Scientific ResearchThe Lyme Bay Potting Intensity Project
The increase in potting effort occurring in the Lyme Bay area since the 2008 mobile gear closure has resulted in concerns being raised by local fishermen over the impacts on target species and on seabed biodiversity. If the working group is to develop a sustainable potting management plan a better understanding of appropriate effort levels and their effects on target species and seabed species needs to be developed.
An experimental potting study has been designed by researchers at Plymouth Marine Institute that will address these questions. The study will work closely with fishermen in the design and maintenance of the experimental areas and in collecting fisheries data. This collaborative fishery research project has been designed in such a way that each of fishing ports in the Reserve (Beer, Axmouth, Lyme Regis, West Bay) will have ownership over their own experimental areas. This approach is key to the success of the study as the researchers will rely on fisherman to maintain and control levels of potting activity.
The study will run over 3½ years and establish a series of 16 experimental areas in which potting effort reflects real world fishing patterns; no potting (no take), low density pots, mid-density pots and high density pots (Figure 2). Potting intensity will be maintained by fishermen from each port who will also keep the no potting/no take areas under surveillance.
Each of these experimental areas will be surveyed using traditional and high-tech methods:
- Towed underwater HD video transects will be undertaken using novel non-destructive high-definition video sampling gear developed by the Marine Institute. This gear consists of a floating frame equipped with HD camera equipment that is towed behind a boat, flying just above the seabed. This approach enables the array to float over rocky ground and fragile species. The footage from the HD video transects are used to assess seabed biodiversity including the key species of importance such as pink sea fans.
- Baited Remote Underwater Video (BRUV) surveys will record quantitative data on the mobile species in each experimental area. For these surveys the HD video cameras are mounted on frames and deployed to the seabed with a portion of bait fixed in the camera field of view. Footage from the HD cameras are used to document the species attracted to the bait (e.g. fish, molluscs and crustaceans).
- Quantitative experimental potting surveys will be undertaken in partnership with fishermen from each port. This survey will collect data on commercial target species and will complement the baited video surveys. Working on board commercial fishing vessels researchers from the Marine Institute will work alongside fishermen to record and data on commercially important crab and lobster species.
Fishermen's Environmental Monitoring Pilot: Exploring the Role of Fishermen in MPA and Environmental Monitoring
The evidence and data requirements for the designation and subsequent monitoring of MPAs place significant logistical and economic burden for official bodies. The fishing industry can play an integral role in marine monitoring and evidence collection using underwater video surveys as a model. Collaborative surveys are shown to have mutual benefits in terms of cost and efficiency savings, knowledge transfer and relationship building. This is how we went about it.
The video equipment was set up and tested on board the fishing vessel while at the mooring, providing a chance for some training on the survey methodology and familiarisation with the kit. A small generator was used to power the camera and topside unit and was secured in a sheltered position on deck. The topside unit was positioned on a raised section in the centre of the deck, and the camera equipment was operated from the stern.
The procedure at each survey station closely followed the Seafish SOP guidance instructions and the video log form was filled out. Key tasks were delegated, with the vessel crew in charge of deployment and recovery of the sledge and the adjustment of lights, cameras and scaling lasers. Plymouth University students operated the topside control unit and completed the video log at each site. Whilst the tow was in progress, all present observed the footage, participated in identification of species and interpretation of habitat type.
Initially the sledge was deployed from the starboard side of the vessel, but it became apparent that it was easier for the skipper to control the speed if it was flying from the stern. Once this was altered, deployment was easy and worked well, allowing the skipper to maintain position and a slow speed. Conditions deteriorated throughout the day, with the wind increasing, causing sea state to worsen. Despite this, it was possible to complete sufficient transects. Conditions were very calm on day two, allowing the remainder of the survey to be completed and some exploratory tows to be conducted at sites of interest to the crew.
