I'd say they are longtails/northern blues.

yep - northerns. Nice fish!

First, longtails arent northern bluefins (though.... they are often incorrectly called it).

That profile in the first pic looks more like a bigeye to me, could be cause it has its mouth open. Though last pic does look longer in the tail, more girth to the head....

I have seen a bigeye in the flesh though, so will have to see if i can get a hold of the pic and compare. Not going to say that one is a bigeye though (but would be interesting to compare to the bigeye photo).

Though, something odd I noticed when finding comparison pics. I had a look in tge marine fishes of NW australia (G. Allen and R. Swainston) and it had this pic:

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Note that on the longtail (951) its gill plate kinda indents near the pectoral fin, while  on the bigeye (949) or the southern blue (950) it is a smooth curved shape.

Have a look at the gill plates in these (indented)

http://fishwrecked.com/image/longtail-tuna-1
http://www.longtailtuna.com.au/Info.aspx/Detail?section=Identification
http://en.wikipedia.org/wiki/File:Thton_u0.gif
http://www.westernangler.com.au/fishing-info/fish-guide/189-longtail-tuna
http://fishwrecked.com/image/hayleys-first-longtail-tuna
http://fishwrecked.com/image/longtail-tuna-0

Compared to these (rounded)

http://fishwrecked.com/image/found-longtail-0
http://fishwrecked.com/image/exmouth-gulf-longtail-tuna-mcarthy-5-pearl-finesse-minnow-may-2010
http://fishwrecked.com/image/little-longtail
http://i19.photobucket.com/albums/b176/alheng/IMGP3358_2.jpg
http://fishwrecked.com/image/tuna-time-1

(and the pic in the original post, particularly last one)

I think there may also be a difference in the notches on the tail. I know bigeye have the notches, and those ones seem to as well (that doesnt make it a bigeye though), but the tuna with the indented gill plates seem to not have tail notches....

Perhaps the fish just come in a variety of gill covers, ranging on how rounded or indented they are. However, looking at the book, and looking at the photos, it seems to me that there might actually be two species here. The indented ones being longtails, the rounded ones perhaps being northern bluefin, perhaps bigeyes, or perhaps a different species. Perhaps just a different 'variety' of longtail (e.g. two populations).

I dont know which those are, or if there is even two types of 'northern longtails', so not making any calls, just trying to find info and figure out what the differences are.

As far as I'm aware, longtails are also known as northern bluefins... I suppose it depends how scientific you want to get.

Secondly, Matt, how could you think this is a big eye man? I've never heard of a big eye being caught in 15m's of water.

Though, I've only been a Westralian for 2 years, so I'm still getting my head around what species inhabit what waters in WA. I've been suprised in some cases. But confident to say a big eye won't come to shore.

Matt, this tuna thing is getting you too puzzled. Hope you're not losing to much sleep dude.

I'd say longtail too, looks too scrawny to be anything else.

Still fun fish on the right year.

Bigeye Tuna or Yellowfin Tuna - How to tell the difference:
http://www.sea-ex.com/fishphotos/bigeyetuna.htm

Bigeye tuna are believed to have recently evolved from a common parent stock of yellowfin tuna.

One of the most difficult fish identification jobs is distinguishing between a Bigeye Tuna (Thunnus obesus) and a Yellowfin Tuna (Thunnus albacares).

There are two methods of examining these fish, exterior and interior. Only the interior examination is 100 percent foolproof. The smaller the size of the tuna, the less effective the exterior examination becomes. The easiest method is to look for first for the characteristics of the Bigeye Tuna first, and by the process of elimination, wind up by concluding you are holding a Yellowfin Tuna.

Exterior Characteristics of a Bigeye Tuna (Thunnus obesus):

1. The Bigeye Tuna's pectoral fins may reach to the second dorsal fin, but are shorter than the Yellowfin Tuna's. A very short pectoral fin indicates that the fish more than likely is a Bluefin Tuna. A very long pectoral fin that reaches beyond the anal fin belongs to an Albacore.

2. There are 18 to 22 gill rakers on the first gill arch of a Bigeye Tuna. There will be 24 to 28 gill rakers on a Bluefin Tuna, and 27 to 33 gill rakers on a Yellowfin Tuna.

3. On a Bigeye Tuna, two dorsal fins are closer together and shorter than on a Yellowfin Tuna. The forward dorsal fin of a Bigeye Tuna has 13 to 14 spines and the rear dorsal fin has 14 to 16 rays.

4. The Bigeye Tuna has a strong lateral keel, between two small keels, located slightly farther back on the tail, on either side of the caudal peduncle.

5. Except for the anterior corselet, the scales of a Bigeye Tuna are small.

6. The Bigeye Tuna's rear dorsal fin is dark brown and edged in black, lacking any yellow.

7. The finlets of the Bigeye Tuna are bright yellow with narrow black edges.

8. Upon expiring, the body of a Bigeye Tuna loses most of its coloration, including the disappearance of its yellow coloration. The dorsal and anal finlets' yellow coloration turns brown after death.

9. The Bigeye Tuna's anal fin is wider and shorter than the Yellowfin Tuna's, and it is colored all silver, with a fringe of yellow and 11 to 15 rays. In a yellowfin tuna the anal fin is long and narrow and only silver in the middle.

10. The corselet (the front area of enlarged scales) of a Bigeye Tuna extends further back than on a Yellowfin Tuna. These front scales are larger up front on both tunas and become smaller along the flanks, which make these tuna appear darker up front. These larger scales cover the fish from the first dorsal fin down around the pectoral fins, and to the ventral fins and then takes a sharp angle backwards. This front area of scales extends further back on a Bigeye Tuna than on a Yellowfin Tuna, all the way to the end of the second dorsal fin. The pectoral fin of a Bigeye Tuna will not cover this extension of scales, while on a Yellowfin Tuna these scales extend barely as far as the second dorsal fin and the pectoral fin will completely cover these scales.

11. The tail of a Bigeye Tuna does not have a white trailing edge.

12. The white spots prevalent in small Bigeye Tuna elongate as the fish becomes older.

Interior Characteristics of a Bigeye Tuna (Thunnus obesus):

1. Without a doubt, positive identification of a Bigeye Tuna can be completed by examining its liver. The Bigeye Tuna has a grooved liver with clearly visible striations (fine lines looking like streaks), or dark blood vessels on the margins of the lobes. There are two lobes that are both of the same size. However in the yellowfin tuna these smooth lobes are devoid of these striations and the right lobe is clearly longer than the left lobe or the middle lobe.

photo from NOAA

the big eyes seem to have a more streamlined anal and second dorsal fins then the three fish in my pictures to.

They all be tongolls, colloquially known as Northern Blues, I call them yum, Sashimi, Sushi and Steaks. Bigeyes and Yellowfin are far more robust (barrel like) can't mistake 'em.

My first post so bear with me.Just thought I would throw a stick in the spokes re fish locations.

In my early days of fishing Hat Head in NSW I was asked to ID a fish that was caught off the beach just north of the creek by a Bream fisherman.On seeing the fish in the local netters freezer I ID'd it as a Dogtooth Tuna.It was 43lbs and the fisho caught it on an Alvey with 9lbs line.A fantastic effort and certainly stayed in my memory.

Although I am sure the tuna in question is a Longtail sometimes fishes do  stray and turn up in the most unlikely places.

Regards Barry