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Marine protected areas (MPAs) potentially enhance the long-term sustainability of coastal fish resources that have been overexploited. The types and quality of habitats, both inside and outside the MPAs, may determine the likelihood of migration by fish to surrounding unprotected areas where spillover to fisheries occurs. We assessed whether MPAs enhanced catches of artisanal fisheries, using an experimental fishing study with the same fishing gear as that used by local fishers. This approach allowed us to test the hypothesis of increased catches along the borders of MPAs in comparison with those in other fishing grounds located at. medium and far distances from 3 Mediterranean MPAs: Tabarca Marine Reserve, Carry-le-Rouet Marine Reserve and Cerbere-Banyuls Marine Reserve. Surveys were clone over 2 homogeneous habitats (Posidonia oceanica meadow and sand), in 3 different seasons. Catches were significantly higher for some species near the borders of the MPAs when fishing on P. oceanica meadows, but not when fishing on sandy bottoms. The spillover effect appears to be limited by a lack of continuous Suitable habitat through the boundaries of the MPA. Some of the species that showed a significant response to protection and concurrent higher catches near the MPA borders, such as Dentex dentex, Mullus surmuletus, Phycis phycis, Sciaena Umbra and Scorpaena porcus, are target species of artisanal fisheries. Although we found that the spatial scale of the spillover-induced density gradient was localized, it was sufficient to provide local benefits to artisanal fisheries. We conclude that spillover effects are not a universal consequence of siting MPAs in temperate waters and that they are related to the distribution of habitats inside and around MPAs.
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Mar Ecol Prog Ser
Vol. 379: 197–211, 2009
doi: 10.3354/meps07892 Published March 30
In recent years, many coastal fish resources have
been overexploited (Castilla 2000), raising doubts
about the long-term sustainability of certain fisheries
(Pauly et al. 2002). Unless changes are implemented
immediately, many fisheries may collapse in the next
few decades (Worm et al. 2006). The solutions pro-
posed by managers for this critical problem are numer-
ous (Pauly et al. 2002) and rely on: (1) reducing fishing
capacity through ‘traditional’ fisheries measures (e.g.
quotas, reducing fishing effort, regulating fishing
equipment); and (2) creating marine protected areas
(MPAs). The first option has not always provided the
anticipated effects, leading many to adopt MPAs as a
fishery management strategy (Roberts et al. 2003).
MPAs potentially facilitate the long-term sustain-
ability of many fisheries (Gell & Roberts 2003, Ramos-
Esplá et al. 2004). Closing areas allows animals to live
longer and grow to maturity, which is important for
© Inter-Research 2009 ·*Email:
Effects of habitat on spillover from marine
protected areas to artisanal fisheries
Aitor Forcada1,*, Carlos Valle1, Patrick Bonhomme2, Géraldine Criquet3,
Gwenaël Cadiou2, Philippe Lenfant3, José L. Sánchez-Lizaso1
1Unidad de Biología Marina, Departamento de Ciencias del Mar y Biología Aplicada, Universidad de Alicante, POB 99,
03080 Alicante, Spain
2GIS Posidonie, Parc Scientifique & Technologique de Luminy, Case 901, 13288 Marseille Cedex 09, France
3Laboratoire Ecosystèmes Aquatiques Tropicaux et Méditerranéens, UMR 5244 CNRS–EPHE UPVD ‘Biologie et Ecologie
Tropicale et Méditerranéenne’, Université de Perpignan, 52 avenue Paul Alduy, 66860 Perpignan Cedex, France
ABSTRACT: Marine protected areas (MPAs) potentially enhance the long-term sustainability of
coastal fish resources that have been overexploited. The types and quality of habitats, both inside and
outside the MPAs, may determine the likelihood of migration by fish to surrounding unprotected
areas where spillover to fisheries occurs. We assessed whether MPAs enhanced catches of artisanal
fisheries, using an experimental fishing study with the same fishing gear as that used by local fishers.
This approach allowed us to test the hypothesis of increased catches along the borders of MPAs in
comparison with those in other fishing grounds located at medium and far distances from 3 Medi-
terranean MPAs: Tabarca Marine Reserve, Carry-le-Rouet Marine Reserve and Cerbère-Banyuls
Marine Reserve. Surveys were done over 2 homogeneous habitats (Posidonia oceanica meadow and
sand), in 3 different seasons. Catches were significantly higher for some species near the borders of
the MPAs when fishing on P. oceanica meadows, but not when fishing on sandy bottoms. The
spillover effect appears to be limited by a lack of continuous suitable habitat through the boundaries
of the MPA. Some of the species that showed a significant response to protection and concurrent
higher catches near the MPA borders, such as Dentex dentex, Mullus surmuletus, Phycis phycis,
Sciaena umbra and Scorpaena porcus, are target species of artisanal fisheries. Although we found
that the spatial scale of the spillover-induced density gradient was localized, it was sufficient to
provide local benefits to artisanal fisheries. We conclude that spillover effects are not a universal
consequence of siting MPAs in temperate waters and that they are related to the distribution of habi-
tats inside and around MPAs.
