Current status and prospect of fisheries resource enhancement in Tianjin

Based on the data of releasing and enhancement of Tianjin Bohai Sea Fisheries Research Institute,this study has entirely summarized the experiences and achievements on releasing and enhancement works in Tianjin since 2006.Since 2006,Tianjin has launched the first multi-proliferation and release activity with"Fenneropenaeus chinensis"as the leader.So far,more than 22 varieties have been proliferated,among which crustaceans are dominant.There are significant ecological,economic and social benefits.Both national and international development trends of releasing and enhancement are summarized,and demands and objective of industrial development are proposed.

Maximum sustainable yield estimation of enhancement species with the characteristics of movement inside and outside marine ranching

Marine ranching can be regarded as a type of artificial fishery,and its construction aims at the sustainable utilisation of fishery resources.Therefore,the sustainable yield level of target species in marine ranching has become one of the concerns of stakeholders.The enhancement surplus production model proposed by Wang(2021)based on the traditional surplus production model can be used to assess the sustainable utilisation of settled species in marine ranches.However,when the target species has the characteristics of migration inside and outside marine ranches,its sustainability assessment will be aff ected.Based on the movement range and resource density levels of enhancement species inside and outside marine ranches,we built a biomass change model that is suitable for enhancement species with migration characteristics inside and outside marine ranches(migration enhancement biomass model).Moreover,we simulated the effects of factors,such as the ratio of the movement range and the ratio of resource density within and outside marine ranches and the fishing strategy for the enhancement species in marine ranches,on the estimation of maximum sustainable yield(MSY).Results show that the large movement range of enhancement species outside marine ranches was associated with the obvious advantage of the proposed migration enhancement model over the traditional enhancement production model.A small difference in the densities of enhancement species inside and outside marine ranches was highly beneficial for improving the accuracy of MSY estimation.The migration enhancement biomass model proposed in this study provides an idea for estimating the MSY of an enhancement species that migrates inside and outside marine ranches.Researchers can adjust the parameters of the model in accordance with the actual situation of resource distribution and changes to improve the scientificity of fishery stock assessment.

Using SSR Marker to Trace Chinese Shrimp Fenneropenaeus chinensis Released in Natural Sea-A Feasible Strategy for Assessment of Release Effect in Natural Resources Recovery Program

Enhancement release has been proven effective in natural resources recovery of Chinese shrimp Fenneropenaeus chinensis in the last several decades in China, however, to assess the effectiveness of enhancement release, we still need to develop a high-efficient and easy-operational method to replace those physical-tagging release method with labor intensive, size-and number-limited. In the present study, single(with maternal known) parentage identification using eight simple sequence repeat(SSR) markers genotype fingerprint was used to trace Chinese shrimp released in Bohai Bay in 2013. A total of 884 shrimp spawners were collected from two hatcheries in Tianjin City respectively after enhancement release of shrimp larvae in May 2013. A total of 844 shrimp samples were recaptured around the release location approximately 4 months after the shrimp larvae were released into the natural sea. Genotype data of 8 SSR loci of the 1,726 samples were used for maternal-offspring parentage identification using CEervus 3.0 software. The allele number in each locus ranged from 8 to 68 with an average value of 33.25, which produced the cumulative exclusion probability with one parent known of all these sight loci up to 99%. Among the 844 recaptured shrimp samples, 448(♂:♀=212:232, gender information was lost for 4 samples) were successfully traced to their 337 maternal parents using a logarithm of odds(LOD) > 3.0 threshold. Among these 337 maternal parents, 253 had a single offspring, 62 had two offspring, 18 had three offspring, 3 had four offspring, and 1 had five offspring. For the first time, a large number of released shrimp were identified from recapture samples, and this study showed that it is possible to trace all released Chinese shrimp without using any type of physical tag in enhancement release activities. This not only means more precise recapture ratio assessment than ever expected, but also this method demonstrates an effective method for large-scale hatchery release as well as for organisms used in hatchery enhancement which are not suitable for physical tagging.

Evidence of return of chum salmon released from Tangwang River by strontium marking method

In order to assess the effect of enhancement release of chum salmon(Oncorhynchus keta),otolith strontium(Sr)marking method was used to tag chum salmon released in Tangwang River in 2016.The homing chum salmon were detected and the samples were collected in Tangwang River,Ussuri River and Suifen River in the autumn of2018.The samples were analyzed by examining Sr and calcium(Ca)fingerprints in the otolith using electron probe microanalysis.The results suggested that two samples collected in Tangwang River had the marking ring near the core of otolith where the Sr concentration and Sr/Ca ratio were significantly higher than comparative samples.Proving that the two fish belonged to the released population in Tangwang River in 2016.This article indicated the success of the enhancement release of chum salmon from the Tangwang River for the first time and also confirmed the validity of Sr marking in enhancement release of fishes.

