Evaluation On The Utilization Of Coastal Fishery Resources In Guinea-Bissau

Marine fishery resources are not only an important component of natural resources,but also a vital source of food for mankind.With the continuous development and innovation of industry and science,fishing capacity to the fishery species,fishing area and number of fishing vessel are increasing unremittingly.Besides,the impacts of the fishing pressure to fishery resources is becoming more and more obvious.Under this circumstance,if the fishing intensity is always increasing,the biomass of fishery speciese might decrease,and the ecosystem structure and function might be affected and even destroyed.In recent years,there is a growing trend of foreign fishing vessel number in Guinea-Bissau coastal waters.Therefore it might influence the yield of China National Fisheries Corp.This corporation’s yield decreased at 2015.In this study,we gave the reason of it.What’s more,we analysed the status of sustainable utilization.In this study,based on the fishery data of catch production(catch species,weight,fishing vessel position,category level,etc.)from 2011 to 2015 provided by China National Fisheries Corp in Guinea-Bissau coastal waters fishing vessel operations,and combining the data of fish spercies’ trophic level(TL)and environmental factors(chlorophyll,sea surface temperature,tropical nothern Atlantic index and Atlantic Oscillation Index),we evaluated the sustainable utilization status of the marine fishery resoures in coastal waters of Guinea-Bissau.Results of this studies are as following.Using the montly/yearly catch data classifying by orders,it suggested that the main target species in Guinea-Bissau was Perciformes,Pleuronectiformes,Carangiformes.From January to April,the dominant target species is the Perciformes,followed by the Carangiformes and the Pleuronectiformes.From April to July,the dominant target species is the Pleuronectiformes,followed by the Perciformes and the Carangiformes.From July to December,the dominant target species is the Perciformes and the Pleuronectiformes.In addition,total catch of Carangiformes were much smaller than the Perciformes.The catch proportion of the Pleuronectiformes was similar with the Carangiformes.The highyielding month of the Perciformes,the Pleuronectiformes,the Siluriformes and the Carangiformes was October and November,from June to July,October and November,February and March,respectively.Based on the length compotison of the Lesser African threadfin decadactylus and Smoothmouth sea Catfish decadactylus,it suggested that Lesser African threadfin decadactylus average length decreases,Smoothmouth sea Catfish decadactylus average length decreases,and production of 20 cm length is much higher than others,and the others yield is steady fluctuations.They were not miniaturized,but due to other factors,the yield of smaller fish is increase.At the same time,the CPUE of the Lesser African threadfin decadactylus and Smoothmouth sea Catfish decadactylus fishery was standardized by the generalized liner model(GLM)and generalized additive model(GAM).The influence of latitude and longitude on the CPUE of the Lesser African threadfin is increasing with the increase of the latitude and decreasing with the increase of the longitude.CPUE steady fluctuated during the year,there is no obvious regular.February and September are the CPUE high yield month,February to September was on the increased trend,Setember to December was a downward trend.And the finshing type has an effect on the CPUE,the B(doublenet)fishing type has a greater impact than the A(single-net)fishing type.The latitude and longitude of the Smoothmouth sea Catfish were increased with the increase of latitude,and decreased with the increase of the longitude.June to September each year were the CPUE high yield month,February to September showed an increase trend,September to December showed a downward trend.And the fishing type has an effect on the CPUE,and the B(double-net)fishing type has a greater impact than the A(single-net)fishing type.Combining the standardized CPUE deriving from GAM and the catch data,we did the stock assenment of the Lesser African threadfin decadactylus and Smoothmouth sea Catfish decadactylu.Results showed that,the Lesser African threadfin and Smoothmouth sea Catfish are not over-fishing.The development of fishery resources in Guinea-Bissau is still at the low evel,and the catching strength does not exceed the potential of resource.The structure and function of the marine ecosystem are intact and have not been destroyed by the increase with fishing perssure.What’s more,the mean trophic level,Fishing-in-balance index and the catch data also indicates that the marine ecosystem was not destroyed and the status of fishery stocks could not be overfishing or overfishied.Lastly,the canonical correlation analysis was used to evaluate the influence of environmental factors to the yield.The northern Atlantic tropical index,the upper boundary depth of the thermocline,and the surface temperature of seawater are the main environmental factors affecting the distribution of catch.In view of the dominant species,the Lesser African threadfin are mainly affected by the environmental factors of the northern tropical Atlantic index and the upper temperature of the thermocline.For Lesser African threadfin,in the case of double-net operation,the environmental factors of the temperature of the NTA and the thermocline are negatively correlated,the annual changes are consistent.Single-net operation,and these two environmental factors no significant relationship.For Smoothmouth sea Catfish,in the case of double-net operation,the environmental factors of the temperature of the thermocline are positively correlated with each other,and the annual changes are basically consistent.And NTA no significant relationship.Single-net operation,and these two environmental factors no significant relationship.In general,The effects of fishing activities on the current marine ecosystems and their changes can be obtained by analyzing the changes in the average trophic level,the trophic level,and the trophic level equilibrium.In this study,the ecosystem of GuineaBissau offshore has not been destroyed,the fishery resources have not been fully developed,and the fishery still has great development and utilization potential.