Status of the Major Commercial Fish Stocks and Proposed Species-specific Management Plans for Lake Victoria

2010 ◽  
Vol 12 (1) ◽  
Author(s):  
R Kayanda ◽  
A Taabu ◽  
R Tumwebaze ◽  
L Muhoozi ◽  
T Jembe ◽  
...  
Keyword(s):  
Lake Victoria ◽  
Commercial Fish ◽  
Fish Stocks ◽  
Management Plans ◽  
Species Specific ◽  
Specific Management

CRITICAL FACTORS OF WATER CONTENT FOR FISH STOCKS IN THE WATER RESERVOIRS OF KAZAKHSTAN

2017 ◽  
pp. 9-18
Author(s):  
Saule Zhangirovna Asylbekova ◽  
Kuanysh Baibulatovich Isbekov ◽  
Evgeniy Vyacheslavovich Kulikov
Keyword(s):  
Water Content ◽  
Water Level ◽  
Water Availability ◽  
Hydrological Regime ◽  
Fishing Effort ◽  
Water Reservoirs ◽  
The Caspian Sea ◽  
Annual Fish ◽  
Commercial Fish ◽  
Fish Stocks

The hydrological regime of water reservoirs in different years has a decisive impact on the abundance of commercial fish stocks and the quality of ichthyocenoses. In this connection in 2015-2016 there was conducted a retrospective analysis and ranking of hydrological regime impact on these factors. The paper gives evaluation of catches and fish stocks under different scenarios of water availability in the main fishing ponds of the Republic of Kazakhstan that give about 80% of the annual fish catch of the country (except the Caspian Sea). There were analyzed 2000 factors of hydrological regime (water level, annual discharge) and 1845 factors of fishing stocks (catches, abundance, fish biomass). The paper determines the critical characteristics of water availability for fish stocks. There have been proposed a number of administrative decisions and actions in case if water content would approach to the critical level. Among them: limitation of fish catches in the following year; widening zones restricted for fishing; intensification of safety measures of the fish young in residual ponds during arid periods; introduction of catch standards for a unit of fishing effort in low-water years, high-water years and years with normal water level in rivers.

scholarly journals Depleted marine fish stocks and ecosystem-based management: on the road to recovery, we need to be precautionary

2010 ◽  
Vol 68 (1) ◽  
pp. 212-220 ◽  
Author(s):  
Anna Gårdmark ◽  
Anders Nielsen ◽  
Jens Floeter ◽  
Christian Möllmann
Keyword(s):  
Fisheries Management ◽  
Marine Fish ◽  
Assessment Model ◽  
Fishing Mortality ◽  
Fish Stocks ◽  
The Road ◽  
Stock Status ◽  
Ecosystem Based Management ◽  
Management Plans ◽  
On The Road

Abstract Gårdmark, A., Nielsen, A., Floeter, J., and Möllmann, C. 2011. Depleted marine fish stocks and ecosystem-based management: on the road to recovery, we need to be precautionary. – ICES Journal of Marine Science, 68: 212–220. Precautionary management for fish stocks in need of recovery requires that likely stock increases can be distinguished from model artefacts and that the uncertainty of stock status can be handled. Yet, ICES stock assessments are predominantly deterministic and many EC management plans are designed for deterministic advice. Using the eastern Baltic cod (Gadus morhua) stock as an example, we show how deterministic scientific advice can lead to illusive certainty of a rapid stock recovery and management decisions taken in unawareness of large uncertainties in stock status. By (i) performing sensitivity analyses of key assessment model assumptions, (ii) quantifying the uncertainty of the estimates due to data uncertainty, and (iii) developing alternative stock and ecosystem indicators, we demonstrate that estimates of recent fishing mortality and recruitment of this stock were highly uncertain and show that these uncertainties are crucial when combined with management plans based on fixed reference points of fishing mortality. We therefore call for fisheries management that does not neglect uncertainty. To this end, we outline a four-step approach to handle uncertainty of stock status in advice and management. We argue that it is time to use these four steps towards an ecosystem-based approach to fisheries management.

scholarly journals Indirect economic indicators in bio-economic fishery models: agricultural price indicators and fish stocks in Lake Victoria

2005 ◽  
Vol 62 (3) ◽  
pp. 483-492 ◽  
Author(s):  
Silvio Simonit ◽  
Charles Perrings
Keyword(s):  
Nutrient Loading ◽  
Agricultural Land ◽  
Lake Victoria ◽  
Leading Indicators ◽  
Fish Stocks ◽  
Chl A ◽  
Run Off ◽  
Fishery Model ◽  
Agricultural Price ◽  
Point Pollution