KEY WORDS: MPA · Export production · Artisanal fisheries · Fish · Habitat connectivity · Spillover ·
Mediterranean Sea
Resale or republication not permitted without written consent of the publisher
Mar Ecol Prog Ser 379: 197–211, 2009
supporting fisheries because of the exponential rela-
tionship between fecundity and body size (Bohnsack
1990). MPAs are predicted to benefit adjacent fisheries
through 2 mechanisms: (1) net emigration of adults and
juveniles across borders, termed ‘spillover’; and (2)
increased production and export of pelagic eggs and
larvae (Gell & Roberts 2003, Kaunda-Arara & Rose
2004, Abesamis & Russ 2005, Sale et al. 2005). Spillover
of juvenile and adult fish to surrounding non-protected
areas could result from random movements of individ-
uals from MPAs to outside their borders or by directed
movements over a large home range (Rakitin & Kramer
1996, Kramer & Chapman 1999, Tremain et al. 2004).
Emigration may also occur through ontogenetic habitat
shifts (Cocheret de la Moriniere et al. 2002, Nagel-
kerken & van der Velde 2002). All these cases are
considered density-independent movements. Another
mechanism that could lead to export is the occurrence
of density-dependent movements of competitively
subordinate individuals from preferred habitats inside
MPAs to suboptimal habitats outside (Sánchez-Lizaso
et al. 2000, Abesamis & Russ 2005). Both density-
independent and density-dependent processes would
produce a gradient of abundance across MPAs borders
and should have an influence on the yields and quality
of the catches in the surrounding fishing grounds (Russ
& Alcala 1996, Gell & Roberts 2003). However, the
patchy nature of the marine environment might act as
a barrier for the movement of fish, although habitat
discontinuities might not be perceived in the same
manner by all animals (Wiens et al. 1993). Many fishes
are habitat specific and are reluctant to disperse across
‘foreign’ habitats (Chapman & Kramer 2000). For this
reason, spillover will also be influenced by the habitat
bordering a reserve (Rowley 1994).
Some of the best evidence for spillover comes from
landings data that have demonstrated increased cap-
tures in fisheries adjacent to MPAs in many parts of
the world: Kenya (McClanahan & Kaunda-Arara 1996,
McClanahan & Mangi 2000), Florida and St Lucia
(Roberts et al. 2001a), New England (Murawski et al.
2000, 2005), the Egyptian Red Sea (Galal et al. 2002)
and Apo Island in the Philippines (Russ et al. 2003).
However, only a few studies have experimentally
tested for spillover through increased captures in adja-
cent fished areas, often along density gradients: Bar-
bados (Rakitin & Kramer 1996), Kenya (McClanahan
& Mangi 2000, Kaunda-Arara & Rose 2004) and Apo
Island in the Philippines (Abesamis & Russ 2005). In
the Mediterranean, few data are available to assess the
value of MPAs as a source of biomass to surrounding
fisheries (Goñi et al. 2006).
Encouraged by the recent findings on spillover re-
sults, many countries and states have started initiatives
to establish networks of marine reserves. However,
too little evidence exists to define the basic responses
of fish populations to reserve protection (Willis et al.
2003) and their potential for improving fisheries yields
(Hilborn et al. 2004). Moreover, reserves remain highly
controversial among fishers and the fishing industry,
who argue that fishery benefits remain unproven.
Protection of breeding stock, enhancement of re-
cruitment to neighbouring areas, and restocking of
exploited marine species were the initial goals of the
3 Mediterranean MPAs studied here. The main objec-
tive of this work was to estimate fisheries enhancement
around these MPAs and to assess the influence of
habitat on this process. We adopted an experimental
fishing approach with commercial trammel nets, the
most common fishing gear used in Mediterranean
artisanal fisheries. This approach allows for testing
the hypothesis that catches will be increased along
the border of MPAs in comparison with other fishing
grounds. We incorporated 2 habitats in the present
study (Posidonia oceanica seagrass meadow and sandy
bottom), with the aim of testing whether habitat type
alters the degree of spillover from MPAs.
Study area. This study was conducted July 2003 to
June 2005 in 3 MPAs in the western Mediterranean
Sea, off the coasts of Spain and France, encompassing
a geographic range >1000 km (Fig. 1). Tabarca Marine
Reserve covers 1400 ha, and is substantially larger
than Cerbère-Banyuls Marine Reserve (650 ha) and
Carry-le-Rouet Marine Reserve (85 ha). Tabarca
Marine Reserve, which is only 4 km from the mainland,
contains 3 management zones with different levels of
protection: the integral reserve area, where all activi-
ties except scientific research are forbidden; the buffer
area, in which selective artisanal fishing gear (trap
nets that target on pelagic species) is allowed; and the
transitional area, in which the prior selective fishing
gear and recreational activities (swimming, diving,
mooring of yachts) are permitted. However, the entire
marine reserve acts as a no-take-zone for the species
targeted by trammel nets, because this gear is banned
inside the MPA. Cerbère-Banyuls Marine Reserve has
2 management zones: the integral reserve, where all
activities except scientific surveys are forbidden, and
the restricted use area, in which commercial and re-
creational fishing, swimming and diving activities are
regulated and spear fishing is forbidden. In contrast,
the Carry-le-Rouet Marine Reserve has no zoning and
is entirely a no-take marine reserve.
