bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessing the relative effects of fishing on the New Zealand marine environment through risk analysis
Authors: Campbell Marnie L. , Gallagher Charmaine 
Published: July 2007

Abstract
Campbell, M. L. and Gallagher, C. 2007. Assessing the relative effects of fishing on the New Zealand marine environment through risk analysis – ICES Journal of Marine Science, 64: 256–270. Risk analysis is a tool often used by management to aid decision-making. We present a risk-analysis framework that was developed to facilitate managing New Zealand fisheries. Using catch-effort and observer data, the likelihood that a certain fishery will impact upon five effects of fishing (EoF) issues (non-target species, biodiversity, habitat, trophic interactions, and legislated protected species) is determined. The consequences (impact and/or change) of such events are then determined to determine a relative risk ranking across fisheries. Consequence matrices were developed to assess each of the five EoF categories. To illustrate the model, a 13-y data set of New Zealand fisheries catch-effort and observer data was analysed, using orange roughy (Hoplostethus atlanticus) as an example fishery. The New Zealand fisheries management framework follows a traditional model in which socio-political imperatives are determined (through risk assessment) after ecological impacts are assessed. By maintaining separation between ecological and socio-political imperatives, a transparent and objective framework is established.
Regional variation in maturation of sandeels in the North Sea
Authors: Boulcott Philip , Wright Peter J. , Gibb Fiona M. , Jensen Henrik , Gibb Iain M. 
Published: July 2007

Abstract
Boulcott, P., Wright, P. J., Gibb, F. M., Jensen, H., and Gibb, I. M. 2007. Regional variation in maturation of sandeels in the North Sea. – ICES Journal of Marine Science, 64: 369–376. The current assessment of lesser sandeel (Ammodytes marinus) in the North Sea assumes a single stock and a knife-edge maturity ogive. However, there is evidence that the North Sea stock consists of several reproductively isolated components, raising the possibility of demographic differences among regional aggregations. We examine regional variation in size- and age-at-maturity in four components of the North Sea stock. Surveys in 1999 indicated pronounced regional differences in length- and weight-at-age, implying a disparity in growth rate across the North Sea. Logistic regression revealed that the onset of maturity was significantly related to regional distribution, in addition to length and age, with a tendency for fish off the UK's northeast coast to mature later and smaller than elsewhere. No significant effect of year on either growth or length-at-maturity was revealed from a comparison with other data collected in 2004. The results show that important regional phenotypic variation not currently represented in stock assessments could have implications for the local sustainability of sandeel aggregations.
Geostatistical simulations of eastern Bering Sea walleye pollock spatial distributions, to estimate sampling precision
Authors: Walline Paul D. 
Published: July 2007

Abstract
Walline, P. D. 2007. Geostatistical simulations of eastern Bering Sea walleye pollock spatial distributions, to estimate sampling precision. – ICES Journal of Marine Science, 64: 559–569. Sequential Gaussian and sequential indicator geostatistical simulation methods were used to estimate confidence intervals (CIs) for biomass estimates from six echo-integration trawl surveys of eastern Bering Sea walleye pollock (Theragra chalcogramma) biomass. Uncertainty in the acoustic and the length frequency data was combined in the calculation of CIs. Sampling in 2002 provided evidence for isotropy in the spatial distribution. Variogram models were characterized by long ranges (75–122 nautical miles for non-zero acoustic data, for example) compared with the smallest dimension of the survey area (∼100 nautical miles) and small nugget effects (∼20% of the semi-variance in transformed normal space for acoustic data). The 95% CIs obtained for the abundance estimates did not vary greatly between years and were similar to those from a one-dimensional transitive geostatistical analysis, i.e. ± 5–9% of estimated total biomass.
Integrated fisheries assessment and possible causes for the collapse of anchovy kilka in the Caspian Sea
Authors: Daskalov Georgi M. , Mamedov Elchin V. 
Published: July 2007

