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Maldivian skipjack pole and line fishery catch rate standardization 2004-2010

Year of publication 2013

Product type Meeting

Edition 1

Statutory body / Meeting title Indian Ocean Tuna Commission (IOTC)

Meeting symbol IOTC-2011-WPDCS08-INF01

Meeting Session Number 8

Language English

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    Maldives skipjack pole and line fishery catch rate standardization 2004-2011: reconstructing historic CPUE till 1985 2013
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    A qualitative description and GLM-based standardization of the Maldivian skipjack (Katsuwo pelamis, SKJ) pole and line fishery catch rate data are presented for the period 2004-2011. The raw data consists of around 124000 records of catch (numbers) and effort (fishing days) by month, atoll and vessel; vessel characteristics were added to the CPUE dataset based on information from the registry of vessels. A subset of 56,698 records were extracted from the dataset, identified as records of fishing activity targeting skipjack. In the process, the paper discusses several data quality issues with the CPUE dataset, notably records with zero skipjack catch with a directed PL fishery and which were eventually discounted from the fil alysis. FAD data was also incorporated into the alysis using the number of active FADS associated with the nearest atoll that the landing data is collected from. In order to do this, the distribution of FADs was split into three regions incorporating the North Atol ls, Middle Atoll and South Atolls. Vessel specific data including hull-type effects, length of the boat (as a vessel size class) and horse power was also used in the alysis. GLM based models using a log response on CPUE were examined. The fil model presented estimated log(CPUE) from independent variables Year, Month, Area (N, S, or M), number of FADs used in the area, and Length of vessel, and interaction effects between the last 3 categories. The data was alysed at a monthly resolution before b eing was collapsed into quarterly sigls for 2004-2011. Filly, using vessel length as a continuous covariate, the CPUE data was estimated for historic periods till 1985.
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