Reducing bycatch of skates and rays – stop tickling them!

Bottom-trawl fisheries may supply us with much of the tasty fish we like to enjoy, but it does come with its problems.  Also known as ‘dragging’, bottom trawling essentially involves dragging a large net, held open either with a beam (beam trawling) or large metal/wooden ‘doors’ (otter trawling) along the sea bed, or just above it.  It is used to catch a range of commercial species like cod, shrimp, flounder, and halibut.  One of the problems of trawling is that it is not a very selective form of fishing.  Other species are caught in the process, and this bycatch can include at risk species such as skates, rays and sharks.  As well as ecological implications, bycatch can be bad for fishers, who often end up throwing away bycatch either because it isn’t worth anything, or because they are not allowed to land it.  Bycatch reduction is a win-win for fishers and for the marine life caught.

Reducing bycatch of sharks, rays, and skates (collectively known as elasmobranchs) in bottom trawls is one of the many fishery-related issues on the mind of scientists at Marine Scotland Science.  As this piece of research from the Marine Scotland Science team shows, one possible solution (though not perfect) may not be all that tricky to implement. Continue reading Reducing bycatch of skates and rays – stop tickling them!

The travelling life of the tiger shark

At 9 foot long, not including the tail, tiger shark (Galeocerdo cuvier) Harry Lindo is not exactly on the small side.  It’s not Harry’s size that is exciting scientists and shark enthusiasts, nor a photograph taken in 2009 by Ian Card showing a shark – suspected to be Harry, trying to eat a 150 lb juvenile tiger shark off the coast of Bermuda.  Between 2009 and 2012 researchers tagged 24 tiger sharks with satellite transmitters in the Challenger Bank, which lies just off Bermuda in the Atlantic Ocean.  In study lead by James Lea (The Guy Harvey Research Institute, Nova Southeastern University Oceanographic Center) and team of international collaborators, those shark movements have been compiled and analysed.  Harry, it turns out, is one heck of an ocean wanderer.  In just over 3 years Harry swam over 44,000 kilometres – that’s more than the circumference of the Earth (just over 40,000 kilometres).  Harry’s track is the longest recorded for a tiger shark, and probably the longest ever published for any shark species.

Continue reading The travelling life of the tiger shark

”Blue Whales have a subtle and not very convincing ability to get out of the way of oncoming ships”

Blue whales (Balaenoptera musculus) truly are the giants of the ocean.  Actually, they are the giants of the whole planet.  Reaching around 30 metres in length and more than 190 tonnes, they are the largest animal currently existing and, to the best of our knowledge, the heaviest animal that has ever existed.  Being so huge, risk of predation is low so they seem not to have really developed much of a threat-response system.  Of course that all changed with humans who became extremely capable predators, but on an evolutionary timeframe, that is an extremely recent event.  Hunting has largely ceased, but many endangered whale populations still face threats to their recovery and long-term persistence, threats like collisions with ships.  Research by Megan McKenna from the Marine Mammal Commission, alongside colleagues from Cascadia Research Collection, NOAA, and Stanford University​ reveals just why the blue whales are so vulnerable to ship strikes.

Continue reading ”Blue Whales have a subtle and not very convincing ability to get out of the way of oncoming ships”

Climate Change Impacts on Kenya’s Fishery-dependent communities

 We now have a number of scientific studies that tell us how climate change is altering coral reef ecosystems, but how will these changes impact on communities that depend on them for their livelihood?  According to Joshua Cinner of James Cook University in Australia and colleagues from around the world, that answer depends more on the  community capacity for adaptation than its location.

