- length. They mature at 8 ft 2 in – 250 cm – (males) and 7 ft 7 in to 9 ft 6 in – 230 to 290 cm – (females) and loose their spots on the white belly. Their color is yellowish brown (since their name).

Even if Tawny nurse sharks are mostly gentle and can be trained (it is said that on some South Sea islands children even ride them), they get wild and spit, grunt and bite when provoked or captured. That’s why they are targeted by recreational fishermen as big game fish. Except in Australia they are fished commercially for their meat, fins, skin and liver oil (partly using explosives or poisons) and caught for aquariums. Additionally they are harassed by divers and their habitat gets often destroyed. Therefore they are considered vulnerable worldwide by the IUCN.

Sources: here, here and here

Shark of the week: Blacktip reef shark — 16. October 2017

Shark of the week: Blacktip reef shark

The Blacktip reef shark (Carcharhinus melanopterus – derived from melas = black and pteron = wing or fin (see Pterosaurs)) is another requiem shark living in coral reefs. It inhabits nearshore waters of the tropical and subtropical Indo-Pacific from South Africa to Hawaii (even colonized the eastern Mediterranean Sea by way of the man-made Suez Canal) and prefers more shallow waters than its colleagues grey reef shark and whitetip reef shark. Their nursery grounds (females are viviparous and give birth to living young after feeding them from yolk and via placental connection) can be so shallow that the pups have to swim with their dorsal fins above the water looking “like a flotilla of tiny sailboats” (quote from here).

An expanse of clear water and white sand, and several sharks swimming with their black-tipped dorsal fins protruding above the water
Carcharhinus melanopterus by Leon Brocard from London, UK – PIMG_2915, CC BY 2.0, Link

Not only pups prefer to stay in groups for protection, but also adult Blacktip reef sharks form stabile groups for social purposes and hunting. Their prey are fishes, crustaceans, molluscs and squids, but also terrestrial and sea snakes and even rats and birds. They have got large eyes with a reflective tapetum lucidum like a cat, indicating that they can excellent hunt at night.

Due to their extremely small home ranges and strong site fidelity, Blacktip reef sharks are susceptible to habitat degradation and fishing pressure (only as bycatch by commercial fisheries, but targeted by artisanal fishermen for their meat, liver oil and fins, and also by recreational fishermen and for aquarium trade). Their small litter sizes (only 2 to 5 pups) and long gestation periods (up to 16 month) are no help, either. They are considered “near threatened” by the IUCN. They are normally timid and despite their size (typically up to 5.2 ft -1.6 m-) no danger to humans, but sometimes bite the legs or feet of waders encroaching into their space or spear fishers for their catch.

Sources: here, here and here

National Geographic: study about plastic waste| Studie über Plastik-Abfall — 7. October 2017

National Geographic: study about plastic waste| Studie über Plastik-Abfall

Mass production of plastics, which began just six decades ago, has accelerated so rapidly that it has created 8.3 billion metric tons … 6.3 billion metric tons has become plastic waste. (Half of all plastic manufactured becomes trash in less than a year)… Of that, only nine percent has been recycled.

via http://news.nationalgeographic.com/2017/07/plastic-produced-recycling-waste-ocean-trash-debris-environment/

And this recycling can make matters even worse: In China fleece are made of disposable water bottles from Germany (as part of the recycling quota) and sold back to Germany, where they pollute the waste water and lastly the sea with micro fibers (microbeads) due to cleaning and still end up as waste, but already broken down in small particles (instead of after 450 years like the original water bottle).
Waste minimisation instead of recycling, I say!


