Abstract
A comparative study of the growth of Nephrops norvegicus among different areas in the Mediterranean Sea and the adjacent Atlantic was conducted. MIX and Bhattacharya´s length-based methods were used for age determination. Both methods were used for all the studied areas. For the estimation of the growth parameters two non-linear methods, based on the results of the length frequency analysis, were used; the Gauss-Newton method, implemented by the SAS program, was applied using the results of the MIX and the FISHPARM program using the results of the Bhattacharya´s method. The identification of the age groups and their mean lengths-at-age as well as the estimation of the growth parameters proved to be difficult. A question regarding the adequacy of the von Bertalanffy model was also posed. Remarkable differences were obvious between sexes in the number of identified age groups and their mean lengths-at-age as well as in their growth parameters in all areas. The comparison of the results obtained for the studied areas showed differences, which could not be considered very important except in the case of the Nephrops population of the Alboran Sea, which was characterised by a high growth rate. All other areas seemed to be close; among them the populations from Euboikos Gulf and Catalan Sea being the most different.
Highlights
The age structure of a population and the growth parameters that characterise each stock constitute basic information for stock assessment
The objective of the present work was a comparative study of growth of N. norvegicus among different areas of the Mediterranean and adjacent Atlantic, using the same length-based methods for all the data
The monthly length frequency distributions of Nephrops norvegicus for the two years of sampling were examined for the various studied areas separately for each sex
Summary
The age structure of a population and the growth parameters that characterise each stock constitute basic information for stock assessment The estimation of these parameters in crustaceans is difficult due to the absence of permanent hard parts, where age can be registered. In such cases, length frequency analysis has often been chosen to estimate mean lengths-at-age and growth parameters It was assumed that any bias that could possibly be introduced by the length frequency analysis techniques used, and arbitrary decisions that such approaches require, will affect all the samples and the comparative aspects of the study will be valid. Sampling strategies were kept as similar as possible among the different areas
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
