Do dietary changes of Australasian gannets (Morus serrator) reflect variability in pelagic fish stocks?

2004 ◽  
Vol 31 (4) ◽  
pp. 383 ◽  
Author(s):  
Ashley Bunce
Keyword(s):  
Fisheries Management ◽  
Prey Species ◽  
Relative Proportion ◽  
Pelagic Fish ◽  
Commercial Catch ◽  
Fish Stocks ◽  
Important Prey ◽  
Morus Serrator ◽  
The Relationship ◽  
Stock Abundance

The relationship between changes in the diet of Australasian gannets (Morus serrator) and commercial fisheries landings was investigated. The contribution of pilchard (Sardinops sagax) to the diet of gannets was significantly related to the commercial catch of that species, suggesting that changes in the relative proportion of pilchard in the diet of gannets may be a useful index of pilchard abundance and availability. Equivalent relationships, however, were not found for other common prey species in the gannet diet. It is considered that the abundance of important prey items in the gannet diet, such as pilchards, and commercial landings are proportional to stock abundance. The implications of this relationship for fisheries management are examined.

Catchability and the spatial distribution of fishing vessels

2003 ◽  
Vol 60 (3) ◽  
pp. 259-268 ◽  
Author(s):  
Are Salthaug ◽  
Sondre Aanes
Keyword(s):  
Gadus Morhua ◽  
Fish Stock ◽  
Melanogrammus Aeglefinus ◽  
Catch Per Unit Effort ◽  
Spatial Concentration ◽  
Commercial Catch ◽  
Fish Stocks ◽  
Fishing Vessels ◽  
The Relationship ◽  
Stock Abundance

A central problem when using commercial catch per unit effort (CPUE) as an index of fish stock abundance is that fishing vessels search for concentrations of fish. For a given stock abundance, CPUE may become high if the vessels succeed in finding patches of fish and low if the vessels distribute their catching operations more randomly. In this work, the relationship between catchability and two measures of the degree of spatial concentration of a trawl fleet (the fleet's spatial extent and the fleet's degree of spatial patchiness) is investigated for four different fish stocks. The catchability of northeast Arctic cod (Gadus morhua) is strongly related to the fleet's degree of spatial concentration, but the relationship is weaker for northeast Arctic haddock (Melanogrammus aeglefinus), and no relationships appear for two saithe (Pollachius virens) stocks. Our findings suggest that adjusting CPUE with a measure of the fleet's average degree of concentration relates CPUE more strongly with abundance for migratory stocks.

Interaction Between Stock Area, Stock Abundance, and Catchability Coefficient

1985 ◽  
Vol 42 (5) ◽  
pp. 989-998 ◽  
Author(s):  
G. H. Winters ◽  
J. P. Wheeler
Keyword(s):  
Stock Assessment ◽  
Population Decline ◽  
Clupea Harengus ◽  
Atlantic Herring ◽  
Population Abundance ◽  
Commercial Catch ◽  
Standard Manner ◽  
Clupea Harengus Harengus ◽  
The Relationship ◽  
Stock Abundance

The relationship between commercial catch-rates and population density upon which many stock assessment models depend assumes that stock area (A) is constant and independent of population abundance. Starting from a theoretical demonstration that the catchability coefficient (q) is inversely proportional to A, we establish the empirical basis of this relationship through comparisons of q and A of various Northwest Atlantic herring (Clupea harengus harengus) stocks and, in more detail, for Fortune Bay herring. For these stocks the relationship was of the form q = cA−b. For Atlantic herring stocks, levels of b were in excess of 0.80. In Fortune Bay herring, reductions in abundance were accompanied by proportional reductions in A, which in turn was inversely correlated with changes in q. School size, measured as catch per set, also declined as population levels declined but the change was not proportional. Published findings indicate that pelagic stocks in particular, and fish stocks in general, exhibit a common response of reductions in A with interactive increases in the q during periods of rapid population decline. We conclude that the conventional assumption of a constant stock area is usually violated due to the systematic interaction between A and population abundance which is reflected in an inverse relationship between stock abundance and q. Calibration of sequential population models should therefore be restricted to research vessel data collected in a standard manner and covering the distributional area of the stock.

scholarly journals Non-Participation in the Fish Stocks Agreement: Status and Reasons

2011 ◽  
Vol 26 (2) ◽  
pp. 195-234 ◽  
Author(s):  
E.J. Molenaar
Keyword(s):  
Fisheries Management ◽  
Law Of The Sea ◽  
Current Status ◽  
Fish Stocks ◽  
The Law ◽  
Regional Fisheries Management Organizations ◽  
The Relationship ◽  
Final Text ◽  
Regional Fisheries Management

