Elsevier

Biological Conservation

Volume 254, February 2021, 108946
Biological Conservation

Policy analysis
Identifying core areas for mobile species in space and time: A case study of the demersal fish community in the North Sea

https://doi.org/10.1016/j.biocon.2020.108946Get rights and content

Highlights

  • Core areas of abundance were calculated for 53 demersal fish species.

  • For each species core areas of occurrence were identified.

  • Many species' core areas changed between winter and summer.

  • Limited overlap between species' core areas and marine protected areas

  • New spatial measures are required to protect demersal fish in the North Sea.

Abstract

Identifying well suited sites for spatial conservation measures to protect mobile species is a challenging task. Intra- and interannual movements of individuals due to foraging, reproduction and environmental change make it difficult to identify the best placed locations. This study presents a generic approach for determining a species' consistent core areas in space and time by using point abundance data from annual surveys. For this approach no statistical modelling is required and thereby it is well suited to obtain distribution maps for all surveyed species without knowledge on environmental predictors, thereby ignoring any issues related to data availability, quality and model confidence. Generating distribution maps for a suite of demersal fish species by using data from a scientific fisheries survey allowed to identify consistent core areas for 53 species in winter and summer over a period of 21 years (1998–2018). By overlaying single species' distribution maps, hotspots of fish diversity could be compared to designated sites of marine protected areas (MPA) within the European Natura 2000 network. A majority of the identified diversity hotspots as well as the core areas of threatened and endangered species are currently not overlapping with the designated Natura 2000 MPAs. These MPAs might therefore not contribute sufficiently to the protection of marine demersal fish as an important component of marine ecosystems. Alternative spatial management options and tools implemented through other marine policies are needed to amend the Natura 2000 MPA network for the effective conservation of demersal fish in the North Sea.

Introduction

Marine protected areas (MPA) have become an important tool to conserve marine wildlife and manage exploited resources (Edgar et al., 2014; Halpern and Warner, 2003). Locating protected areas for mobile species such as marine fish, however, is a challenging task and it has been debated whether MPAs are the appropriate means to protect such species (Breen et al., 2015; Claudet et al., 2010; Hilborn et al., 2004; Kramer and Chapman, 1999). Intra- and interannual movements of individuals due to foraging, reproduction and environmental changes alter the habitat preferences of individuals throughout their life cycle (Harden Jones, 1968; Pittman and McAlpine, 2003). It is therefore difficult to assign areas large enough to conserve all life stages of a species (Horwood et al., 1998; Rayfield et al., 2008). Temporary conservation areas in combination with permanent protected areas have been proposed as solution (D'Aloia et al., 2019). However, in many situations political and societal circumstances will not allow for a flexible and adaptive designation of conservation sites (Halpern and Warner, 2003; Kaiser, 2005). Hence these sites should be chosen based on locations with consistently high abundances of threatened or overexploited ecosystem components (i.e. threatened species, habitats or exploited invertebrates or fishes) through space and time. Identifying such locations allows for an efficient allocation of limited spatial resources to conservation objectives.

The implementation of MPAs to manage marine resources has gained impetus at the beginning of the 21st century, as the impacts of intensive fishing during previous decades led to the perception of a crisis in quota-based fisheries management (Beddington et al., 2007; Jacquet, 2007; Worm et al., 2006). At this time, many experts advocated alternative approaches to fisheries management such as the establishment of networks of marine protected areas (MPAs) (Gell and Roberts, 2003; Roberts et al., 2005). While MPAs were demonstrated to be efficient management tools to improve the abundance and size composition of fish associated with structured habitats such as rocky habitats and reefs (Claudet et al., 2008; Claudet et al., 2010; Roberts et al., 2001), similar beneficial effects for fish species inhabiting boreal soft-bottom communities are still being discussed (Breen et al., 2015). Many fish species in temperate and boreal systems undergo wide ranging seasonal migrations between spawning areas, nursery habitats and feeding grounds (Harden Jones, 1968), and were therefore considered to be too mobile and too long-lived to benefit from localised spatial protection (Breen et al., 2015; Hilborn et al., 2004; Kaiser, 2005). However, there is increasing evidence that MPAs may also have positive impacts on demersal fish populations in boreal waters (Kincaid and Rose, 2017; Moland et al., 2013).

