Redlands muddies

[justjack]

its my grandfathers birthday today so thought ide get him a feed of muddies went down to my local spot last night on the low tide and after an hours walking had enough for a good feed, i catch all my crabs by hand because i got sick of the share farmers and by hand i mean hand no other utensil, so far im up to 263 crabs this year in 09 dont worry people i dont keep them very often, i data record them for research and then they're released ;D

http://i248.photobucket.com/albums/gg164/bigjustjack/IMG_0486-1.jpg

http://i248.photobucket.com/albums/gg164/bigjustjack/IMG_0487.jpg

[sandbankmagnet]

wow! still got all your fingers?

[justjack]

ive been doing it for 7 years now and yes i do get bitten probably on average every 4 months, worste was a claw right through my left hand breaking 3 fingers and snapping 2 tendands, but mainly its just lacerations and bruises, depends on the size of the crab, i actually got a good bite right across the thumb last night but its feeling ok this morning, when im crabing to catch a feed i only get 5 then come home but when doing research i have caught up to 45 in a couple of hours and some are BIG crabs i should scan my data sheets and show you guys what i catch, i list where each crab was caught, time, date, size of carapace, weight, imperfections such as missing left claw and the weather and over the last 4 years of doing it im starting to find familiar paterns :)

[tropicrows]

You should put together a short video of you actually catching them by hand.

[Robsie]

That is really interesting. Out of interest, is teh weight in the months without an 'r' substantially different to those with?

How do you catch them?, Is it by sight in the water, or up in amongst the mangrove roots prodding around?


Cheers
Rob

[justjack]

yeah a short vid is in the process its just a little hard to find a camera man, i actually sneak up on them in the holes at night, they come out to the top of there holes to breath, they mix water which is in there gills with oxygen once the 2 are mixed they can extract the oxygen out of the water to breath see once a mud crab hole is exposed by the tide the available oxygen left in the water is used up so the crab has to make its own, ever seen a crab with foam coming from his gills or making a clicky noise? thats what is happening, actually alot of crabs are full right at the beggining of the season its just once a crab has returned from his migration his sights are not set on eating there actually set on finding a hole to moult in why you may not catch alot of crabs or ones that are empty is mainly because they've been swimming for 4 months straight get home and are to stuffed to eat of have already moulted they moult early not because they are full mainly because they rid themselves of ecsess weight like barnicle at which time alot do die because they dont have the strength once they've moulted they go on an eating spree to buff themselves up and wait for the females which are usually found in numbers after around a month of the males returning.

over my 4 years of research and over 10 years of interest ive found generally i will get 1-2 crabs a week in august around the 12th by the 20th i will be getting 20 a week, after this date for around a months the crabs come in quick and moult quick, though most the time crabs in holes are full unless they have just come out from a moult after they moult they leave there hole to find food, think of it this way if your feeling hungry and your stomach is empty you go looking for food, if your full and cant eat much more you sit at home in your chair crabs are the same, muddies need a whole once there full they will maintain it find a female (end january to end of march) mate (only when full) then kick her out maybe breed with 2-3 more females, moult feed up again for the journey and disapear, and they all leave within a 3 week period just after april except for the odd stragler, if anyone want to know anything about muddies i can almost tell you anything i spend more time out there with the crabs then anything well about 30 hours a week hahaha ;D

i also do keep them as pets i guess, all my crabs are caught as legal crabs or are aquacultured crabs from DPI research centre, i trial them on different food and water temperatures to find out growth rates and so on, i can tell you a crabs age diet just by looking at it, heres a pick of 1 of my guys,
- age 2y 9m
- weight 2.2kg
- size 23.3cm
- diet oysters and other shellfish hence his colour of purple due to high amounts of calcium and zinc

http://i248.photobucket.com/albums/gg164/bigjustjack/IMG_0171.jpg

[Blackened]

G'day

Jack, your knowledge is blowing me away, think we need to have a chat

Dave

[BrandonH]

Thats some great info Jack!! Myself and a lot of Ausfish guys I am sure really appreciate what you have been sharing!! If you have a camera and need someone to film you having some fingers crushed I will tag along one night ;) It will cost you a muddie though :p lol

cheers
Brandon...

