1 Fish, 2 Fish, 3 Fish, No Fish

If you're a fan of seafood like me, I'm sure that you are aware by now that there seems to be a push in Australia to buy wild-caught marine produce, rather than what is farmed or less popular, or "less palatable". The most obvious aspect of purchasing wild-caught fish is the price; farmed and more sustainable produce are by far the cheapest sources of seafood, however, people are actually preferring the more expensive, less sustainable options. This might have something to do with providers flying a banner of "FRESH!" over all the overfished keystone species, a marketing scheme to encourage sales of more expensive seafood that I'll admit I am often tempted by. I mean, sure, if the other stuff is NOT fresh I will pay more for the fresh product out of fear of food poisoning.

Bluefin tuna: "FRESH!"

Why is farmed seafood considered less fresh? Of course, it is against food handling and safety regulations for suppliers of seafood to provide any potentially old or poorly fish for human consumption. Quite often I hear of the public misconception of farmers raising stressed animals, over-using antibiotics, and rearing animals in cramped conditions in fouled water. Having studied aquaculture and biotechnology in Australia, this is definitely not the case. Farmers are very concerned for the well-being of their livestock, and will go to great financial lengths to fund researchers to find the best ways to keep fish calm and happy even during the harvesting process. The belief that farmed produce is less fresh is a a fallacy; there is no difference between flesh quality of wild-caught and farmed seafood, if any, it is the wild-caught seafood that is of lesser quality. And this leads to the next question, why is it that farmed produce is always cheaper? The real reasons farmed seafood in Australia is so cheap is because it is struggling to compete with public misconceptions and the prices set by fisheries that catch their product from the wild.

There are also a myriad other reasons why wild-caught stock are relatively expensive. Feel free to post any questions below, but essentially I want to make the point that there is no reason why people shouldn't buy farmed seafood unless they are concerned about water pollution or the sustainability of fishmeal used to feed aquatic livestock. There are, of course, seafood that is not farmed and can only be wild-caught. In this instance, I recommend that before you buy seafood from anywhere it is worth asking a a few questions about it. You could ask when buying seafood "Is this species overfished?" to assess how vulnerable the desired product is in the wild, "Where was this animal caught?" as local produce does not always mean that it is not vulnerable, and "Is it a deep sea or a long-lived species?" to see if it may be a species that is potentially vulnerable to fishing (long-lived and/or deep sea species tend to reproduce slowly, so overfishing of sexually mature adults could lead to major drops in population size).

Orange roughy is a deep sea, long lived fish. They don't become sexually mature until they are between 30-50 yrs old!

There is also a free iPod app called Australia's Sustainable Seafood Guide compiled by the Australian Marine Conservation Society. For more information on what is sustainable, a good place to first check out is GoodFishBadFish.

Images:
Bluefin tuna image accessed 18.10.2011, URL: http://thewe.cc/thewei/_/images10/valued_life/bluefin-tuna_greenpeace.jpe
Orange roughy image accessed 19.10.2011, URL: http://australianmuseum.net.au/Uploads/Images/3298/255%20Hoplost%20atlanticus%20S07_.jpg

Dance your PhD!

When asked about what my PhD is about, I'm not really sure where to begin. Should I start providing background information about the field so that when I start garbling jargon they'll understand? No, that takes too long and I honestly couldn't be bothered. Lately, when non-scientists ask I just say I look at metabolism in lizards and frogs. It's not the whole story but it is a whole lot more easier to say than "oh, just the evolution of metabolic rate in lepidosaurs and amphibians", to which I am always asked, "what are metabolic rates?"

Recently, I came across a competition that calls for scientists doing their PhDs to turn their thesis into an interpretive dance. First thoughts? How much easier will it be to refer people to this dance than bothering to explain in words! As such, I have entered the competition with my interpretive dance of what I think is my PhD...

Why does the willie wagtail wag its tail?

A small, black-and-white and charismatic bird, the Australian willie wagtail was named as such because of its famous (and seemingly compulsive) side-to-side tail-wagging. The reasons why the willie wagtail wags its tail are not defined: guesswork and a lot of observations have suggested that it may be an exaggerated form of counterbalancing the weight of the upper and front of the body as the bird darts about, otherwise ecological reasoning suggests it may be either a form of signalling of vigilance to predators or a method for flushing out insects from the grass while foraging (which forms a habit that the bird can't control while it's not foraging, like people picking their nose and eating it). However, a direct relationship between tail-wagging and any of the current ecological theories has not been properly examined to date.

Willie wagtail Rhipidura leucophrys strikes a pose for photographer Jeremy Ringma.

Despite its common name, the willie wagtail is not a true wagtail of the genus Motacilla, it is a member of the fantail genus Rhipidura which is closely related to crows and ravens. Australia has a few other species of fantails, however, the willie wagtail stands out in the crowd as being unusually taller and upright in its stance, and its foraging technique and preferred habitat are completely different.

One big happy family 

Other, 'typical' Australian fantails are arboreal in habit, preferring woody habitats. Generally, foraging in fantails is performed by fully fanning the tail, sweeping it vertically and flashing side to side, and the tail is also used as an aid in maneuverability while performing incredible mid-air acrobatics chasing insects. The willie wagtail is more terrestrial in habit, preferring open grasslands and hopping about in the grass. Foraging behaviour in willie wagtails rarely involves full tail-fanning, and wing-flashing has replaced the vertical sweeping of the tail seen in other fantails. The terrestrial habits of the willie wagtail are also evidenced in osteological adaptations; its leg bones are longer and its pelvis longer and narrower to facilitate hopping and horizontal tail-wagging.

Willie wagtails (left) have a more upright stance and longer legs than typical fantails like the rufus fantail (right).

Although related to fantails in Australia, the closest relatives of the willie wagtail are found in South East Asian species R. javanica, R. aureola and R. albicollis, which also forage on or close to the ground and engage in similar wagging behaviour to willie wagtails, however none prefer more open grasslands to forage. This suggests that something evolutionarily interesting is going on: that firstly, the wagging habits of the willie wagtail is most likely inherited from a common ancestor with its South East Asian relatives rather than that of other Australian fantails, and secondly, that the osteological adaptations and open habitat preferences of willie wagtails suggests that they evolved in Australia in a refuge area with a more open habitat.

...and more kangaroos offering free rides

Speciation and adaptation of avifauna to a terrestrial lifestyle is not a new concept in Australia. Many species of parrots and pigeons show a pattern of peripheral isolation and speciation, and given the dry and open nature of a great proportion of Australia, many refuge areas are very likely to have lacked adequate forest conditions that gave rise to terrestrially-adapted species found in otherwise arboreal taxa, such as the terrestrially-adapted ground cuckoo-shrike Coracina maxima.

For Australian avifauna, terrestrial adaptations are common. Ground cuckoo-shrike (left) and arboreal cuckoo-shrike (right).

So why does the willie wagtail wag its tail? To cut a long story short, when willie wagtails are not foraging its an evolutionary quirk, otherwise it seems the most logical solution to foraging on the ground given its evolutionary history.

Literature:

Harrison, C.J.O. (1976). Some aspects of adaptation and evolution in Australian fantailed flycatchers. Emu 76:115-119

Jackson, J. and Elgar, M.A. (1993). The foraging behaviour of the willie wagtail Rhipidura leucophrys: why does it wag its tail? Emu 93:284-286

Nyari, A.S., Benz, B.W., Jonsson, K.A., Fjeldsa, J., Moyle, R.G. (2009). Phylogenetic relationships of fantails (Aves: Rhipiduridae). Zoologica Scripta 38:553-561