| The Mozambique Channel is known for its abundant shrimp fisheries resources and is one of the main fishing grounds for Chinese strategic offshore fishing.This study utilized production data from shrimp trawling fisheries in Mozambique and Madagascar collected by the China National Fisheries Corporation from 2019 to 2021.Based on the generalized additive model(GAM),the study analyzed the spatial and temporal distribution of major catch shrimp species(including Penaeus indicus,Metapenaeus monoceros,Penaeus monodon,Penaeus japonicus,Penaeus semisulcatus,and Penaeus latisulcatus),and their relationships with environmental factors.The study provides a scientific basis for conducting fisheries resource abundance assessments,regulating fisheries management,conserving fishery resources,and ensuring sustainable development of the fishery industry in the region.The main conclusion of this study are:1.Fishing season characteristics of shrimp trawl fishing grounds in the Mozambique Channel.The study found that the total production and fishing effort on both sides of the channel showed significant monthly variations.Generally,from the start of the fishing periods,the monthly production on both sides gradually decreased,with the peak production mainly concentrated in the months from March to June.The fishing effort on the west side(Mozambique)decreased gradually by month,while on the east side(West coast of Madagascar)it showed an increasing then decreasing trend.Analysis of the proportion of each benthic shrimp species on both sides of the channel found that the P.indicus and M.monoceros had the highest production proportion,accounting for 36%and 44% of the total production on the east side,and 36% and 36% of the total production on the west side,respectively.The proportion of the P.semisulcatus was13% on the east side and 3% on the west side,while the proportion of the P.monodon was 6% on the east side and 14% on the west side,the proportion of the P.japonicus was 1% on the east side and 4% on the west side,and the proportion of P.latisulcatus was 7% on the west side.The P.indicus and the M.monoceros are the dominant shrimp species of shrimp trawl fishing grounds in the Mozambique Channel and show clear monthly variations.2.Spatial and temporal distribution of shrimp trawl fishing grounds in the Mozambique Channel.The study found that during the period of changing fishing ground centers in the fishing grounds of the Mozambique Channel,the overall center of the fishing grounds on the west coast varied within the spatial range of 1 degree at 17.61-18.02°S and37.37-37.97°E during the fishing season of April to August,while the fishing grounds on the east coast shifted northeast and then turned southwest from March to December,and the overall center moved within the region of 16.25-17.00°S and 44.71-45.21°E.During the changing process of the center of various benthic shrimp fishing grounds,the latitude center of the P.indicus fishing grounds on the east coast moved northward from March to September and southward from October to December.The center of the fishing grounds mainly distributed within the region of 44.35-44.76°E and16.49-17.19°S,while the center of the P.indicus fishing grounds on the west coast mainly distributed within the region of 37.27-38.03°E and 17.57-18.08°S.The latitude center of the fishing grounds for the M.monoceros,P.monodon and P.semisulcatus on the east coast mostly distributed in the region north of 17°S,with little variation in the longitude center,and the center of the fishing grounds mainly distributed within the region of 44.35-46.12°E and 15.69-17.04°S.On the west coast,the center of the fishing grounds for these three benthic shrimp species mainly distributed within the region of36.98-38.11°E and 17.53-18.22°S.The latitude center of the fishing grounds for the P.japonicus on the east coast moved northward with the month and the longitude center moved eastward.It mainly distributed within the region of 44.41-45.76°E and15.94-18.47°S.The center of the fishing grounds for the P.japonicus on the west coast mainly distributed within the region of 37.21-37.85°E and 17.74-18.27°S.As for the P.latisulcatus,which is a shrimp species unique to the west coast fishing grounds,the center of fishing grounds was mainly distributed in the region of 37.23-37.32°E and18.18-18.28°S.The spatial range of changes was not significant,and the shrimp species only had production in specific waters.3.Relationship between major shrimp resource abundance and spatial and temporal environmental factors in Mozambique Channel shrimp trawl fishing grounds.The study found that in terms of temporal variability,the monthly changes in CPUE(catch per unit effort)for P.indicus,M.monoceros and P.monodon showed a decreasing and then increasing trend.In contrast,P.japonicus,P.semisulcatus and P.latisulcatus showed an increasing and then decreasing trend.Regarding spatial variability,the habitat range differed for different benthic shrimp species.CPUE for P.indicus,M.monoceros,P.monodon and P.semisulcatus showed a gradually increasing trend from south to north in terms of latitude,with P.japonicus having higher CPUE at the two ends of the fishing ground,and P.latisulcatus having higher CPUE in the range of 18.25-19.00°S.CPUE for P.indicus,M.monoceros and P.semisulcatus were higher at a distance of more than 30 km offshore,while CPUE for P.monodon was higher in the range of 20-25 km offshore.CPUE for P.japonicus was higher in the range of 25-35 km offshore,while CPUE for P.latisulcatus was higher in the range of 35-45 km offshore.CPUE for P.indicus,M.monoceros and P.semisulcatus were higher at a depth of less than 25 m,while CPUE for P.monodon was higher in the range of 25-35 m depth.CPUE for P.japonicus was higher near a depth of 40 m,while CPUE for P.latisulcatus was higher at a depth of more than 45 m.Sea surface temperature and Chlorophyll-a concentration had significant effects(P<0.05)on CPUE of five benthic shrimp species except P.latisulcatus;Sea surface salinity had significant effects(P<0.05)on CPUE of P.indicus,M.monoceros and P.semisulcatus;Sea surface height anomaly and Precipitation had significant effects(P<0.05)on CPUE of each benthic shrimp species;Dissolved oxygen had significant effects(P<0.01)on CPUE of four benthic shrimp species except M.monoceros and P.japonicus;Eddy Kinetic energy had significant effects(P<0.01)on CPUE of four benthic shrimp species except P.japonicus and P.latisulcatus.The results indicate that environmental factors have an effects on the major benthic shrimp species in Mozambique Channel shrimp trawl fishing grounds and further affect the abundance of major benthic shrimp species. |
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