• Fishermen sorting catch of Nephrops norvegicus
    Nephrops Survival II

Nephrops Survival II

Post-catch survivability of discarded Norway lobsters (Nephrops norvegicus): Further investigations within the large-scale fleet operation

Background / overview

The aim of the reformed Common Fisheries Policy (CFP, Regulation (EU) 1380/2013) is the sustainable long term exploitation of living marine biological resources at levels which contribute to beneficial environmental, economic and social conditions. A key element is the encouragement of more selective fishing strategies through the introduction of a landing obligation, colloquially termed ‘discards ban’.

Within the reformed CFP there are some allowable exemptions to the requirement to land all catches subject to quotas. One of these exemptions is for those species where evidence indicates high post-catch survivability. This is a sensible measure in that landing these species to port would only increase overall fishing mortality and lead to additional disposal costs for no real conservation benefit.

According to a recent report from the Scottish Industry Discards Initiative the species identified to be good candidates for the definition of ‘Highly survivable’ include plaice, sole, dab and Norway lobster (Nephrops norvegicus).

This project is focused on Nephrops and builds on a previous project funded by FIS conducted by the same consortium which generated new data on survival of discarded Nephrops. Previous work undertaken in FIS07 indicated a high post-catch survivability of this crustacean species after a 48h recovery period in tube-sets (2). However, this study was undertaken in a trawl commercial vessel that mainly targeted the live Nephrops market, which is characterised by relatively short hauls and low volume catches so that data based on this fishery cannot be translated to other larger-scale Nephrops fisheries such as those operating on the Scottish west or east coasts. 

 

Role of SAMS

Field-work

Laboratory recovery trials

Data analysis and report writing

The specific aim of this proposal is to determine the post-catch survivability of discarded Nephrops within west coast trawl fisheries operating in the Minches and the east coast Fladden Ground, taking seasonal differences into account.

This aim will be achieved through the following objectives:

  1. Collect additional data on the condition of discarded Nephrops including damage levels, in relation to gear type, discard locations, tow durations, catch weight and other environmental and on-board relevant causative factors that can affect survivability and which are applicable to the West of Scotland Nephrops commercial fishery.
  2. Conduct survival trials on discarded Nephrops from the Minches fishery in a similar manner to the survival trials conducted in 2015 in the Clyde (FIS07). However, in this case survival will be assessed for a longer period of time to allow mortality to stabilise (estimated at around 15 days) using less restrictive recovery cages so allowing for more natural behaviour than in FIS07, also ensuring that animals are not restricted to the point that tube-sets have an effect on survival. Furthermore, additional tank experiments will be conducted to complement survival trials performed in the marine environment.
  3. Further investigate post-discard behaviour of Nephrops and interactions with potential predators in the Minches following different controlled on-board practices (for logistical reasons this objective is unlikely to be feasible for the east coast study).
  4. Propose relevant changes to on-board operating practices which may increase post-discard survival (related to minimising damage and aerial exposure of discards).
  5. Using the most practical and feasible way determined in objective 2 to conduct a set of survival trials in the East coast.