UV light is given off by the sun, moon and stars, comprising about 60% of sunlight that cuts through the water’s surface.
While the red spectrum does not penetrate below 10m, yellow and green 15m and blue 20m and most visible light has gone by 50m, UV light can penetrate to 300m or more.
UV light is detected by many species of fish and many aquatic insects reflect UV light, which is why UV-tinted lures have landed trout, salmon, and other freshwater species.
UV lures have also proved to be effective attracting deepwater species off the United States. Now its proponents say it can work in shallow water and near the surface too.
New products include UV-coated lures, lures with UV eyes, spray-on, and paint-on UV coatings.
In Hawaii charter skippers have been trolling UV-coated lures to test their viability, comparing their catch rates to those using standard lures and dead bait.
There is a theory the “light-up” seen with marlin readying to attack and after being hooked may be seen by other fish as being amplified in UV. Commercial fishermen and anglers targeting broadbill have long used luminescent bait sticks to attract a bite in deep water. Does UV work better?
Determining scientifically how fish use UV vision when feeding isn’t easy. Time of day, weather, wind, and water clarity affect the availability of natural light in the water column, so how colours and patterns are perceived by fish close to the surface and by game fish depends on the conditions.
Marine biologists are discovering the ability to perceive light differs greatly between fish species and within the same species as fish age. Perhaps they reflect UV light to each other?
Luminescent glow sticks, which can be recharged, absorb and save light energy, then release it gradually. Bait sticks light up when bent as an inner divider is broken that separates two chemicals, which glow when mixed. Neither emits UV light.
Difference
“There is a big difference between luminescent light and UV and the ways in which they work,” Paul Senior, who develops fishing gear under the Oceanangler brand, said.
“The best way I can describe UV is that it’s working like the zinc you put on your nose to stop sunburn. It’s reflecting light but you can’t see that light.”
A UV light will show up pinks and greens on a non-UV lure but that’s luminescence. After testing with UV paint on Hauraki Gulf and in Northland and Coromandel to Bay of Plenty, using his lures against other anglers with more traditional models and bait, Senior is convinced UV adds something to the angler’s arsenal.
“I’ve been at Rangiputa (in the Far North on the east coast where water is clear) and out-fishing the other guys four to one. Then the sun comes out and that advantage is totally gone.”
That was in relatively shallow water but most of his testing has been targeting snapper in 50-60m, at the changeover area, where natural light disappears and UV becomes more effective.
“I’m convinced it works,” he said.
On the back of that he has designed UV-eyed jig heads that will take any soft bait.
They come in ¼, ½, and one-ounce weights and in blue and pink. Each is hand-finished with sandpaper and has a UV eye added, which is coated with a clear protectant. The UV paint is expensive so the jig heads cost more, about $14 for a packet of four.
The range is being expanded to include larger jig heads for deeper water, as well as a green UV range.
Overseas, anglers swear by the chartreuse colour as the number one lure for deepwater species.
“Hapuku and bass have huge eyes. They’re using UV hunting,” Senior said.
“I think we’ve got a way to go in learning how we can use UV effectively.”
New rules reasonable
The decision by Minister for Primary Industries Nathan Guy to increase the snapper size limit for recreational fishers to 30cm and decrease the daily bag limit from nine to seven fish in the SNA1 area from North Cape to East Cape is fair.
He’s recognised the rights of all New Zealanders over the commercial sector by saying the current quota split of 64% to industry and 36% to amateurs will eventually be levelled 50:50.
Commercial activity monitoring will increase markedly, with cameras or on-board observers on 25% of the snapper fleet by December and coverage of all ships by October next year. Commercial snapper boats will be required to move away from areas where a high proportion of juveniles are being caught and to report those catches so other boats can be warned off the area.
Next year Guy will introduce an upper size limit for long-liners so big fish will be released to keep breeding. None of the 820 jobs in the snapper fishery in Auckland and 360 in Waikato will be lost.
One thing missing is a plan to educate the recreational sector about releasing small fish undamaged to decrease their mortality rate.
Waiting on release results
Fisheries officers of the Eastern Region, which includes the Rotorua lakes, have been eagerly awaiting reports from anglers so they can measure the success of their revamped juvenile release programme.
In 2010 they conducted a survey on catch in the lakes and their tributaries that suggested there was a high mortality rate among the released fingerlings.
The practice then was for two large releases, one in April and the other in September.
It was thought both releases were too close to winter and the cold, floods, poor food availability, and predation by larger fish were affecting their survival rate.
So from 2011 spring releases were staggered across September, October, November, and early December and in autumn they went from late February to early May. Two-year-olds from the annual releases are the most frequently caught fish in lakes Rotorua, Tarawera, Rotoiti, and Okataina.
“This season we expect to see a range of sizes from 50-53cm,” Eastern Fish and Game officer Matt Osbourne said.
“But the main thing we’re curious about is the survival rate.”
All the released fish are fin-clipped and many are tagged and it is reports back from the fishing community that provide the information necessary to keep the fishery in good health.
This season’s two-year-olds have enjoyed a mild winter with plenty of food and Osbourne expected them to be in good condition and in the 1.7-2kg range. Early spring signals were good, he said.
“Lake Rotorua is performing well. The water is clearer than it was and we’ve had reports of plenty of smelt in the lake.
“The lower streams are fishing well (upper-stream fishing opened October 1). Fish coming through the Ngongotaha trap (on spawning runs) are averaging 2.5-3kg.”
Off Limits
Many rivers in both islands opened for fishing on October 1. The whitebait season closes November 1.
It’s been a bumper year for salmon and trout in the central South Island canals and also a bumper year for fisheries offences, with 56 anglers charged for breaches ranging from no licence to leaving offal on the banks. In the Fish and Game Central South Island region, which runs from Rakaia River south to Moeraki and across to the Southern Alps, 132 offences were recorded in the 11 months to August. Honorary fishery officers are needed in some areas in Southland. To find out more call Peter Meulenbroek on 03 211 0060.
Off home after this
A keen Aussie angler has been so looking forward to his annual week away fishing with his mates that he doesn’t object when his wife springs it on him that she and her mother are coming too.
They camp beside a billabong and he’s catching plenty of fish, so he’s happy, but one evening his wife rushes into the tent where the boys are drinking, upset and panicking that her mother is missing.
He finishes his beer, then walks off with his wife to look for his mother-in-law. Not far from the camp they hear her shouting and run to the water’s edge to find her backed up against a tree, with a large crocodile facing her.
“What are we going to do?” the wife cries.
“Nothing,” the husband said.
“The crocodile got himself into this mess, let him get himself out of it.”
