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PanamaJack
20-06-2006, 12:13
When I first started Marlin fishing in the late 1970s the norm was to hang up every fish - weigh it and have your picture taken with it. But fortunately now attitudes have changed completely, and very few fish - even in tournaments - are now killed. I can't at this moment remember who said it but the 'strap line' was - a gamefish is too valuable to catch only once. Wise words indeed.

Any rate when I look through our Notable Fish lists, that are recorded on our Club's web site - http://www.scbi.org.uk, I'm aware that by far the majority of weights have been qualified as ‘Released’ or ‘Tag & Release’, and this reflects what is that growing ethos amongst our membership.

Where do these estimates come from though? In the majority of cases they are skippers’ estimates, but obviously, as you’re aware, estimating fish weights is far from being an exact science. And I suspect, as less and less gamefish are killed, the base against which skippers can ‘accurately’ estimate weights will become somewhat vaguer.

Still isn’t that the first question most of us ask when we’ve released a Marlin – just how big did the skipper think it was? Well it’s his best guess but, as I said, nothing more than that an estimate. Realistically it’s just a relative qualification as to whether it was ‘big’ or ‘small’. And one, given that the judgement of the skipper can be likened to that of say a Cricket Umpire, most are prepared to accept, certainly for the award of our Club Trophies. (You'll see I deliberately didn't use 'Football Referee' because just about everyone queries their judgement!)

But, what about our Club Records? Now that’s something, in my view, we’ve quite rightly resisted. Going that route there’re just too many intangibles which will lead to undoubted conflict.

The IGFA - obviously concerned about potentially being characterised as an organisation that ‘promotes’ the needless killing of fish - have recently been considering the possibility of introducing a new category of World records, for a limited range of species, but based purely on length. Whilst though I welcome the strategic thinking behind this initiative I suspect it’s fraught with a whole range of side issues, not least of which is the impact of girth on size, and I suspect it’s likely to be ‘binned’.

We’re still left guessing though about fish weights. And I thought I’d include a couple of practical observations about how, if you wish – and it’s entirely up to you, to make this ‘guessing game’ slightly more accurate, especially with larger fish.

So, and this comes from Ian Carter who skippers the game boats Shy 3 (Ascension Island) and Xacara (Faial, in the Azores). And Ian and caught, and weighed a number of ‘grander’ Blue Marlin and fish very close to that weight. In his view the way to determine whether or not you’ve caught a ‘grander’ is to measure the circumference of its tail root. If it’s at least 20” then, in all probability, you’ve caught a ‘grander’. Far from exact I must admit, but nevertheless based on practical observation and reasonable data from a number of different venues. And that might well be a factor in your own mind in determining whether or not you bring in a fish for weighing.

Then there’s the ‘time honoured’ formula for estimating the weights of gamefish species in general – whether large or small. You take the length of the fish - in inches, tip of lower jaw to tail fork – multiply it by the square of its girth measurement (at its greatest point, but excluding fins) and divide the result by 800.

So working through an example, a Marlin with a fork length of say 12’ (144 inches, tail fork to tip of bottom jaw) and a girth of 5’ (60 inches) is likely to weigh 648lbs. A similar fish, but with a 6’ girth though would probably weigh 933lbs.

Try it yourself though. Once, in Ascension Island, our crew calculated the weigh of a 76lb Yellowfin Tuna and then weighed it. The formula, in that particular case, was accurate to within a pound.
Dave

PanamaJack
21-06-2006, 11:01
Measuring some live fish is relatively easy. But I suppose what I forgot to comment on is how you go about measuring a Marlin. It's certainly far from easy if it's particularly active, as this picture shows - http://www.marlinnut.com/dcforum/User_files/447c77c860b52811.jpg! You just accept the skippers estimate.

But during the mid to late 90s in Madeira when they were catching 'granders'. Some did die or were killed and weighed and the formula was proved to be accurate. But those big fish were often extremely tired, brown in colour, when they were bought boatside and this made measuring them relatively easy.

One of the skippers from that era, Roddy Hays, used to use a modified tape measure that, on one one end, had a hollow plastic cone that fitted over the marlin's bill. The tape measure, with the boat being slowly motored forward, would then 'stream' along the fish's side enabling them to get an accurate length. Obviously the girth measurement was not quite as easy - a big fish is going to have a girth around 6' - and I certainly found it using a piece of dacron into which you could tie a knot. Much easier than using a tape measure.

In terms of the motoring forward that was being used to help revive the fish. And sometimes Roddy would hold the fish alongside for up to 30 minutes before the vibrant colours returned and it was released.
Dave
PS Roddy, who manufactures the famous Legend lures has recently moved to the other side of the world - the Bay of Islands in New Zealand. But he's still selling lures and his 'Hays Handle' - a great device to assist in moving a heavy tackle rod from the rod hold to the chair - through his web site - http://www.legendlures.com

Roddy Hays
15-08-2006, 13:10
Dave,

not sure where you heard about the CONE - but that's patently not true. I measured my fish with a very old Moonraker bronze Daiwa beach caster, no rings, measured off in 6 " intervals with red tape. Simply held the one end against the tip of the lower mandible and saw where the tail was at the other end - anything that ran out of the 12' beachcaster length was, um, large.

Sure did hold the fish alongside for a while - but that was why we invented the snooter.....48 minutes was the longest we held a brown one until it turned into a blue-tailed devil....... never give up on that revival stage my friends.........

Baah, humbug to hearsay and rumours. CONE indeed. Who the hell told you that never fished with me.......grin

Roddy

Kingfish81
16-08-2006, 13:44
This is the geek in me struggling to get out(!), but it would be relatively easy for someone like the IGFA to get data of length vs weight for actual weighed marlin of various species. Then, by measuring the fish (bit with a beachcaster, tape measure or cone), the relevant weight could be read off from the graph. the graph could also provide confidence estimates, i.e. the weight is likely to be between x and x...

This could be tightened even further if girth was also measured and factored into the equation... A little project methinks...

Ravelling Tangler
18-09-2006, 14:33
Dave,

not sure where you heard about the CONE - but that's patently not true. I measured my fish with a very old Moonraker bronze Daiwa beach caster, no rings, measured off in 6 " intervals with red tape. Simply held the one end against the tip of the lower mandible and saw where the tail was at the other end - anything that ran out of the 12' beachcaster length was, um, large.

Sure did hold the fish alongside for a while - but that was why we invented the snooter.....48 minutes was the longest we held a brown one until it turned into a blue-tailed devil....... never give up on that revival stage my friends.........

Baah, humbug to hearsay and rumours. CONE indeed. Who the hell told you that never fished with me.......grin

Roddy

So this new fangled idea of 3-piece beachcaster of 4.5 or 5 m length is really because Daiwa, Grauvell and Shakespeare are expecting you to catch a really big (well, at least, really long) "mamma" , Roddy ? ( grin !)

Congratulations on that 48 minutes revival 'record' - the longest I remember towing one (with either you or Bart, at Madeira) was only about 15 mins and that seemed like a lifetime. I was quite surprised when she gradually came back to life and eventually "lit up" !