The role of marine protected areas

Transcription

1 The role of marine protected areas Angel Pérez-Ruzafa Universidad de Murcia (España) PUBLIC HEARING Mediterranean sea: state of the fishing stock and strategies to adopt, for the conservation and socio-economic situation of the fisheries sector European Parliament, 19 April 216 European Marine Protected Areas as tools for Fisheries management and conservation Contract no. SSP March 25 February 28

2 Main activities affecting the loses of biodiversity in the Marine ecosystems (Committee on Biological Diversity in Marine Systems, 1995) Fishing Chemical pollution and eutrophication Physical alterations of habitat Exotic species invasions Global climate change

3 Framework: overfishing effects From local to global scale, fishing is in crisis. At present, an estimated 76% of the world stocks are depleted, over-exploited or fully exploited (Csirke, 25) (Botsford et al. 1997)

4 Framework: overfishing effects Main effects of over fishing 1. Reduction in the abundance and mean size of the individuals of the species. 2. Decreasing recruitment of larvae and juveniles as a consequence of the spawners biomass reduction. 3. Increasing mortality risks for new recruits as a consequence of changes in environmental conditions. 4. Losses of genetic diversity due to stocks reduction. 5. Increasing risks of irreversible changes in the community structure and the ecosystems stability.

5 Framework: overfishing effects Trophic level of the catch has decreased, from top predators to planktivorous fishes.

6 Framework: over fishing effects and, combined with eutrophication, from planktivorous fishes... to jellyfishes... coming back to Cambrian trophic webs. Ecological shift

7 Framework: overfishing effects Man Fish Macroalgae Diplodus vulgaris Sea urchin

8 Framework: overfishing effects Traditional measures for the management of coastal fisheries Based on singled-species Diplodus vulgaris models of population dynamics and the concept of maximum sustainable yield: controlling the catch and recommending a total allowable catch, And establishing seasonal closures and gear specifications to guarantee a minimum size of fished individuals of target species to ensure enough reproductive success and recruitment. Little fish, no thanks!

9 Framework: overfishing effects But marine organisms have complex life cycles with high mortality in pelagic phases that must be counterbalanced with a huge reproductive effort huevos y/o larvas pelágicos Reclutamiento de juveniles Población de adultos Población de adultos

10 Framework: overfishing effects a Actividad alimento Reproducción Most of the resources in adults are devoted to reproduction and there is a strong relation between fecundity and individual size. b Crecimiento Mantenimiento Reproducción Mantenimiento Reproducción Crecimiento Crecimiento talla edad

11 Framework: overfishing effects 9.3. eggs A high number of medium sized individuals is needed to compensate the loss of the reproductive effort of only one big individual removed by fishing 1 61 cm (12.5 kg) cm (1.1 kg) Plan Development Team, 199

12 To reduce life expectancy involves that fish must reproduce at a younger age in each generation

13 Are MPAs a solution? After the failure of traditional fisheries management measures (Waters, 1991), marine reserves have been strongly advocated as an ideal tool for the management of coastal fisheries (Plan Development Team 199; Roberts and Polunin 1991; Dugan and Davis, 1993; Agardy 1994).

14 Are MPAs a solution? As a consequence, a large number of marine protected areas (MPAs) have been established around the world during the last decades (Jones et al. 1993) including the EU

15 Are MPAs a solution? Expected benefits of MPAs Preserve the natural size and age structure of populations Preserve the spawners stock Maintain the assemblages structure and the ecosystems equilibrium Maintain the genetic diversity Facilitate the recovering of over-exploited areas by mean of the exportation of pelagic larvae and eggs Permits the development of research in non impacted ecosystems Are an alternative source of inputs for fishermen and favors the economic development of the area through the establishment of services related to tourism and diving activities In theory, their interest as fishery management tools reside in their potential to enhance artisanal fisheries production of high-value species in surrounding grounds.

