Category Archives: sea life

New shellfish reefs to be planted in Victorian bay

Mussel reef in Port Phillip Bay. Credit: Fishingworld.com.au

Mussel reef in Port Phillip Bay. Credit: Fishingworld.com.au

Dredging and bottom trawling of Port Phillip Bay in Victoria have destroyed most of the natural shellfish reefs in the 230 years since European settlement of Australia.

This new plan reported in the Age newspaper last week will help to restore shellfish reefs in the bay with the aim of increasing habitat for flathead, snapper and other commercially and recreationally valuable fish.

Shellfish reefs will be re-created on the bottom of Port Phillip Bay in a historic project that aims to improve marine habitats in Victoria’s largest bay.

Researchers say that if the reefs can be successfully established as expected, they would provide healthy habitats for shellfish like mussels and oysters. They would also provide habitat, shelter and food options for fish such as snapper, flathead, rockling and many other fish that live in the bay. They would also help improve water quality.

Shells from mussels, scallops and oysters that have been discarded by the seafood industry and restaurants could be sought as part of the project. They would eventually be placed in the bay at one of three locations, in order to form a base for the early stage of the shellfish reefs. Some artificial material could also be used.

But the project requires more than old shells. Millions of baby oysters and mussels, which will be bred at the Victorian Shellfish Hatchery at Queenscliff, will be used to colonise the reefs in the $270,000 pilot project. The baby oysters and mussels will attach themselves to shells at the hatchery, before they are placed in the water on top of the old shells.

The project, to commence this year, is expected to be formally announced on Saturday by Agriculture Minister Peter Walsh, the minister responsible for fisheries. It will be funded jointly, with $120,000 from the state’s Recreational Fishing Initiative, and $150,000 from The Nature Conservancy, an international organisation that undertakes conservation works around the world.

A patchwork of reefs will be restored at three locations, near Geelong, Chelsea and St Kilda, in about eight to 12 metres of water.

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Oceanic microplastics: the implications of tiny pollution

My classmate Dom Lawler deserves most of the credit for producing this video on microplastics, made in less than four days using iMovie for a university assignment on aquatic pollution.

Check the film out and watch some other related one on YouTube if it sparks your interest.

Here’s some quick details on the plastic pollution issue:

– 10% of the 280 million tonnes of plastic produced annually worldwide ends up in the ocean, contributing to 60−80% of all marine debris (Kaposi et al. 2014)

– First reports of plastic litter in the ocean were in the 1970s (Andrady 2011)

– Plastics could take centuries to completely mineralise or biodegrade (Moore 2008)

– 10% of all static fishing gear – including plastic nets, fishing line and ropes  – is lost worldwide (FAO 1991)

– In the environmental context, microplastics are regarded as pieces of plastic debris less than 5mm in size

– Studies have found that 267 species of marine organisms worldwide are known to have been affected by plastic debris, a number that will increase as smaller organisms are assessed. (Moore 2008)

 

References (and other useful video sources)

Plastic Oceans, broadcast on Catalyst, ABC TV1, 6 September 2012:

http://www.abc.net.au/catalyst/stories/3583576.htm

Plankton film clip: Ren Kyst, Norway www.facebook.com/RenKystFilm

Plastic planet: www.natracare.com/sisters http://youtu.be/73sGgmZoMBQ

FAO (Food and Agriculture Organization), Canada, 1991. In: Smith, A. (Ed.), Report of the Expert Consultation on the Marking of Fishing Gear, Victoria, British Columbia, Canada, 14–19 July, 1991.

Moore, CJ 2008, ‘Synthetic polymers in the marine environment: A rapidly increasing, long-term threat’, Environmental Research, vol. 108, no. 2, pp. 131-9.

Andrady, AL 2011, ‘Microplastics in the marine environment’, Marine Pollution Bulletin, vol. 62, no. 8, pp. 1596-605.

Kaposi, KL, Mos, B, Kelaher, BP & Dworjanyn, SA 2014, ‘Ingestion of microplastic has limited impact on a marine larva’, Environmental Science and Technology, vol. 48, no. 3, pp. 1638-45.

 

Merri Marine Sanctuary, a local protected area with some serious crays

Over the summer, I helped out on the Marine Summer Ranger program that Parks Victoria run across their land and marine parks. Locally, where in live in Warrnambool on the south west coast, the program involved rockpool rambles in the Merri Marine Sanctuary.
This is an area that, from anecdotal reports, was close to being overfished as the population of the town increased from the 1970s to 90s. One of my Deakin University lecturers shot the video above that shows the health of fish and crustacean stocks in the mainly shallow water protected area.
Sweep, magpie perch, salmon, wrasse and zebra fish can be regularly seen in the park, as well as some of the larger crayfish around this area. Commercial cray boats commonly target the borders of the marine park but it is good to see some larger specimens in this video still hiding under ledges throughout the park.
The New South Wales government is trying to wind back protection of some of the most important marine parks in their state, upsetting conservationists and local people who can see the value of large no-fishing zones. Fishing trawler captains may welcome the reduction of marine parks but as usual it will be a short-term win for them versus the possible longer term goal of allowing fish stocks to recover.