Abstract
Daskalov, G. M., and Mamedov, E. V. 2007. Integrated fisheries assessment and possible causes for the collapse of anchovy kilka in the Caspian Sea. – ICES Journal of Marine Science, 64: 503–511. Anchovy kilka (Clupeonella engrauliformis) is the most abundant species of fish in the Caspian Sea. An integrated catch-at-age analysis based on commercial catch data and relative abundance indices from research surveys over the period 1991–2004 indicated two main periods. First, a period of high catches, from 1991 to 2000, sustained by relatively good recruitment and high spawning-stock biomass. At the end of this period, catches peaked at up to 271 400 t, fishing mortality reached 1.8 y−1 in 1999, and overfishing seems to have taken place. Over the next period, 2001–2004, the stock virtually collapsed, recruitment failing in 2001 and remaining very low thereafter. In 2005, total catches dropped to a historical minimum of 54 300 t. The most likely primary cause of the stock collapse is the invasion and spread of the ctenophore Mnemiopsis leidyi in the Caspian Sea. The dramatic recruitment failure from 2001 to 2004 is primarily attributed to competition/predation by this ctenophore, although other factors, including overfishing, likely contributed.
Indications of competition between non-indigenous round goby and native flounder in the Baltic Sea
Authors: Karlson Agnes M. L. , Almqvist Gustaf , Skóra Krzysztof E. , Appelberg Magnus 
Published: July 2007

Abstract
Karlson, A. M. L., Almqvist, G., Skóra, K. E., and Appelberg, M. 2007. Indications of competition between non-indigenous round goby and native flounder in the Baltic Sea. – ICES Journal of Marine Science, 64: 479–486. The Ponto-Caspian round goby (Neogobius melanostomus) was introduced to the Gulf of Gdańsk, southern Baltic Sea, in the late 1980s, and it has now become the dominant demersal fish species in shallow water. This study aimed to assess diet preferences and the degree of diet overlap between the round goby and the native flounder (Platichthys flesus). Results from time-series of stomach contents and stable isotope analyses of wild-caught fish, together with prey preference experiments carried out in the laboratory, showed that the two species consumed similar species and sizes of prey. The similarities in diet suggest potential for food competition. Catch data showed both reverse depth distributions of round goby and flounder when round gobies were abundant and that the abundances of the two species were negatively correlated. The diet overlap between small flounders and round gobies was greatest when goby abundance was least, suggesting that abundance of round gobies may restrict flounder habitat utilization and, therefore, also food availability to the latter. Therefore, round gobies may have a negative influence on the commercially important flounder.
Human activities in UK offshore waters: an assessment of direct, physical pressure on the seabed
Authors: Eastwood P. D. , Mills C. M. , Aldridge J. N. , Houghton C. A. , Rogers S. I. 
Published: July 2007

Abstract
Eastwood, P. D., Mills, C. M., Aldridge, J. N., Houghton, C. A., and Rogers, S. I. 2007. Human activities in UK offshore waters: an assessment of direct, physical pressure on the seabed. – ICES Journal of Marine Science, 64: 453–463. Integrated assessments (IA) and marine spatial planning (MSP) are becoming major drivers for the assessment and management of human activities at sea. To be successful, both require an understanding of the distribution of the pressures caused by human activities. We used spatial data for the major human activities operating in the England and Wales sector of UK waters in 2004 to provide an assessment of direct, physical pressure on the seabed from multiple human activities. Pressure was estimated as the spatial extent of each of the activities; the intensity, longevity, and impacts arising from the pressures were not considered. Estimates of spatial extent were assigned to three pressure categories, subdivided into six pressure types. We estimated that four of the six pressure types affected < 1% of the seabed of England and Wales in 2004, whereas selective extraction caused by demersal trawling affected a minimum of 5.4%, rising to a possible maximum of 21.4%, of the total area of the seabed. This was a greater area than all other pressure types combined. The assessment process described here can be used as the framework for reporting human pressures at regular time intervals and feed into both IA and MSP for regional seas.
Why a management procedure approach? Some positives and negatives
Authors: Butterworth Doug S. 
Published: July 2007

