Chapter 1

In: Fisheries: Management, Economics and Perspectives ISBN 978-1-60692-303-0 Editors: N. F. McManus and D. S. Bellinghouse, pp. © 2008 Nova Science Publishers, Inc.

Short Communication D

FISHERIES AND MARINE CONSERVATION: HOW TO PROCEED IN A KNOWLEDGE-POOR ENVIRONMENT? ON THE NEED OF INTERACTION BETWEEN ECOLOGICAL RESEARCH AND MARINE MANAGEMENT Marijn Rabaut1, Steven Degraer1,2, Magda Vincx1 1

Ghent University (UGent), Biology Department, Marine Biology Section, Sterre Campus, Krijgslaan 281-S8, B-9000 Ghent, Belgium 2 Royal Belgian Institute of Natural Sciences Management Unit of the Mathematical Model of the North Sea, Gulledelle 100, 1200 Brussels, Belgium

1. ABSTRACT Concepts as ‘integrative’ and ‘ecosystem approach’ are often mentioned as key concepts to manage renewable marine resources sustainably. The existing amount of information on how to manage marine ecosystems in a sustainable way, however, is often perceived as insufficient. Combining the aim of putting a halt to ecosystem deterioration with an efficient and sustainable fishery seems to be a major challenge. In areas where the use of bottom gear is common, both overexploitation and the direct damage to bottom life prove to be concerns that need to be addressed urgently. This chapter presents a strategy to gather scientific information to support ecosystem management, taking into account the complexity of the system. The Belgian part of the North Sea (BPNS) was used as a model to apply this strategy. The strategy focuses on small-scale, short-term studies on a limited set of organisms in order to provide ready-to-use scientific information on a short term basis. Organisms investigated are chosen because of their horizontal and vertical links with other (groups of) organisms and because of their (direct or indirect) economic value. For the application in the BPNS, the bio-engineering polychaete Lanice conchilega (Sandmason) has been used. As it enabled specific research to quantify both the importance for commercial fish species as well as the impact of beam

2

Marijn Rabaut, Steven Degraer and Magda Vincx trawl fisheries on the benthic environment, this reef builder was proven to be a good proxy for the quality of the benthic environment The strategy of using small scale, short term studies on a limited number of species makes it possible to study a well defined area in a cost-efficient way; the information gathered in the case of L. conchilega is an example of ready-to-use information for the marine renewable resource management of the soft-bottom area of concern, taking the ecosystem approach into account.

2. INTRODUCTION Problems in marine renewable resource management are arising on a world-wide scale. Most often they are linked to overexploitation (e.g. Myers and Worm (2003)). The selective targeting of too many large specimens leads to the accrement of a so-called ‘Darwinian debt’ which will be borne by future generations (Walsh et al. (2006)). Apart from that, overexploitation leads to the phenomenon that is called ‘fishing down marine food webs’ and which will lead to the succession of local extirpation, followed by global extinctions (Pauly et al. (1998)). Today, we are finding ourselves not only far from a global sustainable use of marine resources, but rather are we moving towards a subsidy driven degradation of the marine environment (Sumaila and Pauly (2007)). In this context, clear management plans are needed. Concepts as ‘integrative’ and ‘ecosystem approach’ are often mentioned as key concepts to manage renewable marine resources sustainably. However, in reality it seems to be very difficult to regulate several human activities. Fisheries are generally recognized as the major critical factor for sustainable marine management (Kelleher (1999)). Kaiser et al. (2002) describe how productivity is decreasing as fishing intensity increases and highbiomass species are being removed from the benthic habitat. However, when policy decisions about the marine environment are made, a coherent approach that integrates both nature conservation and fisheries management appears to be impossible. The policy statement of May 30th, 2008 concerning fisheries of the European Commission (IP/08/828) states that 88% of EU fish stocks are overfished, compared to a ‘mere’ 25% on a global scale. The EC admits there has been a lack of progress since the 2002 Common Fisheries Policy (CFP), probably related to the heavy focus on the Total Allowable Catch (TAC) regime as a way to manage fisheries. At the same time, several European Directives with the objective of reaching sustainability in the marine environment1 came in place. Within the framework of the CFP, fisheries belong exclusively to the competence of the EC. The basic text for the CFP is Council Regulation (EC) N° 2371/2002 of 20 December 2002 on the conservation and sustainable exploitation of fisheries resources. Environmental issues on the other hand, are a shared responsability between the EU and the member states. Furthermore, the EC Treaty requires that environmental matters are integrated into other policy domains, such as fisheries. It is not clear to what extent member states have legal authority to take measures for the restriction of fishing activities within the framework of marine nature conservation, and whether such measures can be taken through the CFP. The aim to stop ecosystem deterioration together with an efficient and sustainable fisheries seems to be a major challenge (Rabaut et al. (in press)). In areas where bottom gear is applied, not only overexploitation is of concern, but also direct damage to bottom life 1