Why sea cucumbers aren’t just another ‘delicacy’ for Asian buffets

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Prickly redfish, a type of sea cucumber. This one was near Opal Reef, part of the Great Barrier Reef an hour from Port Douglas.

io9 is generally a scifi website, full of short monologues on the current state of scifi cinema, but occasionally they run very good articles on real science. Like the one below on the issues with sea cucumber harvesting:

Sea cucumbers are in trouble. Everyone knows about the problems that elephants and rhinos face due to poaching, that dolphins face due to drive hunts, and that sharks face when overzealous governments try to convince their constituents that they’re helping them avoid shark attacks. Sea cucumbers may not be as charismatic as their megafaunal counterparts, but they actually provide an important service for reef ecosystems.

They help to keep the sand in reef lagoons and seagrass beds fresh by turning them over, and by feeding on the dead organic matter that’s mixed in with the sand, the nutrients they excrete can re-enter the biological web by algae and coral. Without the sea cucumbers, that sort of nutrient recycling could not occur. It’s also thought that sea cucumbers help to protect reefs from damage due to ocean acidification. Feeding on reef sand appears to increase the alkalinity of the surrounding seawater.

The problem, according to a study conducted by Steven Purcell and Beth Polidoro, is that sea cucumbers are considered a luxury snack. As they explain at The Conversation, dried-out versions of the tropical species retail between $10 and $600 per kilogram in Hong Kong and on mainland China.

There’s actually one species that is sold for $3000 per kilo, dried. Sea cucumbers are thought of as “culinary delicacies,” and often adorn the buffets of festival meals and are served at formal dinners.
There are 377 known species of sea cucumber. Percill and Polidoro’s study shows that the more prized a species is as a delicacy, the more likely the IUCN is to categorize it as vulnerable or threatened – at least for the species they investigated. It’s plain to see that the more expensive the critters are, the more likely they are to be plotted with orange or red dots.

It’s not just a correlation. In most cases, it’s the rarity of a species that drives up the value, leading to exploitation and eventually, extinction. It’s basic supply/demand economics. But the researchers say that for the sea cucumbers they looked at, the causal relationship is reversed. “High-value drives rarity in sea cucumbers, not vice versa,” they write. “None of the naturally rare species are particularly high value.”

Is there anything that can be done to protect these awkward, squishy creatures? “Species-specific bans have been placed on threatened sea cucumbers in a few instances,” the researchers note, “but these regulations do not prevent serial depletion of other species further down the value chain.” Instead, they recommend that a short list of allowable species be created, sort of like Monterey Bay Aquarium’s sustainable seafood card, but for cucumbers. It would exclude threatened species and those most critical for providing ecosystem services to reefs. If sea cucumber fishing can be controlled, the rarer species just might have a fighting chance to survive.

Seadragon, sunset and seascape

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Reef sharks and aggressive triggerfish: diving on Fiji’s Coral Coast

I’m still sorting through about 200 short videos from my Fiji trip so put together a clip of some highlights from the first week. I could make a Finding Nemo sequel with all the anemonefish footage (though they weren’t the clownfish variety but still very cute). Yes, not all fish in anemones are clownfish – try telling that to kids who grew up watching Nemo and expect to see talking orange and white-striped fish under every rock 🙂

And the fishing shot at the end is from a morning trip with a local villager, who charged tourists FJ$50 to help catch fish for his village. Well worth the (minor) expense and my first chance to see reef sharks up close, though my videos were mainly blurry.

Seal pup all grown up!

20131220-162409.jpgSpotted this seal and his mates a few months ago hanging around the marine sanctuary. It wasn’t long before one of them worked out that begging for fish in front of the pier is an easier way to get snapper carcasses and other tasty leftovers!
Seals in this area don’t have too much to worry about: the larger colony at Lady Julia Percy Island has to contend with a variety of sharks including makos and threshers and the occasional opportunistic orca.

A mild recovery: bluefin tuna stocks may be on the rise

After decades of falling stocks of northern (NBT) and southern bluefin tuna (SBT) in fisheries globally, some possible good news: stocks in certain areas appear to be on the rise, according to this Oceana report on a recent ICCAT Standing Committee on Research and Statistics meeting.

I feel like I should automatically qualify that by skipping to the third paragraph of Oceana’s post, which stated:

Scientists say that the models  (SCRS is) using are flawed and therefore have little confidence in them, so they will spend 2014 working with more recent data and improving their calculations.