The 3 MPAs have all been established for at least
20 yr, and they have yielded evidence of higher bio-
mass within their borders. Overall fish abundance was
Forcada et al.: Effectiveness of MPA for fisheries enhancement
92% higher in Tabarca Marine Reserve (Forcada
2005), 117% in Cerbère-Banyuls Marine Reserve (Bell
1983) and 78% in Carry-le-Rouet Marine Reserve
(Harmelin et al. 1995) with reference to fished areas.
In 2 of the MPAs (Tabarca and Carry-le-Rouet), the
main habitat, Posidonia oceanica meadows, extends
far outside the borders (Fig. 1). Rocky and sandy
bottoms are also present in Tabarca. In Cerbère-
Banyuls Marine Reserve rocky and sandy bottoms are
the main habitats, and seagrass only covers about 1%
of the total area.
Traditional fishing grounds distributed around the
3 MPAs are mainly used by the artisanal fleet, and are
generally composed of boats <10 m long, with small
crews of 1 to 3 fishers. The artisanal fishery fleet uses
trammel nets, gill nets, long-lines and troll-lines. Re-
creational fishing, including spear fishing, handlining
and angling, also occurs around the MPAs.
Sampling design and data collection. Experimental
fishing was used to test the hypothesis that catch is
higher near the MPAs (500 m and closer) and declines
at medium (500 to 1000 m) and far (2000 to 3000 m)
distances from the MPAs. We tested for such differ-
ences in 2 different habitats: Posidonia oceanica sea-
grass meadows and sandy bottoms (Fig. 1). The fishing
survey on homogeneous seagrass was carried out in
Tabarca and Carry-le-Rouet Marine Reserves, at
depths of 10 to 25 m. Experimental fishing on sandy
bottoms was carried out at 30 m depth around Tabarca
and Cerbère-Banyuls Marine Reserves. Surveys were
done in spring, summer and winter, although the sum-
mer survey at Cerbère-Banyuls Marine Reserve was
suspended due to bad weather conditions. Each MPA
was sampled 6 d per season, with six 100 m trammel-
net replicates per day at each distance. Nets were set
before sunset and recovered just after sunrise. After
Fig. 1. Tabarca, Cerbère-Banyuls and Carry-le-Rouet Marine Reserve locations; their limits and zonations are included. General
habitat characteristics and the areas where the experimental fishing was carried out at each distance are also indicated
Mar Ecol Prog Ser 379: 197–211, 2009
fishing, all captured individuals were identified to spe-
cies, and total length and wet weight were recorded.
Data analysis. The experimental design was differ-
ent for each habitat. On Posidonia oceanica meadows
the experimental design consisted of 4 factors: Dis-
tance (3 levels, fixed), MPA (2 levels, fixed and ortho-
gonal), Season (3 levels, fixed and orthogonal) and Day
(6 levels, random and nested in the interaction MPA ×
Season). Thus, with n = 6 trammel nets, there was a
total of 648 observations.
On sand, the experimental design consisted of 3
factors: Distance (3 levels, fixed), Season (3 levels in
Tabarca Marine Reserve and 2 levels in Cerbère-
Banyuls Marine Reserve, fixed and orthogonal) and
Day (6 levels, random and nested in Season). There-
fore, with n = 6 trammel nets, there was a total of 324
observations for the Tabarca Marine Reserve and
216 for the Cerbère-Banyuls Marine Reserve.
Analysis of variance (ANOVA) was used to test for
significant differences in biomass of total catch and
of the abundant species (Underwood 1997). When the
ANOVA F-test was significant, post hoc analyses were
conducted using Student-Newman-Keuls (SNK) mul-
tiple comparisons (Underwood 1981). Before analysis,
Cochran’s test (Cochran 1951) was used to test for
homogeneity of variance. When significant hete-
rogeneity was found, the data were transformed by
(x+ 1) or ln(x+ 1). When transformations did not
remove heterogeneity, analyses were performed on
the untransformed data, but with the F-test α-value
set at 0.01, since ANOVA is robust to departures from
this assumption, especially when the design is bal-
anced and contains a large number of samples or treat-
ments (Underwood 1997).
Posidonia oceanica meadows in Tabarca and
Carry-le-Rouet Marine Reserves
In the survey, 6619 individuals of 76 species were
captured (Table A1 in Appendix 1, available at www. Total
weight of the catch was 1373.5 kg. The most common
family was Sparidae, followed by Labridae, with 14
and 12 species, respectively. Although 57 species were
found in Tabarca Marine Reserve and 56 in Carry-
le-Rouet Marine Reserve, the 2 MPAs differed in their
catch composition. Twenty of the species caught at
Tabarca did not appear at Carry-le-Rouet. In contrast,
19 species were caught exclusively at Carry-le-Rouet.
Despite the large number of species caught in both
Tabarca and Carry-le-Rouet Marine Reserves, around
85% of the catch was represented by 15 species. The
most common species of the total catch in both MPAs
was Scorpaena porcus. Other species common to both
MPAs were Labrus merula, Symphodus tinca and
Sepia officinalis. Some species were only common in
one MPA — Sciaena umbra and Dentex dentex in
Tabarca and Diplodus annularis and Octopus vulgaris
in Carry-le-Rouet.
