基于生态足迹的江苏省渔业资源可持续利用评价

渔业资源可持续利用是实现渔业可持续发展的基础,如何评价其可持续利用是重要的科学问题。本文基于生态足迹理论构建了渔业可持续指数的评价框架,并利用该评价指数对江苏省1949～2007年的渔业资源利用状况进行了定量评价。结果显示:1949～1978年的近30年间,江苏省渔业资源基本处于可持续利用状态,但改革开放以后,尤其是1980、1990年代总体处在较强的不可持续利用状态,过度捕捞是导致渔业资源不可持续利用的重要原因;2000年以后不可持续性程度有所减缓,说明伏季休渔、增殖放流等生态保护措施已初见成效。最后就如何提高渔业资源可持续性水平,降低经济社会发展对渔业资源的负面影响提出了一些建议。     

Age‐dependent distribution of juvenile southern bluefin tuna (Thunnus maccoyii) on the continental shelf off southwest Australia determined by acoustic monitoring

Juvenile southern bluefin tuna (Thunnus maccoyii, SBT) were monitored in nearshore waters off southwest Australia using acoustic tagging and monitoring over five austral summers (2002/2003–2006/2007) to determine patterns in age‐based distribution of SBT. A total of 20–70 receivers were deployed in early December along one to three cross‐shelf transects and at three inshore topographic features (lumps) where SBT are known to occur; and a total of 59–84 juvenile SBT (41–90 cm fork length) were tagged and released each year. After several months, receivers were recovered, and data extracted. In 2002/2003 and 2003/2004, 2‐yr‐old SBT were detected more frequently in nearshore areas than did 1‐yr old fish. Similarly in 2004/2005 and 2006/2007, it was the larger 1‐yr‐old SBT that were detected more frequently at inshore lumps (>85% of detections) while small 1‐yr‐old SBT were detected more widely over the study area. In 2005/2006, although large 1‐yr‐old SBT were still detected more frequently at inshore lumps than small 1‐yr old SBT, the percentage of all detections at lumps was lower at 31.5%, indicating wider distribution of both small and large age‐1 fish. The observed age‐dependent distribution pattern may be enhanced by the distribution of prey, which disperse or concentrate depending on the local oceanography.     

Reforming the European Common Fisheries Policy: a case for capacity and effort controls

I summarize the total allowable catch (TAC) fishery management system, which forms part of the European Common Fisheries Policy (CFP) as complicated, inaccurate and ineffective. Total allowable effort (TAE), i.e. limits on fishing capacity and days‐at‐sea, provides a simpler, readily enforceable control to protect all species affected by a fishery. Fishing capacity of vessels in each region‐gear fleet could be capped through limits on engine power, gear, crew, and fittings, and/or reducing allowances of days‐at‐sea for large, powerful vessels. Two basic, fishery‐dependent indicators are put forward to assess sustainability of a fishery dependably even in the absence of fishery‐independent data. One is socio‐economic, the other is ecological. Fishery working groups within each marine region would recommend a TAE to sustain their fishery while also protecting the most critically affected species or processes. Regional working groups would supervise a consistent approach across the different fisheries in their region. A pan‐European group would set policy, implement external agreements, set rules for trading TAE if necessary and harmonize fishing opportunities across regions. To ease negotiations on TAEs with the fishing industry when an ecosystem needs to recover, I propose compensation payments funded by re‐direction of existing CFP subsidies that promote fishing.     

Space use and inferred spawning activity of three exploited gamefish species on a large artificial reef

Intense fishing pressure has led to changes in species composition, demography and the over‐exploitation of many coastal fishes. To restore populations, artificial reefs (ARs) are used with the assumption that new habitat will increase fish productivity. Kelp bass (Paralabrax clathratus), barred sand bass (P. nebulifer) and California sheephead (Semicossyphus pulcher) are three important recreational gamefish species in southern California. Home ranging behaviour, space use and spawning‐related activity of these three species were quantified on a large AR. Kelp bass used the largest amount of area, but space use was similar among species. While no spawning behaviour could be determined for sheephead, kelp bass exhibited two different activity patterns during spawning months and barred sand bass migrated (indicative of spawning). Results of this study indicate that this large AR is providing suitable habitat for these species, and spawning‐related activity could be a sign that this AR is meeting essential life history demands.     

Using acoustic telemetry and snorkel surveys to study diel activity and seasonal migration of round goby (Neogobius melanostomus) in an estuary of the Western Baltic Sea

In just two decades, round goby Neogobius melanostomus (Pallas) has dispersed throughout most of the Baltic and the North American Great Lakes. It thrives in shallow sheltered areas, where it is impacting native fauna. In Denmark, researchers, governmental institutions and fishers have joined in an effort to establish a sustainable round goby fishery. To do so, basic information about the movement of round goby is essential, so the movements of 50 round gobies were tracked using acoustic telemetry. The results revealed that activity took place mainly at night and seasonal migrations were common. The most frequent migration behaviour observed was a seaward return migration during winter, which was further confirmed by a snorkel survey. Tracking data also revealed riverine upstream dispersal. The results demonstrate that the round goby can be mapped using telemetry, and it is suggested that fishing for round goby may improve efficiency by targeting seasonal migration corridors.     