16 Recover the abundance of exploited populations 5 MPA creation D. annularis 4 MPA creation E. marginatus Nº indiv. 25 m Nº indiv. 25 m Years Years 14 D. sargus Nº indiv. 25 m Cabo de Palos 3 Bajo de Piles Bajo de Dentro 5 2 Bajo de Fuera Islas Hormigas El Mosquito Bajo de la Testa 1 2 N Years metros 1

17 Recover the abundance of exploited populations 6 5 Outside MPA Inside MPA Mean density (+/-1se) Feb'98Dec'May'1Jun'2 Jul'3 Apr'4 Jul'4 Jun'5 Mar'7 Figure 4 Patterns of abundance (nº indiv. m -2 ) of P. ferruginea inside and outside MPAs of Capria Island (Tuscany Archipelago) (data of Benedetti-Cecchi et al. from different projects, including EMPAFISH). The trend towards declining abundances inside MPAs observed in the last two years may be due to global processes and/or poaching (from Benedetti-Cecchi et al., unpublished data, including EMPAFISH data).

18 Recover the size structure of populations Inside MPA Inside* Serranus atricauda outside Outside Before (1994) Frequency Mean = 2,13 Std. Dev. = 6,78 N = 3 Frequency Mean = 14,39 Std. Dev. = 5,22 N = 28 Protected SIZE SIZE After (25) Frequency Mean = 2,52 Std. Dev. = 6,91 N = 17 Frequency Mean = 21,97 Std. Dev. = 4,94 N = SIZE SIZE * Integral reserve + buffer zone. Year of stablishment of the MPA: 1995 Figure 6 Before-after and inside-outside comparison of the size structure (size clases in cm) of Serranus atricauda for La Graciosa marine reserve (from Brito et al., 27a)

19 Recover the size structure of populations 12 1 IR BZ OUT Mean fish weight (g) E. costae E. marginatus M. rubra Figure 5 Mean fish weight (g) of Epinephelus costae, E. marginatus and Mycteroperca rubra in the no-take area or integral reserve (IR), the buffer zone (BZ) and in fished areas (OUT) in Cabo de Palos Islas Hormigas marine reserve (from Harmelin-Vivien et al., 27)

20 Preserve genetic diversity MPAs account for 97.3 % of alleles pool 1 % exclusive alleles A M T G CP Mediterranean Sea B BL MR Mediterranean Sea L E GI Pérez-Ruzafa et al., ( 2 6 ) Biological Conservation, 1 2 9:

21 Are they effective only inside the protected area or they are useful to maintain the productivity in the surrounding exploited area?

22 Improve the fishing yield in adjacent areas The protection produces a rapid response in fishing. Since the first year, fishing effort and CPUE trend to concentrate in the boundaries of the MPAs.. Stelzenmüller et al. 28. Mar. Pol. Bull.

23 Improve the fishing yield in adjacent areas MPA declaration Fishing effort distribution Evolution of catch per unit effort (kg/kw) declared by artisanal vessels at Cabo de Palos between 1993 and 212.

24 Improve the fishing yield in adjacent areas but it can take up to 25 years to reach an equilibrium with fishing effort distribution. In average, the protected areas showed catches about 2.4 higher than those in the non protected areas. Vandeperre, F., Higgins, R., Santos,R. & Pérez-Ruzafa, A. (Coord). 26. Fishery Regimes in Atlanto-Mediterranean European Marine Protected Areas. EMPAFISH Project. Booklet nº pp.

25 Who benefits more from marine reserves? Driving Tourism Opportunity for Science Educational Resource

26 Who benefits more from marine reserves? MPAs benefit both fisheries and tourism development. There is a high level of satisfaction among users of marine reserves. However there may be discrepancies regarding management priorities. On average the benefit:cost ratio of an AMP is at least 1:1, with tourism revenues higher than for commercial fishing 1% 8% 6% 4% 2% Opinions of professional fishers concerning the impact of MPA on fishing activities Very positive Rather positive No impact Rather negative Very negative 1% 8% 6% 4% 2% Opinions of diving operators concerning the impact of MPA on diving activities Very positive Rather positive No impact Rather negative Very negative % % Figure 4 EMPAFISH socioeconomic field surveys: opinions of professional fishers and of scuba divers Roncin et al. (28) Journal for Nature Conservation 16 Alban, F., Roncin, N. & Boncoeur, J. 26. Methodological guidebook for socio-economic field surveys of MPA users. EMPAFISH Project. 38 pp.