Fishery-dependent communities in Kenya are not in a great situation.  Their reefs were heavily affected by a massive bleaching event in 1998 that has been linked to an extreme El Niño event and have not necessarily recovered as well as we might hope, and Kenyan reefs are likely to face increasing amounts of climate-related stress into the future.  Across three years, Cinner and co surveyed 15 ecological sites associated with 10 coastal communities along the Kenyan coast.  Using a range of ecological indicators of vulnerability of these reefs, they linked up the ‘health’ of the ecosystems with the vulnerability of the human communities that depend on them. Continue reading Climate Change Impacts on Kenya’s Fishery-dependent communities

Community-based conservation to rebuild fish stocks

I don’t know about you, but I wouldn’t mind being there right now. This is one of the Fijian islands in the Pacific, and the second largest in the group.  As serene as the picture is, not all is serene for the Islanders.  Fishers in Nagigi, a small community based on the south coast of Vanua Levu Island have been noticing that the number of fish and the size of fish have been decreasing, and habitat degrading – a big problem for a community heavily dependent on its marine resources.  This decline isn’t necessarily down to big foreign boats coming in and taking the critters on which they depend.  Instead, overexploitation and habitat destruction seems to arise from the ever-increasing number of locally based fishers.  The source of this claim?  The villagers of Nagigi.

In this paper,  Abigail Golden from Columbia University and fellow researchers explore the idea of setting up a short-term no take marine protected area within Nagigi’s coastal tenure area (known aqoliqoli ).  This idea hasn’t come from the researchers nor from any top-down government as tends to happen in western countries.  Instead the idea has come from the village leaders themselves.  This sort of bottom-up governance is far from unheard of.  The Pacific Islands are small and numerous, and have a long history of small areas of land and coastal waters managed by local communities.  Some have worked well, some have not, and many have come under strain or been lost through both technological developments, increasing population, increasing demands for resources, and cultural change.  Still, a well-managed community based MPA can work well, particularly in these remoter locations, and especially were more rigorous research and recording is absent.  Regardless of where you are in the world, there are a number of vital steps needed for good management.  One involves getting as much information as possible – about the species that are there now, the fishing methods used, an idea of how conditions have changed, and perceptions towards different management methods.  The other involves bringing the local community into the conservation planning in a meaningful way.  So the team went out and conducted two types of surveys – one looking at the species living on the reef at the time, and one talking to some of the villagers themselves. Continue reading Community-based conservation to rebuild fish stocks

Eavesdropping on an underwater world: Technology for Ocean Science

The ocean is not a quiet place.  Water can move rocks and sediment, even sufficiently to create underwater landslides.  Bivalves make clapping noises, fish make sounds during courtship, and cetaceans communicate with clicks and whistles, just to name a few.  And of course there is human activity – like shipping, drilling, and sonar, which all add to the sounds of the ocean.  There are many different reasons why we might want to hear these noises.  Thanks to acoustic monitoring technology we can.

There are many different types of acoustic monitoring equipment but you will tend to find one type of sensor at their heart – the hydrophone.  Hydrophones are microphones that can be dropped into the water and listens for sounds coming from any direction.  If you have been on a whale-watching boat you may very well have seen one of the crew drop one of these into the water.  With the hydrophone, the crew can hear a noisy whale and even work out their location.  In some places, hydrophones are anchored to the sea floor and float in the water column recording any sounds within their range, until their battery runs out and/or they are picked up again by boat.

Continue reading Eavesdropping on an underwater world: Technology for Ocean Science

Are we really protecting North Atlantic right whales?

With its common name originating from whalers who, because of their tendency to float on the surface once dead, decided that they were the ‘right whale’ hunt, the North Atlantic right whale (Eubalaena glacialis) has had a somewhat difficult past with people.  By 1530s Basque whalers where happily taking these whales (and others too) off Labrador and Newfoundland in the Northeast Atlantic.  By the mid-1600s, shore-based whaling took off down the east coast of the USA.  Between 1634 and 1951, it is estimated that somewhere between 5,500 and 11,000 right whales were killed by hunters.  1935 saw the introduction of the Convention for the Regulation of Whaling – the first protection afforded to these critters but many – but not all – whaling nations (Japan and the then Soviet Union being the exceptions).  Protection was bolsters in 1949 with the International Convention for the Regulation of Whaling (IWC), which banned signatories from hunting them for commercial purposes.  In the US, they were listed under the Endangered Species Conservation Act in 1970, and the subsequent Endangered Species Act of 1973.  Canada, who is not a signatory of the IWC, has listed them under their Species At Risk Act (SARA) as Endangered.  Today it is estimated that there are somewhere between 300 – 400 individuals left, and whilst commercial whaling has ceased, they are still under threat primarily from ship strikes or entanglement in shipping gear.