Abstract We consider the potential for using prices as leading indicators of changes in stocks and yields in the freshwater capture fishery in Lake Victoria. Fertilizer run-off from agricultural land is a major cause of nutrient loading, along with soil erosion, atmospheric deposition, and point pollution from industrial and domestic affluent. The interactions between fertilizer applications, water quality, fish stocks, and yields are modelled in order to predict the effect of changes in the price of fertilizers on the fishery. The fishery model includes a measure of Chl a concentration (a proxy for phytoplankton density). The consequences of changes in Chl a concentration for fish stocks are modelled using Ecopath. We show that fertilizer prices are effective leading indicators of changes in fish biomass and yield.

scholarly journals North Sea cod recovery?

2006 ◽  
Vol 63 (6) ◽  
pp. 961-968 ◽  
Author(s):  
Joe Horwood ◽  
Carl O'Brien ◽  
Chris Darby
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Mortality Rates ◽  
Fishing Effort ◽  
Current Status ◽  
Fishing Mortality ◽  
Commercial Fish ◽  
Fish Stocks ◽  
Stock Assessments ◽  
Low Levels

AbstractRecovery of depleted marine, demersal, commercial fish stocks has proved elusive worldwide. As yet, just a few shared or highly migratory stocks have been restored. Here we review the current status of the depleted North Sea cod (Gadus morhua), the scientific advice to managers, and the recovery measures in place. Monitoring the progress of North Sea cod recovery is now hampered by considerable uncertainties in stock assessments associated with low stock size, variable survey indices, and inaccurate catch data. In addition, questions arise as to whether recovery targets are achievable in a changing natural environment. We show that current targets are achievable with fishing mortality rates that are compatible with international agreements even if recruitment levels remain at the current low levels. Furthermore, recent collations of data on international fishing effort have allowed estimation of the cuts in fishing mortality achieved by restrictions on North Sea effort. By the beginning of 2005, these restrictions are estimated to have reduced fishing mortality rates by about 37%. This is insufficient to ensure recovery of North Sea cod within the next decade.

Multi-year comparisons of fish recruitment, growth and production in two drought-affected Iberian estuaries

2010 ◽  
Vol 61 (12) ◽  
pp. 1399 ◽  
Author(s):  
Marina Dolbeth ◽  
Filipe Martinho ◽  
Vânia Freitas ◽  
Sérgia Costa-Dias ◽  
Joana Campos ◽  
...  
Keyword(s):  
Climate Extremes ◽  
Single Species ◽  
Freshwater Inflow ◽  
Freshwater Wetlands ◽  
Lower Growth ◽  
Fish Recruitment ◽  
Mondego Estuary ◽  
Management Plans ◽  
Species Specific ◽  
Minho Estuary

Climate extremes, such as drought and floods, are increasing and should be considered in ecosystem management plans. The effects of an extreme drought were studied in two estuaries of the Iberian coast, Minho and Mondego, by exploring fish recruitment, growth and production over four years. The two estuaries are located within an area with transitional climate, and differ considerably in size, availability of freshwater wetlands and freshwater inflow. Fishes from the Minho estuary, at higher latitude, generally had lower growth rates and later timing of recruitment. During the drought, freshwater inflow was severely reduced in both estuaries. The overall fish assemblage production in the Minho estuary decreased considerably, whereas in the Mondego estuary it showed an increase. However, the drought effects seemed highly species‐specific and dependent on local geomorphology; the increase in the Mondego estuary was a result of an increase in a single species, whereas other species decreased or maintained similar production levels. Decreases in production in both estuaries were attributed to direct and indirect effects of changes in the freshwater inflow during the study period. This parameter should therefore be considered when undertaking management plans for transitional waters.

scholarly journals What hat are you wearing? On the multiple roles of fishery scientists in the ICES community

2015 ◽  
Vol 73 (2) ◽  
pp. 209-216 ◽  
Author(s):  
Dorothy J. Dankel ◽  
Kari Stange ◽  
Kåre Nolde Nielsen
Keyword(s):  
Pelagic Fish ◽  
Multiple Roles ◽  
Marine Science ◽  
Network Organization ◽  
Fish Stocks ◽  
International Council ◽  
Advisory Councils ◽  
Work Tasks ◽  
Management Plans ◽  
Policy Relevant Science

