Monitoring and Management of the Northeast Atlantic Herring Stocks

1985 ◽  
Vol 42 (S1) ◽  
pp. s207-s221 ◽  
Author(s):  
Jakob Jakobsson

The collapse of all the major herring stocks in the Northeast Atlantic in the late 1960s and the early 1970s was undoubtedly the most striking phenomenon in the history of the European fisheries. The events leading to the collapse show similar features for all the herring stocks: a sharp increase in catches over a few years, followed by a rapid decline and a fishing ban. During the period of declining stock abundance, management actions came too late and were not sufficiently restrictive. It appears that managers found it easier to accept a total fishing ban than to agree on severely reduced catches. In many cases it is clear that the fishing ban has been thoroughly enforced, while in other cases illegal fishing has seriously delayed the recovery of the stocks. This has been monitored by various fishery independent methods, such as tagging experiments, trawl surveys, larval surveys, and acoustic surveys. Before advising the reopening of the fishery it has been the general policy of the ICES Advisory Committee for Fishery Management that the spawning stock would be about to reach a minimum target abundance and that there should be firm evidence that recruitment should be on a similar level as it was prior to the collapse. Some stocks are about to or have already fulfilled these criteria, while others are still at a low level and suffering from recruitment failure. When reopening fisheries, setting of total allowable catches (TACs) and national quotas has been universal. Enforcement practices vary greatly within the European countries. In some countries, enforcement of fishing regulations is very strict and carried out on real time bases, while in other countries there appears to be very little enforcement of the existing regulations. Large quantities of herring are sometimes landed and even sold as sprat, whiting, or mackerel. Overshooting TACs is therefore common, and inadequate reporting of catches makes assessment difficult and less reliable than need be. In those cases where fishery regulations are enforced, management is mainly concerned with restricting the activities of the participating vessels so that they do not overfish. In doing so, the best fishing areas have in some cases been closed to fishing, because otherwise the catches would be far too large for the small quantity allocated to each boat. In other cases the catches per boat per night have to be so restricted (because of the large number of participating vessels) that large but unknown quantities of herring are dumped at sea. With the modernized fleets and the large number of boats participating, management has assumed the image of concentrating on "anti-effectiveness." Although the biological management objectives have been well defined and agreed to, the overall management objectives have neither been defined nor agreed to. These must take into account not only the biological objectives but also socioeconomic aspects. A management objective could be to fish the TACs with minimum expense, thus gaining maximum benefit in terms of profits from harvesting the resource. The traditionally free entry and free participation would then be the main obstacle to such an objective. This is especially acute in the case of a schooling species, which can be fished cheaply in large quantities. It is therefore important to develop new methods to restrict effort and investment. This leads to the basic problem of redefining the ownership of the fish stocks. Before an owner is firmly established, management will be under very severe constraints in limiting the entry to the fisheries.

1981 ◽  
Vol 38 (12) ◽  
pp. 1908-1914 ◽  
Author(s):  
G. R. Spangler ◽  
A. H. Berst ◽  
J. F. Koonce

The Stock Concept International Symposium (STOCS) addressed a broad range of concerns about the relationship between intraspecific stocks and their genetic and environmental origins. STOCS produced an understanding of the stock concept that makes it possible to develop operational stock definitions reflecting the key elements of concern to fishery managers. These definitions can change as circumstances dictate because stocks represent states in a dynamic process. Extensive life history information available for Great Lakes fish provides a basis for estimating the significance of intraspecific stock structure in management of these species. Recognition of the potential for stock formation is important for evaluating the impact of management actions and for planning the restoration of individual species in fishery rehabilitation programs. Finally, we present a brief set of recommendations for research and management based on our perception of the stock concept and its relevance to fish community rehabilitation.Key words: fish stocks, fishery rehabilitation


Science ◽  
2009 ◽  
Vol 325 (5940) ◽  
pp. 578-585 ◽  
Author(s):  
Boris Worm ◽  
Ray Hilborn ◽  
Julia K. Baum ◽  
Trevor A. Branch ◽  
Jeremy S. Collie ◽  
...  

