A year in the life of a one-eyed jewfish

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Dean Overhall looks pretty chuffed with the 136cm beast
Dean Overhall looks pretty chuffed with the 136cm beast

IN April last year, Dean Overhall tagged and released a beautiful jewfish off the rocks of Broken Bay, on the NSW Central Coast. Featured on the August 2015 cover of Fishing World, this fish took a liking to a hardbody lure spun through the washes on dusk.

The swell was pumping and it was clear any fish braving the turbulent waters was going to be hardy. Dean hooked up on 40lb tackle, allowing him to dictate terms to the fish in a brutal, but short fight. Washed up by a wave, the fish was dropped at the back of a sandstone rock shelf. After a pair of lip grips was secured in its lower jaw and the lure removed, we transferred the mulloway onto a wet beach towel. Still green, the large fish flapped about; however minimal damage was sustained to its scales and protective slime.

Old
Old "One Eye" featured on the cover of Fisho in August 2015

The fish measured 136cm, and a bright yellow, pelagic style tag was inserted beneath its dorsal spines. Dean submerged it in a nearby rock pool whilst I went to fetch my camera. Gutters in the rocks fed by persistent swells are like superchargers for big jewies. Holding their mouth open with lip grips allows oxygenated water to flood through their gills.

As we were about to take photos, it became apparent the fish was missing its left eye. Given all the spiny things mulloway are willing to eat, such as crabs, mantis shrimp and spiky fish like flathead, along with the surf zones and rocky washes they are found in, eye injuries such as these can occur from time to time. What is remarkable is that this one-eyed jewfish located a lure at low light in a foamy wash, a reflection of their ability to utilise senses beyond sight to locate prey.

When it came time to release the fish, Dean slipped it into the ocean headfirst with a receding wave. The current at its tail pushing the fish clear of the rocks and out into safer water.

Recapture

Almost a year later, on the 19th of March, Nick Waltibushi recaught ‘One Eye’ again in Broken Bay. The fish was retained by the angler and its frame donated to the Research Angler Program. Where the fish travelled in its 11months of liberty is impossible to know, but it is fair to say it had the opportunity to produce more little jewies over the November – March spawning season. Also, the time of capture and recapture correlates with the annual spawning run of mullet in Broken Bay. It is fair to say this mature sized fish was in the area for feeding purposes.

After recapture, the mulloway measured 130cm, which is a 6cm shrinkage based on the length recorded at time of tagging. Dr Julian Hughes from NSW DPI’s Research Angler Program indicated that some mulloway can shrink in overall length when frozen, which is what may have occurred in this instance. This phenomenon is taken into consideration by Fisheries Officers checking the length of anglers’ catches put on ice, as fish of legal length at time of capture may shrink to be undersized.

By counting the rings on the otoliths (ear bones) scientists can fairly accurately estimate a fish's age. This fish was estimated to be 15 years old.
By counting the rings on the otoliths (ear bones) scientists can fairly accurately estimate a fish's age. This fish was estimated to be 15 years old.

Upon analysing the fish’s frame, Julian extracted its otolith bones. These pearly white ear bones were used to determine the mulloway’s age. By cutting a cross-section through an otolith, and counting the visible rings the fish was estimated to be 15 years old. According to Julian, “130cm is about average size for a 15 year old fish, so not the oldest, but still pretty interesting nonetheless.”

This fish has not only contributed to our knowledge of mulloway movements and growth rates through the Newtag tagging program, the analysis of its frame has also afforded us an insight into information on mulloway anatomy and age.

“One Eye” seemed to have a life of hard knocks, offering us an indication of the hardiness and healing abilities of jewfish. Being caught off the rocks, and losing a few scales in the process, didn’t seem to impact on its long-term post release survival. Hence, I think it is fair to say that mulloway are a viable catch and release species in the ocean rock environment – provided anglers take appropriate steps to care for fish before release.

Despite copping a couple of knocks during the catch and subsequent release, One Eye handled the incident well, as his recapture 12 months later proves.
Despite copping a couple of knocks during the catch and subsequent release, One Eye handled the incident well, as his recapture 12 months later proves.
How you can contribute to the science of jewfish?

Due to bright yellow tags becoming disguised by weed or algae, many anglers do not realise they have caught a tagged mulloway until the fish is on the cleaning table. Keep your eyes peeled for tags inserted beneath the dorsal spines of fish over 60cm. I urge anyone who catches a tagged mulloway to record the tag number, length, time and location and re-release the fish so it may be able to provide us with more information on its growth and movements.

The Research Angler Program has two major aspects you can get involved in. The first is keeping a Keen Angler Diary, a record of your mulloway fishing captures, which is to be used by Fisheries to determine the approximate recreational catch (and release) of mulloway in NSW waters. Accurate data on the commercial take of mulloway has been recorded for many years, and this diary program aims to produce credible data for the recreational sector. At the moment, a smart phone app version of the diary is being trialled.

The second way to contribute to the Research Angler Program is to donate the frames of mulloway you have retained. This can be done at one of the many drop off locations found in tackle stores up and down the coast. You may donate the full frame including the stomach contents, just the head, or a single otolith, all of which are welcomed by Dr Julian Hughes for the program.

More information on how to get involved can be found at the Research Angler Program website.

To read about another of Luke's recaptured jewies from April 2016 click here.

Luke Reilly's article from the August 2015 Fishing World called "Chasing The Tide" can be read by clicking here.

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