DATA-LIMITED MIXED FISHERIES TARGETING DATA-POOR SPECIES: THE ARTISANAL PURSE-SEINE FLEET IN THE CANARY ISLANDS

In waters off The Canary Islands, small pelagic fish are targeted by an artisanal purse seine fleet. This fishery has been monitored within the EU Data Collection Framework since 2013. The status assessment of the most important commercial species (i.e. Scomber colias, Trachurus spp, Sardinella spp and Sardina pilchardus) are included in the Fishery Committee for the Eastern Central Atlantic (CECAF). However, the short time series and the limited knowledge of the life history traits of these species in the Archipelago had been considered too limited to perform any assessment exercise. In this context, a multi-model approach was attempted to assess the status of these species for the first time in the area, using the methods recommended by CECAF and the International Council for the Exploration of the Sea (ICES). Time series of landings and fishing effort includes data since 2009 to 2020, being less reliable at the beginning of the series. In addition, the biological and population information needed as input data in those models, are available depending on the species, this increasing the uncertainty of these analyses. A total of six data-limited (length- and catch-based) methods was applied. Results show that a quantitative assessment of the Canaries small pelagic stocks, with the final aim of providing scientific advice for management purposes, is not yet feasible. Therefore, it is necessary and urgent to address the current uncertainties around these species and fisheries, both by improving the knowledge of their life histories and by solving the shortfalls related to the data of this artisanal and multispecific fishery

Towards effort quantification through VMS and observers' data: the case of shrimps trawlers in Mauritanian waters

The Spanish shrimp trawlers is one of the most important fleets operating in Mauritania. They target 3 species: -Penaeus notialis (at 20-80 m depth) -Parapenaeus longirostris (at 100-350 m depth) -Aristeus varidens (at 400-800 m depth) in 3 types of fishing operations that can be carried out during the same day. A critical challenge is to define suitable metrics of effective fishing effort since logbooks only provide information of catches by day. Accurate CPUE obtained from these vessels could be considered good abundance indices of its target stocks, which is of paramount importance for assessment purposes. The objective of this analysis was to use Vessel Monitoring System (VMS) information to robustly infer fleet activity as well as estimate units of effort directed to each of the three target species of the Spanish trawlers operating within the EEZ of Mauritania. The estimates of trawling effort by target species obtained from VMS data show consistency in both values and temporal trends with those registered by observers on-board. The adoption of a consistent method for analysing VMS data will help to ensure that calculations of trawling effort are repeatable and comparable among studies

Disentangling the influence of fishing, demography and environment on population dynamics of Iberian Peninsula waters fish stocks

Overexploitation and climate change are increasingly causing unanticipated changes in marine ecosystems such as higher variability in fish recruitment or shifts in species dominance and distribution that alter the productivity of fish stocks. This study analyses how external and internal drivers influence population dynamics of hake (Merluccius merluccius), white anglerfish (Lophius piscatorius), four-spot megrim (Lepidorhombus boscii), and horse mackerel (Trachurus trachurus) of Iberian Peninsula waters of the Northeast Atlantic across different spatiotemporal scales. Available spawning stock biomass and recruitment have been used as biological data, whereas fishing mortality, demographic data as well as climatic and oceanographic data have been used as drivers. The obtained results indicate that population dynamics of these species are mainly driven by oceanographic variability at regional scale along with fishing pressure and demographic factors, while the impact of large-scale climate indices was minimal. The identified variables represent relevant oceanographic regional processes candidate to be potentially integrated into the stock assessment models and management procedures of these important fishery resource

