Migración de pescadores artesanales en la pesquería de pequeños peces pelágicos en África occidental: tendencias actuales y desarrollo

This study sought to present the evolutions and new trends of migrant fishing targeting small pelagics in West Africa from fishing to consumption stage. The work involved the characterization of migrant fishers targeting small pelagics in West Africa (country of origin, fishing gear and target species), modalities of access to resources, estimation of their catches and finally the assessment of the impact in the host countries. This work was useful to analyse changes in terms of the actors involved, the volumes and values of catches, and forms of valorisation and marketing of products from the migrant sectors over the period 2008-2018. Overall, the quantities of pelagic fish caught by migrant fishermen were increasing. The production of small pelagic by migrant fisheries has almost doubled over a decade, from an estimated of 180,000 t over the period 2008-2012, to a current estimated production of almost 324,500 t. More than 50% of this production was sold on the market in fresh or frozen form. More than 75,000 t (22%) and 94,000 t (28%) were destined for artisanal and industrial processing, respectively. Migrant fisheries thus supply more to industrial processing than to artisanal processing. Indeed, migrant fisheries have contributed over the last ten years to the emergence of fishmeal factories in West Africa. However, despite their significant evolution in terms of catch volumes and values, migrant fisheries still operate outside of legislative frameworks and without being explicitly accounted for in national statistics. Moreover, conflicts are increasingly important given the current tensions and issues surrounding the exploitation of small pelagic fish in West Africa. This work recommends the development of a common management plan for migrant fishers in the countries of the Sub-Regional Fisheries Commission (SRFC) and the West Central Gulf of Guinea Fisheries Committees (WCGC).Este estudio buscó presentar las evoluciones y las nuevas tendencias de la pesca migratoria dirigida a los pequeños peces pelágicos en África occidental desde los caladeros de pesca hasta los centros de consumo. El trabajo consistió en caracterizar a los pescadores migrantes que se dirigen a estas pesquerías en África Occidental (país de origen, artes de pesca y especies objetivo), presentando las modalidades de acceso a los recursos, estimando sus capturas y evaluando el impacto en los países anfitriones. Este trabajo permitió analizar los cambios en cuanto a los actores involucrados, los volúmenes y valores de las capturas, así como las formas de valorización y comercialización de los productos de los sectores migrantes durante el período 2008-2018. En general, las cantidades de peces pelágicos capturados por los pescadores migrantes están aumentando. La producción de las pesquerías migratorias de estos pequeños peces pelágicos casi se ha duplicado en una década, desde un promedio de 180.000 t durante el período 2008-2012, a una producción promedio actual de casi 324.500 t. Más de 50% de esta producción se vende en el mercado en forma fresca o congelada. Más de 75.000 t (23%) y 94.000 t (28%) se destinaron al procesamiento artesanal e industrial, respectivamente. Así, las pesquerías migratorias suministran más al procesamiento industrial que al procesamiento artesanal. Consecuentemente, las pesquerías migratorias han contribuido en los últimos diez años al surgimiento de fábricas de harina de pescado en África Occidental. Además, su contribución a las economías locales es cada vez más importante. Sin embargo, a pesar de su importante evolución en términos de volúmenes y valores de captura, las pesquerías migratorias todavía operan fuera de los marcos legislativos y no son contabilizadas explícitamente en las estadísticas nacionales. Además, los conflictos son cada vez más profundos dadas las tensiones actuales y los problemas que rodean la explotación de pequeños peces pelágicos en África occidental. Este trabajo recomienda el desarrollo de un plan de gestión común para los pescadores migrantes en los países de la Comisión Subregional de Pesca (SRFC) y los Comités de Pesca del Golfo de Guinea Centro-Occidental (WCGC)

Stock identification: advancing in the knowledge of stock structure as a requirement for stock assessment

DEMERSTEM- Objectives of WP 1: -Improve the knowledge on the selected demersal stocks with a particular effort to solve the problems of stock identification and improvement of the quality of the data used for the assessment. -This follows the recommendations regularly made by CECAF.Peer reviewe

Bonga shad (Ethmalosa fimbriata) key biological parameters variability under the effects of environmental changes

