Mismatch between biological, exploitation, and ...

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mismatch between governance (defined according to political and economic boundaries) and biological scales [2]. • Denso-dependent mechanisms, recurrent in ...
Mismatch between biological, exploitation, and governance scales of sea urchin (Paracentrotus lividus) fisheries in Galicia Rosana Ouréns

1, 2 ,

Inés Naya

1,

Juan Freire

3

1 Recursos Marinos y Pesquerías, University of A Coruña (Spain). 2 Present address: Hopkins Marine Station, Stanford University (USA). 3 Teamlabs, Impact Hub Madrid (Spain)

1. Introduction

2. Echinoid fishery in Galicia Echinoid stocks decline worldwide since 1995 (Fig. 1), including several cases of overfishing and collapse [1].

Fig. 1. Echinoid catches worldwide. Data from FAO (2012) FishStatJ

Two reasons why the current management systems fail: • Spatial structure of echinoids is ignored in management systems, promoting a mismatch between governance (defined according to political and economic boundaries) and biological scales [2]. • Denso-dependent mechanisms, recurrent in many biological processes affecting echinoids [3], are ignored. We present here the fishery of the echinoid Paracentrotus lividus in Galicia (NW Spain) to demonstrate the effects of ignoring the complex spatial distribution of echinoids in fisheries management.

• Galicia is the main fishery for P. lividus, landing annually about 700 t [4]. • Harvesting occurs mainly in subtidal by scuba diving (fleet composed by 174 small boats). • Several local fisheries are temporally closed as a consequence of overfishing [6]. Fisheries management: • 15 subtidal and 5 intertidal territories for the exploitation (Fig. 2), co-managed between Galician Government and fishers’ associations. • Regulations to control effort and catch: daily timetable, maximum harvesting depth, daily quotas and minimum size [5].

Fig. 2. Territories for the sea urchin fishery in Galicia in 2012. Grey rectangles: subtidal territories; coloured coastlines: intertidal territories. Note that the intertidal territory 1 (blue) in the North of Galicia is discontinuous.

3. Spatial scales affecting the sea urchin fishery in Galicia Biological scales Echinoids show a metapopulation structure [6], with multiple and nested spatial scales (Fig. 3): • Patches : Aggregations where sea urchins are very close. • Micro-stocks : Area with similar habitat that comprises several patches changing their location and shape in a dynamical way. • Local populations: Area surrounded by zones without an adequate habitat for sea urchin colonization. • Metapopulations: Local populations connected by larval dispersal.

Operational scales • Micro-stocks: Fishers operate in micro-stocks where the stock density is high. • Fishing grounds: set of micro-stocks that are near, allowing a boat to exploit several of them in the same day. • Fishing areas: Set of grounds exploited by a fleet along the fishing season. Management scales • Regional scale: it accomplishes the complete Galicia. • Territorial scales: defined by the fishing zones delimited by the fishing authority for this fishery (Fig. 2).

4. Uncoupling of scales

Fig. 3. Spatial units involved in the fishery. Ellipses: Biological units (patches, micro-stocks, local populations, metapopulation). Red boxes: Fishing activity units (micro-socks, fishing grounds and fishing area). Brackets: Management units (territories and region).

5. How to adapt sea urchin management in Galicia to the relevant scales? • Fishing territories should be redefined to include complete local populations. • Regulations at the territory scale should assure the sustainability of minimal and static biological units (micro-stocks). • Regulations should also take into account Allee effects experienced by echinoid populations. We suggest two types of spatial regulations: Rotation systems Micro-stocks should be the units for rotations to control effectively density after a harvest pulse.

Fig. 4. Diagram showing the mismatch between biological, operational, and governance scales in sea urchin fishery in Galicia.

• Management scales are too wide to manage effectively microstocks (Fig. 4). • Some local populations are divided between two fishing territories , being exploited according to different management plans. For instance, different plans for intertidal and subtidal areas.

Marine reserves To establish a reserve network in shallow habitats (< 5 m), where recruitment takes place [3]. The migratory pattern of P. lividus heading to deeper areas [3] would secure the spillover of biomass towards the deep fishery areas, while fertilization and recruitment rates would increase inside the reserve (Fig. 5).

refugia. ICES Jounal of Marine Science 2014. doi: 10.1093/icesjms/fst201 [1] Andrew NL, Agatsuma Y, Ballesteros E, Bazhin AG, Creaser [4] Consellería do Mar, Xunta de Galicia. http://www.pescadegalicia.com/ EP, Barnes DKA, et al. Status and management of world sea urchin fisheries. Oceanography and Marine Biology: An Annual [5] Fernández-Boán M, Fernández L, Freire J. History and management strategies of the sea urchin Paracentrotus lividus Review 2002; 40:343-425. fishery in Galicia (NW Spain). Ocean & Coastal Management [2] Johnson TR, Wilson JA, Cleaver C, Vadas RL. Social2012; 69:265-72. ecological scale mismatches and the collapse of the sea urchin [6] Morgan LE, Shepherd SA. Population and spatial structure of fishery in Maine, USA. Ecology and Society 2012; 17:15. [3] Ouréns R, Freire J, Vilar JA, Fernández L. Influence of habitat two common: temperate reef herbivores: abalone and sea and population density on recruitment and spatial dynamics of urchins. In: Kritzer JP, Sale PF, editors. Marine Metapopulations: Elsevier Academic Press; 2006. p. 205-46. the sea urchin Paracentrotus lividus: implications for harvest

Literature cited

Fig. 5. Design of a network of reserves. Black ellipses : microstocks ; White ellipses: local populations; shadowed areas: protected zones. It is assumed that all local populations provide similar larval productions (arrows). Discontinuous arrows represent migration of sea urchins towards fishing areas.

Acknowledgements This poster is based in the information and knowledge developed in two research projects (CTM2005-07645/MAR and CTM200609043/MAR) coordinated by the University of A Coruña and funded by the Spanish Ministerio de Educación y Ciencia and the European Regional Development Fund (ERDF).

Further information Please contact to: [email protected]