Which makes me think of this piece of gold from 30 Rock:

Just like They Might Be Giants’ Dr Worm, Dr Leo Spaceman is not a ‘real’ doctor but he comes up with some very apt quotes that show how people can trust an academic or medical professional just because they “know science”.

Anyway, some fisheries managers and tuna fishers will be pretty excited about the possible stock rebound but hopefully they’ll err on the side of caution before making any changes to quotas. Here’s some research I put together for a uni report that might shed some light on the Antipodean situation:

“Australia’s SBT catch peaked at 21,500 tonnes in 1982 (Farley, J. H. et al. 2007) and quotas established in 1989 restricted the catch to 5265 tonnes annually.

Japanese long-lining catch peaked at 78,000 tonnes in 1961 and quotas were also introduced to restrict Japan to 6065 tonnes annually.

Illegal, unreported and unregulated fishing for the species is also a major concern with the Commission for the Conservation of Southern Bluefin Tuna finding that ‘substantial and continuous unreported catches of SBT had been taken by longline vessels since at least the early 1990s’ (Polacheck 2012).”

That’s just the Australian and Japanese reported data for SBT – areas of the New Zealand and South African coast are also key fishing grounds, as well as the international waters where self-reporting of catches is still a woefully inadequate system.

In my opinion, we need tougher quotas, not leniency for these ocean hunters.

1. Farley, JH, Davis, TLO, Gunn, JS, Clear, NP & Preece, AL 2007, ‘Demographic patterns of southern bluefin tuna, Thunnus maccoyii, as inferred from direct age data’, Fisheries Research, vol. 83, no. 2-3, pp. 151-61.

2. Polacheck, T 2012, ‘Assessment of IUU fishing for Southern Bluefin Tuna’, Marine Policy, vol. 36, no. 5, pp. 1150-65.

Scales tell the story of a farmed rainbow trout

Scales tell the story of a farmed rainbow trout

There are common grumbles during my Marine Biology degree (sometimes from my direction, often from others) that there’s not enough practical work and too much theory.
While both are necessary, the most visually interesting is obviously those good prac classes that people go away raving about, such as yesterday’s look at methods of ageing farmed (and somewhat sickly-looking) rainbow trout.
This  photo is taken from a scale reader – showing scales from below the lateral line on a 1+ year old trout, with growth lines (annuli) helping indicate the age.
The trick is picking scales from the fish that haven’t regenerated and so have been on the fish for its lifetime – not an easy task on a small fish brought up in a farmed environment!
My ancient phone doesn’t take the best shots (I drowned my smartphone on another field prac earlier this year and reverted to the old Nokia) but you can still make out the circular lines on the larger right portion of the scales.
The lecturer also showed us how to remove the otolith (ear stones) from the fish to assist with age identification by measuring the growth rings, and also measuring the teeth and intestine to determine feeding category (such as herbivore, omnivore, predator).
I’m in the middle of writing an essay on the age, diet and reproductive capacity of southern bluefin tuna (thunnus maccoyii), so practical work such as this helps to give an appreciation of the work that goes into academic research on those topics.

Blue shark attacked by Jaws! Ok, not Jaws but still…

Another one from the “Overhyped Shark Attack” Files, this one is a little more unusual than the common ‘Jaws bites man/woman/pet pitbull’ stories.

Bastion of truth and journalistic excellence*, UK’s Daily Mirror had this report on a blue shark caught by fishermen off Cornwall with reasonably small bite marks sustained by a “10 foot” shark of some description…

Supposed experts are said to be looking into the attack, which happened when one of the fishos hooked a 60lb blue shark and then watched a larger shark – thought to be a great white – takes bites out of the blue before they could pull their catch onboard.

The reporter makes the surprising mention that “Although it usually eats other sea creatures, it attacks between five and 10 humans a year around the world and has killed 29 since 1990.”

Many gossip rags don’t usually admit that white sharks are ravenous for human flesh, so this is a big admission for a tabloid.

More from the fisherman who snagged it:

“The blue shark looked like someone had taken a machete to it.

“There’s nothing round here that can do that sort of damage. I sent the ­pictures to a shark expert and he ­believes it could well be a great white.”

Well, that’s sorted then: if an ‘expert’ says so, great white it is! But probably not. Great whites can roam vast distances and aspects such as climate change-affected ocean currents or shortage of food (i.e. seals, not people) may have encouraged one closer to the UK southern coast.

Without more confirmed sightings and review by real experts, we’ll have to wave this off as a poorly-identified mako attacking a small bluey and leave it at that.

 

Photo: Mirror.co.uk

Photo: Mirror.co.uk

*For those not aware of sarcasm, this is a relatively straightforward example. The Mirror sits slightly above other UK papers The Sun and the defunct News of the World for integrity and believability.

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