Abstract
Butterworth, D. S. 2007. Why a management procedure approach? Some positives and negatives. – ICES Journal of Marine Science, 64: 613–617. The origin of the management procedure (MP) approach (sometimes termed management strategy evaluation), with its simulation testing of feedback-control algorithms as a necessary and structured basis for dealing with the inevitable uncertainties associated with fisheries assessments, is briefly reviewed. Also discussed are the advantages that overcome some of the difficulties of the “traditional” approach of coupling an annual “best” assessment to some harvest control rule, such as a failure to consider longer-term trade-offs properly. The MP approach does, however, also have disadvantages, such as the length of time typically required for its development and an argued inflexibility after implementation. Solutions that have been developed to overcome some of these difficulties are discussed.
Random-walk dynamics of exploited fish populations
Authors: Niwa Hiro-Sato 
Published: July 2007

Abstract
Niwa, H-S. 2007. Random-walk dynamics of exploited fish populations. – ICES Journal of Marine Science, 64: 496–502. Fished populations have been heavily fished over a wide range of stock sizes, and the data for such stocks are potentially of great interest. Population variability in stock histories has focused attention on the predictability of conditions of sustainability when harvesting fish. Here, I examine empirically the time-series data on 27 commercial fish stocks in the North Atlantic. The variability in population growth rate (i.e. the annual changes in the logarithms of population abundance) is described by a Gaussian distribution. The signs (up or down) of successive changes in the population trajectory are independent, as if determined by the toss of a coin. The process of population variability therefore corresponds to a geometric random walk.
An altered carrying capacity of the Benguela upwelling ecosystem for African penguins (Spheniscus demersus)
Authors: Crawford Robert J. M. , Underhill Les G. , Upfold Leshia , Dyer Bruce M. 
Published: July 2007

Abstract
Crawford, R. J. M., Underhill, L. G., Upfold, L., and Dyer, B. M. 2007. An altered carrying capacity of the Benguela upwelling ecosystem for African penguins (Spheniscus demersus). – ICES Journal of Marine Science, 64: 570–576. The carrying capacity of an ecosystem for a species is an input parameter that is required for some models that assess population viability. It may be changed by an altered structure or functioning of the ecosystem, e.g. as a consequence of changes brought about by fishing or environmental change. Hence, it cannot necessarily be assumed that the pristine level of abundance of a species reflects the present-day carrying capacity of the ecosystem for that species. Historical and modern information on abundance and density-dependent responses is used to investigate changes in the carrying capacity of the Benguela upwelling ecosystem for African penguins (Spheniscus demersus), a species categorized as vulnerable. The carrying capacity was estimated to decrease from 1.5–3.0 million adult birds in the 1920s to just 10–20% of this value from 1978 to 2006, as a result inter alia of increased competition for food with purse-seine fisheries and fur seals (Arctocephalus pusillus pusillus). From 1988/1989 to 2005/2006, the per capita recruitment of young penguins to a colony where nesting space was not limiting was inversely related to the size of that colony, suggestive of a density-dependent response perhaps related to food availability.
When control rules collide: a comparison of fisheries management reference points and IUCN criteria for assessing risk of extinction
Authors: Rice Jake C. , Legacè Èmilie 
Published: July 2007

Abstract
Rice, J. C., and Legacè, È. 2007. When control rules collide: a comparison of fisheries management reference points and IUCN criteria for assessing risk of extinction. – ICES Journal of Marine Science, 64: 718–722. The quantitative criteria used by the International Union for the Conservation of Nature (IUCN) to assess risk-of-extinction are compared with reference points used by ICES and other fisheries organizations for advising on fisheries management. Criteria based on numbers of individuals and geographic range appear to be in harmony with limit reference points and control rules used in fisheries management, with reference points indicating that fisheries should be closed well before there is any risk of extinction. However, there is huge potential for conflict between fisheries and risk-of-extinction approaches when considering the extent of population declines. Of 89 species examined, the decline criterion suggested a serious risk-of-extinction in 87%, whereas most of the stocks were still within a zone that allowed fisheries management reference points to indicate that exploitation could continue. Much of the conflict seems rooted in different types of tolerance to risk between the two disciplines. The conservation-biology community acknowledges a high tolerance for “false alarms”, to keep the probability of a “miss” very low, whereas tolerance in fisheries management is comparable for both types of error.
FLR: an open-source framework for the evaluation and development of management strategies
Authors: Kell L. T. , Mosqueira I. , Grosjean P. , Fromentin J-M. , Garcia D. , Hillary R. , Jardim E. , Mardle S. , Pastoors M. A. , Poos J. J. , Scott F. , Scott R. D. 
Published: July 2007