Die Massenproduktion von Kunststoff, die erst vor 6 Jahrzehnten begann, hat sich so rasant beschleunigt, dass sie 8,3 Milliarden metrische Tonnen erschaffen hat… 6,3 Milliarden metrische Tonnen davon sind zu Müll geworden (Die Hälfte alles hergestellten Kunststoffs wird innerhalb von weniger als einem Jahr zu Abfall)…Davon sind nur 9 Prozent recycled worden.

via http://news.nationalgeographic.com/2017/07/plastic-produced-recycling-waste-ocean-trash-debris-environment/

Und dieses Recycling kann alles noch schlimmer machen: In China werden aus Einweg-Wasserflaschen aus Deutschland (als Teil der Recycling-Quote) Fleece hergestellt und wieder nach Deutschland zurück verkauft, wo sie das Abwasser und letztlich das Meer mit Mikro-Fasern (Mikroplastik) beim Waschen verschmutzen und doch wieder als Abfall enden, aber schon in kleine Teilchen zersetzt (anstatt nach 450 Jahren wie die originale Wasserflasche).
Müllvermeidung anstelle von Recycling, sage ich!

ideas.ted.com: Vertical ocean farms that can feed us and help our seas| Vertikale Meeresfarmen, die uns ernähren können und unseren Meeren helfen — 30. July 2017

ideas.ted.com: Vertical ocean farms that can feed us and help our seas| Vertikale Meeresfarmen, die uns ernähren können und unseren Meeren helfen

Bren Smith wants to create thousands of decent jobs, transform how we harvest food from the oceans, and blunt the effects of climate change and marine degradation — all at the same time. His big idea: small-scale marine farms.

see Vertical ocean farms that can feed us and help our seas — ideas.ted.com


Bren Smith will tausende von ehrlichen Jobs schaffen, verändern wie wir Nahrung aus dem Meer holen, und die Effekte von Klimawandel und Meereszerstörung abmildern- alles zur gleichen Zeit. Seine große Idee: kleine Meeres-Farmen.

Siehe Vertical ocean farms that can feed us and help our seas — ideas.ted.com

Shark of the week: Whitetip Reef shark — 26. June 2017

Shark of the week: Whitetip Reef shark

Another case of mysterious naming is the Whitetip Reef shark (Triaenodon obesus). Not the English name, which is quite apt due to its white tips on dorsal and caudal fins and its exclusive habitat, but the Latin one is untrue: this slender shark is far from obese. On the contrary, as nocturnal hunter it can detect its prey by electroreception (using its ampullae of Lorenzini) and smell (with unique tubular nasal flaps) and follows it into their resting crevices (well adapted to this hunting practice due to its tough skin, sleek build, blunt snout and ridges to protect its eyes), and some sharks “actually squirm into a hole in one side of a coral head and exit through an opening on the other”.

Three gray sharks lying beside each other on the sea bottom.
By Dorothy from USA – sharks, CC BY 2.0, Link

The Whitetip Reef shark is gregarious (sometimes even hunts in groups) and can be seen resting in groups on the bottom or in caves during daytime. It doesn’t need to swim to breathe, unlike other requiem sharks. Not to be confused with the other Whitetip requiem shark (the Oceanic Whitetip), the smaller Whitetip Reef shark (up to 5.6 ft -1.7 m- long) isn’t dangerous to humans. Sadly, as opportunistic feeder it learnt to associate the sounds of boats and spearfishing with food – the curious shark can become bold and agitated and sometimes bites while trying to steal the fish.

Like all requiem sharks, the Whitetip Reef shark is ovoviviparous: every two years 2 to 3 living young are born at a length of 20 to 24 in -52 to 60 cm. There is a case of Parthenogenesis (asexually reproduction) in Whitetip reef sharks. They grow slowly, mature at about 3.4 feet -1.05 m- and live up to 25 years.

Whitetip Reef sharks live in coral reefs all around the world. They are homebodies and famous for their site fidelity. That means that dangers to their coral reef due to climate change, overheating and pollution have a deep impact on the shark population, too, in addition to commercial and recreational fisheries. They are considered as Near Threatened by the IUCN. Conservation measures like marine protected areas (MPA) seems to help, but only if they are completely no-entry. On the Great Barrier Reef, populations of Whitetip Reef sharks in fishing zones have been reduced by 80% relative to no-entry zones. However, populations in no-take zones, where boats are allowed but fishing prohibited, exhibit levels of depletion comparable to fishing zones, most likely due to poaching (IUU). Demographic models indicate that these depleted populations will continue to decline by 6.6–8.3% per year without additional conservation measures.

Sources: here, here and here