FIS015: Survival of post-catch Nephrops B

Start Date: Apr 2016

End Date: Oct 2017

Main Contractor(s): University of Stirling, SAMS

Other Sponsor(s): European Maritime and Fisheries Fund

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

Main Research Category: Discard Reduction - Technical

Final report now available here


Project Objectives

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, SIDI (1) the species identified to be good candidates for the definition of ‘Highly survivable’ include plaice, sole, dab and Norway lobster (Nephrops norvegicus). The present proposal 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.

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.

We believe results from this project will complement those from FIS07 (Nephrops survival trials conducted in the Clyde) as similar experimental methods will be used, although recovery times will be extended to deal with comments made by STECF in relation to other experimental results presented on Nephrops survivability by French and Portuguese researchers. Further data collection, working with current discards observer schemes (Objective 1), is required to examine links between damage sustained to Nephrops which will be discarded and catching conditions relevant to the Nephrops fisheries. This objective will be undertaken in collaboration with Scottish Fishermen’s Federation (SFF) discards observer programme. Further survival trials (Objective 2) are required that are specific to the trawl fisheries operating in the various areas. This objective will be firstly achieved for thwe west coast with the support of West of Scotland Fish Producers Organisation (WSFPO) and Mallaig and Northwest Fishermen’s Association (MNWFA). Close interaction with the commercial sector (please see letter of support from WSFPO) will ensure that vessels and practices used in the experimental design are relevant to the fishery studied. Further observations on the areas where discarding occurs and levels of scavenging of post-discard Nephrops (Objective 3) is a particular concern because survival trials conducted in protected environments, such as cages or tanks, may over-estimate true post-discard survival (3). Work is also proposed on the east coast Fladden Ground (4). This will utilise the knowledge gained from objective 2 in terms of whether survival trials are feasible using continuous monitoring in novel time-lapse camera survival systems. Otherwise more standard recovery in cages techniques will be applied. Finally, objective 5 will identify practical changes to current fishing operations that will minimise post-discard mortality and therefore ensure positive results should a survival exemption be granted.

The results from this project will be of benefit to Scottish fisheries and may support a potential request for a landing exemption for discarded Nephrops on the grounds of high survivability. To ensure data from this project is relevant from a policy perspective Dr Tom Catchpole, Chair ICES Methods to Estimate Discard Survival (editor on guidance to estimate discard survival) and a leading expert on discard survival at EU Scientific Technical and Economic Committee for Fisheries (STECF) forms part of team in this application.