The influence of life history attributes and fishing pressure on the efficacy of marine reserves

Two key questions regarding “no-take” marine reserves are: (1) how effective are reserves likely to be, and (2) how does effectiveness vary with life history attributes and the relative size of reserves. To investigate these questions, we use a simple Ricker model that includes fishing, larval dispersal, and larval loss while in a planktonic pool, and that tracks protected and unprotected populations. We applied two different measures of reserve effectiveness to our simulation results. One metric was intended to reflect goals oriented towards conservation and the second was intended to reflect fishery enhancement goals. Both metrics compare the situation before reserves are established to after the reserve has been in place and a new equilibrium was reached. Yield effectiveness is defined as the total equilibrium annual harvest after reserves are established divided by the total annual harvest before reserves are established. Conservation effectiveness is defined as the average adult density inside the reserve divided by the average density in the same area prior to reserve establishment. A substantial fraction of the 5120 simulated parameter combinations representing different harvest rates and life history attributes went extinct in the absence of a reserve, and these scenarios leading to extinction could be predicted accurately (85% aptly classified) simply on the basis of exploitation rate and population growth rate. Of the cases that did not go extinct, we compared the performance of reserves as measured by each effectiveness metric. Few of the cases (less than 8%) produced effective reserves as measured in terms of increased harvest; whereas over half of the cases resulted in effective reserves as measured by conservation effectiveness. Moreover, the two measures of reserve effectiveness were only weakly correlated. Simple linear regression or polynomial regression could explain at most 23% of the variation in reserve effectiveness as measured by either metric. As expected, the size of the reserve area had a marked and typically negative effect on total annual yield, which suggests that while marine protected areas may do a good job of conserving protected populations, there will generally be pressure from the fishing community to keep them small because of their tendency to reduce total catch.     

渔船总体计算机辅助设计系统介绍

渔船总体计算机辅助设计系统是目前全国范围内正在被渔船界开始广泛应用的一套完整的渔船计算机辅助设计系统，该系统在微机上用Ｔｕｒｅ－ＢＡＳＩＣ语言开发研制，具有系统性强，功能齐全、技术先进、全部汉语化、结构紧凑等优点。经广州、上海、烟台等地渔轮厂的实际使用，认为该系统的开发、研制大大地提高了渔船设计的效率与精确性，改变了水产界在微机应用方面落后的局面，为我国的渔船事业产生显著的社会效益和经济效益创造了     

Analysing commercial catch and effort data from a Penaeid trawl fishery: A comparison of linear models, mixed models, and generalised estimating equations approaches

Statistical methods are often used to analyse commercial catch and effort data to provide standardised fishing effort and/or a relative index of fish abundance for input into stock assessment models. Achieving reliable results has proved difficult in Australia's Northern Prawn Fishery (NPF), due to a combination of such factors as the biological characteristics of the animals, some aspects of the fleet dynamics, and the changes in fishing technology. For this set of data, we compared four modelling approaches (linear models, mixed models, generalised estimating equations, and generalised linear models) with respect to the outcomes of the standardised fishing effort or the relative index of abundance. We also varied the number and form of vessel covariates in the models. Within a subset of data from this fishery, modelling correlation structures did not alter the conclusions from simpler statistical models. The random-effects models also yielded similar results. This is because the estimators are all consistent even if the correlation structure is mis-specified, and the data set is very large. However, the standard errors from different models differed, suggesting that different methods have different statistical efficiency. We suggest that there is value in modelling the variance function and the correlation structure, to make valid and efficient statistical inferences and gain insight into the data. We found that fishing power was separable from the indices of prawn abundance only when we offset the impact of vessel characteristics at assumed values from external sources. This may be due to the large degree of confounding within the data, and the extreme temporal changes in certain aspects of individual vessels, the fleet and the fleet dynamics.     

Acoustic telemetry versus monitored longline fishing for studying the vertical distribution of pelagic fish: bigeye tuna (Thunnus obesus) in French Polynesia

This study compares detailed, nearly continuous, observations on bigeye tuna, Thunnus obesus equipped with electronic tags, with discrete observations on a larger number of individuals from fishing experiments in order to validate the use of instrumented longlines to study the vertical distribution of fish. We show that the depth distributions obtained from the two different observation techniques regarding different environmental variables (temperature, dissolved oxygen (DO), prey distribution) are similar. Bigeye tuna do not seem to be attracted by baits in the vertical dimension (no modification of their vertical distribution by the fishing gear), which allows the use of instrumented longlines to study the vertical behaviour of pelagic species. This technique, when used with appropriate deployment strategy, could therefore represent an alternative to electronic tags (acoustic or archival tags) when there is a need to determine the vertical distribution of fish species by size or sex, in different environments for the study of fishery interactions.     