Birds Directive, Habitats Directive, Marine Strategy, Water Framework Directive

Fisheries and Marine Conservation

3

urgently needs to be addressed (Bergman and Hup (1992); Kaiser and Spencer (1996); Sparks-McConkey and Watling (2001)). The amount of information that is now available to manage systems in a sustainable way, however, is often perceived as insufficient. In this chapter we advocate the integration of marine conservation and fisheries, as these two aspects of marine management are unarguably closely related. This integration should be based on scientific research that is cost-efficient and ready-to-use in marine ecosystem management. Therefore, we present a strategy to gather scientific information to support management, taking into account the complexity of the system.

Figure 1. The BPNS with indication of both the allocated areas for different human activities (adopted from Maes et al. (2005); updated) and the allocated MPAs.

4

Marijn Rabaut, Steven Degraer and Magda Vincx

3. BELGIAN PART OF THE NORTH SEA The Belgian part of the North Sea (BPNS) is a rather small and shallow shelf area (3600 km²; max. 35 m depth), characterized by the presence of several sandbank systems, more or less oriented parallel to the coast. The characteristic geomorphologic and sedimentological diversity of these soft-bottom habitats is directly responsible for the high biological diversity and richness, reflected in a mosaic of several distinguishable macrobenthic communities (Degraer et al. (2002); Van Hoey et al. (2004)). The most used fishing method is beam trawling and the area has a rich marine management history where an ‘MPA-process’ is evolving (Rabaut et al. (in press)). This well-known and heavily exploited marine area (Figure 1) is particularly useful as a case study area to test the proposed strategy.

4. SELECTION OF SPECIES The presented strategy starts with the identification of possible key stone or indicator species in the area of concern. Species that biogenically create habitat complexity are often good candidates as habitat structuring organisms are known to add or alter physical, chemical and biological factors and are therefore often referred to as bioengineers (Jones et al. (1994)). The ecological mechanisms behind the effect of habitat structuring organisms are well described for all kinds of environments: coral reefs (e.g. Holbrook et al. (1990)), Darwin mounds (Van Gaever et al. (2004)), kelp forests (e.g. Steneck et al. (2002)), ascidians (Castilla et al. (2004)), seagrass meadows (e.g. Hovel et al. (2002); Alfaro (2006)), mussel banks (e.g. Hild & Günther (1999), Ragnarsson & Raffaelli (1999); People (2006)), oyster beds (Lenihan (1999)) and polychaete tubes (e.g. Woodin (1978); Dittman (1999); Hild & Günther (1999); Schwindt et al. (2001); Dubois et al. (2002); Bolam & Fernandes (2003); Callaway (2006)). The structurally complex framework provided by these emergent features constitutes an important organizing aspect and is critical to the functioning of many ecosystems (Jones et al. (1994)). These structures represent important habitats for a variety of marine organisms. They may provide refuge from predation, competition and physical as well as chemical stresses, or may represent important food resources and critical nursery or spawning habitats. In addition, these structures modify the hydrodynamic flow regime near the sea floor, with potentially significant ecological effects on sedimentation, food availability, larval and/or juvenile recruitment, growth and survival. As such, habitat structures and heterogeneity influence faunal abundance, species richness and species composition of invertebrate and fish communities (Turner et al. (1999); Koenig et al. (2000)). Moreover, there is a clear link to fisheries, as these habitats are generally productive and hence attractive for fishermen. An important step in the strategy is the scientific quantification of the the importance of selected habitats and/or species for higher trophic levels, especially for those that have a commercial value. Additionally, fishing activities have the capability of altering, removing or destroying the complex, three-dimensional physical structure of benthic habitats by the direct removal of biological and topographic features (especially trawl fisheries) (Turner et al. (1999)). When looking specifically at soft-bottom areas, locations with biogenic structures are proven to be vulnerable to fishing impacts (e.g. Pectinaria koreni (Bergman and Santbrink (2000)) and Pomatoceros spp. (Kaiser et al. (1999)). Chronic fishing


