Report of the Workshop on sexual maturity staging of cod, whiting, haddock, saithe and hake (WKMSGAD), 4-8 November 2013 San Sebastian, Spain

Type Scientific report
Date 2013
Language English
Ref. ICES CM 2013\ACOM:57
Other localization http://www.ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/acom/2013/WKMSGAD/WKMSGAD%20Final%20Report%202013.pdf
Author(s) ICES
Contributor(s) Bellamy Elise, Metral LuisaORCID
Note ICES WKMSGAD REPORT 2013 ICES ACOM COMMITTEE
Abstract The Workshop on sexual maturity staging of cod, whiting, haddock, saithe and hake (WKMSGAD) met on 4–8 November 2013 in San Sebastian, Spain. In total 15 partici-pants from 7 countries joined the meeting (List in Annex 1). The meeting’s purpose was to test the applicability of the maturity scales proposed by WKMSCWHS 2007 and WKMSHM 2007 and enhance the maturity stages’ descriptions. A further aim was the validation of the macroscopic maturity scales, to-gether with the identification of potential of staging errors, using histological investigations. Evaluation of maturity scales It was ascertained that the maturity scales, as proposed by the two WKs in 2007, have not been incorporated by all countries. Nevertheless most laboratories, succeeded in translating the national (or local) scale into the 2007 proposed scales. Changes in the maturity scale descriptions Stages’ descriptions were evaluated and some changes were made in the assessing criteria, based on participants’ expertise and experiences. The baseline of the new proposed maturity scales was the universal scale (4+2), valid across species and time, developed during the Workshop for maturity staging chairs (WKMATCH) in 2012. The new scale adopts the standardized terminology for de-scribing reproductive development in fish (Brown-Petersen et al., 2011) and introduc-es the term code instead of stage. The macroscopic descriptors were also revised in order to make the scale universal, i.e. suitable for all stocks. Consequently all the characteristics based on subjectivity, such as colour, size and presence/absence of blood vessels, were avoided as considered stock specific. Only objective and validated criteria were chosen by the group as stage descriptors. Concerning hake the group agreed on maintaining the stock specific criteria as indicative criteria. The modifications of the maturity keys do not have any impact on the currently estimated maturity ogives or on historical national time-series. Staging exercises (Three staging exercises were carried out: 1) using fresh fish; 2) using frozen gonads; 3) using pictures.) In fresh sample exercise conducted on hake, the group obtained 74% of agreement evidencing a decline in agreement compared to the 85.5% reached during the Work-shop on Sexual Maturity Staging of hake and monk (WKMSHM) in 2007. The agree-ment between visual inspection and histology was also 74%, highlighting inaccuracies in macroscopic maturity stage identification. In frozen sample exercise, conducted on cod, 61% and 53% of agreement was respectively obtained for females and males. In WebGR exercise, the percentage of agreement based on agreed stagevThe Workshop on sexual maturity staging of cod, whiting, haddock, saithe and hake (WKMSGAD) met on 4–8 November 2013 in San Sebastian, Spain. In total 15 partici-pants from 7 countries joined the meeting (List in Annex 1). The meeting’s purpose was to test the applicability of the maturity scales proposed by WKMSCWHS 2007 and WKMSHM 2007 and enhance the maturity stages’ descriptions. A further aim was the validation of the macroscopic maturity scales, to-gether with the identification of potential of staging errors, using histological investigations. Evaluation of maturity scales It was ascertained that the maturity scales, as proposed by the two WKs in 2007, have not been incorporated by all countries. Nevertheless most laboratories, succeeded in translating the national (or local) scale into the 2007 proposed scales. Changes in the maturity scale descriptions
Stages’ descriptions were evaluated and some changes were made in the assessing criteria, based on participants’ expertise and experiences.
The baseline of the new proposed maturity scales was the universal scale (4+2), valid across species and time, developed during the Workshop for maturity staging chairs (WKMATCH) in 2012. The new scale adopts the standardized terminology for de-scribing reproductive development in fish (Brown-Petersen et al., 2011) and introduc-es the term code instead of stage. The macroscopic descriptors were also revised in order to make the scale universal, i.e. suitable for all stocks. Consequently all the characteristics based on subjectivity, such as colour, size and presence/absence of blood vessels, were avoided as consid-ered stock specific. Only objective and validated criteria were chosen by the group as stage descriptors. Concerning hake the group agreed on maintaining the stock specif-ic criteria as indicative criteria. The modifications of the maturity keys do not have any impact on the currently estimated maturity ogives or on historical national time-series. Staging exercises Three staging exercises were carried out: 1) using fresh fish; 2) using frozen gonads; 3) using pictures. In fresh sample exercise conducted on hake, the group obtained 74% of agreement evidencing a decline in agreement compared to the 85.5% reached during the Work-shop on Sexual Maturity Staging of hake and monk (WKMSHM) in 2007. The agreement between visual inspection and histology was also 74%, highlighting inaccuracies in macroscopic maturity stage identification. In frozen sample exercise, conducted on cod, 61% and 53% of agreement was respectively obtained for females and males. In WebGR exercise, the percentage of agreement based on agreed stage (modal stage) was between 61% and 82% in all gadoid species. The histological vali-dation revealed an accuracy between 66% and 75%, except for males in whiting, had-dock and saithe where the agreement dropped to 51–55% evidencing inaccuracies in visual maturity stage assessment.
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ICES (2013). Report of the Workshop on sexual maturity staging of cod, whiting, haddock, saithe and hake (WKMSGAD), 4-8 November 2013 San Sebastian, Spain. ICES CM 2013\ACOM:57. https://archimer.ifremer.fr/doc/00213/32416/