The Fish Vet's Blog

Q: What do our fishy friends say when they’re having an exciting and fun time?

A: We’re having a whale of a time!

I received this from the aquavetmed mailing list:

The American Fisheries Society’s Fish Health Section Executive Committee recently approved an online / open access format of the Blue Book, with intent to provide others access to information on the detection and diagnosis of aquatic animal diseases.

The primary purpose of the Blue Book is to provide standardized diagnostic laboratory assay protocols for aquatic animal diseases. Standardized procedures and protocols will allow more informed decisions when evaluating weather animals are free of important disease causing agents, that is important in intrastate, interstate or international movement of aquatic animals, certifying disease freedom in an aquaculture operation, and other important regulatory issues.

New or updated in the 2014 edition are parts of the diagnostic section (motile aeromonas septicemia, weissellosis, general procedures for electron microscopy, viral erythrocytic necrosis and Infection with hematodinium) and inspection section (myxobolus cerebralis, a virology position statement and a parasitology position statement).

To access the online version of the Blue Book, go to http://afs-fhs.org/bluebook/bluebook-index.php.

For questions or queries please contact one of the following member of the Blue Book technical standards committee:
Keven Snekvik, Chair (ksnek@vetmed.wsu.edu)
Nick Phelps (phelp083@umn.edu)
Maureen Purcell, (mpurcell@usgs.gov)

___________________________
AquaVetMed e-News provides information to veterinary and veterinary-allied subscribers concerning aquatic animal medicine, health, welfare, public health and seafood safety, obtained from a variety of sources (largely AquaVetMed subscribers). While provided by the American Veterinary Medical Association’s, Aquatic Veterinary Medicine Committee and are for public distribution, they do not necessarily reflect the opinion of the AVMA or the veterinary profession. See the AVMA Terms of Use (http://tinyurl.com/29h2rf) for further information.

Subscription and Contributions: Interested veterinarians and veterinary-allied professionals can subscribe, unsubscribe, or contribute pertinent news or information, by sending a message with “For AquaVetMed -” and the topic in the subject line, to dscarfe@avma.org. If e-News information is used elsewhere please acknowledge AquaVetMed as the source. Encourage individuals to subscribe rather than distribute through list serves.

Note: Undelivered e-mails will not be resent; Subscribers will be deleted from the list after repeated undelivered or bounced messages and will have to re-subscribe. Messages may contain attachments that will have been scanned for known viruses.

Visit our website: http://www.avma.org
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Following on from last week’s post, and just to recap, I was lucky enough to be invited to attend a seminar on ground breaking research into shark sensory perception and how they were developing and testing shark repellants. You’ll need to read the previous post to get a bit of background so we can understand how and why the following devices show promise.

 

Chemical repellants against sharks

Nathan spoke on the use of chemical repellants that would be detected by the olfactory system (sense of smell) of sharks. What they found was that sharks were repelled by the essense of dead shark, special slime produced by the sole fish and sea cucumber and also, some common household detergents. Good news? Yes, in a way. But testing showed that these were impractical because diffusion of the chemical stimuli is too slow, and in the field where there is water current, these smells would not stay put.

 

Accoustic shark deterrents

It is known that sharks can hear low frequency sounds and are attracted to them. Research showed that they do not like loud sounds. But with time, they become habituated to it (used to it) and so they will return. So, loud sounds don’t really work in the long term. They were planning on trialling whale sounds. Not the relaxation ones people use for meditation, but ones from the predatory killer whales (OK, before you kick me, I know they are not considered true whales). They did talk about the theory of neophobia (fear of new things). Here they tried electronic sounds like from the Star Wars’ R2D2 which seemed to repel sharks. What also seemed to work was songs from ACDC! Sharks are no fans of the heavy metal music (frankly, I don’t blame them).

 

Visual protection against sharks

Sharks are attracted to yellow and silver, and they tend to investigate objects sporting these colours. They have found that low contrast material work as camouflage. For divers, they trialled 3 different shades of blue with patterns to break up the silhouette and they found it worked. They also trialed novel, unpleasant visual stimuli like very bright flashing lights which seemed to work. There is also the theory of biomimicry, having contrasting black and white stripes to imitate venemous sea snakes.

 

Electric deterrent system

Some products are being marketed as “shark shields”. These are electric deterrent systems and they do appear to be effective. There is promise for it to be used to protect swimming areas, and as a personal-based device. But more research needs to be done to know what are their limitations. Does it matter what species of shark, shark size, will it work with multiple sharks and will sharks become habituated?