5

disturbance may be sufficient to severely reduce the complexity of such habitats by removing the fragile sessile fauna (Collie et al. (1997); Thrush et al. (1998)), reducing the suitability of the area to species of commercial importance (Sainsbury (1987); Kaiser et al. (1999)). Therefore, the quantification of these impacts for the selected species and/or habitats should be possible within the framework of a short term research programme.

4.1. Lanice Conchilega The common tube-dwelling polychaete Lanice conchilega is a well-known and widely distributed bio-engineer in soft bottom environments. Several aspects of the species are already known. The physiology, tube structure (Ziegelmeier (1952); Jones and Jago (1993)), hydrodynamic influence (Eckman (1983); Heuers et al. (1998); Dittmann (1999)), as well as the occurrence of L. conchilega aggregations (Carey (1987); Hartmann-Schröder (1996)) have already been described at length. The tube aggregations are known to have positive consequences for the distribution and abundance of infaunal species in intertidal and subtidal areas by influencing the habitat structure (Carey (1987); Feral (1989); Zühlke et al. (1998); Dittmann (1999); Zühlke (2001); Callaway (2006); Rabaut et al. (2007); Van Hoey (2008)).

Figure 2. Lanice conchilega.

6


During the development of the strategy, the gradual community shift according to increasing abundances of L. conchilega density was investigated based on long term data (a so called ‘Babushka’ type of community structure; see Rabaut et al. (2007)). This effect is related to the increasing structural complexity linked to the incremental density of this tube builder which in turn creates more niches and consequently more food provision. The speciesspecific explanation for this general increase has been described for different densities of L. conchilega aggregations. Besides, physical chracteristics of high density aggregations of the tube worm were investigated to explain the modulation mechanisms that create this Babushka-like community shift. The characterization of these physical features together with the biological characteristics showed that dense aggregations classify as ‘reefs’ (referring to the guidelines to apply the EU reef-definition provided by Hendrick & Foster-Smith (2006)) (Rabaut et al. (in press)).

4.2. Commercial Flatfish Species Investigating the interaction with commercial species is crucial information to manage these renewable resources. In the Belgian case study, several demersal fish species such as Solea solea (Common Sole) have been chosen to investigate as these species have a high commercial value and are the main target of the beam trawl fisheries. The strategy aims at pointing down the ecological importance of the habitat and/or species that served as a proxy for the value of the benthic system in place (i.e. L. conchilega for the Belgian case study). An experiment with artificial tubeworms is set up to test the habitat preference of juvenile Sole (Solea solea). Besides, an in situ experiment was set up to test whether juvenile Plaice (Pleuronectes platessa) actively selects for L. conchilega reefs. These results are confronted with the results on beam trawl impact on the L. conchilega reefs.

5. QUANTIFICATION OF FISHING IMPACT After the quantification of the biological value of the selected species/habitat, the last important aspect of the strategy is to quantify the impact fisheries has on this biological value. The impact of fisheries on the ecosystem can be quantified, using the same proxy. In the BPNS application, resilience of the particular L. conchilega system to beam trawl Common Sole fisheries has been investigated in a set of laboratory experiments. Results show that L. conchilega is relatively resistant to intermediate fishing pressure. To test for the impact on ecosystem level, in situ experiments are to be performed. For the BPNS application of the strategy, experimental trawling was done in situ. In this case, it was shown that species which are strongly associated with the L. conchilega aggregations are greatly impacted after fishery disturbance (Rabaut et al. 2008)).


