Title: Stock assessment of shrimp, Pandalus borealis, in Skjálfandi bay northern Iceland

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The shrimp (Pandalus borealis) stock in Skjálfandi Bay northern Iceland is assessed in this report. Management and assessment methods of shrimp in Iceland are reviewed and suggestions for improvements are given for Sierra Leone. The analyses are based on time-series data of annual autumn surveys between 1991 and 2007 by the Marine Research Institute in Iceland. Length-frequency analysis was also conducted. Five age classes were identified and their proportions calculated using cohort slicing. Mean lengths corresponding to relative ages were estimated. Growth of P. borealis was modelled using non-linear minimisation to find the best fit according to the von Bertalanffy growth curve. Growth parameters estimated were L∞ =24.28 mm (carapace length), growth k = 0.46 and t0= -0.42. The dynamic production model from the commercial catches and autumn surveys from1988 to 1999 gave an average biomass of 2047 tons. Maximum Sustainable Yield per recruit was 1.42 g which corrresponds to Fmax = 1.97. Maximum Sustainable Yield = 566 tons and F0.1 = 0.72. The dynamic production model has advantages over the surplus production models generally used in Sierra Leone. A review of this model showed that it could be used to assess penaeid shrimps in Sierra Leone provided that scientific surveys are done which give a more reliable estimate of the abundance index than catch from commercial vessels. Data should be collected monthly or seasonally and because it is very expensive to conduct surveys, seasonal surveys should be done. Periodic collection of data, relating to selectivity, maturity, length and weight are a prerequisite for proper assessment of the shrimps of Sierra Leone. The economy of Iceland is to a large extent dependent on cod and the current management strategy is to enhance the cod stocks. This does not favour shrimp. Perhaps it is time to revise the current management strategy.

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