Tag Archives: Deep Sea

How deep is too deep for commercial fishing?

Our ever-improving technology has allowed us to fish longer, catch more, and move further from land.  It has also allowed us to fish deeper.  EU statistics indicate that between 1950 and 2006 fishing depths increased from an average depth of 407 metres, to 535 metres.

Life in the deep is slow-paced.  Food is scarcer than in the sunlit surface waters.  Species grow slower and live longer.  Some deep-sea corals, like the one in the image, are thought to be over 4,000 years old. Traits like these are why organisations like Marine Conservation Institute that ” The deep-sea is the world’s worst place to catch fish” .  It’s not just the sustainability of targeted species that is causing concern, but of those caught as bycatch, as well as damage to the seabed and the flora and fauna living in and on it – like the coral in the photo.  So can deep-sea fishing ever be managed sustainably?    A recently published study from Joanne Clarke, a PhD student at the University of Glasgow, and colleagues suggests that there might be a way to make the practice less damaging. Continue reading How deep is too deep for commercial fishing?

News from the life aquatic

There are three great open access papers out this week that I want to share. Three! But which to share? Well why not all three. Here’s a quick round-up of some of the latest research in ocean science. Best served with a nice slice of your favourite treat.

Can you tell what (species) it is yet?
Every time we explore life in the deep sea we find more and more creatures that bioluminensce. Around 80% of all eukaryotic life in waters below 200 meters are thought to have this ability. In this study by Matthew Davis of The University of Kansas (USA) and fellow researchers, it emerges that diversity of species (species richness) in deep sea fish groups may be influenced by photophores – light emitting cells on the body of fish. The researchers work found that some lineages of the lanternfishes (Myctophidae) – which are made up of over 250 species – have photophores with species-specific patterns. This means species can clearly be identified from one another. This diversification seems to have happened after the evolution of the lanternfishes photophores some 73 – 104 million years ago. As diversification of photophores occurred, so too did speciation.  http://dx.doi/10.1007/s00227-014-2406-x

 

Where the young turtles swim
We watch baby turtles hatch and make their way into the open ocean. We watch them when they show up in coastal waters years later as ‘teenagers;. But where do they go when they are growing up? That is what Kate Mansfield of the University of Central Florida and fellow researchers set about to discover for loggerhead turtles (Caretta caretta) . 17 young turtles – all between 3.5 and 9 months old and reaching a maximum length of just 18 cm were tagged with small solar-powered satellite transmitters. And what an adventure these guys had. Staying mostly at the surface, these critters were found enjoying a wide area of the ocean past the continental shelf, – with one turtle travelling up to 2,672 miles! What was particularly surprising for the researchers was that they didn’t just hang out in gyre-associated currents – sometimes they went off exploring
http://dx.doi10.1098/rspb.2013.3039

 

I’m sure there used to be people living there
With changing climate comes changing sea levels. And for many areas that means a sea level rise. In this study by Ben Marzeion from the University of Innsbruck (Austria) and Anders Levermann from Potsdam University (Germany), looked at all 720 UNESCO World Heritage Sites to see what increasing sea levels would mean for them. The researchers decided to take a not-too unrealistic prediction of 3 degrees Celsius above pre-industrial levels in the next 2000 years. Under this scenario, their models indicated that 136 sites (19%) would be impacted by sea level rise. Doesn’t sound too bad, on the grand scheme of things but those sites do include key heritage areas like the Sydney Opera House, the Tower of London, and Independence Hall. Check out some visualisations from The Weather Channel, created using ‘Drown your Town’. But the researchers didn’t stop there. They also looked at how much of the current human population would be impacted by sea level rise. The same scenario indicated that 7% of the world’s population is living on land that will be undersea within 2000 years. Around 60% of those affected live in just 5 countries – China, India, Bangladesh, Vietnam, and Indonesia. Sobering thoughts for the future.  http://dx.doi:10.1088/1748-9326/9/3/034001

 

Image: ‘Drown your Town’ used on Cape Town, South Africa (50m rise – possibly a little extreme!). Credit: Drown your Town