Total mean biomass was greater in Tabarca (2.59 ±
0.08 kg per 100 m of net) than in Carry-le-Rouet (1.65 ±
0.07 kg per 100 m of net). Differences between dis-
tances were greater during winter in Tabarca and
during summer in Carry-le-Rouet (Fig. 2a,c). Higher
catches usually occurred near the borders of both
MPAs, but there were exceptions. In spring, total mean
biomass was higher far from the border of Tabarca
(Fig. 2a). In Carry-le-Rouet, catches were similar at
near and far distances in winter (Fig. 2c). With respect
to seasonality, only Tabarca showed a clear pattern,
with the greater values in winter.
In ANOVAs for catch, the 3-way interaction of Dis-
tance, MPA and Season was significant (Table 1). In
SNK comparisons, catch was significantly higher near
the border in Tabarca during winter and in Carry-le-
Rouet during spring. Moreover, during summer in
Carry-le-Rouet, total catch was highest near the
At the species level, catches of Scorpaena porcus
decreased away from the boundaries at both MPAs
(Fig. 3a), and the interaction between Distance, MPA
and Season was significant (Table 1). SNK test results
indicated that far from Tabarca catches were lowest.
However in Carry-le-Rouet, higher catches were
obtained near the MPA border only in summer (p <
0.01). Labrus merula also had a decreasing trend with
distance at both MPAs (Fig. 3b), but catches were only
significantly higher close to Tabarca. Furthermore,
catches of this species were significantly higher in
Tabarca than in Carry-le-Rouet during all seasons (p <
0.01). Catches of Mullus surmuletus declined with
distance in both MPAs, but only in winter (Fig. 3c).
However, these differences were significant only in
Tabarca, with higher catches near the boundaries (p <
Other important species, such as Sciaena umbra
(Fig. 4a) and Dentex dentex (Fig. 4b), showed catches
decreasing with distance, but only in Tabarca Marine
Reserve (p < 0.01); these species were rare or absent
at the other MPAs. In contrast, decreasing trends
with distance of Conger conger (Fig. 4c) and Phycis
phycis (Fig. 4d) were observed only in Carry-le-Rouet;
catches around Tabarca were low. C. conger was
always caught more frequently (p < 0.05) close to
Carry-le-Rouet boundaries, while catches of P. phycis
were significantly higher (p < 0.01) only in winter and
Forcada et al.: Effectiveness of MPA for fisheries enhancement
ANOVA results for Symphodus tinca (Fig. 3d) and
Diplodus vulgaris (Fig. 3e) produced a significant inter-
action between Distance, MPA and Season (Table 1);
the SNK multiple comparisons reflected inconsistencies
with the primary hypothesis. Catches of S. tinca were
significantly higher in summer and spring near Carry-
le-Rouet (p < 0.05) and in winter near Tabarca (p <
0.05); during spring the highest catches were far from
Tabarca (p < 0.01). In contrast, D. vulgaris catches were
not significantly different with distance at Carry-le-
Rouet, even though the trend in winter and spring was
of decreasing catches with distance. At Tabarca, the
pattern of D. vulgaris changed depending on the
survey. Biomass was significantly higher near the MPA
in summer (p < 0.05), but catches were significantly
greater far from Tabarca during winter (p < 0.01) and at
a medium distance during spring (p < 0.05).
The rest of the species analyzed (Diplodus annularis,
Diplodus sargus, Muraena helena, Octopus vulgaris,
Sepia officinalis and Torpedo marmorata) did not show
significant differences in catch among distances, but
their catches differed significantly between both MPAs
in some or all of the seasons studied (Table 1).
Some catches of species displayed significant season-
ality (Table 1). The most clear was for Sepia officinalis,
the catches of which were significantly different
among all the seasons at both MPAs. Torpedo mar-
morata also had this seasonality in its catches, but with
a different pattern at each MPA. Some species showed
significant differences among seasons only in Tabarca
Marine Reserve (Labrus merula, Dentex dentex and
Sciaena umbra), whereas others showed significant
differences only in Carry-le-Rouet Marine Reserve
(Diplodus annularis and Octopus vulgaris).
Sandy bottoms in Tabarca Marine Reserve
During the fishing survey, 2427 individuals of 56 spe-
cies were caught (Table A2 in Appendix 1, available
Total weight catch was 444.2 kg. The most well-
represented family was Sparidae, with 13 species, and
82% of the catch was represented by 18 species. Once
again Scorpaena porcus was the most abundant spe-
cies, although sandy bottoms are not their preferred
habitat. Scorpaena scrofa, Torpedo marmorata, Sciaena
umbra and Myliobatis aquila also represented a high
proportion of the total catch (Table A2).
In contrast with the results in Posidonia oceanica
meadows, there was no clear trend related to distance
over the sand habitat (Fig. 2b). There was, however,
Posidonia oceanica Sandy bottoms
Tabarca Tabarca
(kg 100 m
of net)
(kg 100 m
of net)
(kg 100 m
of net)
(kg 100 m
of net)
Nea r
Summer Winter Spring
Summer Winter Spring Summer Winter Spring
Summer Winter Spring
Nea r
Fig. 2. Trends in total catch of nets fished in (a,c) Posidonia oceanica seagrass meadows and on (b,d) sandy bottoms at different
distances (see Fig. 1) from the Tabarca, Cerbère-Banyuls and Carry-le-Rouet Marine Reserves during the different surveys.
