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Assessment of Red Shrimp Stocks in the Spanish Trawl Fishery of Balearic Islands and Northern Spain

DESCRIPTION

This study evaluates the red shrimp (Aristeus antennatus) population exploited by the Spanish trawl fishery in the Balearic Islands (GSA-5) and Northern Spain (GSA-6). It includes an analysis of size-weight relationships, size at first maturity, and growth curves. Various methodologies, such as GLM standardized CPUEs and Separable VPA, are applied to assess fishing mortality and yield over time. Key recommendations include maintaining current fishing effort and adjusting mesh sizes to support stock conservation and reproductive capacity.

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Assessment of Red Shrimp Stocks in the Spanish Trawl Fishery of Balearic Islands and Northern Spain

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  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. Poblational characteristics Box-plot figures Size-Weight relationship Size at first maturity Von Bertalanffy growth curves GSA-5 GSA-6

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

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

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

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

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

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

  9. Surveys: GSA-5 (BALAR)

  10. CONCLUSIONS

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. RECOMMENDATIONS

  16. RECOMMENDATIONS • To not increase the fishing effort.

  17. 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,favouringmating and spawning process with temporal or spatial closed fishing seasons, zones or effort reduction during these processes.

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