AbstractKell, L. T., Mosqueira, I., Grosjean, P., Fromentin, J-M., Garcia, D., Hillary, R., Jardim, E., Mardle, S., Pastoors, M. A., Poos, J. J., Scott, F., and Scott, R. D. 2007. FLR: an open-source framework for the evaluation and development of management strategies. – ICES Journal of Marine Science, 64: 640–646. The FLR framework (Fisheries Library for R) is a development effort directed towards the evaluation of fisheries management strategies. The overall goal is to develop a common framework to facilitate collaboration within and across disciplines (e.g. biological, ecological, statistical, mathematical, economic, and social) and, in particular, to ensure that new modelling methods and software are more easily validated and evaluated, as well as becoming widely available once developed. Specifically, the framework details how to implement and link a variety of fishery, biological, and economic software packages so that alternative management strategies and procedures can be evaluated for their robustness to uncertainty before implementation. The design of the framework, including the adoption of object-orientated programming, its feasibility to be extended to new processes, and its application to new management approaches (e.g. ecosystem affects of fishing), is discussed. The importance of open source for promoting transparency and allowing technology transfer between disciplines and researchers is stressed.
Element composition of sardine (Sardina pilchardus) otoliths along the Atlantic Coast of the Iberian Peninsula
Authors: Castro B. G. 
Published: July 2007

Abstract
Castro, B. G. 2007. Element composition of sardine (Sardina pilchardus) otoliths along the Atlantic Coast of the Iberian Peninsula. – ICES Journal of Marine Science, 64: 512–518. The element composition of sardine (Sardina pilchardus) otoliths along the Atlantic Coast of the Iberian Peninsula was determined by bulk analysis, using Inductively Coupled Plasma-Mass Spectrometry. Samples (collected 2003–2005) were classified by area [Bay of Biscay (GV), Northwest (OCN), and Southwest (GC) of the Iberian Peninsula] and size group ( ≤ 15, 16–18, and ≥ 21 cm total length). The chemical composition was compared statistically between areas within size groups and between size groups within areas by ANOVA and a Support Vector Machine method, using 10-fold cross-validation. The element composition of sardine otoliths was similar to that of other marine fish. In all, eight elements (Li, Ba, Mg, Mn, Na, Sr, K, and Ca) were useful in discriminating between areas and/or size groups. Discrimination between areas within size groups was less effective for the biggest size group (67%) than for the middle (89%) or smallest size groups (84%). Discrimination between size groups within areas was better for GC (76%) and GV (84%) than for OCN (60%). The results are interpreted in terms of a net balance of migration of large sardine from OCN towards GV and GC.
Oceanic changes in the Sargasso Sea and declines in recruitment of the European eel
Authors: Friedland Kevin D. , Miller Michael J. , Knights Brian 
Published: July 2007

AbstractFriedland, K. D., Miller, M. J., and Knights, B. 2007. Oceanic changes in the Sargasso Sea and declines in recruitment of the European eel. – ICES Journal of Marine Science, 64: 519–530. Anguillid eel recruitment in the North Atlantic has declined in recent decades, raising concerns that climatic changes in the Sargasso Sea may be influencing oceanic reproduction and larval survival. There is a significant negative correlation between the North Atlantic Oscillation and long-term variations in catches of glass eel stages of the European eel Anguilla anguilla recorded by the fishery independent Den Oever recruitment index (DOI) in the Netherlands, lagged by one year. Ocean-atmospheric changes in the Sargasso Sea may affect the location of spawning areas by silver eels and the survival of leptocephali during the key period when they are transported towards the Gulf Stream. A northward shift in a key isotherm (22.5°C), defining the northern boundary of the spawning area, a declining trend in winds and transport conditions in larval transport areas, and a shallowing of the mixed layer depth could affect primary productivity in areas where leptocephali feed. The relationships between these ocean parameters and the DOI suggest that these changing ocean conditions could be contributing to declining recruitment of the European eel and probably also of the American eel (A. rostrata), but anthropogenic factors during their continental life stage must also be considered.
Contribution of artificial reefs to the diet of the white sea bream (Diplodus sargus)
Authors: Leitão Francisco , Santos Miguel N. , Monteiro Carlos C. 
Published: July 2007

