Bluefin Tuna Sampling

Bluefin Tuna
Bluefin Tuna

 

Work has kept us pretty busy lately, so in the spirit of adding new content as often as possible, I wanted to share some pictures from a few years ago. The Atlantic Bluefin Tuna, Thunnus thynnus is an incredibly large, fast growing, and pelagic fish native to just about the entire Atlantic basin. Our job was to take biological samples, including otoliths and fin clips, from recreationally landed fish for ageing and DNA samples. Unfortunately this is an incredibly dirty process, and I was unable and unwilling to subject my camera to the onslaught of oil and blood. Words cannot express how greasy these fish are! I did manage to take a few cell phone photographs of some of the age structures, but a majority of the photos were of the unloading process, and not of the sampling.

Initially, the fish are tagged, and hoisted off the boat. During the hoist, the fish are weighed for an initial weight.

 

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Bluefin Tuna Processing
Bluefin Tuna Processing

 

You will notice in the second picture, that the operculum and gills have been removed. This is done by the angler’s at sea, in order to cool the fish down as quickly as possible after the long fight. The gill cavity is then filled with ice for the ride back in.

 

Bluefin Tuna Processing
Bluefin Tuna Processing

 

 

Once the fish are off the boat and weighed, they are measured using the curved fork length. This information will be submitted along with the tag numbers to federal and state fisheries. The fish are then picked back up, and lowered onto a cleaning table, this is where the job gets messy!

 

Bluefin Tuna Processing
Bluefin Tuna Processing

 

The dorsal, anal, and pectoral fins are cut off first:

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Then the head is removed:

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Next up, the caudal fin:

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Now the remaining gills, and all of the guts!

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Bluefin Tuna Processing
Bluefin Tuna Processing

 

What is left is then loaded into a harness and craned into a deep freezer for the ride to the market. (Most likely in Japan, although some NY and LA restaurants will buy them)

Bluefin Tuna Processing
Bluefin Tuna Processing

 

Until sometime in the 1970’s, bluefin tuna wasn’t really marketed for human consumption, as it is an in incredibly bloody fish. Old timers talk about selling them to dog food manufacturers, or to burying parts of them in their gardens for fertilizer. How much of this talk is just hyperbole, I don’t know, however in today’s market, these fish command very high prices, and I can’t imagine any dogs getting to enjoy it.

Bluefin Tuna Processing

 

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New Photography Methods

Lately we have been playing around with shooting fish on white backgrounds. The gist of the process is to use two strobes behind a phototank and pointing at a white wall, then a third strobe to illuminate the fish. You want to overexpose the wall to create the white background. The process is a bit tricky, and one that Jesse can explain much better than I can, but the results speak for themselves!

We still aren’t sure if we like this method better, I am still a fan of the black, but it is very useful for showing features of fins that are lost on black. Since it is winter and fish weren’t exactly jumping into our dipnets, we picked up a few aquarium fishes to test. Any thoughts?

 

 

Cherry Barb - Puntius titteya
Cherry Barb – Puntius titteya

 

Shortfinned Molly - Poecilia sphenops - Var Gold Dust
Shortfinned Molly – Poecilia sphenops – Var Gold Dust

 

Zebra Danio - Danio rerio - Var. 'frankei'
Zebra Danio – Danio rerio – Var. ‘frankei’

 

Bluefish - Pomatomus saltatrix
Bluefish – Pomatomus saltatrix

 

'Oriental River Shrimp' - Macrobrachium sp. c.f. nipponense
‘Oriental River Shrimp’ – Macrobrachium sp. c.f. nipponense

 

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Fishmap.org

Speckled Killifish - Fundulus rathbuni
Speckled Killifish – Fundulus rathbuni

 

 

In the last few months, Ryan Crutchfield over at www.fishmap.org, has been working to create an API in order for us to display his wonderful range maps on ncfishes. Because this coincided with a database rewrite, we have been slow to implement it, but I wanted to share a sneak peek of what it will look like when finished:

 

Fundulus rathbuni

 

 

Check out his website at www.fishmap.org !

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