7

Figure 3. Schematic presentation of the research strategy in the BPNS case study.

CONCLUSION As the approach for nature conservation is not integrated with the one for fisheries management, there is a need to underpin marine management with directed ecological research. Most difficulties with the effectiveness of marine conservation originate at the relation between fisheries and MPA-management. Not only conflicting interests, but also institutional differences are important bottlenecks. Current fisheries management leads to genetic changes, food web simplification and a historic amount of stocks being overfished. A strategy has been presented to integrate natural value with ecosystem services, using the Belgian part of the North Sea as a case study. The strategy starts with the identification of species that have horizontal and vertical links with other (groups of) organisms. Reef builders or ecosystem engineers in general are good candidates. The second selection criterion is the relation to ecosystem services and hence economic value. Research on the ecological value of the selected species and/or habitats together with the quantification of their (indirect) economic value is likely to be a good basis for integrated management of the system. Directed research on the impact of specific activities on the selected species will provide inside in both the ecological degradation and potential economic loss. The information gathered in the case of L. conchilega is an example of ready-to-use information for the marine renewable resource management of the soft-bottom area of concern, taking the ecosystem approach into account. This strategy of using small scale, short term studies on a limited number of species allows studying a well defined area in a cost-efficient way. We advocate the integration of fisheries management and marine conservation and are confident that scientific research programmes can be designed as such that they fully underpin decision making in an integrative way.

8


ACKNOWLEDGEMENT The first author acknowledges an aspirant grant provided by Flanders’ Research Foundation (FWO-Vlaanderen), Belgium. The authors are indebted to Liesbeth Hiele for proof reading an early draft of the manuscript.

REFERENCES Alfaro, A.C. (2006). Benthic macro-invertebrate community composition within a mangrove/seagrass estuary in northern New Zealand. Estuarine, Coastal and Shelf Science 66, 97-110. Bergman, M. & Hup, M. (1992). Direct effects of beam trawling on macrofauna in a sandy sediment in the Southern North Sea. ICES J. Mar. Sci. 49, 5–11. Bergman M.J.N. & van Santbrink J.W. (2000). Mortality in megafaunal benthic population caused by trawl fisheries on the Dutch continental shelf in the North Sea. ICES Journal of Marine Science 57, 1321-1331. Bolam, S.G. & Fernandes, T.F. (2003). Dense aggregations of Pygospio elegans (Claparède): effect on macrofaunal community structure and sediments. Journal of Sea Research 49, 171-185. Callaway R. (2006). Tube worms promote community change. Marine Ecology Progress Series 308, 49-60. Carey, A.D. (1987). Sedimentological effects and palaeoecological implications of the tubebuilding polychaete Lanice conchilega Pallas. Sedimentology 34, 49-66. Castilla, J.C., Lagos, N.A., Cerda, M. (2004). Marine ecosystem engineering by the alien ascidian Pyura praeputialis on a mid-intertidal rocky shore. Marine Ecology Progress Series 268, 119-130. Collie J.S., Escanero G.A., Valentine P.C. (1997). Effects of bottom fishing on the benthic megafauna of Georges Bank. Marine Ecology Progress Series 155, 159-172. Dittmann, S. (1999). Biotic interactions in a Lanice conchilega dominated tidal flat. In: Dittmann, S. (Ed.), The Wadden Sea Ecosystem: Stability Properties and Mechanisms. Springer-Verlag Berlin, Heidelberg, New York, pp. 153-162. Eckman, J.E. (1983). Hydrodynamic processes affecting benthic recruitment. Limnology and Oceanography 28, 241-257. Feral, P. (1989). Influence des populations de Lanice conchilega (Pallas) (Annelida, Polychaeta) sur la sedimentation sableuse intertidale de deux plages bas-nomandes (France). Bulletin de la Société Géologique de France 8, 1193-1200. Hartmann-Schröder, G. (1996). Annelida, Borstenwürmer, Polychaeta. 2nd revised ed. The fauna of Germany and adjacent seas with their characteristics and ecology, 58. Gustav Fisher, Jena, Germany, 648 pp. Hendrick F.J. & Foster-Smith R.L. (2006) Sabellaria spinulosa reef: A scoring system for evaluating 'reefiness' in the context of the Habitats Directive. Journal of the Marine Biological Association of the United Kingdom 86, 665-677. Heuers, J., Jaklin, S., Zühlke, R., Dittmann, S., Günther, C.P., Hildenbrandt, H., Grimm, V. (1998). A model on the distribution and abundance of the tube-building polychaete