Error bars = standard error
Mar Ecol Prog Ser 379: 197–211, 2009202
Table 1. Results of analysis of variance (ANOVA) with 4 factors (Ds: distance; MP: marine protected area; Se: season; Da: day), for the total catch and the catch of the spe-
cies selected in the experimental fishing carried out on Posidonia oceanica adjacent to the Tabarca Marine Reserve and in the Carry-le-Rouet Marine Reserve. df: degrees
of freedom; MS: mean square; F: Fratio. Levels of significance were *p < 0.05, **p < 0.01 and ***p < 0.001). Dash (–) indicates that there is no transformation.aIndicates
that there is no homogeneity of variance, the levels of significance being: *p < 0.01; **p < 0.001
Sources of df Total catch Conger conger Dentex dentex Diplodus annularis Diplodus sargus Diplodus vulgaris F versus
Ds 2 4341.63 15.37*** 662944.3 5.48* 22.8160 5.75** 1.0705 0.21 234.5220 4.36* 14.9639 0.64 Ds ×Da (MP ×Se)
MP 1 20300.64 35.35*** 427761.1 5.03 210.8840 23.51*** 760.3625 66.03*** 473.1201 4.37* 2621.878 92.85*** Da (MP ×Se)
Se 2 2135.77 3.72** 126580.2 1.49 42.3772 4.72* 68.0909 5.91** 9.8566 0.09 254.0028 9.00*** Da (MP ×Se)
Da (MP ×Se) 30 574.26 3.71*** 85122.4 0.64 8.9706 4.75*** 11.5153 3.64*** 108.2850 2.92*** 28.2380 1.57* Residual
Ds ×MP 2 612.48 2.17 737268.0 6.09* 21.5710 5.43** 2.7305 0.52 0.5615 0.01 31.1866 1.33 Ds ×Da (MP ×Se)
Ds ×Se 4 326.26 1.15 152947.8 1.26 6.4894 1.63 3.7620 0.72 42.0760 0.78 70.9730 3.02* Ds × Da (MP ×Se)
Ds ×Da (MP ×Se) 60 282.56 1.82*** 121004.2 0.91 3.9698 2.10*** 5.2207 1.65** 53.7390 1.45* 23.4632 1.30 Residual
MP ×Se 2 1701.47 2.96 544796.9 6.40* 34.6509 3.86* 174.5174 15.16*** 37.9958 0.35 114.6357 4.06* Da (MP ×Se)
Ds ×MP ×Se 4 1033.43 3.66** 101049.3 0.84 5.4000 1.36 0.6610 0.13 48.8744 0.91 152.6391 6.51*** Ds ×Da (MP ×Se)
Residual 540 154.95 133222.0 1.8867 3.1619 37.1205 17.9864
Transformation (x+ 1) aLn(x+ 1) Ln(x+ 1) (x+ 1) (x+ 1)
Sources of variation df Labrus merula Mullus surmuletus Muraena helena Octopus vulgaris Phycis phycis F versus
Ds 2 2623858.43 9.91*** 180.0987 8.00*** 65870.55 0.86 0.9234 0.17 285260.5 10.78** Ds ×Da (MP ×Se)
MP 1 51534484.84 126.70*** 408.3636 7.28* 1822957 8.29* 80.8252 29.20*** 505492.8 15.77** Da (MP ×Se)
Se 2 1061359.18 2.61 487.3677 8.69** 415259.8 1.89 2.3031 0.83 141364.8 4.41 Da (MP ×Se)
Da (MP ×Se) 30 406749.84 2.86*** 56.0874 2.77*** 219987.6 2.08** 2.7675 0.85 32052.07 1.65 Residual
Ds ×MP 2 629315.36 2.38 60.4272 2.69 117044.1 1.52 1.4102 0.26 320765.1 12.12** Ds ×Da (MP ×Se)
Ds ×Se 4 172372.15 0.65 87.1327 3.87** 41161.41 0.54 1.9276 0.36 90455.16 3.42 Ds ×Da (MP ×Se)
Ds ×Da (MP ×Se) 60 264788.79 1.86*** 22.5011 1.11 76934.46 0.73 5.3892 1.65** 26472.81 1.37 Residual
MP ×Se 2 2667616.72 6.56** 40.0030 0.71 853120.6 3.88 15.1050 5.46** 107325.2 3.35 Da (MP ×Se)
Ds ×MP ×Se 4 116715.73 0.44 59.8454 2.66* 42591.38 0.55 8.5975 1.60 107239.7 4.05* Ds ×Da (MP ×Se)
Residual 540 142114.17 20.2820 105719.6 3.2699 19389.76
Transformation – Ln(x+ 1) aLn(x+ 1) a
Sources of variation df Sciaena umbra Scorpaena porcus Sepia officinalis Symphodus tinca Torpedo marmorata F versus
Ds 2 9.79 3.40* 2340.332 26.22*** 22.4602 0.15 1557.132 9.13*** 45847.29 1.56 Ds ×Da (MP ×Se)
MP 1 1597.32 163.6*** 2683.913 12.11** 27.5085 0.10 2790.430 14.41*** 77124.09 3.28 Da (MP ×Se)
Se 2 109.15 11.18*** 1023.905 4.62* 7139.430 26.79*** 1509.188 7.79** 128074.7 5.45* Da (MP ×Se)
Da (MP ×Se) 30 9.76 2.76*** 221.6127 3.60*** 266.4929 2.83*** 193.6125 2.44*** 23480.04 0.84 Residual