Abstract Trends towards a more participatory agenda in policy-relevant science imply that the roles and work tasks of scientists become more multifaceted. In Europe, the increased use of multiannual plans creates a need for fishery scientists to contribute with their expertise in a wide variety of situations. We identify and characterize four roles for scientists as developers , reviewers , judges , and messengers in arenas where management plans are produced and evaluated. Using examples of producing and evaluating management plans for pelagic fish stocks in Europe, we present different scientific roles and how they may intertwine. The examples illustrate that fishery scientists increasingly interact with advisory councils and industry stakeholders when performing roles as developers and messengers. The roles as reviewers and judges are typically affiliated with evaluation processes carried out under the auspices of the marine science and advisory organization International Council for the Exploration of the Sea (ICES). While it may be difficult to separate the roles in practice, we argue that it must be emphasized to be aware of their different requirements to ensure that scientific credibility is not compromised. By asking the question “What hat are you wearing?”, we encourage individual fishery scientists, their employers, and ICES as a network organization of expertise to reflect on roles, affiliations, mandates, and possible consequences of wearing different “hats”.

scholarly journals Brown bear and Persian leopard attacks on humans in Iran

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0255042
Author(s):  
Jamshid Parchizadeh ◽  
Jerrold L. Belant
Keyword(s):  
Ursus Arctos ◽  
Brown Bear ◽  
Carnivore Species ◽  
As Species ◽  
Management Plans ◽  
Persian Leopard ◽  
Temporal And Spatial ◽  
The Government ◽  
Species Specific ◽  
National Reporting System

Large carnivore attacks on humans are a serious form of human-wildlife interaction which has increased globally in recent decades. When attacks occur, both humans and large carnivores suffer, highlighting the need to characterize these conflicts toward mitigation of attacks. We investigated brown bear (Ursus arctos) and Persian leopard (Panthera pardus) attacks on humans across Iran using reports provided by the Government of Iran during 2012–2020. We characterized temporal and spatial patterns of attacks, as well as species-specific attributes. We identified 83 attacks resulting in 77 human injuries and 6 fatalities. Bears were responsible for more attacks (63%) than leopards (37%). Attacks occurred more frequently during defensive reactions by bears and leopards on adult male people while livestock herding during the day in spring and summer. Bears reportedly attacked people more often in western provinces of Iran, while leopards attacked more frequently in northern provinces. We recommend that the Iran Department of the Environment consider implementing a national reporting system to document bear and leopard attacks on people. We further suggest development of national bear and leopard management plans that emphasize mitigating human risk to improve human attitudes toward these carnivore species to facilitate their conservation.

scholarly journals ANALYZING STOCK STATUS OF MAIN COMMERCIAL FISH IN KUIBYSHEV RESERVOIR IN 2000–2018 AND EFFECTIVENESS IN FISHING

2021 ◽  
Vol 2021 (1) ◽  
pp. 38-50
Author(s):  
Firdauz Mubarakovna Shakirova ◽  
Yuri Aleksandrovich Severov ◽  
Olga Konstantinovna Anokhina ◽  
Mikhail Aleksandrovich Gorshkov ◽  
Guzel Damirovna Valieva ◽  
...  
Keyword(s):  
Kuibyshev Reservoir ◽  
Age Composition ◽  
Commercial Fish ◽  
Fish Stocks ◽  
Biological Resources ◽  
Temperature Regimes ◽  
The Republic ◽  
Effective Development ◽  
Reproduction Efficiency

The article presents a review of the main commercial fish stocks of the Kuibyshev Reservoir based on the long-term research data (2000–2019). The Kuibyshev Reservoir is the leading fishery reservoir in the Republic of Tatarstan, Mari El, Chuvashia, Ulyanovsk and Samara Re-gions. There have been given the data of regular observing species, sex, size-weight and age composition of fish, their reproduction efficiency, distribution, abundance and reproduction of aquatic biological resources, their habitat, as well as control over their fishing and conservation. The analysis of the influence of environmental factors (level and temperature regimes) and fishing on the fish stocks formation is presented. Based on the presented materials, there have been shown the data about the stocks of the main commercial fish species of the Kuibyshev Reservoir (bream, zander, pike, carp, catfish, sterlet) and of the small-sized ordinary fish stocks, the optimal development of which will bring the catches up to 10 thousand tons and more. It has been inferred that for rational fishing in the reservoir, it is necessary to develop a strategy for the integrated effective development of biological resources of the reservoir on an ecosystem basis for better use of the bioproduction capabilities of its biological resources.

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