International audienceEthmalosa fimbriata (Bowdich 1825) is a small, often overexploited, pelagic fish species that occurs off tropical and subtropical coastlines. It constitutes the main catch of artisanal fisheries off the coast of West Africa. We examined growth rates and reproductive characteristics of E. fimbriata off The Gambia and other coastal areas to determine how they relate to variations in environmental characteristics of coastal waters. Using fish length-frequency data and a coastal upwelling index, it was found that recruitment of E. fimbriata tends to occur during periods of intense upwelling when nutrient-rich water is brought to the surface. The evolutionary trait of peak reproduction corresponds to low sea surface temperature periods. We hypothesize that E. fimbriata takes advantage of the higher zooplankton productivity in coastal waters when upwelling brings nutrient-rich water to the surface (i.e., it increases its growth rate and accumulates energy reserves for spawning). Growth performance appears to be intensely dependent on environmental conditions. The timing of spawning seems to occur when food (zooplankton) is most available to supply the energy requirements adults need for spawning and early development of larvae. Environmental changes seem to significantly affect E. fimbriata growth and reproduction, which endorses their high phenotypic plasticity

Observational study of vaccine efficacy 24 years after the start of hepatitis B vaccination in two Gambian villages: no need for a booster dose.

OBJECTIVES: To determine the duration of protection from hepatitis B vaccine given in infancy and early childhood and asses risk factors for HBV infection and chronic infection. METHODS: In 1984 infant HBV vaccination was started in two Gambian villages. Cross sectional serological surveys have been undertaken every 4 years to determine vaccine efficacy. In the current survey 84.6% of 1508 eligible participants aged 1-28 years were tested. A spouse study was conducted in females (aged 14 years and above) and their male partners. RESULTS: Vaccine efficacy against chronic infection with hepatitis B virus was 95.1% (95% confidence interval 91.5% to 97.1%), which did not vary significantly between age groups or village. Efficacy against infection was 85.4% (82.7% to 87.7%), falling significantly with age. Concentrations of hepatitis B antibody fell exponentially with age varying according to peak response: 20 years after vaccination only 17.8% (95% CI 10.1-25.6) of persons with a low peak response (10-99 mIU/ml) had detectable HBs antibody compared to 27% (21.9% to 32.2%) of those with a high peak response (>999 mIU/ml). Time since vaccination and a low peak response were the strongest risk factors for HBV infections; males were more susceptible, marriage was not a significant risk for females. Hepatitis B DNA was not detected after infection, which tested soley core antibody positive. An undetectable peak antibody response of <10 mIU/ml and a mother who was hepatitis B e antigen positive were powerful risk factors for chronic infection. CONCLUSIONS: Adolescents and young adults vaccinated in infancy are at increased risk of hepatitis B infection, but not chronic infection. Married women were not at increased risk. There is no compelling evidence for the use of a booster dose of HBV vaccine in The Gambia

Probability of remaining anti-HBs positive by time since vaccination and peak response for HBsAb.

<p>Table shows number at risk, number of subjects with undetectable HBsAb (HBsAb <10), and the percent of subjects with detectable HBsAb (HBsAb>9) at 0, 5, 10, 15, 20 and 23 years post-infant vaccination, by HBsAb peak response category (10–99, 100–999, >999).</p

Probability of remaining uninfected (as determined by lack of anti-HBc) by time since vaccination and peak response for anti-HBs (1256 individuals).

<p>Table shows number of subjects at risk, number of subjects with HBV infection, and the percent of subjects remaining uninfected at 0, 5, 10, 15, 20 and 23 years post-infant vaccination, by HBsAb peak response category (<10, 10–99, 100–999, >999).</p

Decrease in antibody to hepatitis B surface antigen (anti-HBs) by time since vaccination, and peak anti-HBs response (mlU/mL).

<p>Decrease in antibody to hepatitis B surface antigen (anti-HBs) by time since vaccination, and peak anti-HBs response (mlU/mL).</p

Risk factors for HBV infections.

<p>The analysis includes 1040 subjects; 211 out of the 1251 subjects were missing information on peak bleed.</p

Frequency of HBV infection and chronic infection in 2008, by age group and village, among all vaccinated subjects (regardless of peak bleed).

<p>Frequency of HBV infection and chronic infection in 2008, by age group and village, among all vaccinated subjects (regardless of peak bleed).</p