Ds ×MP 2 9.80 3.40* 156.4869 1.75 36.9837 0.24 832.9524 4.89* 16560.14 0.56 Ds ×Da (MP ×Se)
Ds ×Se 4 6.97 2.42 256.3111 2.87* 86.7419 0.57 554.0033 3.25* 36148.85 1.23 Ds ×Da (MP ×Se)
Ds ×Da (MP ×Se) 60 2.88 0.81 89.2636 1.45* 152.8656 1.62** 170.4929 2.15*** 29385.52 1.05 Residual
MP ×Se 2 109.15 11.18*** 5358.034 24.18*** 476.0154 1.79 112.4399 0.58 159557.7 6.80* Da (MP ×Se)
Ds ×MP ×Se 4 6.97 2.42 379.5330 4.25** 66.0392 0.43 934.5086 5.48*** 86217.14 2.93 Ds ×Da (MP ×Se)
Residual 540 3.54 61.5490 94.1687 79.4591 27985.84
Transformation Ln(x+ 1) (x+ 1) (x+ 1) (x+ 1) a
Forcada et al.: Effectiveness of MPA for fisheries enhancement 203
Fig. 3. Trends in catches of: (a) Scorpaena porcus, (b) Labrus merula, (c) Mullus surmuletus, (d) Symphodus tinca and (e) Diplo-
dus vulgaris fished in Posidonia oceanica seagrass meadows at different distances (see Fig. 1) from the Tabarca and Carry-
le-Rouet Marine Reserves during the 3 surveys. Error bars = standard error
Mar Ecol Prog Ser 379: 197–211, 2009
a significant interaction between Distance and Day
(Table 2), because significant differences among dis-
tances occurred on only 9 of 18 d. Of these, only
2 exhibited the expected trend (significantly higher
catches near the boundaries), while the remaining
7 exhibited catches that were significantly higher at
intermediate or far distances.
In general, trends in catch at the species level were
inconsistent with our main hypothesis, with the highest
biomasses existing at the intermediate or far distance.
The biomasses of Myliobatis aquila, Octopus vulgaris,
Raja spp., Scorpaena scrofa and Uranoscopus scaber
were higher in the intermediate distance catches. How-
ever, these patterns were only significant (Table 2) for
the biomasses of M. aquila (Fig. 5a), Raja spp. (Fig. 5b)
and U. scaber (Fig. 5c). Moreover, there was a sig-
nificant interaction between Distance and Season for
S. scrofa biomass (Table 2), with significantly higher
catches at medium distances in summer and winter.
In addition, other species such as Diplodus vulgaris,
Labrus merula, Pagrus pagrus, Sciaena umbra, Sepia
officinalis, Spondyliosoma cantharus and Symphodus
tinca had the smallest catches close to the Tabarca
boundaries. This pattern was only significant for the
biomass of S. umbra (Fig. 5d) in all seasons (p < 0.01),
and of S. tinca in summer (p < 0.05). Furthermore,
biomasses of D. vulgaris, S. officinalis and S. cantharus
showed a significant interaction between Distance and
Day (Table 2), with biomasses higher at intermediate
or far distances.
Pagellus erythrinus (Fig. 5e), Scorpaena porcus (Fig. 5f),
Spicara maena (Fig. 5g) and Torpedo marmorata
(Fig. 5h) displayed a decreasing trend with distance from
Tabarca in at least 2 seasons. However, none of these
were significant by Distance (Table 2). The interaction
between Distance and Day was only significant for P.
erythrinus and S. maena. Biomass was higher for P. ery-
thrinus near the MPA boundary on 3 of the 4 d when
significant differences occurred, whereas biomass was
higher for S. maena near the MPA boundary on 2 of the
3 d when there were significant differences.
In surveys in Posidonia oceanica meadows, some
species catches showed significant seasonality: catches
of Torpedo marmorata and Sciaena umbra were signifi-
cantly greater in winter, whereas the catches of Sepia
officinalis were highest in spring (Table 2).
Sandy bottoms in Cerbère-Banyuls Marine Reserve
A total of 537 individuals of 42 species were caught
(Table A2). Total weight of the catch was 174.1 kg.
