THIS CONTENT IS BROUGHT TO YOU BY Nofima The Norwegian Institute of Food, Fisheries and Aquaculture Research - read more

To ensure the highest quality, haddock should not be slaughtered on board the fishing vessel

Haddock should be delivered live to the fish processing facility and filleted early. This significantly improves quality and increases value creation.

The difference in quality between live-caught and traditionally caught haddock is noticeable – even to the naked eye.
Communications Adviser
Presented by: Nofima The Norwegian Institute of Food, Fisheries and Aquaculture Research
Published

This is the conclusion of the final report of an extensive research project conducted by Nofima and the Institute of Marine Research.

Currently, the most common practice is to bleed and slaughter the fish on board the fishing vessel. Bleeding involves cutting the blood vessels that lead from the fish's heart.

Researchers have documented how good fish welfare during capture and transport is directly linked to quality and yield. 

Haddock that has been handled optimally and delivered live produces fillets with less degradation of the fish meat, a firmer consistency, less blood, and a longer shelf life compared to haddock that arrives dead at the facility.

Best quality from live-caught fish

And the differences in quality persist during storage. Even after 8 and 12 days, the fillets from haddock delivered live for processing still maintain superior quality.

“Current knowledge until now has been that rapid bleeding is the main principle for achieving good fish quality. This is not necessarily the case anymore," says researcher Torbjørn Tobiassen. 

He emphasises that bleeding is still important. However, the principle of keeping fish in good condition and alive until slaughter belongs in a completely different league when it comes to quality.

Main findings

  • Live-delivered haddock has less degradation of the fish meat, a firmer consistency, and less blood in the fillets
  • Longer shelf life of the products
  • Live-delivered haddock yields significantly higher quality products than regular haddock deliveries
  • Good welfare leads to high survival rates, which in turn leads to high quality and good yield
  • Vitality measurements are useful for assessing the welfare and survival chances of haddock
  • Correct oxygen levels and water supply are critical for survival
  • Weather conditions and catch depth affect the fish's vitality

“One fact is indisputable: You get the best quality from fish that are alive and minimally stressed at the time of slaughter. If increased quality of raw materials is the goal, live catch and/or live landing and live storage is the solution. The principle that fish must be well-treated to achieve top quality is broadly documented,” adds colleague Sjurdur Joensen.

Joensen is the editor of the Handbook for Live Catch and Live Storage of Fish, which was launched in August 2024.

“As the title suggests, the handbook provides an introduction to proper handling of fish that are to be kept alive. In other words, the path to good quality and welfare both in live catch and in ordinary fishing,” he says. 

High survival rates with proper handling

To achieve good survival rates and, consequently, high-quality haddock, researchers state it must be caught gently with small demersal seine nets. Demersal seining is a fishing method where a weighted net is dragged along the seabed to catch bottom-dwelling fish like haddock. 

“Boarding must be carried out quickly and gently. Fish that are damaged or exhausted should be sorted out. In the tanks, it's important to have a good supply of seawater. The most crucial factor for the haddock to survive during transport is to ensure a supply of clean, oxygen-rich water through the bottom of the tanks," says Torbjørn Tobiassen.

He also highlights the importance of adjusting the number of fish in each tank. During transport, most of the fish rest at the bottom of the tank. 

A simple method for better sorting

As part of the project on seine-caught haddock, researchers have tested various methods to determine which fish are suitable for live landing and which should be slaughtered on board. 

Perhaps the simplest and most effective method is to assess the haddock's eye reflex.

“A live haddock in good condition will adjust its eye. Typically, the eye looks downward when the fish lies on its side. A dead or reduced fish stares straight out, and it should not be selected for live landing,” says Tobiassen.

Significance for the industry

The design of new fishing vessels plays a crucial role in ensuring the highest possible quality of the catch. Fishing practices must also be adjusted to support the goal of live fish delivery.

Live delivery gives the industry better control over the slaughter process and allows for early filleting, which provides products of the highest quality. Early filleting involves filleting the fish before rigor mortis sets in. 

“Live delivery strengthens profitability throughout the entire value chain. Better raw material quality leads to fewer complaints and higher prices, which benefits fishermen, industry, and local communities alike,” says Torbjørn Tobiassen.

Reference:

Tobiassen et al. 'Catch and delivery of live haddock from demersal seine', Report from Nofima, 2024. (Summary) 

About the project

The project is funded by FHF - The Fishery and Aquaculture Industry Research Fund and carried out in collaboration with Båtsfjordbruket AS, Lerøy Norway Seafood AS, Gunnar Klo, Båtsfjord Central Freezer Storage, and the seine net vessel MS Julie Pauline.

More content from Nofima:

fisheries nofima partner fish natural sciences food
Powered by Labrador CMS