From single-species advice to mixed-species management: taking the next step

Abstract Fishery management advice has traditionally been given on a stock-by-stock basis. Recent problems in implementing this advice, particularly for the demersal fisheries of the North Sea, have highlighted the limitations of the approach. In the long term, it would be desirable to give advice that accounts for mixed-fishery effects, but in the short term there is a need for approaches to resolve the conflicting management advice for different species within the same fishery, and to generate catch or effort advice that accounts for the mixed-species nature of the fishery. This paper documents a recent approach used to address these problems. The approach takes the single-species advice for each species in the fishery as a starting point, then attempts to resolve it into consistent catch or effort advice using fleet-disaggregated catch forecasts in combination with explicitly stated management priorities for each stock. Results are presented for the groundfish fisheries of the North Sea, and these show that the development of such approaches will also require development of the ways in which catch data are collected and compiled.

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Reconciling single-species TACs in the North Sea demersal fisheries using the Fcube mixed-fisheries advice framework

ICES Journal of Marine Science ◽

10.1093/icesjms/fsr060 ◽

2011 ◽

Vol 68 (7) ◽

pp. 1535-1547 ◽

Cited By ~ 59

Author(s):

Clara Ulrich ◽

Stuart A. Reeves ◽

Youen Vermard ◽

Steven J. Holmes ◽

Willy Vanhee

Keyword(s):

North Sea ◽

Single Species ◽

Simple Approach ◽

Total Allowable Catch ◽

Traditional Management ◽

The North ◽

Management Objectives ◽

Species Management ◽

The North Sea ◽

Management Advice

Abstract Ulrich, C., Reeves, S. A., Vermard, Y., Holmes, S. J., and Vanhee, W. 2011. Reconciling single-species TACs in the North Sea demersal fisheries using the Fcube mixed-fisheries advice framework. – ICES Journal of Marine Science, 68: 1535–1547. Single-species management is a cause of discarding in mixed fisheries, because individual management objectives may not be consistent with each other and the species are caught simultaneously in relatively unselective fishing operations. As such, the total allowable catch (TAC) of one species may be exhausted before the TAC of another, leading to catches of valuable fish that cannot be landed legally. This important issue is, however, usually not quantified and not accounted for in traditional management advice. A simple approach using traditional catch and effort information was developed, estimating catch potentials for distinct fleets (groups of vessels) and métiers (type of activity), and hence quantifying the risks of over- and underquota utilization for the various stocks. This method, named Fcube (Fleet and Fisheries Forecast), was applied successfully to international demersal fisheries in the North Sea and shaped into the advice framework. The substantial overquota catches of North Sea cod likely under the current fisheries regimes are quantified, and it is estimated that the single-species management targets for North Sea cod cannot be achieved unless substantial reductions in TACs of all other stocks and corresponding effort reductions are applied.

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Influence of trends in fishing power on bioeconomics in the North Sea flatfish fishery regulated by catches or by effort quotas

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f02-057 ◽

2002 ◽

Vol 59 (5) ◽

pp. 829-843 ◽

Cited By ~ 34

Author(s):

Clara Ulrich ◽

Sean Pascoe ◽

Per J Sparre ◽

Jan-Willem De Wilde ◽

Paul Marchal

Keyword(s):

North Sea ◽

Fishery Management ◽

Single Species ◽

Simulation Modelling ◽

Economic Benefits ◽

Total Allowable Catch ◽

The North ◽

Control Rules ◽

Solea Solea ◽

The North Sea

Total allowable effort quotas (TAEs) are often considered as promising alternatives to single-species total allowable catch quotas (TACs) in fisheries management. However, implementing TAEs would primarily require converting nominal effort into fishing mortality rate, i.e., developing a relevant model of the dynamics of catchability. Assuming that trends in the catchability may occur through fishing-power creeping linked to increased capital invested and technology, we compare, by stochastic and dynamic simulation modelling, the relative biological and economic benefits and drawbacks of TAEs and TACs in the North Sea sole (Solea solea L.) and plaice (Pleuronectes platessa L.) fishery. Management targets are based on the Precautionary Approach and Harvest Control Rules developed by the International Council for the Exploration of the Sea (ICES). Fishermen are assumed to set their effort at the most (TAE) or least (TAC) conservative level. Overall, the outcomes are more sensitive to the catchability model when implementing TAEs, especially in the medium and long term, but the variability in catchability has a much greater impact on stock levels than on the fisheries profit.