After a long history of overexploitation, increasing efforts to restore marine ecosystems and rebuild fisheries are under way. Here, we analyze current trends from a fisheries and conservation perspective. In 5 of 10 well-studied ecosystems, the average exploitation rate has recently declined and is now at or below the rate predicted to achieve maximum sustainable yield for seven systems. Yet 63% of assessed fish stocks worldwide still require rebuilding, and even lower exploitation rates are needed to reverse the collapse of vulnerable species. Combined fisheries and conservation objectives can be achieved by merging diverse management actions, including catch restrictions, gear modification, and closed areas, depending on local context. Impacts of international fleets and the lack of alternatives to fishing complicate prospects for rebuilding fisheries in many poorer regions, highlighting the need for a global perspective on rebuilding marine resources.


2007 ◽  
Vol 64 (4) ◽  
pp. 768-774 ◽  
Author(s):  
Verena M. Trenkel ◽  
Marie-Joëlle Rochet ◽  
Benoît Mesnil

Abstract Trenkel, V. M., Rochet, M-J., and Mesnil, B. 2007. From model-based prescriptive advice to indicator-based interactive advice. – ICES Journal of Marine Science, 64: 768–774. Traditional advice for fisheries management, especially in the ICES world, focuses on short-term stock projections relative to reference points. Primarily, two numbers, spawning-stock biomass and fishing mortality rate, are considered in the advice, although a range of biological processes are included in the stock assessment models. We propose an alternative form of final advice that would not rely on stock predictions and only two numbers, but on a suite of indicators that are combined to provide stock assessment and management advice. For a single stock, the approach consists of monitoring a set of indicators of population state and fishing pressure. Stock reference status at some time in the past is assessed, based on these indicators and/or other available information. Changes in indicator values after this reference time are then estimated, interpreted, and finally combined into a diagnostic that highlights possible causes of the changes observed. After considering management objectives, appropriate management actions can then be proposed. The proposed approach is illustrated for anglerfish stocks in the Celtic Sea and the Bay of Biscay.


Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1803
Author(s):  
Valentino Palombo ◽  
Elena De Zio ◽  
Giovanna Salvatore ◽  
Stefano Esposito ◽  
Nicolaia Iaffaldano ◽  
...  

Mediterranean trout is a freshwater fish of particular interest with economic significance for fishery management, aquaculture and conservation biology. Unfortunately, native trout populations’ abundance is significantly threatened by anthropogenic disturbance. The introduction of commercial hatchery strains for recreation activities has compromised the genetic integrity status of native populations. This work assessed the fine-scale genetic structure of Mediterranean trout in the two main rivers of Molise region (Italy) to support conservation actions. In total, 288 specimens were caught in 28 different sites (14 per basins) and genotyped using the Affymetrix 57 K rainbow-trout-derived SNP array. Population differentiation was analyzed using pairwise weighted FST and overall F-statistic estimated by locus-by-locus analysis of molecular variance. Furthermore, an SNP data set was processed through principal coordinates analysis, discriminant analysis of principal components and admixture Bayesian clustering analysis. Firstly, our results demonstrated that rainbow trout SNP array can be successfully used for Mediterranean trout genotyping. In fact, despite an overwhelming number of loci that resulted as monomorphic in our populations, it must be emphasized that the resulted number of polymorphic loci (i.e., ~900 SNPs) has been sufficient to reveal a fine-scale genetic structure in the investigated populations, which is useful in supporting conservation and management actions. In particular, our findings allowed us to select candidate sites for the collection of adults, needed for the production of genetically pure juvenile trout, and sites to carry out the eradication of alien trout and successive re-introduction of native trout.