 

But the most simple, and most promising thing researchers have found is….

…. in my blog post next week 🙂

 

 

 

 

 

Check out the review here:
http://vetpracticemag.com.au/tools-trade-premiere-portable-rechargeable-monocular-microscope/

Q: what do you call a loud, coarse-mannered woman?

A: fishwife.

Then I wonder what you’d call a fish vet’s wife…

Last Thursday, I attended a very good lecture on this topic at the University of Western Australia. Each of 3 lecturers took it in turns to present their unique findings: Prof. Shaun Collin, Assoc. Prof. Nathan Hart and Dr Ryan Kempster, all from the School of Animal Biology.

So what have we learnt?

 

The presentation started with describing their findings of the shark senses. Being living animals, it is not surprising that they have the 5 senses: sight, hearing, smell, taste, touch. These will be explained below.

 

Sight

They have found that sharks are monochromats, having peaks in receptors for the green-yellow wavelengths (with a secondary low peak at purple). Practically, this means they are somewhat “colour-blind”. Characteristics of colour-blind animals is that they are very good at detecting contrasts. They’ve found the greatest density of receptors in their eyes lie in the posterior-ventral part of the retina and this means that their line of best site is diagonally above, and in front of them. However, their visual acuity is only moderate which means they have to get close to see more clearly.

 

Hearing

On sound, sharks do have ears. The opening to the ear is in the dorsal surface (top) of the head, a slight distance behind the eye. It detects vibrations and hydrodynamic sounds (e.g. waves, splashing, eating, bubbles). They have good directional hearing, meaning they can tell where sound is coming from. Of the 10 shark species studied, they’ve found they can hear low frequency sounds, in the range of 10-800 Hz (cf humans 20-20,000 Hz).

 

Smell

Sharks have nostrils and they point downwards. They have folded skin to increase the surface area, making them able to detect as little as 1 drop of blood in a olympic-size swimming pool. This said, the olfactory bulbs in the brain of different elasmobranchs differ in size, so we can’t quite make sweeping generalisations.

 

Taste

Sharks have no external taste buds. Their taste buds are located in the oropharynx, basihyal (tongue) and gill arches. The highest concentration of taste buds are behind their teeth. This explains why they need to bite, or to mouth at things, in order to taste it.

 

Touch

I think I was late in to the lecture, and might have missed this section, or maybe they didn’t cover it. But if you’re reading this, and you were there, please do elaborate in the comments section. Thank you.

 

So, sharks have all the 5 senses that we have. But they have a couple more! Firstly, like all fishes, they have a “lateral line system“. These are little pits along the length of the body, each pit contains hairy cells and the pits are connected to adjacent pits by a channel. The lateral line system detects water motion and low frequency sounds (20-200 Hz). It is used for detecting obstacles.

 

The second special sense they have is called the “ampullae of Lorenzini“. These a small pits around the area of their snout and within the pits is a gel-like substance that helps conduct electrical currents from the environment to the electroreceptors within. These are so sensitive that they can detect electrical currents as low as 1 billionth of a volt! They use this to detect prey since all fishes produce small electric fields. Thus, electrical stimuli actually attract sharks to check things out. The abundance of these ampullae vary between species. A Port Jackson shark has only 200 pits, making them less adept at locating electrical stimuli, whereas the hammerhead shark as as many as 3000 pits, making them finely tuned. The great white shark has 800 and the shovelnose ray has 1200.

 

So now we know about their 7 special senses, how do we use this knowledge to our advantage? How do we create safer beaches for swimming? How do we create personal protective devices for divers?

 

Stay tuned to find out in my post next week.

This is a common guilt-trip question every non-enthusiasts puts to us. My argument is that it’s one of the healthiest “static” hobbies around.

Anyway, I came across a FB post by Boronia Aquarium that led me to find this humorous article on how you can decrease your power consumption.

http://www.practicalfishkeeping.co.uk/mobile/content.php?sid=6508

Recently I gave a presentation at the koi club about the myriad reasons for koi developing skin ulcers. It’s an opportune time since they may get scrapes from the mating acts, damaged from shifting, predator attack, etc.

For uncomplicated ulcers, I’d like to point you to a video I uploaded on on how to treat fish ulcers.

See http://youtu.be/GHJtZRrx8IU