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Assessment of red shrimp (Aristeus antennatus) exploited by the Spanish trawl fishery: in the geographical sub-area Balearic Islands (GSA-5) and Northern.

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Presentation on theme: "Assessment of red shrimp (Aristeus antennatus) exploited by the Spanish trawl fishery: in the geographical sub-area Balearic Islands (GSA-5) and Northern."— Presentation transcript:

1 Assessment of red shrimp (Aristeus antennatus) exploited by the Spanish trawl fishery: in the geographical sub-area Balearic Islands (GSA-5) and Northern Spain (GSA-6)

2 The assessments were made: -Separable VPA: determine mortality from a matrix of catch-at age, over tha assumption of constant exploitation pattern. -Extender Survivor Analysis XSA: focuses on the relationship between CPUE and population abundance. -Yield per Recruit analysis Y/R, from the outpus of the XSA.

3 Poblational characteristics GSA-5 GSA-6 Box-plot figuresSize at first maturityVon Bertalanffy growth curvesSize-Weight relationship

4 Landings Palma CPUEs Sampling on board GLM standardised CPUEs CALIBRATION: TUNING FLEET Santa Pola CPUEs Total daily catch by vessel

5 Generalized lineal model: CPUEs standization

6 GSA-5 Size distribution GSA-6 By sex Combined sex Catch at age Slicing Summed By sex Catch at ageWeight at age Combined sex Natural mortality and Age at first maturity

7 Combined sex Separable VPALowestoft Stock Assessment suite program (Darby and Flatman, 1994). Log catch residuals

8 GSA-5 Separable VPA Fishing mortality by age and year GSA-6

9 Log catchability residuals GSA-5 GSA-6 XSA Lowestoft Stock Assessment suite program (Darby and Flatman, 1994).

10 GSA-5 GSA-6 XSA Lowestoft Stock Assessment suite program (Darby and Flatman, 1994).

11

12 Y/R analysis from the XSA combined sex output GSA-5 GSA-6

13 Surveys: GSA-5 (BALAR)

14 MEDITS-ES Recruitment size<20 mm CL

15 CONCLUSIONS

16 The overall performance of the sex combined assessment fits the data well and seems reasonable with the sum of separate estimates of males and females XSA method.

17 CONCLUSIONS The overall performance of the sex combined assessment fits the data well and seems reasonable with the sum of separate estimates of males and females XSA method. Separable VPA and XSA give similar results.

18 CONCLUSIONS The overall performance of the sex combined assessment fits the data well and seems reasonable with the sum of separate estimates of males and females XSA method. Separable VPA and XSA give similar results. Combined sex results are more easily understandable assessment in order to apply management measures and give an improved perception of the status of the stock as a whole.

19 CONCLUSIONS The overall performance of the sex combined assessment fits the data well and seems reasonable with the sum of separate estimates of males and females XSA method. Separable VPA and XSA give similar results. Combined sex results are more easily understandable assessment in order to apply management measures and give an improved perception of the status of the stock as a whole. From the surveys abundance and yield fluctuated between years and it seems quite stable.

20 RECOMMENDATIONS

21 To not increase the fishing effort.

22 RECOMMENDATIONS To not increase the fishing effort. increasing the mesh size or changing to square mesh could contribute to increase the current Y/R Conserve the spawning capacity of the stock to reproduce, favouring mating and spawning process with temporal or spatial closed fishing seasons, zones or effort reduction during these processes.


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