AMBIO ◽  
2021 ◽  
Author(s):  
Ingunn M. Tombre ◽  
Fredrik Fredriksen ◽  
Odd Jerpstad ◽  
Jan Eivind Østnes ◽  
Einar Eythórsson

AbstractImplementing management objectives may be challenging when decisions are made at different scales than where they are supposed to be carried out. In this study we present a situation where local goose hunting arrangements respond to objectives in an international management plan for pink-footed geese (Anser brachyrhynchus) and a local wish to reduce goose numbers as means to reduce grazing damage on farmland. A unique ten-year dataset provides an evaluation of the efficiency of voluntary actions at a local scale for implementing a policy of population control of geese, and general lessons are drawn for collaboration and co-production of knowledge for adaptive management. The study demonstrates how both the hunters and geese adapt in a situation where increasing the harvest of geese is the main objective. Introducing hunting-free days and safe foraging areas significantly increased goose numbers in the study area, with a corresponding increase in hunting success in terms of number of harvested geese. The geese’s behavioural response to hunting also triggered the hunters to adapt accordingly by optimal timing and placement in the landscape. Based on the results of the present study we suggest a framework for local implementation of management actions. Bringing end-users on board, facilitates processes and strengthens the achievements, as they represent the actors where implementation occurs. Specifically, our findings demonstrate how optimal goose hunting can be practiced by the use of an adaptive framework with active stakeholder participation.


2005 ◽  
Vol 62 (7) ◽  
pp. 1310-1321 ◽  
Author(s):  
Hans-Joachim Rätz ◽  
Josep Lloret

Abstract Growth variation was estimated from mean lengths-at-ages 4 and 5 for Atlantic cod off Greenland based on 52 973 fish taken from commercial and scientific catches from 1955 to 2002. Mean length-at-age values were corrected for area and seasonal effects, and significant growth reductions occurred during the 1960s and from the mid-1970s until the mid-1980s. Annual growth rates of cod in Greenland waters during the most recent decade (1993–2002) were consistently among the highest recorded. Statistical growth models accounting for temperature, fishing mortality, and stock abundance effects were constructed. Multiple linear regressions revealed significant positive temperature effects on growth of both age groups and a significant negative stock density effect on length-at-age 4. Correlations between exploitation intensity and length-at-age were statistically insignificant. During the period 1955–2002, the number of recruits at age 3 was significantly correlated with the Greenland cod spawning-stock biomass, June water temperature on top of Fyllas Bank (West Greenland), and Iceland cod recruitment. All factors had a positive effect on the number of Greenland recruits and, combined, accounted for 60% of the observed variation. Spawning stock size was, by far, the most important factor contributing to recruitment variability, while June water temperature below 1°C and Iceland recruits below 150 million never coincided with high year-class strength in Greenland during the past 50 years. Thus, previous conclusions regarding a close relation between the Greenland and Icelandic cod stocks might need to be reconsidered in the light of a continued recruitment failure in Greenland waters over the two most recent decades, despite the improved environmental conditions and near-average recruitment of the Icelandic stock. The low precision of the recruitment model, however, prevents reliable predictions in the short or medium term, but a substantial short-term recovery of the Greenland cod stock remains unlikely.


2016 ◽  
Vol 73 (9) ◽  
pp. 2190-2207 ◽  
Author(s):  
Chantel R. Wetzel ◽  
André E. Punt ◽  

Abstract Ending overfishing and rebuilding fish stocks to levels that provide for optimum sustainable yield is a concern for fisheries management worldwide. In the United States, fisheries managers are legally mandated to end overfishing and to implement rebuilding plans for fish stocks that fall below minimum stock size thresholds. Rebuilding plans should lead to recovery to target stock sizes within 10 years, except in situations where the life history of the stock or environmental conditions dictate otherwise. Federally managed groundfish species along the US West Coast have diverse life histories where some are able to rebuild quickly from overfished status, while others, specifically rockfish (Sebastes spp.), may require decades for rebuilding. A management strategy evaluation which assumed limited estimation error was conducted to evaluate the performance of alternative strategies for rebuilding overfished stocks for these alternative US West Coast life histories. Generally, the results highlight the trade-off between the reduction of catches during rebuilding vs. the length of rebuilding. The most precautionary rebuilding plans requiring the greatest harvest reduction resulted in higher average catches over the entire projection period compared with strategies that required a longer rebuilding period with less of a reduction in rebuilding catch. Attempting to maintain a 50% probability of rebuilding was the poorest performing rebuilding strategy for all life histories, resulting in a large number of changes to the rebuilding plan, increased frequency of failing to meet rebuilding targets, and higher variation in catch. The rebuilding plans that implemented a higher initial rebuilding probability (≥60%) for determining rebuilding fishing mortality and targets generally resulted in fewer changes to the rebuilding plans and rebuilt by the target rebuilding year, particularly for stocks with the longer rebuilding plans (e.g. rockfishes).


