Introduction

In this film, we will look at how to ensure good quality fish through correct handling of the catch. Norwegian fishing vessels are modern and have all the prerequisites for producing fish of the highest quality. There will, however, still often be room for improvements when it comes to how the catch is handled. Correct handling is important for the quality of the fish, and to improve profitability for crew and owners. Bruising that is invisible on the outside can result in extensive internal bleeding and ruin the fish.   Other problematic areas may involve a an extended time between the fish being caught and bled,, incomplete bleeding, or the fish being cut, packed or frozen in the wrong manner. Different species of fish must also be treated differently after the catch.

There are different challenges for the different gear groups. The following points are important for fishing with trawl and Danish seine:

• Avoid over-filling the net
• Adjust the haul to the production capacity
• Do not mix fish from separate hauls in the tanks

The following points are important for longline-fishing:

• Make sure that the line is not left standing too long
• The long rod and the gaff must be used on the head of the fish, not the body
• Bleed the fish as soon as they cross the railing

The following points are important for net fishing:

• Make sure that the net is not left standing too long
• Remove the fish from the mesh carefully to avoid damage, and bleed it immediately
• Sort the fish that are already dead separately

Correct bleeding is vital for the quality of the fish, and it should be done as the fish is brought on board. It is important that the fish is bled while still alive: the pumping of the heart and the muscle contractions will then help to empty the blood vessels. Cutting the fish must never begin before the fish is emptied of blood, and the flesh of the fish is nice and white. To avoid reduced quality caused by blows and bruises, the fish must be handled with care after the bleeding. Bleeding methods There are several bleeding methods. We will illustrate the two cut- and the stabbing methods: Two cut method: If you use the two cut method, you first cut the throat. Then you guide the knife diagonally down towards the neck, cutting both main arteries down towards the back. If you only cut one of these arteries, the fish will be bled only on one side. Stabbing method: if you use the stabbing method, you stab the knife in right behind the gills, cutting the main arteries. If your stab is aimed in the wrong direction, it can easily damage the heart.

The bleeding tank

The fish must be left to bleed out in running water for at least 15 minutes. To bleed them well, there must be good circulation of running water and not too much fish in the tank. Fish that have died before the bleeding should also be bled, but must be sorted separately. The following points are important when bleeding fish:

• Bleed immediately with the correct cut
• Avoid damaging the heart
• Let the fish bleed out in running water for at least 15 minutes

Methods for checking the stage of bleeding out in the fish. If the fish is poorly bled, we can see visible remnants of blood in the flesh. We will demonstrate three simple methods to check if the fish has been sufficiently bled. Method 1 Slide your finger along the natural slit at the back side of the filet. If the veins are filled with blood, the fish has not been bled sufficiently. Method 2 Stroke your finger along the ribs down towards the belly. If blood seeps from the veins, the fish has not been bled sufficiently. Method 3 Scrape off the black membrane on the inside of the belly. Press your fingers up towards the belly. If there are visibly blood-filled veins in the belly, the fish has not been bled sufficiently. A well-bled fish has a nice, white belly.

All species of fish except mackerel, herring, red fish, spiny dogfish and sea trout must be gutted.

The gutting can be done manually or mechanically. The gutting cut can vary by species.

The gutting cut should be done mid-belly, between the pelvic fins in an even cut towards the anal vent. Coley, haddock, common ling and tusk should be cut to the left of the anal fin and all the way back to the abdominal cavity.

Gutting of roe-bearing fish and large fish

When gutting large fish and roe-bearing fish, it can be an advantage that the gutting cut does not open the whole belly. When the cut starts at the pelvic fins, the collar bones remain connected, and it is easier to handle the fish without causing damage.

If the fish liver and roe is to be preserved, it is important to cut in carefully aslant from below the belly. Use a knife with a rounded point to avoid damaging the roe sac and the liver. Cut the intestine at the throat and remove the entrails carefully from the abdominal cavity.

Gutting flatfish

We will here demonstrate bleeding and gutting of halibut in one operation.

The gutting cut should be done on the lighter side of the fish, to make it easier to see if the cut has been performed correctly. It is not wrong to cut on the darker side, but it makes it more difficult to check where you cut. Begin your cut from the upper edge of the gill cover, right behind the pectoral fin and cut down towards the anal vent.

If the flatfish is to be sold with the head, remove the entrails and gills.

The blood along the back bone of halibut and Greenland halibut must be removed. It can be scraped off with a spoon.

At the front of the neck of the halibut and the Greenland halibut there are two glands which can discolour the flesh of the fish, and must therefore be removed.

To remove blood in the veins of halibut, the rear of the abdominal cavity can be washed out with water. This results in an effective removal of the blood.