[Fish_gutz]

thats some great info on the muddies there champ! now for some questions! 1.what is the average life span of the humble muddie?
2.is it true they have been seen way of shore in big floating schools or packs or whatever a group of crabs are called, excuse my ignorance?
3.do all muddies from say different locations like far north compared to SE Queensland have the same habits for example do the crabs in stanage bay follow the same sort of feeding breeding habits as the ones in Brissy?
thanks again for all your info as one can never know too much. Cheers Andrew

[Spaniard_King]

JJ, Thanks for the insight into your crabing endevors.

Do you ome across many crabs a second or third time?

[BAT]

Your inbox must be full of people trying to ride on your coat tails and pick your brain for info! I would be playing your cards close to your chest.

Cheer's BAT.

[justjack]

1. it takes on average 1.8 years to reach legal size 15cm though it can be as quick at 1.2 years water temp plays a big role the warmer the water the quicker they grow there are 3 sub species of mud crabs in AUS Scylla serrata our main species, Scylla olivacea, Scylla tranquebarica.

although they all have simular growth habbits most crabs these day are very lucky to reach 3 years old but i have seen crabs up to 4 years thats around 3.5kg

2. yes it true but still really unknown 99% of the time they are female crabs, females must travel out to see to release there young into the currents, can i ask has anyone ever seen a female with eggs? muddies have been recorded up to 200 nauticle miles out to sea, i beleive males have a different moving patern i think due to there size they couldnt handle such a long trip and they dont have to release eggs, some males dont go anywhere they fill there hole in behind them and go into a hybernatinon mode i beleive others head north find warmer current and burry themselves, i was diving of cape Moreton once and came across a patch of male muddies probably 200 strong crabs all burried in the same place the water temp there was 2 degree warmer then anywhere else i recorded, look at a females body shape to males, females have smaller claws and a big bouyent body designed for swimming, males are bulky and travel over the bottom if a male traveled any further then the depth of the water being 70m deep the pressure would kill them because there sub terestrial crabs.

3. same habbits yes but different time periods the closer you get to the equator the longer these periods are a crab wouldnt even migrate at the equator but the same process applies the females still migrate around the same times due to moon and tide phases to release there young, the males still moult around the same time to get ready for the female, when the females are migrating the males do things a little differnt depending on the individual, they eat when there full they moult this process happens alot quicker the closer you get to the equator because the water temp is warmer speeding up the matabalism and there for speeding growthrate, crabs are like homing pigeons they can feel the electronic feilds in the earth to navigate, alot of crabs do return to relatively the same area as they grew up.

anymore questions? hahaha

[justjack]

and yes i did once catch the same crab 3 concecutive years in a row wanna know the funny thing it was caught everytime within a 3km area each time and everytime in january hahaha

[Fish_gutz]

Cheers for that, i have plenty of questions but they were the main bug bears. all very interesting info thanks again Andrew.

[mudskipper]

that's an amazing amount of information Justjack , how far away are we from seeing any sizable commercial farming

[justjack]

well if i had the money the inforstructure and a few keen people its possible but not in my for see able future i dont think, ide like to see some of my research go to good use :P

[tropicrows]

Just amazing.

[needTHEnet]

if you but that effort in to your jack fishing you would be the jack king. it good to see you do release most of them a lot of people should take a leaf my your book. i wont have to blind fold you now when i take you to my hot spot. did you she the jack and flaty i got wednesday.

[snagking]

Mmmm Nice muddies there :)
Good work, I'd love to catch crabs with my hands, I just always seem to have a fishing rod in my hands.

