360 Tuna Fishers Forum banner
1 - 5 of 5 Posts

·
Senior Member
Joined
·
1,386 Posts
Discussion Starter · #1 ·
A few times in the past month, someone has called or written to ask how much a Bluefin of a certain length might weigh. Fish vary a lot, and if you don't weigh them, you can't know for sure. However, if you practice catch and release, you may be satisfied with knowing what the averages are.

NOAA/NMFS (National Oceanic and Atmospheric Administration/National Marine Fisheries Service) provides a table of data for the weight of Atlantic Bluefin Tuna (from the NMFS Library: Bluefin Tuna Size/Class Data). As you can see in the table, weight estimates are provided only for the end points of each range. For example Bluefin Tuna with a Curved Fork Length (measured from the bottom of the "V" at the tail, along the body to the lower jaw) between 59" and 73", have an average Round Weight (whole fish) of 135 lbs. to 235 lbs.

At the bottom of this page, Bluefin Tuna Weight vs Length, I've added a calculator that figures the weight in between the end points, using the official NOAA/NMFS information. It takes into account that the girth of a fish increases as the length goes up. It calculates the Round Weight for any Curved Fork Length for Atlantic Bluefin Tuna with a length between 27" and 81". Of course every fish is different, but it might be useful for letting friends know how much that fish in the photo weighs.
 

·
Senior Member
Joined
·
3,483 Posts
The only thing I would add to that is that some tuna are definitely fatter than others. The formula used for Yellow Fin Tuna is [Length x (circumference x circumference)] / 800 for a "taped" weight.

If you catch a fattie then you get the benefit of the extra width this way. For instance in Panama I caught a fish that was only 62" but was 48" around which led to an estimate a full 20lbs more than the calculator you posted.

Just another way to do it. Certainly the calculator you posted is more than adequate and a nice tool for any fish that doesn't look especially porky.
 

·
Senior Member
Joined
·
1,386 Posts
Discussion Starter · #3 ·
The only thing I would add to that is that some tuna are definitely fatter than others. The formula used for Yellow Fin Tuna is [Length x (circumference x circumference)] / 800 for a "taped" weight.

If you catch a fattie then you get the benefit of the extra width this way. For instance in Panama I caught a fish that was only 62" but was 48" around which led to an estimate a full 20lbs more than the calculator you posted.

Just another way to do it. Certainly the calculator you posted is more than adequate and a nice tool for any fish that doesn't look especially porky.

The length x circumference x circumference is the "formula" inside my calculator on the web page. But rather than use l*c*c/800, I took the AVERAGE ROUND WEIGHT data points provided by NMFS and use a cubic interpolation between those points.

That means that the answers the calculator comes up with will be AVERAGE for an ATLANTIC BLUEFIN TUNA (not those skinny ones down in the GOM ;) ). Fatter tunas will weigh more than the average, thinner ones less. So if you're experienced, you could say something to yourself like, "the calculator says the average Round Weight for the 68.5" fish I caught today is 200lbs, but mine is fat so I'll add 10%, or mine is thin so I'll subtract 10%."

Thanks again for the feedback.
 

·
Senior Member
Joined
·
2,835 Posts
That means that the answers the calculator comes up with will be AVERAGE for an ATLANTIC BLUEFIN TUNA (not those skinny ones down in the GOM ;) ).

Some of our GOM YF's get fat also. Take a look at the one on the left in the below photo's taken last week. It has a girth of 41" with a 60 1/2 length. The ones on the ground are fairly common size for YF's taken here while fishing at night.

I've heard of two separate battles in the last two weeks that went over two hours with accomplished fisherman. Both tuna were lost with pulled hooks. Both of these fish saw color and both were estimated to be around 200#s. I think we will see a cow YF taken on a popper this year.
 

Attachments

·
Senior Member
Joined
·
1,386 Posts
Discussion Starter · #5 ·
Some of our GOM YF's get fat also. Take a look at the one on the left in the below photo's taken last week. It has a girth of 41" with a 60 1/2 length. The ones on the ground are fairly common size for YF's taken here while fishing at night.

I've heard of two separate battles in the last two weeks that went over two hours with accomplished fisherman. Both tuna were lost with pulled hooks. Both of these fish saw color and both were estimated to be around 200#s. I think we will see a cow YF taken on a popper this year.

Your response exceeded my wildest expectations. What an impressive array of fish. I'm looking forward to the popping 200# cow when it's taken.
PF
 
1 - 5 of 5 Posts
Top