9

Lanice conchilega (Pallas, 1766) in the intertidal of the Wadden Sea. Verhandlungen der Gesellschaft für Okologie 28, 207-215. Hild, A. & Günther, C.P. (1999). Ecosystem engineers: Mytilus edulis and Lanice conchilega. In: Dittmann, S. (Ed.), The Wadden Sea Ecosystem: Stability Properties and Mechanisms. Springer-Verlag Berlin, Heidelberg, New York, pp. 43-49. Holbrook, S.J., Schmitt, R.J., Ambrose, R.F. (1990). Biogenic habitat structure and characteristics of temperate reef fish assemblages. Australian Journal of Ecology 15, 489-503. Hovel, K.A., Fonseca, M.S., Myer, D.L., Kenworthy, W.J., Whitfield, P.E. (2002). Effects of seagrass landscape structure, structural complexity and hydrodynamic regime on macrofaunal densities in North Carolina seagrass beds. Marine Ecology Progress Series 243, 11-24. Jones S.E. & Jago C.F. (1993). In situ assessment of modification of sediment properties by burrowing invertebrates. Marine Biology 115, 133-142. Jones, C.G., Lawton, J.H., Shachak, M. (1994). Organisms as ecosystem engineers. Oikos 69, 373-386. Kaiser, M. & Spencer, B. (1996). The effects of beam-trawl disturbance on infaunal communities in different habitats. J. Anim. Ecol. 65, 348–358. Kaiser M.J., Collie S., Hall S.J., Jennings S., Poiner I.R. (2002). Modification of marine habitats by trawling activities: Prognosis and solutions. Fish and Fisheries 3, 114-136. Kaiser M.J., Cheney K., Spence F.E., Edwards D.B., Radford K. (1999). Fishing effects in Northeast Atlantic shelf seas: Patterns in fishing effort, diversity and community structure VII. The effects of trawling disturbance on the fauna associated with the tubeheads of Serpulid worms. Fisheries Research 40, 195-205. Kelleher G. (1999). Guidelines for marine protected areas. World commission on protected areas of IUCN. Best Practice Protected Area Guidelines Series 3. Koenig, C., Coleman, F., Grimes, C., Fitzhugh, G., Scanlon, K., Gledhill, C., Grace, M. (2000). Protection of fish spawning habitat for the conservation of warm temperate reef fish fisheries of shelf edge reefs of Florida. Bulletin of Marine Science 66, 593-616. Lenihan, H.S. (1999). Physical-biological coupling on oyster reefs: how habitat structure influence individual performance. Ecological Monograph 69, 251-275. Maes F., De Batist M., Van Lancker V., Leroy D., Vincx M. (2005). Towards a Spatial Structure Plan for Sustainable Management of the Sea: Mixed actions - Final report: SPSD II (MA/02/006). Belgian Science Policy: Brussels, Belgium, 384 pp. Myers R.A. & Worm B. (2003). Rapid worldwide depletion of predatory fish communities. Nature 432, 280-283. Pauly D., Christensen V., Dalsgaard J., Froese R., Torres F. (1998). Fishing down marine food webs. Science 279, 860-863. People, J. (2006). Mussel beds on different types of structures support different macroinvertebrate assemblages. Austral Ecology 31, 271-281. Rabaut M., Guilini K., Van Hoey G., Vincx M., Degraer S. (2007). A bio-engineered softbottom environment: The impact of Lanice conchilega on the benthic species-specific densities and community structure. Estuarine, Coastal and Shelf Science 75, 525-536. Rabaut M., Degraer S., Schrijvers J., Derous S., Maes F., Vincx M., Bogaert D., Cliquet A. (in press). Policy analysis of the ‘MPA-process’ in temperate continental shelf areas. Aquatic Conservation: Marine and Freshwater Ecosystems