2003 ◽  
Vol 47 (1) ◽  
pp. 133-135 ◽  
Author(s):  
Jon C. Lovett

During the 1980s and 1990s there were two major changes to forest management objectives in Tanzania. Firstly, it was recognized that some of the forests, notably those on mountains in the east of the country and the coastal plain, are exceptionally rich in species of restricted distribution. Recent analysis has even placed these forests amongst the most important biodiversity hotspots world-wide. Secondly, there was a recognition that communities needed to be much more involved in forest management. The Forest Act, 2002, which replaces the 1957 Forest Ordinance, tackles both of these objectives and introduces some new concepts of forest ownership. Moreover it makes arrangements for establishing a fund that promotes protection of biodiversity and sustainable development of forest resources. This note first briefly reviews the history of forest law in Tanzania and then discusses innovations introduced by the 2002 Act.


PEDIATRICS ◽  
1994 ◽  
Vol 93 (6) ◽  
pp. 977-985
Author(s):  
Cesar G. Victora ◽  
Sandra C. Fuchs ◽  
José Antonio C. Flores ◽  
Walter Fonseca ◽  
Betty Kirkwood

Objective. To investigate risk factors for pneumonia for infants <2 years of age. Design. Hospital-based, case-control study with neighborhood control subjects. Setting. Urban area in southern Brazil. Subjects. Five hundred ten infants with radiologically confirmed pneumonia who were admitted to a pediatric hospital. One age-matched neighborhood control subject was selected for each case. Results. Multiple conditional regression modeling was used to control for confounding, taking into account the hierarchical relationships between risk factors. The incidence of radiologically confirmed pneumonia was associated with low paternal education, the number of persons in the household, young maternal age, attendance at day-care centers, low birth weight and weight-for-age, lack of breast-feeding and of non-milk supplements, and a history of previous pneumonia or wheezing. Day-care center attendance showed the highest risk, with an adjusted odds ratio of 11.75. Conclusions. In addition to continued efforts toward appropriate case management, actions directed against the above risk factors may help prevent the major cause of deaths of children younger than 5 years.


<i>Abstract.</i>—This chapter provides the history of the Caspian Kutum <i>Rutilus kutum</i> (Kamensky 1901) fishery in the Caspian Sea, analyzes long-term changes of stock condition and the main causes of fluctuations in abundance, and describes conservation measures that allowed resumption of fishing. Caspian Kutum (Cyprinidae family) is an endemic, semi-anadromous, medium-sized fish, reaching 53–67 cm in total length (rarely 71 cm) and weighing up to 4.0 kg (rarely 5.0 kg). Commercially important fisheries occur in Russia, Azerbaijan, Iran, and Turkmenistan. Flesh and roe are enjoyed as food and have a high price in markets. Variability in sea level, construction of hydroelectric power plants on rivers, water irrigation withdrawals, industrial and domestic pollution, overfishing, and illegal fishing resulted in a sharp decline of Caspian Kutum abundance and resulted in a total ban on harvest in Russia between 1995 and 2004. In Iran, fishing for Caspian Kutum continued due to their stocking program. Conservation measures for Caspian Kutum stocks (e.g., listing in federal and local Red Data books, fishing ban, fight against illegal fishing), as well as an increase of artificial propagation in Iran, Azerbaijan, and Dagestan (Russia) during subsequent years, have allowed the recovery of stocks in Russian waters to 1990s levels as well as the resumption of fishing. The follow lessons may be applicable to fishery management programs elsewhere:


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