Amberjack and Almaco Jack... how often are they mis-identified?

[Mark Harris]

The answer I think is... all the time!

Recently my friend and fellow GT Popping member Simon Bomholt was in fishing in Mexico and correspondence centred a bit on this subject as he was catching what he thought were Amberjacks and the boat guides were calling them as Almaco. I vaguely knew about some structural differences and that the two fish could be very similar, but that was it. So I got researching.

As I thought I vaguely remembered, Almaco Jacks (seriola rivoliana) tend to be rounder than Amberjacks (seriola dumerili), giving a more trevally-like profile.  Without a lot of experience of both species though, such differences can be hard to ascertain.  The identification clincher seems to be the 2nd dorsal fin which is much longer on an Almaco and hooked backwards towards the tail when fully extended. The same fin in an Amberjack is a completely different, flatter shape.

What this means is that I have certainly been calling Almaco Jacks I have caught as Amberjacks!

There are also other more subtle differences such as the head shape and eye position, but those will never be easy to determine on a boat when you are keen to get a photo and release the fish. There are sometimes colour differences as well but they are very variable, and I hate using colour as an ID guide for any fish.  Assessing the shape of the 2nd dorsal is though very easy.

The geographical range of both fish is very similar. Those of us fishing in Asia and Australia for example could certainly be catching both species.  Amberjack range: http://www.fishbase.org/Summary/SpeciesSummary.php?ID=1005&AT=amberjack#  Almaco Jack range: http://www.fishbase.org/Summary/SpeciesSummary.php?ID=1007&AT=almaco+jack .

Here's a couple of pics I have handy which will help:

This is definitely an Amberjack - note the relatively short and flat 2nd dorsal fin (caught by my friend Ben at Batu Abah, Bali):


These two are definitely Almaco Jack - note the long and hooked 2nd dorsal fin (caught by me only about 1 km south of the Amberjack above):


If folks here were already aware of these differences, then my apologies for wasting space.  I wasn't though and would not mind betting I am not the only one who was making these ID errors.

[Charlie Chew]

thanks mark ! it's something new for me...if not i will think almaco is the juvenile.

[Cameron Mundy]

In South Africa we call the Almaco Tropical amberjack and generally look to the dark stripe that runs through their eye to identify them another tell tale is the mouths which are different they can be a bugger to get right when they are similar sizes and you're in the heat of moment though. 

[Steve Li]

So what is this??? 

[Mark Harris]

Charlie - Almaco Jacks get to be very big, so size is no indication.

Steve, that's an Almaco Jack.  The long and hooked 2nd dorsal fin shows very well in your picture.

Cameron, yep those "facial" features are definitely indicative as well, as are olive tones on the upperparts (Almaco) and the relationship of the eye position to the inner extent of the mouth.  Can be damned hard to pick those type of features though as you say. The length and shape of the 2nd dorsal is relatively easy and totally unequivocal, and I think that is what folks should look at.

[Jon Li]

Hi Mark ,

How about the specie usually called " lesser amberjack " ?

Jon .

[Mark Harris]

Thankfully Jon I don't think those occur in our waters. But I am sure where they do and overlap with the other two species (Central America I think?) then there is another ID problem.

[Nathan Tsao]

Here in Hawaii, both species are referred to as "Kahala". A few years ago i used to grow Almaco jacks from egg to adult as table food. THe farm raised ones are very high in fat content and make excellent sashimi. Here in Hawaii both species are notorious for being super "hot" with ciguatera, so they are rarely targeted at all, even for sport. Most of our fleet ignores the AJ's since the Marlin/Tuna/MahiMahi/Wahoo fishing provides much better table fare. Usually the Almacos are very much smaller than the Greater Amberjack; which often times get to over 50kilos here in our deep Hawaiian waters.
For the most part, both species are considered a trash fish around here because of both the ciguatera issue and that they are often full of worms. The Almacos are the more common for us up to about 15kilos, and can be readily caught jigging, whereas the jumbo AJ's over 50kilos are most often caught by dropping live Skipjack Tuna down to about 120-175m of water on "the ledge". If you ask me, dragging a 50k AJ up from 150m is just waaaay to damn painful to want to deal with! But if anyone wants a real trophy AJ, come try the ledge in Kona, i'll drive and drink beer while you reel it up! 

[Mark Harris]

Hey Nathan, sorry for the late reply, but somehow I missed your post.

Interesting perspectives there, especially given your considerable experience with Almacos. Given their popularity elsewhere, I am surprised the Hawaiian Amberjack fishery has not received more attention from sportsfishermen (jigging).

From reading, it seems that Almacos can get very big as well.