Incorrect  gutting cuts

Gutting the fish incorrectly can reduce profitability, and even completely ruin the fish.  If the gutting cut opens the fish flesh, the fish will be exposed to bacterial growth and bleeding  in the flesh.

Poorly gutted fish will darken in colour and deteriorate in quality during storage.  All the liver must be removed to avoid the fish flesh growing rancid. This results in a yellowish colour and an unpleasant taste. If the gall bladder is punctured, there will be green discoloration of the flesh.

We will now demonstrate the consequences for the quality and appearance of the fish of incorrect gutting and cleaning. This is a poorly cleaned cod with traces of liver and blood. After 14 days in cold storage the liver traces have resulted in yellow spots in the flesh and the blood has caused dark spots in the belly. The damage is even more visible in the filet. The discoloration in the abdominal cavity has been transferred to the filet.

The following points are important when gutting:

• Cut down the middle of the belly and in a straight line towards the anal vent
• Do not cut into the intestines
• Remove all intestines from the abdominal cavity

It is important that the head is cut correctly with nice and clean cuts. If the head is cut incorrectly with loose collar bones and ruined necks, it results in poor quality or even in the fish being ruined.

The decapitation can be done manually or mechanically. There are several methods of cutting.

Round cut: cut through the throat and the upper intestine. Avoid harming the collar bones. Cut through the cartilage between the neck vertebrae and press the head backwards while cutting. The head is to be cut with a crescent-shaped cut, without tearing it off.

The round cut is used when the fish is to be used when the fish is to be salted, salted and dried, or just dried (stockfish).

Straight cut: remove the head in one continuous cut.

The straight cut can be used when the fish is to be filleted or sold as whole, fresh cod.

You can clearly see the difference between round cut and straight cut here.

Japanese cut: In a Japanese cut, one cuts from the neck diagonally behind the collar bones and pectoral fins down towards the anal vent. Cut as close to the collarbone as possible. Do not cut all the way to the anal vent, one to two centimeters of the abdominal cavity is supposed to remain.

Icelandic halibut and red fish is often Japanese cut.

The following points are important when cutting:

• Use the correct cutting method
• Make the cuts straight
• Do not damage the collarbone and the post-clavicle bone

When cutting cod, it is important to be aware of the post-clavicle bone. It is attached to the collarbone and goes diagonally into the filet. If you handle the fish too roughly, the post-clavicle bone can cut into the flesh and cause bleeding.

Freezing time depends on size and species. In oily fish such as red fish, halibut and Greenland halibut, the fat may separate if the freezing is too slow. The following points are important when freezing fish:

• The freezer must be at least minus 30° centigrade before the freezing begins
• Fish will be damaged if left too long in the freezer
• The fish must be thoroughly frozen before being removed from the freezer

It is important to have an unbroken refrigeration chain to preserve the quality, from the fishing boats to the final customers.

Packaging, labeling and frozen storage.

The fish must be packaged correctly to ensure good protection of the product. Sorting and labeling depends on customer requirements and quality regulations.

The following points are important:

• The products must be correctly labeled
• The packaging must not be damaged or contaminated
• The fish must be put in frozen storage quickly after packing
• The temperature in frozen storage must not  be warmer than minus 18° centigrade

During unloading the following points are important:

• The labels must be turned outwards, to make sure they are visible for registration and control
• The packaging must not be damaged or contaminated
• The fish must be taken quickly to cold or frozen storage

This is a fish which has been correctly bled. You can see that

• The flesh is nicely white
• The bellies are nicely white
• There are no traces of blood

Four examples of fish with quality errors

We will here illustrate the difference between fish with quality errors and of good quality.

• Here we see faulty cutting, with loose collarbones
• This fish has been manually cut in an incorrect manner, and there are traces of liver
•  Here there are many fissures, and the flesh has a flabby consistency
• Here, the gutting cut is incorrect. The cut is made to the left of the anal fin. If the cut is made to the right, there will be a loose flap.

Traces of liver will contaminate the flesh and cause yellow discoloration. The fish flesh will turn rancid.   A fish of good quality:

• Correct cutting, with a rounded neck area
• No loose collarbones
• Nicely white fish which has been well bled

 

The fish processing industry is the fisherman’s customer, and it is the customer who pays for the resulting product. This presents a number of requirements to the product. It must be

• Fresh and healthy
• Not affected by external influences, such as bruising, gaff holes etc.
• Correct bleeding, head-cutting and gutting
• Correct cleaning of the abdominal cavity
• Sorting of fish species and sizes
• Correct packaging
• Correct and complete labeling
• Correct temperature at both icing and freezing

If one or more of these points are neglected, it will result in a lower price for the product, and faults in the raw material cannot be corrected in the processing. Good raw materials result in satisfied customers!