[melony]

Jack
U are the malcom douglas of the muddie world, damn u have some awesome info there keep up the awesome work

Melony

[timddo]

Bugger , correct me if i'm wrong, i though it was illegal to catch crabs in their breeding holes,
Walking along the mangroves at high tide you will see the occasional one. Low tide will expose the holes. I' ve also seen people put crab pots high and dry next to the holes.

[crab man]

great work mate keep it up!!!!

[bermo82]

Hey Tim,

From my understanding it's illegal to use a hook or some other appartus to remove them from the there hole, termed "hooking" but if they come out of the hole then it's game on. Ive caught some great crabs by setting pots in front of holes where i can see a crab is working.

Cheers

Bermo

[justjack]

correct bermo, the reason hooking was banned is because it was killing under size males females and destroying the holes i love the muddy and there is alot more to them then people think using my hands doesnt affect them in anyway lol they usually effect my hands hahaha i laugh so hard when i see pots next to holes alot of the time you wont catch the crab, as i said the crabs in the hole because he isnt hungry but yes sometimes they like a snack

[justjack]

i saw a guy at the boat ramp today with over 50 crabs in his boat i called fisheries but he was gone before they got there, so i thought ide share some info out of my study journal.

my studies have shown that the transition of immature crabs to physiological maturity probably occurs between 90-110 mm carapace width at water temp 26c and higher In similar studies, 50% of crabs produced sperm at 92 mm when the water reached 28c, a male approaching a female in premolting condition climbs over her, clasps her with his chelipeds and the anterior pair of walking legs, and carries her around. They may remain so paired for 3 to 4 days until the female molts. The male then turns the female over for copulation, which usually lasts 7 to 12 hours. Although the spermatozoa of S. serrata are non-motile sperm can be retained by the female, and fertilization may not take place for many weeks or even months after spawnings. While most of the life cycle of S. serrata is spent in inshore waters, especially estuaries, the females migrate offshore with the fertilized eggs (up to about two million eggs at a time) attached to the pleopods, where they hatch in a few weeks. Under laboratory conditions, at temperatures between 18-24 °C, hatching of the eggs takes place over a 1-2 h period, any lower or higher crabs larvae dies,


a few facts people might not know

- 20 out of 2,000,000 crabs survive to just become crabs 2/20 become mature

- females can breed at any size they just need a male bigger then themselfs to copulate

- in SE QLD water temps sit around at the highest of 26 mud crabs mature here at 14cm

- females actually choose the male whom they wish to mate with

- 50% of all female crabs will not get to mate with males each year because limited amounts of mature males are available either because there to young, empty, missing limbs or not big enough, each year this becomes worse,

i particularly beleive and this is through evidence that muddies are over fished in areas leaving alot of females not being able to carry out spawning, see muddies arent like fish, fish spawn in mass schools each mixing sperm and egg mud crabs have a mating agender that could last 2 weeks i beleive to much impact is put on them at these times, the problem is also that females are resorting to breed with smaller and more unexperianced males then they would prefer, therefor creating weaker genes for the next population, weaker genes alows for atleast 50% more larva death is new offspring and a higher chance of disease and infertility,

anyone find this interesting or am i dribbling again?


its amazing your pig muddy are born smaller then a pin prick and are a food source for alot of fish especially mullet, funny hey;D
http://i248.photobucket.com/albums/gg164/bigjustjack/y2257e0g.jpg

[tunaticer]

In SEQ how often do mud crabs moult?

You say that male crabs can not handle depths of more than 70m, I believe that sand crabs however are regularly trawled up in excess of 100m.

Do sand crabs and mud crabs have similar seasonal migrations?

What would be a better bait for mudcrabs? oyster/mussel lumps that are partially crushed or fish baits?

[justjack]

mud crabs and sand crabs have completly different patterns, muddies are sub terestrial meaning they can live out of water and function sand crabs can't, muddies moult at the begining of the season purely to get ready for the females after the breeding season each crab will moult differently depending on there food intake and water temp, some crabs moult only once more or up to 6 times, they are oportunistic feeders, fresh fish is good depending on the smell it secretes, muscle and oysters are great and they love them but they dont secrete much smell

[Fish_gutz]

hey just jack , the info is great keep it coming! how easy is it to keep muddies at home in a tank? do they need to be tied up or can they keep the company of other bucks? do they need constant water changes? cheers Andrew

[coraltrout68]

Great information Jack.

