Originally Posted by KiwiAussie
BRD's were not around when I was last fishing in NZ. My only understanding of them is that they're essentially a "string mesh filter" around the throat/mouth of the net in an attempt to keep from catching smaller fish, am I correct?
BRD:s have been arround for quite a long time now. The Nordmore grill, for example, has probably been arround for about 12 years.
Most BRDs rely on one of two methods of excluding bycatch. The first is mechanical or physical exclusion, achieved by blocking the passage of bycatch into the codend and guiding it towards an escape opening. This is the most common method of excluding large animals from prawn trawls. The second method utilises differences in behaviour between the bycatch and prawns. Fishes for example, are capable of swimming in a moving net, orientating to the direction of tow and swimming through an escape opening. Prawns on the other hand generally exhibit little directional swimming and are passively filtered into the codend.
Also, although most of the time you can reasonably target the correct species (while fishing), you can never get it right all the time. Eg: I've gone mid water trawling for hoki & yet bi-caught too much ling, & long lining a reef for blue eye & yet bi-caught too much grouper (while the line was sinking to the required depth). Yet I've gone back to the same WP another week & had very little bi-catch or caught bugger all fish at all (yet I've been at some anchorages & caught a lobster (on his 2 teeth) using only a colored lure (no bait)). With all the technology, history & science, fishing is still a game that involves an amount of luck.
This is very true but the likelihood of by-ctach differs from fishery to fishery. For example prawn trawling (without BRD:s) would give a higher by-catch than catch of target species. On the other hand, purse-seining or mid-water trawling for atlanto-scandic herring gives completely clean catches.
I think the decision Auzzee mentioned by the Northern Territory Government to support recreational fishing is the right one. Tourists will come in, they will spend nights in hotels, eat in restaurants, buy fishing gear and whist the anglers are doing their thing their families will be looking for other activities, all of which generates income. This is good but it can only work in coastal areas and in inland waters. The deep seas will still be the hunting ground for the big boys and the problems of over-fishing, by-catches, high-grading etc. will continue
But despite all the talk of dumping the basic problem is that of the over capacity of fishing fleets. For the resourse it makes no difference if we catch and eat the fish or dump it. It is the mortality rate that is important. To ensure a healthy stock all mortality beyond the maximum sustainable yield should be prohibited and enforced. It is not difficult. In fact the now deceased Peter Durham once gave the acronym MCS, Monitoring, Control and Surveillance (of marine capture fisheries) the new meaning of Mostly Common Sense. What is difficult, if not impossible, is getting politicians, big buisiness, boat owners, individual fishermen and the housewife buying the fish in the freezer store or at the market to take their responsibility.
Aye // Stephen