In Europe an extensive network of MPAs is established through the Birds and Habitat Directives (BD and HD), requiring European Union (EU) member states to designate MPAs in their coastal seas and exclusive economic zones (Agnesi et al., 2017; Fock, 2011; Mazaris et al., 2019). This network of MPAs is referred to as the Natura 2000 network. Borders of the national Natura 2000 MPAs had to be designated by each member state until 2008, resulting in about 23% of the North Sea being covered by the Natura 2000 network (Agnesi et al., 2017). However, while the BD and HD require the establishment of MPAs to protect sensitive benthic habitats (sandbanks and reefs), marine mammals, and sea birds, neither directive is addressing the conservation of marine fish species apart from a small number of diadromous fish species. As a consequence, very few Natura 2000 MPAs were designated with the aim of protecting marine fish species. In addition, there have been considerable delays to this day to agree upon and implement management measures such as fishing restrictions (Álvarez-Fernández et al., 2017; Dureuil et al., 2018). Therefore, identifying areas of consistent fish abundance and diversity remains a prerequisite to evaluate the potential conservation effect of the Natura 2000 MPAs on demersal fish.

This study interpolates and condenses point-abundance data in space and time to identify consistent patterns of demersal fish distribution within the North Sea. We used data from an internationally coordinated bi-seasonal scientific fisheries surveys covering a 21-year period to 1) demonstrate the concept of identifying consistent core areas for mobile organisms in space and time, and 2) analyse the potential of the designated Natura 2000 MPA network to protect demersal fish biodiversity in a heavily fished temperate/boreal region.

Section snippets

Study area and data sources

The Greater North Sea is a semi-enclosed shelf-sea area of the temperate North East Atlantic with a surface area of approximately 570,000 km2 and an average depth of 95 m. The Greater North Sea includes the Kattegat and Skagerrak, connecting the central basin of the North Sea with the Baltic Sea. The North Sea has been affected substantially by anthropogenic impacts (Emeis et al., 2015), but still remains one of the most productive fishing grounds in the world, being the habitat of more than

Patterns of consistent core areas and diversity

Seasonally consistent core areas (CCAW and CCAS) were identified for all 53 species, while species inter-seasonal consistent core areas (CCAWS) were identified for 49 species (Table 2). The only species without overlapping CCAWS were tope Galeorhinus galeus and topknot Zeugopterus punctatus. For five-bearded rockling Ciliata mustela and sea scorpion Taurulus bubalis catch records were too low to identify consistent CCAS. Therefore CCAWS which are important throughout the year could be

Discussion

In this study we provide a generic interpolation and aggregation protocol allowing the identification of important core areas for a large suite of mobile fish species. The method presented herein to identify consistent core areas has several advantages: It is modular by species, seasons and years, it is independent of environmental data, avoids the need for specialist statistical knowledge to apply the appropriate statistical model for highly skewed (zero inflated) distribution while providing

Author statement

We assure that

  • The work is all original research carried out by the authors.

  • All authors agree with the contents of the manuscript and its submission to the journal.

  • No part of the research has been published in any form elsewhere, unless it is fully acknowledged in the manuscript. Authors should disclose how the research featured in the manuscript relates to any other manuscript of a similar nature that they have published, in press, submitted or will soon submit to Biological Conservation or

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This study is part of the Thünen-Institute (TI) research initiative on the implementation of the Marine Strategy Framework directive (MSFD) “Definition and validation of indicators and environmental status assessment” (www.thuenen.de) and has been initiated as a result of cooperation between members of the Working Group on Biodiversity (WGBIODIV) of the International Council for the Exploration of the Sea (ICES). SPRG and MM received support for this work under Service Level Agreement ST02G (

References (62)

  • S.B.M. Kraak et al.

    RTI (“Real-Time Incentives”) outperforms traditional management in a simulated mixed fishery and cases incorporating protection of vulnerable species and areas

    Fish. Res.

    (2015)
  • A.D. Mazaris et al.

    Threats to marine biodiversity in European protected areas

    Sci. Total Environ.

