Interesting topic (aside) from the main thylacine topic...that is and I am somewhat reluctant to derail the thread.
One contract job I had as a fisheries consultant was a project funded by FRDC (Fisheries Research & Development Corporation) and it went on for some 6 months.... and involved the cray industry.
Back at the time the WA Cray Industry exported some $600 Million a year, in Live Lobster exports. At that time - we had a ban on the Canadians exporting Canadian Salmon into Australia for disease reasons.
We have a thriving Canadian Salmon Farming Industry down in Tasmania, and wanted to prevent a dreaded northern hemisphere disease called whirling disease from entering Australia's trout and salmon farming industry.
Whirling Disease has no known cure and causes spinal deformation in fry - such that the resultant fish can only ever swim in tight circles due to a bent spine. It's insidious in that it can persist in the dry dust of a dry river bed for 20 or more years and the first sign of water the disease is instantly active again - i.e. once you have it you can never eradicate it.
It's spread thru the infected cartilage and bone of infected fish.
The Canadians claimed that because they exported fillets (supposedly boneless, but we all know you never get all the rib cage bones out when you fillet a fish) that there was zero chance of whirling disease getting introduced into Australian waterways from an imported Canadian Salmon fillet.
They claimed we were using disease quarantine laws as a defacto trade tariff barrier to protect our Tasmanian Canadian salmon farmers from legitimate competition.
So they took us (Australia) to the world trade court.
They knew that the Lobster industry in WA alone imports 100,000 tonnes a year of raw frozen north sea herring worth $20 million a year, that gets put raw into the ocean every year as cray bait, in order to obtain our annual $600 million a year in lobster exports.
They were going to push the world trade court to thus ban the importation of all raw north sea herring into Australia on disease protocols rationale, as well as ban all live fish aquarium industry imports etc.
Thus the Fed govt thru FRDC wanted me to find out if I could come up with an artificial lobster bait from local products that could replace north sea herring if the Canuks indeed took us to the world trade court and won...(which they eventually did - and we now allow imports of Canadian Salmon go figure).
It had to cost no more than normal bait costs (~$1.20 a kilo) and catch crays as well or better than the current north sea herring bait.
If it could be made to not need refrigeration so much the better (coz thats a large cost saving for the cray industry).
So went the project to find an artificial cray bait...
You don't wanna know what things I put into cray pots as potential baits.
Principally I stuck with chicken processing waste from Inghams (heads, beaks, legs etc) - the stuff you now all buy as chicken nuggets - what - no one told you that? ;D
Anyway - in some cases the artificial baits out caught the traditional fish bait by up to 200%...BUT there were problems in that it wasn't consistent across ALL the cray fishing zone - as you went north and the water temp increased the effectiveness of the baits diminished in relation to normal fish bait (about 80% was the worst result).
So...
Fed Govt caved to the Canadians and now we get Canadian Salmon imported to Australia and we are allowed to keep shoveling thousands of tonnes of raw north sea herring into our oceans in order to keep catching crayfish for export despite all the pilchard mass mortality events etc.
Tis all about the $ at the end of the day!
Dead cats is a great bait!
If you could develop something to keep the occy out of the cray pots (maybe put the skin of a moray eel - the octopus mortal enemy) thru a mass spec and analyze the chemical compounds and synthesize a repellent tablet or something, you could end up a wealthy man.
Occys are definitely the scourge of the cray industry.
Some of the research was tank testing various baits, (shark livers, abalone gut and blue mussels were favorite additives that REALLY upped the performance of the chicken waste) to assess the response times of captive crays....
One university prof was contracted to do a likewise similar research as a "control" against my efforts.
This guy completely misread his project outline..
The idea was to catch crays.... i.e lure them into a pot and hold them there..
This guys "research" was entirely based around the crays energy requirements for healthy growth and he created an orange cookie made from grain protein (probably lupin based at around 26% crude protein) that was baked hard inside an oven.
During the trials testing phase at sea 0 his orange biscuits were tried every day for 2 weeks in hundreds of pots while my chicken waste baits were also trialed and the control was normal fish baits.
My average for most of the trial was 120% - best was 200% of raw fish and worst ~86% in the warmer waters out around WA's Houtman Abrolhos Islands.
The Uni Orange cookie had the distinction of not catching a single cray for the entire 2 weeks of the trial in any of the pots except for the very LASt day of the trial one pot had one cray in it and it turned out that was only because the pot landed on a fish and killed it and trapped it below the pot so the cray went into the pot to get at the dead fish but was counted as a positive result for the ubiquitous cookie!
What makes the perfect aquaculture diet for a crayfish won't necessarily attract them into a pot or keep them there was the lesson.
Again sorry for derailing the original topic...
It was an interesting time in my life... working in the cray industry.
One of the key things that came OUT of the research?
There's a direct relationship between the catch and the VOLUME of bait used - quite simply more bait = more lobsters caught (not necessarily legal size to keep mind you).
The interesting thing was - that bait at $1.20 a kilo is the cheapest input cost for the cray skipper compared to fuel, wages, & license + boat capital cost etc.
Input costs are around $14.50 a kilo of which bait is only $1.20 a kilo.
Yet - when the catch starts to diminish - what do most skippers do?
Yes cut back their bait useage...to save money!
Its a kind of self fulfilling prophecy thing, catch reduces they reduce bait thus the catch reduces and they reduce bait etc.
When you think that the landed shore price of the catch can be between 25 and 40 a kilo - it would make more sense to maximize the bait to make expenditure on fuel and everything else more equitable.
There were other industry considerations at the time tho... that prevented skippers increasing their catch via increased bait use age (principally that the managing authority, Fisheries WA monitor the catch and if stats went up by 10% they would just reduce the number of traps allowed to be set by 10% - and the capital value of the business at the bank was based on the number of pots on the license and the value per pot to sell...
So catching more crays and being more profitable could work against the skippers in terms of the capital value of their license and pots and boat against which they borrow to build new bigger faster more efficient boats!
Another interesting thing that came out of it was the practice of handing bait - the industry practice was to empty the previous days old bait over the side and replace with new bait each day..
The problem is that this bait then :fouls: the very ground where they will re set their next string of pots. I.e some of the crays that would otherwise have gone into their pots, instead went off in search of small bits of discarded bait that drifts down and gets caught among the corals etc on the bottom - yesterdays discarded bat luring a %age of the catch away from the freshly re baited re set pots.
In one example I altered the process to store all discarded bait in tubs on deck for the week and dispose of it on the rip back to port away from the fishing area and the catch immediately went up 10%
So with the right artificial bait or by simply not tapering bait usage thru the season, combined with not fouling their own fishing grounds with discarded bait - I could easily increase the catch of each boat in the industry (600 at the time) by easily 20 or more %
20% of annual $600 Million in exports?
I wouldn't mind some of that!
But Fisheries would just cut their pot numbers by 20% when they saw the increased catch figures and each business making a million a year would lose 200k in capital value..
Its whats called the old catch 22 situation.
Catching crays is something I do know more than a little about!
Cheers!