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Connect and Divide

The Journal of Transport History ◽

10.7227/tjth.35.2.5 ◽

2014 ◽

Vol 35 (2) ◽

pp. 200-219

Author(s):

Eike-Christian Heine

Keyword(s):

North Sea ◽

Transport Infrastructure ◽

Military Strategy ◽

Environmental Consequences ◽

The North ◽

Starting Point ◽

History Of ◽

The North Sea ◽

The Baltic ◽

Kiel Canal

The Kiel Canal (built between 1886 and 1895) connects the North Sea and the Baltic for seagoing vessels, yet, being 100 km long, about 10 m deep and 100 m wide, it also divides a landscape. This finding is the starting point for analysing the effects of infrastructure that facilitates communication and exchange but also produces obstructions and rivalries. This article explores the ambiguous effects this piece of infrastructure had on politics, technology, labour, trade and military strategy. The ‘deep ditch’ also had severe environmental consequences that were palpable until well into the twentieth century. By considering both the ‘positive’ and the ‘negative’ of the waterway, the narrative of ‘connect-and-divide’ avoids the still-too-often told affirmative story of transport infrastructure. Instead, it and opens the outlook to a multi-faceted history of transport infrastructures.

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Predicting the effects of area closures and fishing effort restrictions on the production, biomass, and species richness of benthic invertebrate communities

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2006.02.006 ◽

2006 ◽

Vol 63 (5) ◽

pp. 822-830 ◽

Cited By ~ 76

Author(s):

J.G. Hiddink ◽

T. Hutton ◽

S. Jennings ◽

M.J. Kaiser

Keyword(s):

Species Richness ◽

North Sea ◽

Fishery Management ◽

Benthic Communities ◽

Fishing Effort ◽

Management Actions ◽

The North ◽

The North Sea ◽

Effort Reduction ◽

Positive Effect

AbstractTo effectively implement an Ecosystem Approach to Fisheries (EAF), managers need to consider the effects of management actions on the fishery and the ecosystem. Methods for assessing the effects on target stocks are generally well developed, but methods for assessing the effects on other components and attributes of the ecosystem are not. Area closures and effort controls are widely used fishery management tools that affect the distribution of fishing effort and may therefore have consequences for a range of species and habitats. An approach is developed to predict the effects of area closures and effort control on the biomass, production, and species richness of benthic communities in the North Sea. The redistribution of beam trawling effort as a result of management action was modelled with a random utility model, assuming that fishers selected fishing grounds on the basis of their knowledge of past catch rates. The effects of trawling on benthic invertebrates were predicted using a size-based model that accounted for differences in habitat among fishing grounds. Our simulations demonstrated that closures of different sizes and in different locations could have positive or negative effects on benthic communities. These predicted effects resulted from the trade-off between recovery in the closed areas and additional trawling effects in the open areas that arose from displaced fishing activity. In the absence of effort controls, closure of lightly fished areas had the strongest positive effect on benthic communities. Effort reduction also had a positive effect. Therefore, area closures in lightly fished areas, coupled with effort reduction, are expected to minimize the effects of fishing on benthic communities. As it was not possible to access full international data for the North Sea beam trawl fleet, the results of the analyses are illustrative rather than complete. Nevertheless, what is demonstrated is an effective approach for assessing the environmental consequences of fishery management action that can be used to inform management decision-making as part of an EAF.