27 Who benefits more from marine reserves? a) Conservation Perceptions of stakeholders Fishers only All other respondents While valuation of the reserve effect on biodiversity increase with time due to the increasing pressure of tourism, Score R 2 =.6 F = 6.9, p < Length of protection (years) b) Fisheries management Fishers only All other respondents perceptions of fishers starts very high but decrease after 25 years due to the stabilization of the yield after fishing effort redistribution and short memory. Score R 2 =.7 F = 7.5, p < Length of protection, years Roncin et al. (28) Journal for Nature Conservation 16 Mangui and Austin (28) Journal for Nature Conservation 16

28 The optimal design of a MPA Importance of connectivity Are islands the best choice to install an MPA? Not all coastal areas would be adequate, in terms of connectivity, for establishing a reserve. Some island populations tend to display an impoverished genetic structure and show heterozygote deficit due probably to a combination of factors as isolation, smaller population size and fishing pressure. Pérez-Ruzafa et al. (26)

29 The optimal design of a MPA Size of the no-take zone and time of protection are the main factors determining the effectivity of an MPA on preserving the abundance and size structure of fish assemblages. Figure 2 Effect of EMPAFISH MPAs case studies on commercial fish densities as a function of time since protection and the size of the no-take zone. Plane gives the fitted effect, size of points is proportional to the weight of each study, and stems indicate the distance between the calculated weighted effect size and the fitted effect. [1] Claudet, J. et al. 28. Marine reserves: Size and age do matter. Ecol. Let. 11:

30 The optimal design of MPAs Exportation from a MPA IR boundary low diffusion/strong reserve effect Evolution with reposition (logistic model and catches) IR Strong fishery MPA MODELO DE EXPORTACIÓN DE BIOMASA

31 The optimal design of a MPA Size do matter but how big must be an MPA? abundance (individuals per 1 m 2 ) b flux (individuals m 1 day 1 ) Fish abundance Carrying capacity distance from IR centre (m) Fish exportation to fished areas Does not work Works very well Reserve radius (m) abundance at start IR size D =5 (m -2 day -1 ) F =.14 day -1 r =.15 day Pérez-Ruzafa et al. (28) Journal for Nature Conservation 16: Distance from the reserve border (m)

32 The optimal design of a MPA costs ( ) costs ( ) costs ( )/ ha Total costs y = 13,74x R² =, Total Reserve size (Ha) Total costs y = 3443e,x R² =, Total costs / ha IR size (ha) y =,x 2 1,389x + 658,8 R² =, IR size (Ha) Large MPAs (> 6 ha) are to be preferred to small-tomedium sizes to maximize protection on biodiversity and exportation of biomass... But total management costs increase with reserve size, and total cost per ha shows a minimum for integral reserves between 6 and 15 ha (14-22 m radius). Alban F., Person J., Roncin N. and Boncoeur J., 28. Analysis of Socio Economic Survey Results. EMPAFISH Project 139 pp.

33 The optimal design of an MPA Fisheries vs conservation objectives / Mediterranean vs Northern Europe approach over-fished FISH BOX under-fished NO-TAKE AREA B P N potential spill-over t km -2 year -1 P/B P G R Fishery objectives Biodiversity objectives YEARS Pérez-Ruzafa et al. (28) Journal for Nature Conservation 16:

34 The optimal design of a network of MPAs The optimum size of no-take zones range between 6 and 15 ha, in addition, sizes of each zone within the MPA should be scaled to maximize the size of the no-take area in detriment of buffer zones (about half size of no-take area) km and any further improvement should come from a network of several MPAs, and taking into account that the effects on fisheries would be improved when the distance between MPAs is not higher than a few tens of km. No-take area (6-3 Ha) Buffer area (3-1 Ha) Pérez-Ruzafa et al. (28) Journal for Nature Conservation 16:

35 Thanks for your attention Angel Pérez-Ruzafa Universidad de Murcia (España) European Marine Protected Areas as tools for Fisheries management and conservation Contract no. SSP March 25 February 28