Unbelievable game of Russian roulette that you play with animals that can do some serious damage to hands and fingers. Lucky crocs or sharks aren't your passion.

I must take some serious courage to place your hand somewhere, where you know its just a matter of time before you get bitten. I've have plenty of sand crab nips, but always treat muddies with respect and touchwood haven't yet been bitten.

Whats your method of getting the crab off your hand / finger?

Each time a crab moults how much bigger does he get? I.e. does a 13cm male become a 15cm legal crab in one moult or does it take a couple of moults?

Thanks

Shane

[Nowhere Bob]

Justjack, thanks for the excellant info.

RE: "I saw a guy at the boat ramp today with over 50 crabs in his boat.."
I hope you took a photo or at least noted & passed on the rego # on the boat. The more info you can give the Fishos the better action they can take.

Again - top work & thankyou.

[Blackened]

G'day

Jack, have a question for you.

In your knowledge, does a crab population of the same area all moult/gro at the same rate?

What I'm saying is, if you're finding a few legal crabs that aren't as full as they can be.... if that maybe a location thing or purely luck of the draw and time of the year?

Also, have you had much to do with a "mutated" species of sand crab, aka hermaphrodite, spongy shell?

Dave

[justjack]

Muddies in populations still grow at different rates it depends on how much each crab eats, the more each crab eats the more they moult, if your catching a lot of emty crabs its most likely because this is where crabs are searching for food, empty crabs are actually more likely to stay away from full crabs because an empty crab has no defence in defending himself against a full crab, so yes its location, it can be time of the year because as explained they do moult after migration and before breeding, and a lot of the time crabbing is luck but you increase your chances buy crabbing where full bucks can be found, I actually have a recipe I use when occasionally using pots its not a bait to attract hungry crabs its actually a recipe that recreates the scent of a female crab ready to mate, has anyone ever caught over 20 legal full bucks in the 1 pot? I have hahaha I don’t use it anymore because its not fair on the crabs, like leading lambs to the slaughter.

As for sand crab hermaphrodisation, is caused by a barnacle, Sacculina granifera the barnacle belongs to the group of parasitic barnacles known as the Rhizocephala, a bizarre group only recognisable as being barnacles by their cyprid larvae stage. As adults they have no hard external shell or limbs. The body is reduced to an interna of root-like absorptive filaments and the externa, a fleshy sac consisting of the reproductive structures. Sacculina granifera is an internal parasite of swimming crabs, characterised by a cream-brownish, oval externa. The mantle opening is slightly raised, small and placed almost opposite the stalk. The externa, reaching 2.5 cm in width, protudes from underneath the abdomen of the host.

The barnacle attach to male sand crabs and secrete a feminizing hormone that induces maternal behavior, The zombified crabs then migrate out to sea with brooding females and make depressions in the sand ideal for dispersing
Larvae, The males, naturally, won’t be releasing any, But the barnacles will, in male crabs the increased amount of female hormones makes the males body resemble more and more of a females after each moult though the males still have male reproducting parts, females are also affected just no noticeable changes occur, theoretically they aren’t hermaphrodites because they still only have there original sex organs rather then having both male and female, though when infected the crabs play no beneficial role to the species because they both male and female becomes sterile to only benefit the barnacle.

thats just the basics i hope that gives some insight, i probably havent had as much to do with sandies as muddies but i do follow alot of other species of crustaceans and fish closely ;D

[justjack]

here is a video of my big angry boy they make great pets, i first started keeping them because i was feeding empty crabs up for food though when they finally became ready i couldnt do it hahaha so they became a huge interest ;D

http://www.youtube.com/watch?v=weeUUqa_lvM

[Blackened]

G'day

Nice set of claws there jack,. any idea what the measure around?

