Lotte Worsøe Clausen, a specialist consultant at the National Institute of Aquatic Resources, gives an update on the Danish case study’s progress. The aim of the study is to develop a tool which both industry, stock-assessors and managers can use to predict the behaviour of the Western Baltic Herring stock, under a range of management scenarios.
“We’re trying to come up with a tool which can predict the migration, growth and ‘production’ of the Western Baltic Spawning Stock (WBSS) of herring. This tool will then be built into the assessment model and in turn used in the Management Strategy Evaluations (MSEs). The results of the scenarios defined by the industry and managers will then form the basis for a Long Term Management Plan (LTMP) for WBSS in the Western Baltic and Skagerrak-Kattegat. Such a LTMP will help resolve many hard political trade-offs and make the fishery more predictable and stable.
In turn, this will make it easier to manage the fishery sustainably.”
“Our overarching achievement so far has been to lay a common ground for a Long Term Management Plan (LTMP) for the Western Baltic Herring Stock. A wide range of stakeholders (industry, management, science, NGO’s) agreed, that the objectives of any LTMP were that the plan should be Specific, Measureable, Achievable, Realistic and Time-limited (SMART); it needs to be simple to grasp by all stakeholders and the most important objective to aim for is a high and stable yield based on a sensible “F” (fishing mortality rate).
This debate resulted in set order of priorities for LTMPs, agreed on by all stakeholders:
- High and stable yield
- Flexibility between IIIa and North Sea in terms of TAC usage
- Balanced allocation of fishing opportunities between 22-24 and IIIa
- Fishing at MSY
Given the priority to the more politically delicate features of a LTMP for Western Baltic Spring-spawning herring, the case study is developing results along two lines now: “Management and Model” as an alternative to the more usual ‘first data, then model and then management’ approach used when developing LTMPs.
During the past 6 months, the case study has been a part of one large scale workshop, and has held three small scale meetings between the lead scientist and stakeholders, and one debate at a RAC meeting. A very significant result is that the common ground and perception of what is to constitute the LTMP (from Workshop 1, November 2011) withstood the test of thorough debate among a wider group of fishery and science stakeholders during the workshop held in February 2013.
This workshop also confirmed the importance of the more political related parts of the management defined as the division of the catch opportunities between SD 22-24 and Div. IIIa as identified in Workshop 2, April 2012. Fishery stakeholders are taking the lead in reaching a common base for the TAC share and flexibility across management areas, which then can be fed into a stochastic MSE setup.
For the Model part, the case study has now gained a solid knowledge of the biology of the herring and a detailed insight in the data available for the model. A pre-requisite for the Management Strategy Evaluation (MSE) modelling exercises is to have a common perception of the stocks, their exploitation patterns and their relative importance to the herring fishery and the preservation of biodiversity in a changing climate.
The accuracy and historical availability of data can vary. But because precise data is a prerequisite for the model, stakeholders are checking data quality using historical knowledge, logbooks and ‘grey data’.
Accordingly, we now have quality ensured input data on catch compositions regarding the spatial distribution of the major herring stocks.
These results have led to the first stages of defined migration pattern for the various life stages of the major herring stocks based on historical data (10 years).
Furthermore, the case study has managed to get a description of the fleet behaviour in relation to the defined migration patterns of the major stock movements and the related economic priorities set to maximise the value of the fishery.
The modelling of stock components to improve the statistical evaluation of the migration patterns of the herring stock components – and thus their availability to the defined fishery pattern – has been fine-tuned as part of the case study.”
Previously, attempts to engage both (EU) Member State and non-member States in debating Total Allowable Catch (TAC) share and geographical flexibility were unsuccessful. So over the next 6 months, fisheries stakeholders from all member states will propose commonly agreed management measures to their Norwegian counterparts. If successful, these suggestions will result in a common ground and will be used in the final MSE modelling exercises. This will in turn act as background for the recommendation of alternative methods to set a TAC for herring.
During the next 6 months, we will also continue the formation of a corrected input data set in terms of catch allocation and separation of the different herring stock components. We anticipate presenting a final model of the spatial and temporal resolutions and distribution of stock components, thus improving the statistical evaluation of the migration patterns of the herring stock components. It is the suggested rules for TAC share and flexibility suggested by the Stakeholders to their Norwegian counterparts, which we’ll be using when running simulations of the MSE.”