AbstractAlthough the Fish Stocks Agreement was adopted by consensus after around only 2.5 years of negotiation, the final text did not fully resolve all significant differences of view. As it was feared that participation in the Fish Stocks Agreement would remain as troublesome as in the 1958 Geneva Fisheries Convention, considerable efforts have been made to promote wider participation since the Agreement’s entry into force in 2001. On 22 November 2010 there were 78 parties to the Fish Stocks Agreement and 161 to the Law of the Sea Convention. This article examines the current status and reasons for non-participation in the Fish Stocks Agreement by, inter alia, categorizing non-participation, appraising participation in light of the current participation in the Law of the Sea Convention and examining the relationship between the Agreement and regional fisheries management organizations.

scholarly journals The relationship between Oceanographic Parameters and Fish Larvae Dispersal in the Fisheries Management Area of the Republic Indonesia (FMA) 717

2021 ◽  
Vol 925 (1) ◽  
pp. 012032
Author(s):  
Y H Restiangsih ◽  
I M Radjawane ◽  
A Mamun ◽  
D Kembaren ◽  
E Nurdin
Keyword(s):  
Chlorophyll A ◽  
Fisheries Management ◽  
Larval Dispersal ◽  
Fish Larvae ◽  
Direct Interaction ◽  
Principal Component ◽  
Environmental Parameters ◽  
Pelagic Fish ◽  
Management Area ◽  
The Relationship

Abstract Cendrawasih Bay and the Pacific Ocean are known as potential fishing areas and as fish spawning locations in Fisheries Management Area 717. Larval dispersal in the waters is strongly influenced by oceanographic parameters. This study was conducted to examine the relationship between oceanographic parameters and fish larval dispersal in FMA 717. This research was conducted using KR Bawal Putih III in November 2019. A number of 42 stations were determined for observation. Environmental parameters included temperature, salinity, dissolved oxygen, chlorophyll-a, turbidity, and photosynthetic active radiation (PAR), were measured using SBE 19 plus V2 CTD while pelagic fish larvae were collected using a bonggo net. Analysis of the correlation of oceanographic parameters with pelagic fish larvae abundance and spatial distribution was calculated using PCA (Principal Component Analysis) statistical analysis. The results showed that the pelagic fish larvae was influenced by temperature, salinity, PAR, chlorophyll-a, turbidity, and DO. Temperature and salinity have a direct interaction to the abundance of pelagic fish larvae.

Assessment of Lamprey and Fish Stocks in the Great Lakes in Relation to Control of the Sea Lamprey (Petromyzon marinus): Report from the SLIS Assessment Measurements Task Force

1980 ◽  
Vol 37 (11) ◽  
pp. 2197-2201 ◽  
Author(s):  
P. S. Maitland
Keyword(s):  
Great Lakes ◽  
Prey Species ◽  
Task Force ◽  
Stock Assessment ◽  
Control Program ◽  
Sea Lamprey ◽  
Nontarget Organisms ◽  
Fish Stocks ◽  
Important Prey ◽  
The Impact

Available and potential methodology for assessing lamprey and prey fish populations is related to existing and future requirements of the sea lamprey control program of the Great Lakes Fishery Commission (GLFC). For lamprey, we recommend that the classification of Great Lakes tributaries according to their potential for larval production and the quality of lamprey attack data should be improved and standardized; standardized collections of spawning run adults should be continued; research should be encouraged on attractants and repellents, a male sterilization program, and the biology of parasitic phase animals. For fish, we recommend that more emphasis be given to the precision and standardization of estimates to allow better comparison between places and years, and the assessment of fish stocks other than major prey species; the GLFC support an evaluation program of an important prey species; and that other assessment methods (e.g. acoustic; counts of entrained fish) be explored. Because lamprey control is a long-term process that may span periods of environmental change, monitoring of physical, chemical, and biotic factors should be encouraged. Research on the impact of lampricides on nontarget organisms should be expanded. We also discuss and offer suggestions on the future of sea lamprey control.Key words: stock assessment, fishery surveys, methodology, populations control, proposed research

Diet

2017 ◽  
Author(s):  
M.G.L. Mills ◽  
M.E.J. Mills
Keyword(s):  
Prey Species ◽  
Radio Tracking ◽  
Relative Occurrence ◽  
Important Prey ◽  
Individual Prey ◽  
Sibling Groups

Four methods were used to document the diet of cheetahs: incidental observations, radio tracking, tracking, spoor, and continuous follows. A combination of continuous follows and tracking spoor gave the best results. Steenbok were the most frequently killed species, but they did not dominate the diet in the same way as Thomson’s gazelle do in the Serengeti. Coalition males have a different diet profile from single males, single females, females with cubs, and sibling groups. For all but single males, the relative occurrence of prey species in the diet reflected its dietary importance in terms of kilograms of meat obtained. Gemsbok calves and adult ostrich were important prey for coalition males and springhares were important for single males. Three individual prey specializations for females were found; namely springbok specialists, steenbok/duiker specialists, and intermediates. Contrary to an earlier study, springbok were not found to be the most important prey species.

