| This paper is based on the statistics of the pre-release seedlings from 2010 to 2018,the local resource survey before discharge,the release of the release effect after discharge and the relative quantity survey before the arrest,offering comparative analysis of the distribution and biological characteristics of the resources of the crab and the interannual variation.Combined with the return of autumn scorpion,the various contributions of proliferation and release to the Portunus trituberculatus are summarized in the text.The preliminary conclusions are as follows:1.In 2010—2018,the number of released seedlings of the Portunus trituberculatus of the southern Shandong Peninsula were distributed between 1.07×10~4~2.10×10~4,and 13.45×10~4 crabs were released in 9 years.The release sites are concentrated in the bays along the southern Shandong Peninsula.The specifications of the released seeds are basically the same.Considering the control cost and ecological impact,the number of discharges has not been blindly expanded,and the choice of discharge sites is more scientific.2.As 2010—2016 background survey shows,the catch mantissa is distributed between 4~206,relative resource density is distributed between 0.40~17.17 ind/net·h,the average length is 63.71mm,and the average weight is 33.51 g,the background resource distribution is between 52.43~2104.18 t.The wild population resources of Portunus trituberculatus in the southern Shandong Peninsula are scarce and have a downward trend.3.As 2010—2016 release of proliferation effect survey shows,the catch mantissa is distributed between 77~688,relative resource density is distributed between 6.88~40.47ind/net·h,the average length is 79.03 mm,and the average weight is 50.61 g,resource distribution is between 179.19~12870.38 t.The data are greatly improved compared with the background investigation,and the proliferation effect is better.4.As the relative quantity survey of 2010—2018 shows,the catch mantissa is distributed between 3~266,relative resource density is distributed between 0.93~27.80ind/net·h,the average length is 109.69 mm,and the average weight is 87.23 g,resource distribution is between 1274~23710.15 t,the forecastable catch is distributed between765~11855.08t.In August,the Portunus trituberculatus gradually moved to the open sea.In terms of distribution,it is still concentrated in the waters near the discharge point.The resources in the northeastern coastal areas of Shandong were more concentrated than those in the southwest.5.The contribution rate of the release population of the Portunus trituberculatus in2010—2018 was between 55.82 and 96.83%.The ecologically important index indicates that due to the large-scale proliferation and release in recent years,the dominantness of the Portunus trituberculatus in the community has increased and it has become a common species in some years.6.To judge from the data of the recalls in each year,the natural population was not the cause of the change in the yield of the recall.Combined with the analysis of the recovery rate,it shows that the discharge group has a great correlation with the yield of the harvest.The output value fluctuated greatly,but the average output value was higher,indicating that the economic benefit of releasing the Portunus trituberculatus was huge.7.The important impact brought about by proliferation and release was not only at the ecological and economic level,and it also has a certain positive impact on the society,increasing income,employment,local output value and driving the development of related industries. |
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