The solution is as simple as it is effective – doubling the number of escape holes from four to eight to catch larger male crabs while the smaller and female animals are released.
Crab fisherman Erling Haugan and Nofima crab researcher Sten Siikavuopio have been looking at the options for making crab traps so that the meaty male animals are retained while the smaller crabs and females can escape, and adjusting escape holes appears to be the answer, according to the report that has now been made available.
This straightforward solution of providing more effective escape routes could result in better yields, better management of the crab stock and better animal welfare.
‘The point is to catch the male crabs, while the female crabs and small crabs are released again,’ said Nofima senior researcher Sten Siikavuopio.
King crab is important to both fishermen and the seafood industry in Finnmark. Norway exported 2500 tonnes of king crab worth NoK1.2 billion in 2023. However, due to challenges in maintaining the stock, quotas have been sharply reduced in recent years.
‘Developing fishing technology that better contributes to preserving the population has therefore been imperative,’ said Sten Siikavuopio.
Today, only collapsible single-chamber traps are used for catching king crab on the Finnmark coast. Even with escape routes in the crab pots, it is not uncommon for up to 80% of the catch to consist of undersized crabs, which must be sorted out.
‘The entire catch is lifted on board, where small crabs are sorted out of the catch and returned to the sea. Sorting and handling the crabs leads to impact injuries and crushing injuries. In addition, injuries can occur when the king crabs are thrown into the sea by fishermen. During the actual lifting of the pots, some crabs will also get caught in the mesh. This leads to a higher risk that crabs can lose a leg or a claw,’ he said.
‘Sorting on board is also labour-intensive and time-consuming. So it’s preferable to sort out as many undersized crabs as possible while fishing at sea and not on deck.’
The goal of the research was to compare and document the effectiveness of commercial king crab traps that have four legally required escape routes – selection rings – compared against king crab traps with twice as many opportunities for female crabs and small crabs to escape.
‘A sustainable fishery for king crab starts with a fishing gear that does not harm the stock and that fishes selectively on size. A not uncommon situation today is that a commercial king crab trap with a legally required escape route can have up to 200 kilograms of undersized crabs,’ he said.
‘We also see that the proportion of injured crabs and the proportion of female crabs is higher in the traps with four selection rings compared to those with eight.’
For fishermen, traps with multiple escape routes are preferable. Erling Haugan has contributed to Nofima’s field research for many years and in several projects. Together with colleagues at Bugøynes in East Finnmark, he has for several years seen a tendency for today’s crab pots to have poor selection. The conclusion for both the fisherman and the researcher is therefore that today’s pots, with current regulations, can be made more sustainable by increasing the number of escape routes from four to eight.
‘This way we can improve the fishing gear so that it is possible to sort out undersized crabs before they are taken on board the boat and damaged,’ Erling Haugan said.
‘Another important factor in increasing the number of escape routes is that the proportion of large crab will increase and we will spend less time sorting the crabs on deck. In this case, we will have a win-win situation where we take care of the resource in a sustainable way.’