Continue reading Are we really protecting North Atlantic right whales?

Are we really protecting North Atlantic right whales?

With its common name originating from whalers who, because of their tendency to float on the surface once dead, decided that they were the ‘right whale’ hunt, the North Atlantic right whale (Eubalaena glacialis) has had a somewhat difficult past with people.  By 1530s Basque whalers where happily taking these whales (and others too) off Labrador and Newfoundland in the Northeast Atlantic.  By the mid-1600s, shore-based whaling took off down the east coast of the USA.  Between 1634 and 1951, it is estimated that somewhere between 5,500 and 11,000 right whales were killed by hunters.  1935 saw the introduction of the Convention for the Regulation of Whaling – the first protection afforded to these critters but many – but not all – whaling nations (Japan and the then Soviet Union being the exceptions).  Protection was bolsters in 1949 with the International Convention for the Regulation of Whaling (IWC), which banned signatories from hunting them for commercial purposes.  In the US, they were listed under the Endangered Species Conservation Act in 1970, and the subsequent Endangered Species Act of 1973.  Canada, who is not a signatory of the IWC, has listed them under their Species At Risk Act (SARA) as Endangered.  Today it is estimated that there are somewhere between 300 – 400 individuals left, and whilst commercial whaling has ceased, they are still under threat primarily from ship strikes or entanglement in shipping gear.

To help tackle the ship strike threat, Seasonal Management Areas (SMAs) were introduced off the east coast of America in 2008.  The rules are fairly straight forward, limiting speeds to under 10 knots (18.5 km/hour) for commercial vessels larger than 65 feet (20 meters) long.  There are currently 10 SMAs, which become active seasonally to capture when right whales are actually in the area, and then deactivate when the whales should have moved off.  Alongside the SMAs, Dynamic Management Areas (DMAs) were also brought it.  These zones are implemented when aggregations of the whales are detected in areas outside the SMAs.  For 15 days after detection, mariners are asked to avoid DMAs.  If they do pass through, they are asked to voluntarily reduce their speeds.  So do these zones work to reduce ship strikes on the right whales – and indeed any other large whale population that may find itself inside these zones?  According to this latest study lead by Julie van der Hoop from Woods Hole Oceanographic Institution… sort of.

Julie and her fellow researchers obtained confirmed mortality data for a whole host of whale species – not just right whales – that were reported along the American east coast between 1990 and 2012, alongside cause of death (if identified).  They also obtained sighting data from North Atlantic Right Whale Consortium database from 1990 to 2008.  This, the team report, will help them assess the whales’ occurrence inside – and indeed outside – the SMAs.  Some statistical, spatial, and temporal analysis later, and the team were able to tell us a little more about the effectiveness of these SMAs.

First to the mortalities.  Between 1990 and 2012, 1,198 confirmed mortalities were reported along the US east coast.  Most of the whales species were identified too – good news for the researchers, but cause of death was only confirmed with certainty in 458 cases.  In line with other study findings, entanglement was the leading cause of death, followed by vessel strikes.

