Final report to the Caribbean Fishery Management Council on project “Priority 1 to improve understanding of queen conch conversion factors by reanalyzing existing data”
The queen conch databases (number and weight of individuals per % meat processing category) from 7 Caribbean countries were re-analyzed in order to validate the statistical databases used to estimate conversion factors.
Regression and covariance analyses were used to classify the information used in the % clean meat weight conversion factor estimates. The results of the statistical analyses showed that the shell weight of the queen conch is not a good predictor of dirty meat weight a conclusion supported by a low statistical significance of shell weight as a predictor of dirty weight. Analyses and results show that dirty weight data best correlates with different levels of % clean meat processing.
These results are important for the estimation of live weight conversion factors (shell weights + tissue weights), which will introduce a large and significant variance due to the greater variance of shell weight relative to meat weight variance. The averages of the total dirty weights expanded from corresponding % clean meat levels using the corresponding mean CFs for the categories estimated in this study always resulted in total weight values greater than 99% of the original dirty weight observed in the samples. A mean regional conversion factor for live weight (i.e. shell weight + tissue weight) from dirty weight was 5.36, which is similar to that estimated in FAO (2014). A new regression method was developed to estimate conversion factors based on queen conch morphometry, which allows the application of conversion factors by individual size frequencies in the different categories of % clean meat of juvenile and adult queen conch.
To accompany this report, the authors have also developed a worked example to estimate the conversion factors for queen conch meat products, based on the regression methods of Ehrhardt and Perez (2019). The worked example is available (in English and Spanish) in .xls format at the following link: