could potentially mean......less prawns per kilo of "discard"assuming standard natural mortality and limited effects of trawling given that juvenile bycatch species may not occur on trawl grounds). In theory a historical increase in bycatch catch rates (accounting for effort)could potentially mean that bycatch species are increasing in abundance???
juvenile bycatch = prawnsize
Kev,
so areas outside of their normal trawl grounds that may not usually get fished could have high level of bycatch species and hence when the effort shifts to these areas bycatch levels go up???? Could these unfished communities support the communities in the trawl grounds??
would a 40% reduction in effort lead to less bycatch???
Gazza,
not the ratio increase but an increase in bycatch kg per ha trawled. if you catch more bycatch for each hectare you trawl from one year to the next then couldnt that mean there is more there to be caught??
double-edge sword mate.....e.g. per kg. of 'target' prawns
less bycatch??....more efficient!!
more bycatch??....less prawns available (as a percentage)
jmo...reduction in mortality of "bycatch" ,is the real key
p.s. reduction in bycatch, brought aboard by waldo & co. is commendable , but "has to" happen...jmo
where did the bycatch photo come from??? looks like shallow ekp judging by the crabs, grinners and apogons in the shot done over a sandy bottom, off the sunny coast somewhere????
http://www2.dpi.qld.gov.au/far/12589.html
"The vast majority of these species have no commercial value and although they are returned to the water, many species die as a result of being trawled. The weight of the bycatch weight is generally several times (i.e. 5 to 10 times) that of the targeted catch of prawns and scallops"
hoppers deal with the mortality of bycatch but arent used in the east coast prawn fishery
The single largest component of bycatch reduction since introduction of the trawl plan has been reduction of effort.
If you want less bycatch reduce the effort.,,,,, Bring it on I say
The next most important thing is bycatch mortality, Legislate for universal use of hoppers on ALL trawlers AND the adoption of the MOST EFFECTIVE BRDs.
Rando
On a different tangent.
I have heard from an person who dives, that the trawl boundary in the bay is clearly defined on the seabed,
this is hear-say,but I am interested to know
can anyone confirm they have seen this, or is it an urban myth
oops double post
hey gazza great bycatch foto there. looks to me like about 2:1 by catch to catch[will include the crab as is pewrmitted species for trawlers] maybe 2.5:1 at the very outside. great to see others posting pictorial evedence to refute unfounded claims of 10;1 catch to bycatch.
Originally Posted by dinga1
Mate, if they don't usually get fished, I would assume (from what I have read) that it is likely because of high by-catch rates....that is, higher than the average. Too much like hard work sorting when you could perhaps be in better grounds that may give a lower catch but a higher return on effort and hence, profitability.
The recent fish kill on the Sunny illustrates this. That area wasn't usually fished due to the expected high by-catch (whiting) rates, but there was such a good run of prawns there, due to the wet, that some pros took the gamble with the results that we all have seen, and which has started the current controversy.
Yes, a 40% reduction in effort would lead to less by-catch in the fishery overall, but not neccessarily per fisher.
We mustn't lose sight of the fact that by-catch is not simply fish other than prawn, that is too small. It can be composed of monsters (although TED's are very efficient at excluding these) otherwise marketable fish that is prohibited to be landed, and,..........juveniles of the targetted species (prawn-too small for market).
The estuarine and bay trawl fishery is not only a pain to the rec fishers, but if the "offshore" pros stop to think about it, the estuarine and bay fishers also prevent the exodus of juvenile prawns (King, Tiger, Banana) to offshore which would otherwise later be caught in a better condition for marketing. The Bay fishery accounts in the main for greasyback with a few hardback and endeavour thrown in, (approx 70%) but estimates place the other 30% as King, Tiger and Banana which I would assume, and from what I have read, are not yet fully grown, but I would stand corrected on this if there is documentation proving otherwise.
The fishery (prawn) may appear to be sustainable, but as the fish that feed on prawn are not viably researched, there is (IMHO) a real danger that they will diminish in quantity due to food chain removals and by-catch trauma.
kev
It is not the lofty sails, but the unseen wind that moves the ship.
Waldo, the 10:1 claim is taken from DPI&F documents. That aside, I think 2:1 is still pretty appalling.
Here's another pic from the NSW fishery.......discards being shovelled overboard.......hoppers could avoid this.
kev
data is scant on bycatch species but that doesnt mean they are in danger of being overfished. Until i see some more work done on bycatch species (difficult due to high numbers, where to start) i am not willing to suggest that the species caught in the bycatch are unsustainable as i am not convinced that the area impacted by trawlers doesnt allow populations elsewhere to support the fishing mortality of populations of species in the trawl grounds.
the survival of non fish bycatch eg crustaceans, echinoderms, sea snakes etc would be pretty good i would imagine
Mate, my gripe is with the fishing of nursery grounds and small fisheries like the Pine and Logan that cannot be replenished by natural means via "return to spawn".
If we take the juveniles from the nurseries, then they don't mature to come back and begat more juveniles. If we have 3 trawlers, simultaneously working a small area such as the Pine (as they frequently do) then something has got to give.
As I said on my closing of the by-catch/trawling thread, I intended to remain impartial until such time as I had gathered enough data to reach a sound conclusion. This was getting more and more difficult due to one lot of data being based on previous data....based on previous data blah blah. The inital data from the previous years is highly suspect to say the least and current data seems to constantly refer back to previous (sus) data. Yes, more observers are now on the water and we are all becoming more conscious/aware of the issues that are of great concern, but that isn't good enough for me to sit on my bum and wait till some data with *real, sound*base is published.
Seeing is believing, and any fool who'd never looked at a piece of research in his bloody life wouldn't need a text book to convince him of the reality of the carnage that was the Pine the other day. Anyone who doubts as to the sustainability of small fisheries such as the Pine need only compare recreational catches from 10 yrs ago to todays or simply take a walk down to deepwater bend on any day that those "pros" are working............mate, it's bloody appalling.
kev
It is not the speaker who controls communication, but the listener.
kev ur pictures show a fish trawl and from nsw so really its hardly evidence of anything.
as to what prawn is caught in the bay u should be asking rather than telling. the bay produces beautiful big prawns of all species.
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