10


Rabaut M., Braeckman U., Hendricks F., Vincx M., Degraer S. (2008). Experimental beam trawling in Lanice conchilega reefs: Impact on the associated fauna. Fisheries Research 90, 209-216 (DOI 10.1016/j.fishres.2007.10.009). Rabaut M., Vincx M., Degraer S. (in press). Do Lanice conchilega (sandmason) aggregations classify as reefs? Quantifying habitat modifying effects. Helgoland Marine Research: DOI 10.1007/s10152-008-0137-4. Ragnarsson S.A. & Raffaelli, D. (1999). Effects of the mussel Mytilus edulis L. on the invertebrate fauna sediments. Journal of Experimental Marine Biology and Ecology 241, 31-43. Sainsbury K.S. (1987). Assessment and management of the demersal fishery on the continental shelf of Northwestern Australia. In: Polovina J.J. & Ralston S. (Eds). Tropical snappers and groupers: biology and fisheries management, 465-503. Westview Press. Sparks-McConkey & P.,Watling, L. (2001). Effects on the ecological integrity of a softbottom habitat from a trawling disturbance. Hydrobiology 456, 73–85. Steneck, R.S., Graham, M.H., Bourque, B.J., Corbett, D., Erlandson, J.M., Estes, J.A., Tegner, M.J. (2002). Kelp forest ecosystems: biodiversity, stability, resilience and future. Environmental Conservation 29, 436-459. Sumaila, U.R. & Pauly D. (2007). All fishing nations must unite to cut subsidies. Nature 450, 945. Thrush S.F., Hewitt J.E., Cummings V.J., Dayton P.K., Cryer M., Turner S.J., Funnell G.A., Budd R.G., Milburn C.J., Wilkinson M.R. (1998). Disturbance of the marine benthic habitat by commercial fishing: Impacts at the scale of the fishery. Ecological Applications 8, 866-879. Turner, S.J., Thrush, S.F., Hewitt, J.E., Cummings, V.J., Funnell, G. (1999). Fishing impacts and the degradation or loss of habitat structure. Fisheries Management and Ecology 6, 401-420. Van Gaever, S., Vanreusel, A., Hughes, J.A., Bett, B., Kiriakoulakis, K. (2004). The macroand micro-scale patchiness of meiobenthos associated with the Darwin Mounds (northeast Atlantic). Journal of the Marine Biological Association of the UK 84, 547-556. Van Hoey G., Guilini K., Rabaut M., Vincx M., Degraer S. (2008). Ecological implications of the presence of the tube-building polychaete Lanice conchilega on soft-bottom benthic ecosystems. Marine Biology 154, 1009-1019. Van Hoey G., Degraer S., Vincx M. (2004). Macrobenthic community structure of softbottom sediments at the Belgian continental shelf. Estuarine, Coastal and Shelf Science 59, 599-613. Walsh, M. R., Munch, S. B., Chiba, S., Conover, D. O. (2006). Maladaptive changes in multiple traits caused by fishing: impediments to population recovery. Ecology Letters 9, 142. Woodin, S.A. (1978). Refuges, disturbance, and community structure: a marine soft-bottom example. Ecology 59, 274-284. Ziegelmeier, E. (1952). Beobachtungen über den röhrenbau von Lanice conchilega (Pallas) im experiment und am natürlichen standort. Helgol Wiss Meeresunters 4, 107-129. Zühlke, R. (2001). Polychaete tubes create ephemeral community patterns: Lanice conchilega (Pallas, 1766) associations studies over six years. Journal of Sea Research 46, 261-272.


11

Zühlke, R., Blome, D., van Bernem, K.H., Dittmann, S. (1998). Effects of the tube-building polychaete Lanice conchilega (Pallas) on benthic macrofauna and nematodes in an intertidal sandflat. Senckenbergiana maritima 29, 131-138.