A total of 12 video stations were worked recording in excess of 2 hours of seabed footage over the 2 days of survey. Basic analysis has been conducted, with more detailed analysis to be completed at a later date by Plymouth University students, NE staff and Southern IFCA staff. Video analysis conducted to date has identified the habitat types present and produced species lists for each site for conspicuous species. Table 1 shows a summary of the habitat type and list the most abundant species at each site. Sites 1-6 were in the area where confidence in the reef habitat data was low, and fishing permitted for all static gear vessels, and those mobile gear vessels fitted with iVMS, and sites 7-12 those in the sensitive reef area closed to fishing with mobile gear.
Fisheries Advice by Cefas for the Lyme Bay Fisheries & Conservation Reserve Project
Cefas has been approached to give advice on certain areas relating to the management of the fisheries in this area. Given the nature of this project and what it hopes to achieve the current requirement is for the Working Group to be able to a) ascertain what state the fishery is currently in, b) Know what options are available to management, and what the effect these options would have on the fishery and population, and c) how to monitor the situation in the future in order to implement an effective adaptive management approach.
Proposed Advice from Cefas
Cefas would be happy to provide advice to the Working Group, and can provide guidance on all the areas mentioned above. The Working Group would thus benefit from a detailed account of the current effort in the area, an overview of the various management options available and the likely effects of adopting them, and also a range of options detailing how to monitor the stock in the future. Details for each element of this work are given below:
1.1.1 Effort Analysis
Question: Anecdotal reports from local fishermen, IFCA sightings data and MMO VMS data all indicate that potting effort has dramatically increased since the 2008 closure. What is not apparent is whether this increase in effort is affecting the target stocks or is sustainable in the long-term.
Proposal: Cefas will analyse data from the Fishing Activities Database (FAD) which contains data relating to landings and effort. The aim would be to produce and analyse relevant trends of effort, landings and LPUE (Landings Per Unit Effort) to ascertain whether these support the perception of a dramatic increase in effort. If vessel details can be given by the local relevant authority this analysis will be disaggregated by: Local boats.
Those from adjacent ports.
Larger >15m vessels working in the area.
The data will also be analysed to ascertain whether the trends are indicative of the fleet as a whole, or biased by a small number of vessels. These analyses will be used to provide background to the current status of the area.
1.1.2 Fisheries management options
Questions: The fishermen of the Working Group have already committed to developing a voluntary Static Gear Code of Conduct which includes a variety of effort limitation measures. In order that their voluntary Code and future local regulations are well informed the Working Group would benefit from an analysis of potential management measures that identifies the most effective. Also lobster stock enhancement has been proposed by some members but before investment is made in this area the project requires an assessment of its efficacy.
Proposal: Cefas will conduct an analysis of potential management options to provide an indication of the likely relative effects (gains and losses) on yield and egg production for the population in place. This will be achieved by creating a generic inshore fishery model and reporting the effects on the stock when subjecting it to changes in the MLS, v-notching, berried bans and gear limitation. Previous work on lobster stock enhancement will be reviewed to give advice on the suitability of this approach to this area and project.
1.1.3 Monitoring programme designs and recommendations
Question: The project is adopting an adaptive management approach and therefore requires timely feedback on the performance of the management measures and regular updates on the fishery and population state. As Cefas have expertise in developing monitoring programmes and large scale experiments Cefas could propose cost-effective but effective approaches that would enable the gathering of relevant information.
Proposal: Cefas will provide a list of potential methods for monitoring the fishery and population. Such methods will include logbook schemes, observer estimates of catch and industry led scientific surveys. These methods will be assessed for suitability for future usage, and the pros and cons of each discussed. Baring-in-mind the cost effectiveness of each method, Cefas then advise on the suitability of the methods to this particular project. Cefas will also liase with Plymouth University to ascertain whether any collaboration would be possible, linking their scientific studies in the area to the proposed monitoring scheme, which could benefit both parties. Please note that although advice can be given by Cefas on a number of options, the final implementation of a monitoring method will need to be agreed by the Working Group based on not only the scientific integrity, but the financial and logistical state-of-play at the time.