The most well-represented family was Sparidae, with
10 species. Only 12 species represented around 85 % of
Fig. 4. Trends in catches, at different distances (see Fig. 1) during the 3 surveys, of nets fished in Posidonia oceanica seagrass
meadows for: (a) Sciaena umbra and (b) Dentex dentex in the Tabarca Marine Reserve and for: (c) Conger conger and (d) Phycis
phycis in the Carry-le-Rouet Marine Reserve. Error bars = standard error
Forcada et al.: Effectiveness of MPA for fisheries enhancement 205
Table 2. Results of analysis of variance (ANOVA) with 3 factors (Ds: distance; Se: season; Da: day), for the total catch and the catch of the species selected in the experimental
fishing carried out on sandy bottoms adjacent to the Tabarca Marine Reserve. df: degrees of freedom; MS: mean square; F: Fratio. Levels of significance were *p < 0.05, **p <
0.01 and ***p < 0.001. Dash (–) indicates that there is no transformation. aIndicates that there is no homogeneity of variance, the level of significance being: *p < 0.01; **p < 0.001
Sources of variation df Total catch Diplodus vulgaris Labrus merula Myliobatis aquila Octopus vulgaris F versus
Ds 2 3036.38 8.37** 164.5112 3.06 0.5325 0.25 2197108.2 5.83* 243304.3 4.51 Ds ×Da (Se)
Se 2 432.51 0.20 114.7718 1.30 10.7729 0.75 581927.1 1.54 107922.2 2.65 Da (Se)
Da (Se) 15 2179.10 12.16*** 88.0170 2.98*** 14.3807 4.62*** 376768.7 0.74 40661.83 0.87 Residual
Ds ×Se 4 403.89 1.11 68.2882 1.27 1.2855 0.61 631852.5 1.68 26926.94 0.50 Ds ×Da (Se)
Ds ×Da (Se) 30 362.64 2.02** 53.6878 1.82** 2.1152 0.68 376768.7 0.74 53949.62 1.15 Residual
Residual 270 179.16 29.5467 3.1149 506241.3 46863.72
Transformation (x+ 1) (x+ 1) Ln(x+ 1) aa
Sources of variation df Pagellus erythrinus Pagrus pagrus Raja spp. Sciaena umbra F versus
Ds 2 10.53 1.71 141.8069 2.55 335592.0 5.79* 304.0054 5.42** Ds ×Da (Se)
Se 2 10.35 0.58 259.3364 2.25 105783.3 1.24 1460.040 8.76** Da (Se)
Da (Se) 15 17.83 6.40*** 115.1465 2.49** 85312.89 1.59 166.7302 3.49*** Residual
Ds ×Se 4 1.08 0.18 71.6693 1.29 43888.68 0.76 108.2151 1.93 Ds ×Da (Se)
Ds ×Da (Se) 30 6.17 2.22** 55.6765 1.20 57963.90 1.08 56.0394 1.17 Residual
Residual 270 2.79 46.3350 53589.37 47.7370
Transformation Ln(x+ 1) (x+ 1) a(x+ 1)
Sources of variation df Scorpaena porcus Scorpaena scrofa Sepia officinalis Spicara maena F versus
Ds 2 328773.75 2.39 22.2463 4.30* 169.5525 3.22 14061.41 1.73 Ds ×Da (Se)
Se 2 9782352.91 4.35 3.3789 0.34 676.2028 7.56** 131105.2 1.55 Da (Se)
Da (Se) 15 2248589.37 26.43** 9.8228 2.55** 89.4475 2.64*** 84851.57 16.86** Residual
Ds ×Se 4 371841.53 2.70 14.4261 2.79* 64.7010 1.23 13820.00 1.70 Ds ×Da(Se)
Ds ×Da (Se) 30 137703.02 1.62 5.1766 1.34 52.6158 1.55* 8128.786 1.61 Residual
Residual 270 85065.86 3.8551 33.8501 5033.570
Transformation – Ln(x+ 1) (x+ 1) a
Sources of variation df Spondyliosoma cantharus Symphodus tinca Torpedo marmorata Uranoscopus scaber F versus
Ds 2 59.97 12.37*** 5.4624 1.32 71.5921 0.77 133907.4 9.91** Ds ×Da (Se)
Se 2 1.45 0.05 2.4709 0.18 395.339 6.18* 106.539 0.01 Da (Se)
Da (Se) 15 28.24 10.62*** 13.7958 5.43*** 64.0216 0.93 14695.1 1.07 Residual
Ds ×Se 4 5.50 1.13 12.1499 2.94* 38.8826 0.42 3887.03 0.29 Ds ×Da (Se)
Ds ×Da (Se) 30 4.85 1.82** 4.1340 1.63* 93.5657 1.35 13506.3 0.98 Residual
Residual 270 2.66 2.5410 69.0613 13742.3
Transformation Ln(x+ 1) Ln(x+ 1) (x+ 1) a
Mar Ecol Prog Ser 379: 197–211, 2009
the catches, with the main species being Phycis phycis
and Pagellus acarne. Other important species in the
total catch were Scorpaena scrofa, Scorpaena porcus
and Sepia officinalis.
As with the results for sandy bottoms in Tabarca, there
was no clear trend with distance in total catch (Fig. 2d),
though there was a significant interaction between Dis-
tance and Day (Table 3). On only 2 of the 12 sampling
days were there significant differences among distances.
Season was periodically important (Table 3); total bio-
mass was significantly greater in spring than in winter.
At the species level, catches of Pagellus acarne
(Fig. 6a) and Palinurus elephas (Fig. 6b) decreased
with distance from the MPA borders. However, only
the interaction between Distance and Day was sig-
nificant for the biomass of P. acarne (Table 3). There
were 3 d with significantly higher catches close to the
MPA, in contrast to 1 d with a significantly different
trend. Additionally, there were decreasing trends with
distance of Mullus surmuletus (Fig. 6c), Sepia offici-
nalis (Fig. 6d) and Uranoscopus scaber (Fig. 6e), but
only in one season.