    (2019)
  • S.J. Pittman et al.

    Movements of marine fish and decapod crustaceans: process, theory and application

    Adv. Mar. Biol.

    (2003)
  • B. Rayfield et al.

    Comparing static versus dynamic protected areas in the Québec boreal forest

    Biol. Conserv.

    (2008)
  • J.T. Reubens et al.

    Diel variation in feeding and movement patterns of juvenile Atlantic cod at offshore wind farms

    J. Sea Res.

    (2014)
  • G. Rilov et al.

    Adaptive marine conservation planning in the face of climate change: what can we learn from physiological, ecological and genetic studies?

    Glob. Ecol. Conserv.

    (2019)
  • V. Stelzenmüller et al.

    Monitoring and evaluation of spatially managed areas: a generic framework for implementation of ecosystem based marine management and its application

    Mar. Policy

    (2013)
  • V. Stelzenmüller et al.

    Co-location of passive gear fisheries in offshore wind farms in the German EEZ of the North Sea: a first socio-economic scoping

    J. Environ. Manag.

    (2016)
  • S. Agnesi et al.

    Spatial analysis of marine protected area networks in European Seass II, Voluma A, 2017

  • N. Bailey et al.

    Real Time Closures of Fisheries

    (2010)
  • J.R. Beddington et al.

    Current problems in the management of marine fisheries

    Science

    (2007)
  • L. Bergström et al.

    Effects of an offshore wind farm on temporal and spatial patterns in the demersal fish community

    Mar. Ecol. Prog. Ser.

    (2013)
  • J. Claudet et al.

    Marine reserves: size and age do matter

    Ecol. Lett.

    (2008)
  • J. Claudet et al.

    Marine reserves: fish life history and ecological traits matter

    Ecol. Appl.

    (2010)
  • C.C. D’Aloia et al.

    Coupled networks of permanent protected areas and dynamic conservation areas for biodiversity conservation under climate change

    Front. Ecol. Evol.

    (2019)
  • M. Dureuil et al.

    Elevated trawling inside protected areas undermines conservation outcomes in a global fishing hotpsot

    Science

    (2018)
  • G.J. Edgar et al.

    Global conservation outcomes depend on marine protected areas with five key features

    Nature

    (2014)
  • EEC

    Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora

    Official Journal of the European Communities

    (1992)
  • EU
  • EU-COM

    Commisson implementing regulation (EU) No 783/2011 of 5 August 2011 amending Regulation (EU) No 724/2010 laying down detailed rules for the implementation of real-time closures of certain fisheries in the North Sea and Skagerrak

    Off. J. Eur. Communities

    (2011)
  • H.O. Fock et al.

    Patterns of extirpation. II. The role of connectivity in the decline and recovery of elasmobranch populations in the German Bight as inferred from survey data

    Endanger. Species Res.

    (2014)
  • Cited by (7)

    • Modelling the distribution of rare and data-poor diadromous fish at sea for protected area management

      2023, Progress in Oceanography
      Citation Excerpt :

      Few MPAs within European waters protect marine fish and instead focus on protecting seabed features with a few exceptions (e.g., protected seabirds and marine mammals). Therefore the only protection measure that exist for vulnerable marine fish is through the removal of targeted fishing (Dureuil et al., 2018; Probst et al., 2021; Stratoudakis et al., 2016). There is, however, increasing evidence that MPAs may have positive impacts on fish populations if appropriate management measures are implemented (Davies et al., 2021; Moland et al., 2013; Probst et al., 2021; Worm et al., 2006).

    • From policy to practice: Addressing bycatch for marine species-at-risk in Canada

      2022, Marine Policy
      Citation Excerpt :

      While a single species may represent a small fraction of the total bycatch in a fishery, this can impose disproportionately greater impacts on the species in question if it is heavily depleted or endangered, as small populations of marine fishes are less resilient to additional mortality [12]. Most marine species are not distributed evenly throughout regional seascapes but concentrate in core habitats [13]. High bycatch rates in such habitats can give the false impression of an abundant population, an established phenomenon known as ‘hyperstability’ [14].

    View all citing articles on Scopus
    View full text