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Das Verb „brauen“ im Helgoländischen: mit Beibehaltung der starken Flexion und reich entwickelter Semantik

Us Wurk ◽

10.21827/5fb7c8c82fc0a ◽

2020 ◽

Vol 69 (3-4) ◽

pp. 105-114

Author(s):

N. Århammar

Keyword(s):

20Th Century ◽

North Sea ◽

Dictionary Entry ◽

Figurative Meaning ◽

Beer Brewing ◽

The North ◽

Starting Point ◽

The North Sea ◽

The Senses ◽

Germanic Languages

The verb „brew“ in the North Frisian dialect of the North Sea island of Heligoland is in two respects remarkable: first it has retained its original strong inflection (section 1) and secondly it developed a number of special meanings during the 19/20th century (section 2). I have tried to demonstrate how this great diversity came about: The starting point for thesemantic development was probably the analogy ʽbrew kettleʼ (for beer brewing) ~ ʽsteam boilerʼ (of steam-boats). In a small seafaring nation a shift of meaning from ʽbrew (beer)ʼ → ʽdrive (a ship)ʼ may seem rather natural; less so the further steps via *ʽmove in generalʼ → ʽwalk briskly, runʼ and so on (→ ʽlive, keep house, manage to get on well (as a single)ʼand ʽbe busy, workʼ etc.). Sense 8. of the dictionary entry, a figurative meaning, stands apart, namely ʽconcoct, contrive, prepare, bring about, causeʼ: spec. evil, mischief, trouble, woe (OED). It is noted that this sense was developed in most Germanic languages and it probably represents a much older sprout on the helig. brau-tree than do the senses 2. to 7. Insection 3, I deal with the helig. idiom Bin brau ʽto bring into disorderʼ and the helig.-wfris. parallel uun Bin ~ yn ʼe/ʼt bûn ʽin disorderʼ. – In the appendix the revised and enlarged word article brau with its prefix compounds is presented

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Mesh-size matters in epibenthic surveys

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s002531540200512x ◽

2002 ◽

Vol 82 (1) ◽

pp. 1-8 ◽

Cited By ~ 14

Author(s):

Ruth Callaway ◽

Simon Jennings ◽

John Lancaster ◽

John Cotter

Keyword(s):

Community Structure ◽

North Sea ◽

Processing Time ◽

Mesh Size ◽

Community Analysis ◽

Single Species ◽

Spatial Gradients ◽

The North ◽

Significant Difference ◽

The North Sea

This study aimed to identify the effects of different sieve mesh-sizes on processing time, the number of species retained, diversity measures and multivariate community analysis in the North Sea. Samples were collected at 63 sites throughout the North Sea and washed through two successive sieves, 10-mm and 5-mm mesh respectively. Processing time for whole samples (5- and 10-mm fraction) averaged 91± 25 min compared with 55±16 min for the 10-mm mesh fraction. Altogether 40% of free-living species and 9% of attached species were recorded exclusively in the 5-mm fraction. The majority of these species were rare. Spatial gradients of species diversity and community structure were identical, independent of the mesh-size used. Multivariate community analysis showed no significant difference between descriptions of community structure based on fauna from 10-mm or 5-mm mesh. The use of coarser sieving mesh would save time and money, if the aims of an epibenthic survey were to describe broad patterns of community structure and relative diversity. It would be possible to process approximately 50% more samples, if the time saved with 10-mm mesh were allocated to additional sampling. However, if information on single species is required, then sorting with the finer sieve mesh will yield crucial information. It was decided to employ a 5-mm mesh for epibenthic monitoring of the North Sea.