大亚湾核电临近海域中国毛虾声学探测分析

于2019年1月11―14日在大亚湾核电基地临近海域尝试采用声学探测技术,同时辅以拖网调查与水下视频观测的方法,对该海域中国毛虾(Acetes chinensis)的空间分布特征、定向迁移聚集规律和种群资源评估方法进行了研究分析,以期为大亚湾核电基地典型冷源致灾生物中国毛虾的监测预警与应急防控提供新的思路。调查发现,拖网渔获物中中国毛虾所占比重在99%以上,仅有数量极少的水母和鱼类。19:00―07:00的声学原位观测结果显示,不同时段中国毛虾海里面积反向散射系数(NASC)波动较大(0.56～170.30m~2/nmile~2),整体呈先增后减的变化趋势,最高值出现在22:30―22:40时段。垂直空间分布上,中国毛虾主要集群分布于水深5.2～7.2m的中下层水域,在22:50―00:10期间有明显向底层迁移的趋势。水平空间分布上,中国毛虾生物量密度由湾内至湾口断面逐渐增大。结合不同时段中国毛虾资源动态规律与水下视频观测结果,调查海域中国毛虾很可能在19:00―23:00期间向湾内迁移,23:00之后向湾口迁移。综上分析可知,声学评估方法较传统的渔业调查手段具有生态、高效、时空分辨率高、能提供实时监测数据等诸多优点,更能满足大亚湾核电站冷源生物安全预警与应急防控的现实需求。     

Effects of anthropogenic noise as a source of acoustic stress in wild populations of Hippocampus guttulatus in the Ria Formosa,south Portugal

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Improving management advice through spatially explicit models and sharing information

Recent assessments of Chilean shrimp, Heterocarpus reedi, in central Chile have been conducted separately for the northern and southern zones of the fishery and treating them as two separate stocks. However, it is not clear whether H. reedi of the two zones interact with one another or whether they share similar characteristics. Such knowledge is necessary to determine whether they should be modeled as separate “stocks” or as a single stock. This has motivated the use of the Pella–Tomlinson model to test whether there are spatial differences in the population dynamics of H. reedi in the two zones and whether sharing information between the zones improves management advice. We test if it is better, from a stock assessment point of view, to model the stock as one unit in the whole area, or as two separate stocks. In the single-stock model, we sum the catch data of both zones, but each catch-per-unit-of-effort index is fit as a separate data set, using a joint likelihood. Under the single-stock hypothesis, the best model fit was the symmetric production function (i.e. the Schaefer model for which the biomass that supports maximum sustainable yield as a proportion of carrying capacity (B_MSY/B₀) = 0.5), with different catchability coefficients for each CPUE index, but a shared standard deviation of the log-normal likelihood function. Under the two-stock hypotheses, both catch and CPUE data were separated for each zone in the model. In this case, the best model fit is also the one with symmetrical production curve, and the only parameter that differed between the zones was B₀. However, B₀ per unit of habitat was similar for the two zones. Also, the precision of estimated management quantities was improved by modeling the appropriate spatial structure and sharing information among zones. The results suggest that the demographic parameters are similar for the two zones. It appears that the main difference between the two zones is the exploitation history, with the catch in the southern zone being reduced earlier than in the northern zone and consequently the biomass in the southern zone increased earlier than in the northern zone. This implies that local depletion can occur in this stock and that differences in management among zones may require explicitly modeling sub-stocks in the assessment of this and other species.     

稻渔综合种养技术研究进展

稻渔综合种养可使农业从单一经营转变为复合经营,从平面生产转变为立体生产,是农业转方式、调结构的重要发展方向。为进一步促进稻渔综合种养研究的深入开展和稻渔综合种养模式的推广应用,综述了中国稻渔综合种养技术的发展概况,阐明了稻渔综合种养模式的增产增效作用及与之配套的稻田工程技术、安全植保技术、安全施肥技术、鱼病防治技术、水质管理技术的实施过程,指出了稻渔综合种养模式对产业的支撑作用,展望了稻渔综合种养模式的发展前景,并提出了稻渔综合种养模式的重点研究方向。     

Use of acoustic testing to detect decay and sort western juniper for modulus of elasticity and modulus of rupture

While wood has numerous attributes that make it an excellent material for many uses, its properties can also vary widely according to wood species and even within the same species. Wood used in structural applications is categorized into classes. For many wood products, these classes or grades are based upon visual assessments that account for grain characteristics along with natural defects such as knots or splits. These approaches are simple, but also limit the potential for identifying products based upon actual material properties. One alternative is to use acoustic tests to estimate modulus of elasticity and then correlate these values to actual material properties. The potential for using acoustic tests to estimate wood properties was assessed with a prototype acoustic device (Metriguard Model 242) on western juniper (Juniperus occidentalis) posts that were then tested using a destructive bending test. These tests could allow the identification of decayed areas within a post if they were directly in the tested area, but predicted modulus of elasticity was poorly correlated with actual modulus of rupture (r^2?=?0.23). The correlation was improved by only considering those samples where the acoustic test was made through the same area where the test load was applied, but the relationship was still weak (r^2?=?0.33). Acoustic testing did appear to be able to identify unacceptably weak samples with minimal rejection of acceptable samples, suggesting that acoustic testing might be a useful sorting tool to improve the reliability of timbers.