Dave

[justjack]

22.7cm he's nearly ready to moult again aswell

[f.t.r.]

probably the most interesting thread i have read on here mate

well done on all the hard, sometimes painfull work.

hopefully all your info gets put to constructive use.

matty

[bayfisher]

Muddies in populations still grow at different rates it depends on how much each crab eats, the more each crab eats the more they moult, if your catching a lot of emty crabs its most likely because this is where crabs are searching for food, empty crabs are actually more likely to stay away from full crabs because an empty crab has no defence in defending himself against a full crab, so yes its location, it can be time of the year because as explained they do moult after migration and before breeding, and a lot of the time crabbing is luck but you increase your chances buy crabbing where full bucks can be found, I actually have a recipe I use when occasionally using pots its not a bait to attract hungry crabs its actually a recipe that recreates the scent of a female crab ready to mate, has anyone ever caught over 20 legal full bucks in the 1 pot? I have hahaha I don’t use it anymore because its not fair on the crabs, like leading lambs to the slaughter.

As for sand crab hermaphrodisation, is caused by a barnacle, Sacculina granifera the barnacle belongs to the group of parasitic barnacles known as the Rhizocephala, a bizarre group only recognisable as being barnacles by their cyprid larvae stage. As adults they have no hard external shell or limbs. The body is reduced to an interna of root-like absorptive filaments and the externa, a fleshy sac consisting of the reproductive structures. Sacculina granifera is an internal parasite of swimming crabs, characterised by a cream-brownish, oval externa. The mantle opening is slightly raised, small and placed almost opposite the stalk. The externa, reaching 2.5 cm in width, protudes from underneath the abdomen of the host.

The barnacle attach to male sand crabs and secrete a feminizing hormone that induces maternal behavior, The zombified crabs then migrate out to sea with brooding females and make depressions in the sand ideal for dispersing
Larvae, The males, naturally, won’t be releasing any, But the barnacles will, in male crabs the increased amount of female hormones makes the males body resemble more and more of a females after each moult though the males still have male reproducting parts, females are also affected just no noticeable changes occur, theoretically they aren’t hermaphrodites because they still only have there original sex organs rather then having both male and female, though when infected the crabs play no beneficial role to the species because they both male and female becomes sterile to only benefit the barnacle.

thats just the basics i hope that gives some insight, i probably havent had as much to do with sandies as muddies but i do follow alot of other species of crustaceans and fish closely ;D



You really should quote where you get your information from, and even then its Sacculina carcini not "Sacculina granifera" ::)

http://www.marlin.ac.uk/species/Sacculinacarcini.htm

[justjack]

actually bayfisher the species your refering to "Sacculina carcini" is in the same genus as Sacculina granifera and still has simular habbits though carcini is not found in Australian water, your link is based through UK research even though they have exactly the same body features and very simular developments to there life cycle the barnacles still have a couple of noticable diffrences, Sacculina granifera is actually the species found in Australian waters and is the primary species that effect sand crabs, heres a snippet out of the Ecological Assessment ot the Queensland Blue Swimmer Crab Pot Fishery Developed by DPI&F

The parasitic barnacle Sacculina granifera commonly infests blue swimmer crabs, and is visible as an egg sac beneath the tail flap of nearly 10% of mature blue swimmer crabs in Moreton Bay. Infestation rates vary between sexes, areas and seasons. The parasite destroys the infected crab’s reproductive organs, and results in a reversion of some of the male’s external sexual characteristics toward those of the female. Fishers are still required to return all female and undersized crabs infected with Sacculina granifera to the water although legal sized male crabs are either marketed or destroyed (severe infection affects the presentation of the crab making it unmarketable). The ecological effect of the parasite on the population is unknown but the problem is predominantly restricted to estuarine areas in Moreton Bay.

more info can be found at http://www.environment.gov.au/coasts/fisheries/qld/blue-swimmer-crab/pubs/blue-swimmer-crab-submission.pdf

[bayfisher]

The point i was trying to make is if your going to write something word for word off a website and only change Sacculina carcini to Sacculina granifera you really should quote where this information came from.

