Bioeconomic analysis of Engraulicypris sardella (USIPA) in South east arm of Lake Malawi

Usipa Engraulicypris sardella is the most abundant small pelagic species in Lake Malawi. It plays an important part in the lake communities’ economy and food security. However, much remains unknown on their stock status and bioeconomic importance. This study is carried out to estimate the maximum economic yield and maximum sustainable yield for Usipa fishery in the South-east arm of Lake Malawi. Structured quantitative questionnaire was used to collect information from 139 informants on the price of usipa landings and cost of fishing effort. Catch and effort data for Usipa were used in a biomass dynamic model (ASPIC) to estimate key parameters (r, q and k). A bioeconomic model was further developed based on the Gordon-Schaefer model using cost and revenues of the Usipa fisheries to derive the Maximun Sustainable Yield (MSY) and the Maximum Economic Yield (MEY). Model estimates of MSY and MEY were 9,228.8 and 8,227.1 tonnes, respectively. The corresponding fishing effort was estimated to be 40,000 net-hauls and 30,000 net-hauls at MSY and MEY, respectively. Revenues at MSY were estimated at MWK42.280 billion, while at MEY the revenues were MWK39.309 billion. The analysis shows that the current effort of 65,232 net-hauls has a yield of 6,000 tonnes, indicating that the Usipa fishery is currently overexploited over the optimum bio-economic level and even beyond the open access yield. We recommend reducing the fishing effort by 54% to realize the best economic benefits (Production at MEY) and end overfishing to protect the fishery from biological and economic collapses

Contribution to the Study of the Size Structure, the Length-Weight Relationship, the Condition Factor and the Sex-ration of Shrimp Farfantepenaeus notialis (Pérez Farfante, 1967) in the Estuary of Sine-Saloum (Senegal)

This study was carried out within the context of USAID/COMFISH project for establihing a biological data base for some fish species including shrimp Farfantepenaeus notialis to support management plans for these species. This study on Farfantepenaeus notialis in the Sine-Saloum estuary revealed that the sampled individuals are relatively small sizes.The average cephalothoracic sizes are less than 20 mm at Bettenty (male = 18.0 ± 2.9; female=18.5 ± 3.9) and at Foundiougne (male = 17.6 ± 2.9; female = 18.5 ± 3.8). The allometric rate «b» is more important at Bettenty (b = 2.94) than at Foundiougne (b = 2.75) and condition factor K is higher during the hot season in both locations (Bettenty: K = 0.80 in hot season; K = 0.78 in cold season; Foundiougne: K = 0.82 in hot season, K = 0.75 in cold season). The sex ratio of Farfantepenaeus notialis is in favor of females at Bettenty (54.6%) and at Foundiougne (51.2%). The size classes show that below 15 mm and beyond 20 mm, the number of female is higher than that of male. Beween 15 to 20 mm, male are higher.

Ecological-Fishery Forecasting of Squid Stock Dynamics under Climate Variability and Change: Review, Challenges, and Recommendations

24 pages, 3 figures, 5 tablesGlobally, cephalopods support large industrial-scale fisheries and small-scale to partly large-scale local artisanal fisheries. They are of increasing economic importance as evidenced by the rapid rise in their global landings from 1950 to 2014. Cephalopods are sensitive to environmental variability and climate change and many if not all species show wide fluctuations in abundance. This is most evident in ommastrephid nerito-oceanic squid since their life cycle is associated with boundary currents that are changing with climate change. The inter-annual variability in catch presents challenges for fishers and managers due to the ‘boom-or-bust’ nature of the fishery. A key barrier to rational management of squid fisheries is the low level of development of fishery forecasting. Despite substantial progress made in relating squid population dynamics to environmental variability and change, several challenges remain to develop forecast products to support squid fisheries management. Ideally, squid fisheries management needs a forecasting system that includes all time-scales of forecasting, and especially short - and medium-terms forecasts. The present overview first provides current knowledge of the effects of climate change and variability on squid population dynamics, challenges and opportunities to advance ecological-fishery forecast products, and finally a roadmap is proposed for future development of forecasts products to support squid sustainable fisheries management. As for the adoption of specific forecasting methods to the squid fishery management process, what is important is the relationship between needs, feasibility, and the ultimate success of a forecast will be determined by whether it is used by end-usersPeer reviewe

Effects of Climate Variability and Change on the Population Dynamics of Cephalopods and a Predictive and Forecast Framework to Inform Fisheries Management

AFS Global Conference, 22-23 October 2020, onlineN

Ecological-Fishery Forecasting of Squid Stock Dynamics under Climate Variability and Change: Review, Challenges, and Recommendations

World Fisheries Congress 2021 (WFC), 20-24 September, onlineN

Resilience of Key Biological Parameters of the Senegalese Flat Sardinella to Overfishing and Climate Change

00000International audienceThe stock of the Senegalese flat sardinella, Sardinella maderensis , is highly exploited in Senegal, West Africa. Its growth and reproduction parameters are key biological indicators for improving fisheries management. This study reviewed these parameters using landing data from small-scale fisheries in Senegal and literature information dated back more than 25 years. Age was estimated using length-frequency data to calculate growth parameters and assess the growth performance index. With global climate change there has been an increase in the average sea surface temperature along the Senegalese coast but the length-weight parameters, sex ratio, size at first sexual maturity, period of reproduction and condition factor of S . maderensis have not changed significantly. The above parameters of S . maderensis have hardly changed, despite high exploitation and fluctuations in environmental conditions that affect the early development phases of small pelagic fish in West Africa. This lack of plasticity of the species regarding of the biological parameters studied should be considered when planning relevant fishery management plans

Length-weight parameters in West Africa for <i>Sardinella maderensis</i>.

<p>The length is expressed as fork length.</p

Size distribution of <i>Sardinella maderensis</i> specimens (n = 7708) collected in Senegalese waters from March 2012 to February 2013.

<p>Size distribution of <i>Sardinella maderensis</i> specimens (n = 7708) collected in Senegalese waters from March 2012 to February 2013.</p

Length at sexual maturity of <i>Sardinella maderensis</i>.

<p>Measured male (white dots), measured female (black dots). Expected distribution of mature individuals is represented by a solid line for females and a dashed line for males.</p

<i>Sardinella maderensis</i> sex ratios based on the published literature for West Africa.

<p><i>Sardinella maderensis</i> sex ratios based on the published literature for West Africa.</p