Shark ID

[Backfromthedead]

I disagree. With numerous shark species around Malaysia, it is very likely that the subject shark was caught locally.

List of Sharks in Malaysia with Pictures

Know if there are sharks in Malaysia. Get details about their size and aggressiveness

www.sharksider.com

What do you think it is?

I was mostly hinting at its obvious intended purpose there. The dorsal and pectoral fins are the main ingredients in sharkfin soup which this half-fish is obviously prepared for...seems to me like a fish prized for its fins might find its way to where demand is high.

Like you said, mostly. But regardless of the fact ive never been to malaysia i can 100% guarantee not everything in every fish market is local.

Bluefin tuna at singapore fish auction:

 

[thiswasgone]

100% not a Mako but if I had to take a guess it's a milk shark (Rhizoprionodon acutus) or a silky shark (Carcharhinus falciformis) but without a full body image or multiple viewpoint & tooth photo it's basically impossible for me to give a 100% ID.

For nerdy people my reasoning is explained below to the best of my researching capabilities:

There are a multitude of shark species used in shark fin soup but using this a research paper to determine which species are most commonly found in the soup ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8997153/ ) I isolated it down to the two species mentioned above. However, as this is a study with limited sampling methods, size, and location it is possible that my guesses are still incorrect.

There are 3 physical features used to identify silky sharks when comparing them to similar looking species:
1. Second dorsal fin with long free tip, usually greater than twice the fin height
2. First dorsal fin is rounded
3. First dorsal fin originates behind the free tips of the pectoral fins

Unfortunately the most decisive feature (1) is obviously gone from that carcass.

(source: https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-falciformis/)

However features 2 & 3 still match the description and shape of the silky and they are known to have rounded snouts. Granted, the snout does look pushed in though so it could actually be a pointed snout leading us into it being a milky.

For milky sharks their mouths have the best identifying physical features:
1) long labial folds at the mouth corners
2) usually 7-15 enlarged pores just next to the mouth corners on both sides

(source: https://en.wikipedia.org/wiki/Milk_shark#/media/File:Rhizoprionodon_acutus_mangalore2.jpg)

As seen in the image above there are ~10 enlarged pores just to the side of the mouth corner with the labial fold extending quite far from the mouth. Unfortunately the original image in the thread does not have an angle for us to see side/underside of the mouth. Another secondary feature is this species is reported to have a long pointed snout and as previously mentioned the original image does show a "smashed-in" nose. Additionally, the original image closely matches this image of milky sharks being sold in malaysia

(source: https://upload.wikimedia.org/wikipedia/commons/e/eb/Rhizoprionodon_acutus_malaysia.jpg)

 

[Backfromthedead]

100% not a silky, you seemed to have missed the most defining characteristic of silky sharks, the space between the pectoral and dorsal fin. The fish in OP fins nearly overlap, no space at all. Moreover, the have quite long pectoral fins, the OP pic is not clear, but the fins to do not appear very long.

Afaik every shark has ampullae(not called pores lol) and nearly every carcharhinid has a pattern of ampullae like you describe.

Id like to hear your rationale as to how its not a mako, you know, for us nerdy people out there.

Milk shark is possible, fish looks quite bulky to be a milk shark imo though.

 

[thiswasgone]

100% not a silky, you seemed to have missed the most defining characteristic of silky sharks, the space between the pectoral and dorsal fin. The fish in OP fins nearly overlap, no space at all. Moreover, the have quite long pectoral fins, the OP pic is not clear, but the fins to do not appear very long.
View attachment 1541111
Afaik every shark has ampullae(not called pores lol) and nearly every carcharhinid has a pattern of ampullae like you describe.

Id like to hear your rationale as to how its not a mako, you know, for us nerdy people out there.

Milk shark is possible, fish looks quite bulky to be a milk shark imo though.

Yeah I wasn't sold on it being a silky as well but the placement of the gills/pectoral is not 100% straight so I didn't want to throw it out completely since the colors match & the physical features are similar but I can't say for certain they are 100% identical.

Ampullae (of Lorenzini) are the actual electroreceptors within/at the end of the pores; the surface openings are still called pores. Placement of ampullae and their pores are not uniform throughout shark species (although their general location around the face/nose is not unique) and as far as I could find online an identifying feature of milky sharks, compared to similar looking species, is the fact they have 7-15 enlarged pores at the corner of their mouth. Outside of that we would need the whole carcas to identify if the shark is a milky but at that point we could ID it 100% regardless of species with more angles. Thus, once again, I could be 100% wrong on the ID but I know for certain this is not a mako.

As for why it isn't a mako there are three obvious signs to me:
1) The fins & gills
2) The color
3) The eyes

For those who don't know there are only two known mako species which are the longfin mako shark (Isurus paucus) and shortfin mako shark (Isurus oxyrinchus). It would be clear in the image if it was a longfin mako as that species pectoral fin is adnormally long hence the name. That still leaves the possibiliy of it being a shortfin mako but IMO the placement of the fin in relations to the gill and the gill size indiciates that is not a mako. Makos fall under the lamnidae taxinomical family which have two distinct features that we can use: the pectoral fins start behind the 5th gill opening and the gills are very large. Of course I said IMO earlier because as stated above the pectoral fin is a little smashed inwards so I find it difficult to determine the starting and end point of the fin. In addition if it is a mako it would be a young one so it's possible that the gills match one of that size although IMO it's still undersized for a shark within the lamnidae family.

Thus we go the 2nd piece of evidence which is the color. I don't know of any living shark species within the lamnidae family that has a light grey/brown coloration which includes: great white, salmon, porbeagle, and mako sharks. All these species are either black, a variation of blue (typically metalic dark blue), or rarely a variation of dark grey to medium grey from the top and silver/white at the bottom. Now it is 100% possible that the fish lost coloration postmortem and it was infact a medium grey which is why the next sign is the final nail in the coffin for me.

I've never seen a mako, living or dead, with eyes as small as the shark shown in the original post and without deep black eyes. Even when young makos have extremely large black eyes that are quite clearly "too large" for their body when you compare them to other sharks; similar to how young german shepards may have extremely large ears that they "grow into".

All of these traits can be seen in the photos below of a juvenile shortfin mako but are not visible in the original image hence I can say with certainity that the OP is not seeing a mako.


(source: https://www.researchgate.net/figure...ark-Photo-Sezginer-Tuncer-Sl-3_fig2_303736925 Photo: Sezginer Tunçer)

HTH

 

[Backfromthedead]

Im on board with milk shark at this point. It was a species i didnt even consider, took it for a larger shark initially. Totally makes sense being in that market as well. Well done.

I will only add that ive generally found color to be very unreliable when identifying really any fish, especially a shark thats been bled, gutted, possibly frozen or thawed, and sat out for an undisclosed time. Mako in particular can be quite amorphous ime, around here they are commonly mistaken for young white sharks and vice versa.