Taking Stock of Genetic Concepts in Fisheries Management

1991 ◽  
Vol 48 (4) ◽  
pp. 722-731 ◽  
Author(s):  
R. W. Gauldie
Keyword(s):  
Fisheries Management ◽  
Growth Rates ◽  
Allele Frequencies ◽  
Frequency Variation ◽  
Sustainable Yield ◽  
Fish Stocks ◽  
Meristic Count ◽  
Intuitive Idea ◽  
Selection Mechanisms ◽  
Insight Into

The historical development of the idea of isolated stocks of fish that can be managed as separate management units has been as strongly tied to the intuitive idea of separate races as it has been to the practical necessities of jurisprudence and the estimation of both biomass and sustainable yield by fisheries managers. Demonstrating the existence of isolated fish stocks and delineating their boundaries has generally proved unsuccessful. Various techniques ranging from meristic count differences to polymorphic allelism have usually failed. However, in the pursuit of isolated stocks, biochemists have uncovered a great deal of information about the variation of polymorphic allele frequencies over time and space. Following the shift in opinion away from stochastic to natural selection mechanisms in allele frequency variation, it is evident that the observed variation in allele frequencies allows more insight into the biology of fishes than into the breeding structure of populations. These insights argue against the idea of isolated stocks of fish with homogeneous growth rates that are the basis of the sustainable yield models in favour of migration-linked stocks with heterogeneous growth rates.

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 Herring and ICES: a historical sketch of a few ideas and their linkages

2009 ◽  
Vol 66 (8) ◽  
pp. 1652-1661 ◽  
Author(s):  
Mike Sinclair
Keyword(s):  
Paradigm Shift ◽  
Pelagic Fish ◽  
Marine Ecology ◽  
Effective Management ◽  
Paradigm Shifts ◽  
Population Thinking ◽  
Fish Stocks ◽  
Considerable Debate ◽  
Historical Sketch

Abstract Sinclair, M. 2009. Herring and ICES: a historical sketch of a few ideas and their linkages. – ICES Journal of Marine Science, 66: 1652–1661. This introduction to the Symposium on “Linking Herring” sketches the development of some ideas generated from herring research within an ICES context. The work of Committee A (1902–1908), under the leadership of Johan Hjort, led to a paradigm shift from “migration thinking” to “population thinking” as the interpretation of fluctuations in herring landings. From the 1920s to the 1950s, the focus on forecasting services for the herring fisheries, although ultimately unsuccessful, had the unintended consequence of generating ideas on recruitment overfishing and the match–mismatch hypothesis. The collapse of the East Anglian fishery led, in 1956, to considerable debate on its causes, but no consensus was reached. Three consecutive symposia dealing with herring (1961, 1968, and 1970) reveal a changing perspective on the role of fishing on recruitment dynamics, culminating in Cushing’s 1975 book (“Marine Ecology and Fisheries”, referred to here as the “Grand Synthesis”), which defined the concept of recruitment overfishing and established the future agenda for fisheries oceanography. The 1978 ICES “Symposium on the Assessment and Management of Pelagic Fish Stocks” is interpreted as the “Aberdeen Consensus” (i.e. without effective management, recruitment overfishing is to be expected). In conclusion, herring research within ICES has led to many ideas and two major paradigm shifts.

Elemental signatures in otoliths of hatchery rainbow trout (Oncorhynchus mykiss): distinctiveness and utility for detecting origins and movement

2009 ◽  
Vol 66 (4) ◽  
pp. 513-524 ◽  
Author(s):  
Daniel K. Gibson-Reinemer ◽  
Brett M. Johnson ◽  
Patrick J. Martinez ◽  
Dana L. Winkelman ◽  
Alan E. Koenig ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Water Chemistry ◽  
Fisheries Management ◽  
Valuable Insight ◽  
Otolith Chemistry ◽  
Considerable Potential ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
The Relationship ◽  
Ambient Levels

Otolith chemistry in freshwater has considerable potential to reveal patterns of origin and movement, which would benefit traditional fisheries management and provide a valuable tool to curb the spread of invasive and illicitly stocked species. We evaluated the relationship between otolith and water chemistry for five markers (Ba/Ca, Mn/Ca, Sr/Ca, Zn/Ca, and 87Sr/86Sr) in rainbow trout ( Oncorhynchus mykiss ) using the existing hatchery system in Colorado and Wyoming, USA, to provide controlled, seminatural conditions. Otolith Ba/Ca, Sr/Ca, and 87Sr/86Sr reflected ambient levels, whereas Mn/Ca and Zn/Ca did not. Using only the markers correlated with water chemistry, we classified fish to their hatchery of origin with up to 96% accuracy when element and isotope data were used together. Large changes in 87Sr/86Sr were evident in otolith transects, although subtler changes in Sr/Ca were also detectable. Our results suggest the relatively few otolith markers that reflect ambient chemistry can discriminate among locations and track movements well enough to provide valuable insight in a variety of applied contexts.

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