| Themes |
Stock
|
| Name of the indicator |
Proportion of catches (numbers) by age
|
| Definition |
Catches are describe by proportion of landings (numbers) and discards (numbers) by age.
|
| Objectives |
Main objective is to analyse the reason of the discards. If all the discards are too young fishes, there is a size-selectivity problem. If not the problem is due to the market or prefered target species.
|
| View | |
| Calculation description |
We filter the FDI data for the specific species and list of statistical rectangles defined for the stock.
We get the number of landed and discarded fishes along the time series. We also get the total number of species landed and discarded. We divide the number of fhishes by age by the total number of fishes to calculate the proportion of
fhishes of each age in the discards and in the landings.
|
| Reading guide |
We get the proportion of the discards by age and the same time serie for the landings.
|
| Data sources |
FDI landings
|
| Comments |
|
| Query |
with part1 as
(select distinct age_val as ABSCISSE,value_type as GROUPE,sum(value) as TOTAL from age_data
inner join def_stocks_area using(species,reg_area)
where fishstock like 'ple.27.7e'
group by ABSCISSE,GROUPE)
,somme_par_groupe as
(
select distinct GROUPE,sum(TOTAL) as TOT from part1 group by GROUPE
)
select distinct ABSCISSE,GROUPE,100*TOTAL/TOT as TOTAL from part1
inner join somme_par_groupe using (GROUPE) order by ABSCISSE;
|
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