Atlas Halieutique
Themes Stock
Name of the indicator Proportion of discards by rectangle
Definition Discards are describe by proportion of estimated discards by reacangle
Objectives Main objective is to analyse a spatial distribution mainly based on landing. The estimation is a starting point for the discussion.
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Calculation description We filter the FDI data for the specific species and list of statistical rectangles defined for the stock. We calculate amound of discards with landing by rectangle and discard ration by sub area. Then we can estimate discards by rectangle for the stock. We also a total value of estimated discard for the stock. Finaly we divide the discards by rectangle by the total discard to get a proportion of discards in each rectangle.
Reading guide We get the proportion of the estimated discards by rectangle.
Data sources FDI landings and discards
Comments
Query with part1 as ( select distinct country,annexe,A.reg_area,reg_gear_cod,species,year_d,rectangle,english_name,reg_gear,sum(A.landings) as landings,sum(discards)/(sum(discards)+sum(B.landings)) as tx_discards from landing_rect_sd A inner join discard_landings_sd B using(country,annexe,reg_area,reg_gear_cod,species,year_d,vessel_length,reg_gear,specon) inner join def_stocks_area using (species,rectangle) left join asfis on (species=a_code) where fishstock like 'bss.27.4bc7ad–h' and year_d=2015-1 and discards>0 group by reg_gear,country,annexe,A.reg_area,reg_gear_cod,species,year_d,rectangle,english_name order by year_d,sum(A.landings) ), part2 as ( select country,annexe,reg_gear_cod,species,year_d,rectangle,english_name,landings,reg_area,case when tx_discards=1 then 0.99 else tx_discards end as tx_discards from part1 ) ,part4 as ( select distinct rectangle as LIEU,sum(((1/(1-tx_discards))*landings)-landings) as TOTAL from part2 left join countries using(country) group by LIEU ) select distinct lieu,100*TOTAL/TOT as VAL from part4, (select sum(TOTAL) as TOT from part4) T1 where 100*TOTAL/TOT>0.05

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