The sightings data indicated that just 17% of the right whale sightings between 1990 and 2008 were outside the areas that would become SMAs.  In other words, when the SMAs were implemented in 2008, they were located in areas where 83% of sighting had previously occurred.  Not bad – its tricky to capture every individual in a management zone when those individuals tend to move around a lot.  So what of the strikes themselves… are they reduced?  Well the good news is that over the years right whale ship-strikes have shown a decline… though not directly coincident with the introductions of the SMAs (the decline started from 2007, the zones were implemented in 2008).  The researchers also note that active SMAs only encompass 36% of historical right whale strikes.  32% of the historical strikes occurred when the SMAs were active, but not in the areas the SMAs covered.

So whats going on here?  Well the team believe that the decline is right-whale strikes is likely down to a combination of measures introduced earlier – like voluntary and mandatory routing changes in the Bay of Fundy.  They also suggest that the SMAs themselves may not be as effective as they could be because of low vessel compliance (estimated to be around 21 – 33% between 2009 & 2011).  They also suggest that there is insufficient monitoring to detect just how effective these management areas are…meaning the management strategy could never adapt to be ‘better’ because no one knew that there was a potential issue.  The last major issue the researchers highlight is the timing and location of the SMAs.  The SMAs cover critical habitat and calving areas for the right whales but they are missing in the ‘migratory corridor’ that run along the east coast.  It is in this corridor where whales are most often sighted, and it in this corridor where strikes were frequent outside the active SMAs.  In essence, the SMAs are “spatially insufficient in certain seasons”.

Because the researchers only included records of animals found dead (either at sea or on shore) and not those found with serious injuries that most likely lead to death, actual mortality could be underestimated…and likely is – not all dead whales end up on shore, or float on the surface until spotted.  Which brings up another point.  Where the dead whales were spotted is not necessarily where they died (especially on shore).  The researchers recognise this, but note that drift data dead whales that were struck by ships is limited, and that drift would differ with location, making it difficult to determine where the whales actually died.

The paper which was published in Conservation Letters , and has been made open access.  You can have a read of it here http://dx.doi.org/10.1111/conl.12105

 

Image: North Atlantic Right Whale.  Credit Florida Fish and Wildlife Conservation Commission/Flickr (CC BY-NC-ND 2.0)

With ever-warming waters, some European fish are on the move

We all have our favourite types of environment and weather.  Some love those warm, sunny days spent on a beach of golden sands.  Some love those rainy days in the forest, when everything glistens with the raindrops.  Some love nothing more than a cold crisp day in snowy mountains.  We humans are lucky.  We can not only survive but enjoy a wealth of different environmental conditions.  Many other species are not so adaptive.  In the oceans some creatures live in the seabed itself, others on top.  Some may stay in the water column dominated by a particular type of habitat like a kelp forest, whilst others roam into a variety of different locations throughout their lives.  Then there are the varying conditions of the ocean itself.  Some areas are generally calm whilst others may experience a lot of movement.  Salinity levels also vary, as does oxygen, as does temperature.  Actually temperature – as many a fisher will know – is a super important driver of species distribution.  There are a few reasons for this.  First, unlike us, most fish do not have the ability to control their own body temperature.  Their internal body temperature reflects that of the environment they are in.  The second primary reason relates to food.  If the major food of a fish – be it plant (phytoplankton) or animal – changes its abundance (how many) or its distribution (where it is), then the fish may follow. Continue reading With ever-warming waters, some European fish are on the move

Deep sea sediments gives insight into plutonium-244 origin

We can learn a lot about the history of our planet from ocean exploration.  As it turns out, we can also learn about processes beyond our solar system.  Supernova (star) explosions are large, violent processes.  Current theory suggest that supernovae distribute elements essential to life, such as potassium and iron, and heavy elements, such as the radioactive element plutonium-244, throughout space, with some eventually settling on the sea floor.  However, research recently published in Nature Communications suggests that recent heavy element production may not originate from standard supernovae.

Continue reading Deep sea sediments gives insight into plutonium-244 origin

"I don’t think that I can change the world, I just wanna punch it up a little" ~ Joss Whedon

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