FISHERIES scientists and regulation makers are really disdainful of anecdotal evidence. Try to convince them that the average size of a species has dropped over time or that the size of individual anglers’ catches has reduced and they’ll inevitably say “where’s your evidence?” If you reply with saying you’ve been observing and recording catches for 50 years the answer usually is “your memory or diary might be faulty” or “were your observations properly recorded and peer reviewed”, or “that’s only anecdotal evidence”.
So they might not be all that interested in the following information, as they ponder over whether or not to be brave enough to lift the minimum sizes of yellowtail kingfish and mulloway to levels to give every female fish a chance to spawn at least once, but here goes…
Over the last two years or so luderick numbers in NSW appear to have rebounded dramatically. Sydney Harbour, Botany Bay and southern rivers and estuaries are holding really big numbers of fish, but mainly in the 26-28cm size range. Results in spots that haven’t fished particularly well for years have been exceptional and around Sydney the action has been pretty well continuous, whenever the fickle weather has permitted fishing.
Now while there have been heaps of hungry fish, the increase is at a size smaller than “normal” in many places. Noted big fish spots still have some big fish, but on some days in a session’s fishing up to 75 per cent of the fish can be right on or just under the 27cm size limit, usually only by a centimetre or two.
How come? Well, here’s one theory. In July 2007, NSW Fisheries decided to lift the minimum size of luderick from 25 to 27cm as their rec licence fee funded research had shown that the average size at which a female luderick first spawns is 26cm. So lifting by just 2cm should increase the likelihood of all female fish spawning once dramatically. Compliance on releasing undersized luderick is reported (anecdotally) by the fisheries wallopers to be very high.
So far so good. About five years back the change came in. Five years later there are armies of luderick around 27cm happily taking baits. And how long does it take the average luderick to grow to 27cm, according to that Fisheries research? Five years.
Coincidence? I’d like to think not, but of course it can’t be proved. But if mulloway and kingfish minimum sizes went up to 75cm, to allow every female to breed at least once, would we be “pestered” in a few years time by outrageous numbers of these fish around their minimum sizes, as we currently are with the luderick? For my money, I reckon it would be well worth the gamble, you fisheries regulation makers.
John Newbery is Fishing World’s Environment Editor.
