Publication Abstract

Medium term simulations to answer the question: “Is the plan likely to achieve MSY by 2015?”

Medium term simulations to answer the question: “Is the plan likely to achieve MSY by 2015?”

J.A.A. De Oliveira*, T.J. Earl*, M.P. Parker-Humphreys* and C.D. Darby*

 

A common feature across all stocks is fishing mortality been driven to levels much lower than previously seen, because the imposition of TAC constraints (± 20%) pre-vents TAC increases from keeping pace with the rapid recovery that occurs as a result of the relatively low target F (0.4) of the management plans. A consequence is that in all cases for "standard" recruitment and for the way in which the stocks are currently assessed, fishing mortality has a high probability of reducing to Fmsy or below by 2015: 100%, 100% and 90% for North Sea, West of Scotland and Irish Sea cod, respec-tively. This reduces somewhat for "low" recruitment, but nevertheless remains high: 84%, 99% and 76% for North Sea, West of Scotland and Irish Sea cod, respectively.

When TAC constraints are removed, all stocks have a fishing mortality in 2015 that is closer to the target of 0.4, and higher yields in the case of "standard" recruitment, than when TAC constraints are imposed. This is also the case for "low" recruitment for North Sea and West of Scotland cod, but not for Irish Sea cod, where performance of the management plan in terms of both recovery and yield is poorer when TAC constraints are removed compared to when they are imposed. This implies that for a stock in poor condition, it may be beneficial to impose TAC constraints to prevent a harvest control rule from setting TACs too high based on inaccurate information, thus damaging the resource further.

 

In order to answer the question "Is the plan likely to achieve MSY by 2015?", simula-tions were carried using the MSE simulation framework previously used for an Im-pact Assessment of the HCR components (Articles 7 and 8) of Council Regulation (EC) 1342/2008 for West of Scotland and Irish Sea cod, and using a similar framework for North Sea cod. North Sea and West of Scotland cod have a high probability (>95%) of recovery above Blim by 2015 for both recruitment models ("standard" and "low") for the scenarios that correspond to the way in which these stocks are cur-rently assessed (bias in catch). This drops to 80% for "standard" recruitment and <60% for "low" recruitment for Irish Sea cod, because of the poor state of this stock.

Reference:

J.A.A. De Oliveira*, T.J. Earl*, M.P. Parker-Humphreys* and C.D. Darby* (2011) Medium term simulations to answer the question: “Is the plan likely to achieve MSY by 2015?” Annex 13, Report of the ICES WKROUNDMP2 2011 / STECF EWG 11-07. Evaluation and Impact Assessment of Management Plans PT II, 20 - 24 June 2011, Hamburg, Germany. ICES CM 2011/ACOM:56. 331 pp.

J.A.A. De Oliveira*, T.J. Earl*, M.P. Parker-Humphreys* and C.D. Darby*

Annex 13, Report of the ICES WKROUNDMP2 2011 / STECF EWG 11-07. Evaluation and Impact Assessment of Management Plans PT II, 20 - 24 June 2011, Hamburg, Germany. ICES CM 2011/ACOM:56. 331 pp.