EVALUATION DU STOCK DE LA SARDINELLE RONDE ZONE NORD – OUEST AFRICAINE PAR LA MÉTHODE CMSY

Le taux élevé en protéine et en graisse font de cette espèce le choix privilégié des fariniers depuis 2013. Malgré, l’augmentation de l’effort de pêche, les captures ont commencé à chuter depuis 2014 annonçant ainsi le début de la surexploitation de ce stock. Du fait de la discontinuité des séries d’indices d’abondance pour la sardinelle, le modèle de surplus de production utilisé antérieurement pour fournir un avis de gestion n’a cette année encore pas pu être appliqué. Afin d’estimer les points de référence pour la sardinelle, de donner un diagnostic sur l’état des stocks, une approche basée sur les données de captures uniquement, CMSY (Froese et al. 2017), a été considérée. Depuis 2016, le stock de la sardinelle ronde n‘a pas été évalué par le groupe COPACE faute de données. Cette situation de manque de données fait de cette espèce un stock à données limités d’où le choix du modèle CMSY

Discards from a deep-sea shrimp fishery in Angolan waters (SW Africa)

A programme of observers on board Spanish shrimp trawlers in Angola was initiated by IEO in 2018 in order to improve the scientific information required by Sustainable Management of External Fishing Fleets (SMEFF Regulation of the EU). In this context, discard studies are considered very relevant, both for assessment purposes and for obtaining information on adverse ecological impacts in marine ecosystems. Most fishing hauls performed during the observed period November 2018 to December 2019 were carried out at depths between 384 and 649 m, with classic bottom otter trawl targeting the striped red shrimp Aristeus varidens. Discards accounted for 60% of the total catch during the analysed period. The estimated global discard rate for 2019 (2.2 discard/retained catch) indicates that 1915 tonnes of retained catch produced 4213 tonnes of discards, of which a small amount is of commercial species, as A. varidens (3.8 tonnes) and Merluccius polli (153 tonnes). A total of 131 discarded species were identified, with the highest group contribution being fish (70%), followed by crustaceans (20%). The most abundant species in discard weight were Ariomma melanum, Lamprogrammus exutus, Chaunax pictus, Centroscymnus owstonii, Hoplostethus cadenati, Lophius vaillanti, Yarrella blackfordi and Ariomma bondi (all together accounting for 55% of discards). The most frequent species were H. cadenati and L. exutus, discarded in 95% of the analysed fishing hauls. Discards estimations of commercial species obtained through a long-term observers program might result in improving the assessments of main commercial species from Angolan deep sea waters

Biólogos-Observadores a bordo, una Ventana a la Información Pesquera

Informe de Divulgación del Proyecto “Estimación del Descarte de las Flotas de Arrastre Españolas en las Áreas VI, VII, VIII y IX del ICES y Mediterráneo. Aproximación al descarte total por Métier. Optimización del proceso de ponderación”. (IBDES)

Growth of the deep water rose shrimp Parapenaeus longirostris in Mauritanian waters (NW Africa)

The deep water rose shrimp Parapenaeus longirostris is the main target species of a Spanish fleet of shrimp bottom trawlers operating in the Mauritanian EEZ. The life history of this species is well known in north eastern Atlantic and Mediterranean waters, while the information is quite limited for the eastern central Atlantic. Biological samplings of the species were conducted by scientific observers onboard this fleet, from catches obtained during 17 fishing trips performed between March 2014 and June 2019. The carapace lengths (CL) of 91662 specimens (54% females and 46% males) were grouped in 33 monthly length frequency distributions. For the study of the length–age relationship, the Von Bertalanffy Growth Function (VBGF) was fit to the monthly length distributions by using the ELEFAN I routine followed by separating the frequency histograms into normal components through the Bhattacharya’s method and the NORMSEP routine. These analyses were carried out separately for males, females, and combined sexes, using the FISAT II automatic calculation program. CL of females and males ranged from 11.6 to 39.2 mm and 10.5 to 30.5 mm, respectively. Three and five modal components (annual cohorts) were identified for females and males, respectively. The growth function estimated parameters were CL∞=41.74, k=0.51 for combined sexes, CL∞= 41.67, k= 0.51 for females and CL∞= 32.24, k=0.84 for males. Estimated growth performance indices were around 2.95 for combined sexes, females and males. The estimated parameters may be used as input to test length-based methodologies for the assessment of this data-limited stock, for which only production models have been used so far