Record sizes of jenahak/Ang Cho

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AussieFishBiologist
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Record sizes of jenahak/Ang Cho

Post by AussieFishBiologist » Thu Jan 31, 2013 2:21 pm

Hello all,

I am a scientist writing a paper on age and growth of Lutjanus johnii in Australia. We call them "Fingermark" or "Golden Snapper". I wish to find out fishing club (or other) records of the maximum weights and sizes of this species in waters of Singapore, Malaysia, Indonesia and Thailand to compare with maximum sizes in Australia. Can anyone help me? My idea is that L.johnii grows faster, larger and lives longer in cooler waters.

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Re: Record sizes of jenahak/Ang Cho

Post by Peace » Thu Jan 31, 2013 7:48 pm

Welcome to HLF, AussieFishBiologist. In my opinion, Singapore may not be the best representation of any fish species size in the region due to its poor water condition and relatively high fishing activities (although there are no true commercial fishing in Singapore).

With regards to your question, I have only witnessed L.johnii up to ~3kg but anglers here have caught much bigger ones. To give you a realistic idea, 1-2kg size can be considered relatively common. That is to say, if I were to go 10 offshore day fishing trips it is possible to get at least one of these size half the time assuming we go fishing for them specifically. Chance is increased when fishing during the night. The ones below 1kg are common and you can practically land them on every trip, especially on the eastern part of Singapore.

There's another factor skews the population growth of L.johnii in Singapore waters. This species of snapper is commercially bred on local floating fish farms located off northeastern waters. These fishes often make their way into the wild due to breaches in captivity net as well released by religious organization in large numbers on a frequent basis. It's part of the reason why eastern part of Singapore tend to have more L.johnii, but they're not often large. The fishes are usually range from 500g - 1kg when they are being sold.

A record size locally is probably at least 7kg. I ever spoke with one of the local fishing charter and captain told me he ever caught a 9kg L.johnii. He did show me a photograph of him with the fish but it's difficult to gauge its size accurately from the picture. It's really big though. Landing these sizes are like hitting the jackpot for anglers here.

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Re: Record sizes of jenahak/Ang Cho

Post by AussieFishBiologist » Sun Feb 03, 2013 7:09 am

Thank You, Peace,

For the scientific paper I need to cite the source of information, so any links to books or magazines with record jenahak photos would be good. In my paper I have written:
"...
An internet search for record fish sizes landed by line and spearfishing was conducted for countries in the Indo-West Pacific. None were found for south-east Asian countries, so the 2011 records maintained by the International Game Fishing Association (IGFA), Australian National Sportfishing Association (ANSA), Australian Angler’s Association (AAA), and Australian Underwater Federation (AUF), were used to plot the maximum weights of L. johnii and six other large lutjanids with latitude. The others were L.argentimaculatus, L.bohar, L. malabaricus, L. sebae, Symphorus nematophorus and Aprion virescens. ..."

and
"...
The latitudes furthest from the equator produced the largest individuals for all seven species, in a steeply concave relationship, but we could not locate any records for equatorial countries or south-east Asia to fit statistical relationships (Figure 6). Most of the lutjanid records were landed in the southern hemisphere, but several world records came from Japan. The largest records for L.johnii showed a steep rise over about 8 degrees South from 7.2 kg in Darwin (Australian all-tackle record; AAA), to weights of 10.5 kg and 97 cm (world all-tackle record; IGFA), 12.420 kg (6kg line-class record; ANSA) and 12.0 kg (spearfishing; AUF) near Cairns. The maximum published weight from scientific samples was 4.7 kg for a 71 cm L.johnii from the Andaman Sea (Druzhinin and Hlaing, 1968)...."

When I learn how to post an image on this forum I will send the graph (Figure 6) of these records.

Thank You

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Re: Record sizes of jenahak/Ang Cho

Post by Peace » Sun Feb 03, 2013 8:34 pm

You can try approaching Singapore Sports Fishing Association but I doubt they have proper documentation of record sizes like how IGFA has. RMBR can possibly provide you with some useful data, try approaching Professor Peter Ng or Kelvin K.P. Lim. I believe the data from this webpage also came from RMBR.

You should also try asking at fishingkaki if you're looking for photos of large specimens, majority of local anglers visit that site.

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Re: Record sizes of jenahak/Ang Cho

Post by AussieFishBiologist » Fri Sep 27, 2013 8:47 am

Dear Peace, and other keen fishers for jenahak (ang cho, golden snapper, fingermark).

I would like to tell you that we have published our paper on this species at:

http://fishbull.noaa.gov/1114/cappo.pdf

A maximum age of 28.6 years, nearly 3 times previous estimates, was recorded and the largest individual was 990mm in fork length.

However, there is still a major gap in knowledge of the biology of this fish outside of Australian waters.
Good fishing!

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Re: Record sizes of jenahak/Ang Cho

Post by ilurbtambans » Fri Sep 27, 2013 10:21 am

Thats a really good writeup! :) any chance of doing a writeup on squids? the squids over here in adelaide seems to be bigger than the ones i've seen back home in singapore! dont have a measurement, but its definitely bigger :shocked:

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Re: Record sizes of jenahak/Ang Cho

Post by AussieFishBiologist » Fri Sep 27, 2013 10:37 am

Hi,

The squid from Singapore are probably northern calamari (Sepioteuthis lessoniana) which do not grow as big as southern calamaris found in southern half of Australia (Sepioteuthis australis). I am no no expert, but I recall weights of up to 6 kg for southern calamari.

We get northern calamari here in Queensland on the Great Barrier Reef

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Re: Record sizes of jenahak/Ang Cho

Post by Peace » Fri Sep 27, 2013 9:40 pm

That's a very well written paper, though I doubt the most of angling community can appreciate the findings and its indepth technicality. I didn't know till now that fish ages are measured that way. :o Excellent work and thanks for sharing it with us!

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Re: Record sizes of jenahak/Ang Cho

Post by AussieFishBiologist » Wed Oct 02, 2013 1:48 pm

Thank You,Peace,

I have written a pictorial guide on how to collect fish "earstones" to estimate fish age. This will appear in December this year in "About Fishing North Queensland" magazine. It shows how to dissect out the pair of earstones from a 855mm (fork length) jenahak.

Unlike my technical, scientific paper given on the link above, this new one is for anglers to understand and use. I will try and send a link when the article and photographs are published.

Thank You

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Re: Record sizes of jenahak/Ang Cho

Post by Peace » Wed Oct 02, 2013 9:22 pm

I look forward to your upcoming article and I believe more anglers will be interested in this as well. I bet it'll make me dig out those "earstones" when I gut my catches. :shiftyeyes:

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