Marine scientists at the ready for Port Stephens Interclub

STUDIES: Researchers examine a marlin at a past Interclub event. Pictures: DR JULIAN PEPPERELL.

STUDIES: Researchers examine a marlin at a past Interclub event. Pictures: DR JULIAN PEPPERELL.

It's not just fishos whose pulses race when the NSW Game Fishing Association's State Championships, known as Interclub, approaches.

Marine biologist Dr Julian Pepperell said Interclub would once again offer a very valuable opportunity for the scientific community.

"Scientists take advantage of any fish that are weighed in during the competition, keeping in mind that about 95 per cent of fish are tagged and released," he said.

"It is very valuable from a scientific perspective."

The scientific program, which operates through the Department of Primary Industries, is funded by the recreational fishing fees paid by anglers.

Every year each fish that is weighed in is weighed and measured, and their sex determined, by marine science students. Samples of muscle are taken and stored.

The frozen muscle samples have formed a tissue bank which is made available to researchers from all over the world.

"We now have more than 1000 specimens of muscle samples taken from different species," Dr Pepperell said.

A lot of information has been garnered from these samples over the years, from comparing DNA to see how closely groups of fish across the globe are related, to judging the makeup of a species' diet by looking at the chemical signatures left in the muscle.

"This sampling at the Interclub has been going for a really long time. I've been doing it since 1977," Dr Pepperell said.

As a result, the muscle samples, as well as data collected on numbers, weight and sex, allow for comparisons to be made in fish populations over time.

Dr Pepperell said, among the shifts observed included an increase in the numbers of blue marlin caught compared to black marlin, a trend which could be explained by improved boat technologies which allowed fishermen and women to explore the deeper waters inhabited by the blue marlin.

A decline in the numbers of yellowfin tuna caught in shallower water had also been recorded, while their numbers in deeper waters were not affected in the same way.

While researchers including Dr Pepperell and the Department of Primary Industries' Dr Nick Otway will be continuing their research at the 2020 competition, it would also be an invaluable opportunity for students to be trained in fieldwork.

This year, PhD students from Australian universities will be at the competition looking for specific data, including information on marlin eyesight, as well as external and internal parasites.

"As part of the event, the fish come in whole and fresh. Especially for those studying parasites, this can offer an opportunity to collect live parasites," Dr Pepperell said.

Events have previously attracted researchers from as far away as the US and Oxford University in the UK as well as from fisheries departments across Australia.

The research would not be possible without the "terrific cooperation" from anglers and NSW Game Fishing Association officials, Dr Pepperell said. Sometimes researchers had specific requests that fisherman keep certain species, and they did so, including a recent request for specimens of suckerfish (remoras).

This year anglers were being asked to bring in specimens of wahoo, a very toothy and speedy game fish which offers a big challenge to anglers, to aid in an investigation into the worms that live in their stomach.

The cooperation of game fishing crews had also played a vital role in allowing pop up satellite tags to be deployed, gathering data on fish depth, sea temperature and light levels over several months.