[justjack]

well actually i didnt get this info out of any web site i actually have all this text in an old uni lecture book from when i studied marine science, maybe thats where the lecturer found the information, plus the only info given text for text was just a discription of the barnicle and this discription is also found almost word for word on other sites so im not to know where it originated and i wouldnt want to mention that site anyway it would confuse people because its talking about another species other then the one im talking about , im sorry but i didnt no anything about this site :-/

[bayfisher]

That's fair enough, interesting information none the less.

Cheers Chris

[Horse]

i saw a guy at the boat ramp today with over 50 crabs in his boat i called fisheries but he was gone before they got there, so i thought ide share some info out of my study journal.

my studies have shown that the transition of immature crabs to physiological maturity probably occurs between 90-110 mm carapace width at water temp 26c and higher In similar studies, 50% of crabs produced sperm at 92 mm when the water reached 28c, a male approaching a female in premolting condition climbs over her, clasps her with his chelipeds and the anterior pair of walking legs, and carries her around. They may remain so paired for 3 to 4 days until the female molts. The male then turns the female over for copulation, which usually lasts 7 to 12 hours. Although the spermatozoa of S. serrata are non-motile sperm can be retained by the female, and fertilization may not take place for many weeks or even months after spawnings. While most of the life cycle of S. serrata is spent in inshore waters, especially estuaries, the females migrate offshore with the fertilized eggs (up to about two million eggs at a time) attached to the pleopods, where they hatch in a few weeks.

All good information there but you should have given recognition to the people who did the original research as did the original authors of the document you used:-/ . This gives credibility to the facts you are presenting

"Recent studies in northern Australia, have shown that the transition of immature crabs to physiological maturity probably occurs between 90-110 mm carapace width (CW) (Heasman et al. 1985; Knuckey, 1996). In similar studies, 50% of crabs produced sperm at 92 mm CW in South Africa (Robertson and Kruger 1994). During copulation, a male approaching a female in premolting condition climbs over her, clasps her with his chelipeds and the anterior pair of walking legs, and carries her around. They may remain so paired for 3 to 4 days until the female molts. The male then turns the female over for copulation, which usually lasts 7 to 12 hours. Although the spermatozoa of S. serrata are non-motile (Bhavanishankar and Subramoniam, 1997), sperm can be retained by the female, and fertilization may not take place for many weeks or even months after spawnings (Chen, 1976). While most of the life cycle of S. serrata is spent in inshore waters, especially estuaries, the females migrate offshore with the fertilized eggs (up to about two million eggs at a time) attached to the pleopods, where they hatch in a few weeks (Hill, 1974, 1994)."

By the way this info did not come from an old Uni text book;)

[justjack]

i apolagise ive had alot of this info on a word sheet since doing this study and didnt have a biliography on everything next time i think ill back research to find the site i found some original information on and post each book and site i ever found any of the info i post about in each post, my bad i spose it would be easier just to post a link to 1 site then post about the collective information ive found of other researchers and myself

[Horse]

I just thought it a bit strange that you had taken the time to remove the citations (not bibliography) when you cut and pasted the info. This system gives credibility to your info and credit to the people who did the research

It is all very interesting information and shows how complex the crabs lifecycle actually is. By the way how did you identify the same crab over a three year period?

Cheers

Neil

This

[Te Whiti]

Keep up the good work and time spent posting here Jack.

I am just one of many out there who is enjoying reading this thread and your other insightful posts...

Cheers

Mark

[Braddles]

would love to know your bait recipee that was too good to use for attracting the male mud crabs... (feel free to pvt if you have a weak moment lol) ... Blimey - I am lucky to get one male keeper these days for a w/end work... (although plenty of big females last time I went) :-(