Abstract
Leitão, F., Santos, M. N., and Monteiro, C. C. 2007. Contribution of artificial reefs to the diet of the white sea bream (Diplodus sargus). – ICES Journal of Marine Science, 64: 473–478. An evaluation of the trophic relationship between Diplodus sargus and artificial reefs (ARs) in the Algarve (southern Portugal) is based on a comparison of stomach contents and the macrobenthic communities present at the AR and in surrounding sandy bottom areas. Only adult white sea bream were observed in the vicinity of the ARs. The percentage of items found in the stomach that were characteristic of AR hard substratum was high (67%). Although the diet contained a wide variety of items, namely reef algae, invertebrates (crustaceans, gastropods, and bivalves), and fish, Balanus amphitrite and Gibbula spp. contributed most to the diet. The diet of D. sargus was strongly associated with prey availability on the AR, so highlighting the importance of these artificial habitats to the species. It seems that these artificial feeding areas, owing to their extent and benthic production, are enhancing the local D. sargus stock and hence the fishery.
Sustainable management of mixed demersal fisheries in the North Sea through fleet-based management—a proposal from a biological perspective
Authors: Rätz Hans-Joachim , Bethke Eckhard , Dörner Hendrik , Beare Doug , Gröger Joachim 
Published: July 2007

Abstract
Rätz, H-J., Bethke, E., Dörner, H., Beare, D., and Gröger, J. 2007. Sustainable management of mixed demersal fisheries in the North Sea through fleet-based management—a proposal from a biological perspective. – ICES Journal of Marine Science, 64: 652–660. Cod, haddock, whiting, saithe, plaice, sole, and Norway lobster are main target species for the mixed demersal fisheries of the North Sea, Skagerrak, and eastern Channel. Management by total allowable catch has not been able to constrain exploitation of individual species, so the potential for a fleet-specific effort management system to reach the management objectives established for the stocks is simulated. Relative fleet-specific effort factors are estimated based on the sum of partial fishing mortalities of the species caught, weighted by the stocks at risk of reduced reproductive capacity. The strategy promotes the use of selective gear and levies non-selective gear. The factors were applied in medium-term simulations of the annual decision process in accordance with existing and proposed multi-annual management plans (including for cod recovery). Strict effort reduction would be required for fleets targeting cod, plaice, or sole (specifically large- and medium-mesh trawler fleets, beam trawlers, and gillnetters) for ∼5 years, reducing the exploitation rates on all stocks substantially. Cod and plaice are predicted to recover by 2010 and cod catches to exceed recent levels continually, with the more selective longliners and some other gear types profiting most. Management objectives for cod dominate annual effort adjustments, resulting in substantial underexploitation of other stocks. However, even a 10% bias caused by non-compliance would largely halt cod recovery and the restoration of other stocks.
The dual role of indicators in optimal fisheries management strategies
Authors: Rice Jake C. , Rivard Denis 
Published: July 2007

Abstract
Rice, J. C., and Rivard, D. 2007. The dual role of indicators in optimal fisheries management strategies. – ICES Journal of Marine Science, 64: 775–778. Indicators are used in two different ways in the assessment and advisory cycle. One is to audit performance of the management plan relative to achieving the objectives for the fishery. The second is to trigger control rules to manage the subsequent harvest. Traditionally, the assessment and management community has used spawning-stock biomass and fishing mortality for these functions, and as management strategies are being developed, generally continues to test the same indicators in both the audit and control functions. There is no reason to use the same indicators in both functions, and management of a few specialized commercial fisheries has recognized this, using different indicators in different roles for many years. That different indicators may be optimal for both roles presents a richer range of opportunities for exploring robust management strategies, and will be essential as ecosystem considerations and integrated management tools are included in assessment and management.