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Implications for current management advice for North Sea plaice: Part I. Migration between the North Sea and English Channel

Journal of Sea Research ◽

10.1016/j.seares.2003.10.004 ◽

2004 ◽

Vol 51 (3-4) ◽

pp. 287-299 ◽

Cited By ~ 17

Author(s):

L.T. Kell ◽

R. Scott ◽

E. Hunter

Keyword(s):

North Sea ◽

English Channel ◽

Current Management ◽

The North ◽

The North Sea ◽

Management Advice

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The integration of public domain lithostratigraphic data into a series of cross-border North Sea well-penetration maps

Geological Society London Special Publications ◽

10.1144/sp494-2020-25 ◽

2020 ◽

pp. SP494-2020-25

Author(s):

Henk Kombrink ◽

Stefano Patruno

Keyword(s):

North Sea ◽

Public Domain ◽

Petroleum Exploration ◽

The Public ◽

Cross Border ◽

The North ◽

Starting Point ◽

Geological Information ◽

Paper Form ◽

The North Sea

AbstractAs geological information about the North Sea is increasingly made available to the public, there is great potential to build cross-border datasets to enable people to more rapidly filter relevant geological data and also to better understand and further study the subsurface. This paper discusses the construction of such a geological database and presents the associated map set. Public domain lithostratigraphic data from petroleum exploration and appraisal wells drilled in the Norwegian, Danish, German, Dutch and UK North Sea sectors were used to create a series of 13 well-penetration maps, ranging from Basement to Eocene age. In order to produce the maps, lithostratigraphic well tops had to be translated into a chronostratigraphic scheme, followed by building a database and subsequent mapping in a GIS. Three well categories were used for each of the maps: wells that (1) fully penetrate a chronostratigraphic interval, (2) prove it is absent or (3) reach total depth in the interval under consideration. The resulting maps, which will all be discussed and presented in this paper, form a starting point for multiple types of (petroleum) geological screening studies. The North Sea database is freely available in QGIS format and can be easily imported into any geospatial software platform.

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Emergence of a new predator in the North Sea: evaluation of potential trophic impacts focused on hake, saithe, and Norway pout

ICES Journal of Marine Science ◽

10.1093/icesjms/fsw050 ◽

2016 ◽

Vol 73 (5) ◽

pp. 1370-1381 ◽

Cited By ~ 5

Author(s):

Xochitl Cormon ◽

Alexander Kempf ◽

Youen Vermard ◽

Morten Vinther ◽

Paul Marchal

Keyword(s):

North Sea ◽

Negative Impact ◽

Stock Assessment ◽

Single Species ◽

Bottom Up ◽

The North ◽

Spatial Shift ◽

Spawning Stock ◽

The North Sea ◽

Indirect Impacts

Abstract During the last 15 years, northern European hake (Merluccius merluccius) has increased in abundance, and its spatial distribution has expanded in the North Sea region in correlation with temperature. In a context of global warming, this spatial shift could impact local trophic interactions: direct impacts may affect forage fish through modified predator–prey interactions, and indirect impacts may materialize through competition with other resident predators. For instance, North Sea saithe (Pollachius virens) spatial overlap with hake has increased while saithe spawning-stock biomass has decreased recently notwithstanding a sustainable exploitation. In this context, we investigated the range of potential impacts resulting from most recent hake emergence in the North Sea, with a particular focus on saithe. We carried out a multispecies assessment of North Sea saithe, using the Stochastic MultiSpecies (SMS) model. In addition to top-down processes already implemented in SMS, we built in the model bottom-up processes, relating Norway pout (Trisopterus esmarkii) abundance and saithe weight-at-age. We simulated the effects, on all North Sea species being considered but focusing on Norway pout and saithe, of combining different hake abundance trends scenarios with the inclusion of bottom-up processes in SMS. North Sea saithe FMSY was then evaluated in a multispecies context and contrasted with single-species value. The different scenarios tested revealed a negative impact of hake emergence on saithe biomass, resulting from an increase of predation pressure on Norway pout. These results confirm the competition assumption between saithe and hake in the North Sea and might partially explain the most recent decrease of saithe biomass. This study also highlighted that taking into account bottom-up processes in the stock assessment had a limited effect on the estimation of saithe FMSY which was consistent with single-species value.

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