A multitracer approach to assess the spatial contamination pattern of hake (Merluccius merluccius) in the French Mediterranean

Chemical contamination levels and stable isotope ratios provide integrated information about contaminant exposure, trophic position and also biological and environmental influences on marine organisms. By combining these approaches with otolith shape analyses, the aim of the present study was to document the spatial variability of Hg and PCB contamination of the European hake (Merluccius merluccius) in the French Mediterranean, hypothesizing that local contaminant sources, environmental conditions and biological specificities lead to site-specific contamination patterns. High Hg concentrations discriminated Corsica (average: 1.36 ± 0.80 μg g− 1 dm) from the Gulf of Lions (average values < 0.5 μg g− 1 dm), where Rhône River input caused high PCB burdens. CB 153 average concentrations ranged between 4.00 ± 0.64 and 18.39 ± 12.38 ng g− 1 dm in the Gulf of Lions, whatever the sex of the individuals, whereas the highest values in Corsica were 6.75 ± 4.22 ng g− 1 dm. Otolith shape discriminated juveniles and adults, due to their different habitats. The use of combined ecotracers was revealed as a powerful tool to discriminate between fish populations at large and small spatial scale, and to enable understanding of the environmental and biological influences on contamination patterns.

Campagne SELECT 13 N/O Gwen-Drez - Du 10 au 28 avril 1997

Influence of the nature of the twine on the codend selectivity: Reminder: During the “SELECT 12” campaign in April 1996, we demonstrated that the nature of the material used for the manufacture of the trawl codend has an influence on the selectivity. Results showed that the use of single twine made of polyamide in the codend was more selective on hake and Nephrops than single twine made of polyethylene. Nevertheless single twine made of polyamide codend loses “flexibility” with use and therefore a study should be done to investigate its impact on selectivity (fishermen do not often use this equipment: however this 150 mesh net is particularly selective and it would be premature to discard it). Influence of the diameter of the twine and the mesh number on the selectivity of codends: These results show the high variability of codend charactistics tested on hake. The parameters tested during this campaign - e.g., diameter of the twine and mesh number (length of codend) - influence the selectivity of codends. It seems that the capture volume and the length of the codend are essential for the selectivity, while the nature of the equipment is secondary. However each parameter should be investigated in a future campaign. Furthermore, any regulatory measure that would seek to suppress the use of double twine polyethylene codend would be premature. Perspective: further experiment should be considered with the standard polyamide codend of 32.5 mm. • An additional experiment with the 100 mesh and 65 mm polyethylene double twine test codend to determine the influence of the mesh number on the selectivity; • An additional experiment with the 100 mesh deep and 65 mm polyethylene double twine (4 mm diameter) test codend to determine the influence of the diameter of the twine on the selectivity.

Report of the Working Group for the Bay of Biscay and the Iberian waters Ecoregion (WGBIE). 13-19 May 2016, ICES HQ, Copenhagen, Denmark

The ICES Working Group for the Bay of Biscay and the Iberic waters Ecoregion (WGBIE) met in Copenhagen, Denmark during 13–14 May 2016. There were 22 stocks in its remit distributed from ICES Divisions 3.a–4.a though mostly distributed in Sub Areas 7, 8 and 9. There were 21 participants, some of whom joined the meeting re-motely. The group was tasked with conducting assessments of stock status for 22 stocks using analytical, forecast methods or trends indicators to provide catch forecasts for eight stocks and provide a first draft of the ICES advice for 2016 for fourteen stocks. For the remaining stocks, the group had to update catch information and indices of abundance where needed. Depending on the result of this update, namely if it would change the perception of the stock, the working group drafted new advice. Analytical assessments using age-structured models were conducted for the northern and southern stocks of megrim and the Bay of Biscay sole. The two hake stocks and one southern stock of anglerfish were assessed using models that allow the use of only length-structured data (no age data). A surplus-production model, without age or length structure, was used to assess the second southern stocks of anglerfish. No ana-lytical assessments have been provided for the northern stocks of anglerfish after 2006. This is mostly due to ageing problems and to an increase in discards in recent years, for which there is no reliable data at the stock level. The state of stocks for which no analytical assessment could be performed was inferred from examination of commer-cial LPUE or CPUE data and from survey information. Three nephrops stocks from the Bay of Biscay and the Iberian waters are scheduled for benchmark assessments in October 2016. The WGBIE meeting spent some time review-ing the progress towards the benchmark (see Annex 6) together with longer term benchmarks (2017 and after, see section 1.) for sea bass in the Bay of Biscay, all an-glerfish and hake stocks assessed by the WG. For the northern megrim stock, the sched-ule an inter-benchmark meeting was completed successfully and the group reviewed the outcome and accepted the category 1 update assessment. A recurrent issue significantly constrained the group’s ability to address the terms of reference this year. Despite an ICES data call with a deadline of six weeks before the meeting, data for several stocks were resubmitted during the meeting which lead to increased workloads during the working group, as in that case, the assessments could not be carried out in National Laboratories prior to the meeting as mentioned in the ToRs. This is an important matter of concerns for the group members. Section 1 of the report presents a summary by stock and discusses general issues. Sec-tion 2 provides descriptions of the relevant fishing fleets and surveys used in the as-sessment of the stocks. Sections 3–18 contains the single stock assessments.