The Study of Visible Implant Elastomer(VIE)Tag on Small-sized Chinese Shrimp(Fenneropenaeus chinensis)

[ Objective] The paper was to prove the feasibility of using visible implant elastomer （VIE） tags to mark Chinese shrimp of about 1 em in length. [Method] In June 2014, 2 856 Chinese shrimps with an average length of 1.14 cm were tagged with red VIE. After temporary rearing for one day, 2 321 tagged shrimps were cultured in the same pond with 60 000 untagged shrimps in this experiment. In predation test, spottedtail gobies （Synechogobius ommaturus） were se- lected as the predator, and the predation rate of spottedtail gobies on small-sized Chinese shrimps was measured. [ Result] On September 21,2014, 206 kg of Chi- nese shrimp was harvested in the pond. There were 389 tagged shrimps, with an average body weight of 16.84 g, and an average length of 11.15 cm. The untagged shrimps had an average body weight of 17.08 g, and average length of 11.23 cm. The results indicated that there was no significant difference in growth between the tagged and untagged shrimps. The survival rate of the tagged shrimps was 2.7% lower than the untagged ones. Mthough the fluorescent tag dispersed and the posi- tion changed, the tag was still distinct both under ultraviolet light and to the naked eye. The predation test revealed that the fluorescent tag of shrimps did not in- crease the predation rate by spottedtail gobies. [ Conclusion] Red VIE tagging is feasible in Chinese shrimps. There was no significant difference in predation rate between untagged and VIE tagged shrimps.

Analysis on Growth of Released Black Carp and Annual Benefits from Released Fish in Yantan Reservoir

The research explored growth and development, economic profits, and eco- logical benefits of released black carps on basis of 21 group ecological data on 52 365 fish within 6 months. The results indicated that the age and growth index of released black carp were normal and body length and size were coordinated; 88.89% released black carps exceeded theoretical weight, with an average of 25.15%, which indicated that black carps are hardly to reproduct naturally. In 2013, 310 000 black carps were released in the Reservoir, and 123 tons black carps were obtained, with direct economic value of 2.46 million yuan and indirect econom- ic value of 3.84 million yuan. It can be concluded based on averages that 123 tons black carps can be produced in 2013 and 3 690 kg nitrogen and 740 kg phospho- rus can be removed. The releasing of fish has shown much more economic, ecological and social benefits in Yantan Reservoir, but the hidden dangers still exist on fishery environment. Therefore, it is necessary to further increase the number of re- leased black carps in the Reservoir.

Current Situation, Problems and Countermeasures of Marine Ranching Development in Guangdong Province, China

Combining the literature review and marine field investigation in the sea area,this article summarized the development and current situation of marine ranching at home and abroad.It analyzed the construction process of artificial fish reefs,proliferation and release,and national-level marine ranching demonstration areas,as well as the current development situation and existing problems of marine ranching-related industries in Guangdong Province.Guangdong has built 50 ecological artificial reef areas,3 large-scale artificial reef demonstration areas,1 local artificial reef area and 15 national marine ranching areas,with a total sea area of 1499.68 km^(2),and 2.004 million m^(3) of reefs.However,there are some problems in Guangdong marine ranching,including imperfect management mechanism,inconsistence in development concept and understanding,unclear rights and responsibilities in using sea area,lack of construction technology standards and specifications,low scientific and technological level and limited industrial development.In view of these problems,this article came up with countermeasures,including insisting on ecology-prioritized development,and strengthening the coordination of multiple departments;creating a management mode conducive to market-oriented operation;breaking through the issue of sea area ownership;establishing a technical standard system for marine ranch construction in Guangdong;strengthening the research on the basis of high-quality construction and key common technologies of Guangdong marine ranching;establishing industrialization modes of Guangdong marine ranching according to local conditions.Understanding the development status of marine ranching in Guangdong and exploring the development strategies of marine ranching industry by referring to the relevant experience at home and abroad can provide references for the effective management,efficient and sustainable development of marine ranching in Guangdong and the integration of three industries in the development of marine ranching in Guangdong.

Enhanced release of the poorly soluble drug itraconazole loaded in ordered mesoporous silica

It is known that the energy of the amorphous state of itraconazole loaded in ordered mesoporous materials is high relative to that of the crystalline state and is responsible for enhanced solubility and dissolution rate. We investigated the effects of particle size(0.7–5μm), mesostructure(2D p6 mm, cubic Ia-3d and cubic Fm-3m) and pore size(2.2–15.4 nm) of mesoporous silicas on the release performance of itraconazole. Results indicated that the release performance was not influenced by the particle sizes tested here, that the release performance increased with increasing pore diameter due to the lower probability of drug molecules colliding to recrystallize in large pores, and that the release performance was decreased in the cage-type pore structure(Fm-3m) compared to that in the cylindrical pore structures(p6mm and Ia-3d) because of the small entrance to the cagelike pores that retards the drug release.