Are tidal fronts good recruitment areas for herbivorous copepods?

Horizontal distributions of phytoplankton biomass and numerical abundance of copepod nauplii were investigated across a tidal front in the northern part of Bungo Channel, the Inland Sea of Japan, in May and June 1988. The frontal area was characterized by abrupt changes in subsurface (3 m deep) temperature and salinity, and by an increased standing stock of phytoplankton. The density of copepod nauplii was lower in the frontal area than in adjacent stratified and mixed areas. The population egg production rate of a predominant copepod species (Paracakmus sp.) was higher due to elevated fecundity on an individual basis in response to increased chlorophyll concentrations, in the frontal zone. However, the frontal population was subjected to higher mortality, probably due to predation by carnivores that were mainly accumulated passively within the area. From these facts, we conclude that tidal fronts are not always good areas for recruitment of herbivorous copepods, although fronts give rise to high standing stocks of phytoplankton.     

闽南渔场大黄鱼年间生殖群体组成相似程度的模糊识别

闽南渔场大黄鱼年间生殖群体组成相似程度的模糊识别张澄茂（福建省水产研究所，厦门３６１０１２）关键词闽南渔场，大黄鱼，生殖群体，模糊识别ＡＦＵＺＺＹＤＩＳＴＩＮＧＵＩＳＨＡＢＩＬＩＴＹＯＮＳＩＭＩＬＡＲＤＥＧＲＥＥＯＦＣＯＭＰＯＳＩＴＩＯＮＯＦＳＰＡＷ...     

太仓浮桥拖网网具性能初探

本文报道了使用斯玛捞作业监控仪对太仓浮桥拖网海上作业实测结果，在拖速３．３－３．９节条件下，该网浮拖作业网口高度为１１．７－１３．８米，底拖作业网口高度１１．８米。分析讨论了在投放不同曳纲长度时，椭圆形网口形状和变化趋势，其长，短轴之比浮拖作业为０．５１，底拖作业为０．４６。     

蔷薇科12种植物导管类型的解剖学观察

该文初步研究了蔷薇科(Rosaceae)9属12种代表植物的导管类型、数量及导管分子的长度、口径,纤维分子的长度、口径。结果表明:较进化的树种,一般都是孔纹和网纹导管,较原始的树种,一般都是环纹和螺纹导管;导管分子长的则导管口径小,导管分子短的则口径大;纤维分子长度普遍大于导管分子长度,而纤维分子的口径也普遍小于导管分子的口径。     

菠萝蜜次生木质部导管分子观察

运用计算机显微图象分析系统(北京泰克4.0)及显微照相的方法对菠萝蜜Artocarpusheterophyllus次生木质部导管分子进行了观察研究。研究表明,在菠萝蜜次生木质部导管分子中存在着许多不同的样式,分别对其进行了描述。导管分子具有如下特征:圆形宽大的导管、巨大的单穿孔、侧壁上大型的单纹孔等。这些特征为菠萝蜜生长过程中水分的需求提供了强有力的保证作用。并从导管分子个体发育与系统发育的角度进行了讨论。     

Is Willingness to Pay for Non-Consumptive Wildlife Watching Falling? Evidence From Three Rounds of the National Survey of Fishing,Hunting, and Wildlife-Associated Recreation

Since 1955, the United States Fish and Wildlife Service has conducted the National Survey of Fishing, Hunting, and Wildlife-Association Recreation (FHWAR) with the purpose of evaluating outdoor recreation. Using the socioeconomic, activity, and contingent valuation data collected from the last three rounds of this national survey (2001, 2006, 2011), econometric modeling demonstrates that variables such as age, income, gender, and type of land visited (public/private) explain variation in wildlife watching willingness to pay (WTP) and consumer surplus (CS). Although not having been fully investigated in the previous FHWAR contingent valuation literature, results suggest that distinguishing between in-state and out-of-state wildlife watching is important. Additionally, analyses indicate that CS for out-of-state wildlife watching along with CS and WTP for in-state wildlife watching are temporarily reliable. Given the study period overlaps the recent recession, this outcome suggests that welfare is stable across time and in the face of business cycles.