Fig. 5. Trends in catches of: (a) Myliobatis aquila, (b) Raja spp., (c) Uranoscopus scaber, (d) Sciaena umbra, (e) Pagellus erythri-
nus, (f) Scorpaena porcus, (g) Spicara maena and (h) Torpedo marmorata fished on sandy bottoms at different distances (see
Fig. 1) from the Tabarca Marine Reserve during the 3 surveys. Error bars = standard error
Forcada et al.: Effectiveness of MPA for fisheries enhancement 207
Table 3. Results of analysis of variance (ANOVA) with 3 factors (Ds: distance; Se: season; Da: day), for the total catch and the catch of the species selected in the experi-
mental fishing carried out on sandy bottoms adjacent to the Cerbère-Banyuls Marine Reserve. df: degrees of freedom; MS: mean square; F: Fratio. Levels of significance
were *p < 0.05, **p < 0.01 and ***p < 0.001. Dash (–) indicates that there is no transformation. aIndicates that there is no homogeneity of variance, the level of significance
being: *p < 0.01; **p < 0.001
Sources of variation df Total catch Conger conger Mullus surmuletus Pagellus acarne Pagellus erythrinus F versus
Ds 2 0.62 2.03 37778.42 0.46 21054.18 1.38 301.7312 2.75 1.9218 0.53 Ds ×Da (Se)
Se 1 2.32 7.93* 116111.4 0.98 50081.12 2.74 44.1456 0.22 10.2432 2.29 Da (Se)
Da (Se) 10 0.29 1.68 118954.9 2.50* 18258.60 2.52* 202.7286 5.09*** 4.4710 1.53 Residual
Ds ×Se 2 0.99 3.24 97664.94 1.19 35637.03 2.33 19.8974 0.18 1.0914 0.30 Ds ×Da (Se)
Ds ×Da (Se) 20 0.31 1.76* 82236.18 1.73 15293.86 2.11* 109.8275 2.76*** 3.6541 1.25 Residual
Residual 180 0.17 47652.10 7253.982 39.8600 2.9295
Transformation Ln(x+ 1) aa(x+ 1) Ln(x+ 1)
Sources of variation df Palinurus elephas Phycis phycis Raja clavata Scorpaena porcus F versus
Ds 2 3611.13 0.74 348.0851 1.53 56601.5 1.73 223248.6 1.76 Ds ×Da (Se)
Se 1 5869.80 0.74 118.3079 0.67 162800.1 2.18 776400.5 7.45 Da (Se)
Da (Se) 10 7917.62 1.54 177.4796 1.64 74730.1 1.38 104272.9 3.08* Residual
Ds ×Se 2 282.24 0.06 486.9147 2.14 56601 1.73 184054.8 1.45 Ds ×Da (Se)
Ds ×Da (Se) 20 4903.53 0.96 227.6789 2.10** 32803 0.60 126502.8 3.73** Residual
Residual 180 5134.12 108.2667 54315.9 33884.2
Transformation –a(x+ 1) aa
Sources of variation df Scorpaena scrofa Sepia officinalis Pegusa lascaris Uranoscopus scaber F versus
Ds 2 3611.13 0.74 4.6682 0.82 9378.389 0.22 4.3636 1.36 Ds ×Da (Se)
Se 1 5869.80 0.74 0.1846 0.03 241335.2 6.42 19.4419 2.32 Da (Se)
Da (Se) 10 7917.62 1.54 6.5912 1.78 37606.59 1.43 8.3944 2.58** Residual
Ds ×Se 2 282.24 0.06 2.3585 0.42 4284.574 0.10 4.2857 1.34 Ds ×Da (Se)
Ds ×Da (Se) 20 4903.53 0.96 5.6761 1.53 43196.35 1.64 3.1970 0.98 Residual
Residual 180 5134.12 3.7045 26305.39 3.2582
Transformation –aLn(x+ 1) aLn(x+ 1)
Mar Ecol Prog Ser 379: 197–211, 2009
In general, trends in the catch of Pagellus erythrinus,
Phycis phycis, Scorpaena scrofa and Pegusa lascaris
were inconsistent with our hypothesis, with higher
catches at the intermediate or far distances. Moreover,
species such as Conger conger, Raja clavata and
Scorpaena porcus were absent at some of the distances
or in some of the seasons, complicating the identi-
fication of a general trend. P. lascaris was the only spe-
cies that showed significant differences between sea-
sons (Table 3); catches in winter were significantly
higher than in spring.
Fisheries spillover was detected in some surveys
in the Posidonia oceanica meadows near the MPA
boundaries of both Tabarca and Carry-le-Rouet
Marine Reserves. However, differences between sur-
veys indicated that spillover did not occur consistently.
This inconsistency may be related to differences in
abundance (Harmelin et al. 1995) or catchability
(Maunder et al. 2006) of the species due to seasonal
Species that showed a significant response to protec-
tion were those typical of Posidonia oceanica meadows
or shallow rocky bottoms, which are the main pro-
tected habitats at both MPAs (Conger conger, Dentex
dentex, Labrus merula, Mullus surmuletus, Phycis
phycis, Sciaena umbra, Scorpaena porcus and Sym-
phodus tinca). Other species, like Diplodus spp.,
Muraena helena, or cephalopods, did not present clear
trends in spite of their high contribution to the catches.
Some of the species that responded to protection
with higher catches near the border, such as Dentex
dentex, Mullus surmuletus, Phycis phycis, Sciaena
umbra and Scorpaena porcus, are important target
species of artisanal fisheries (García-Rodríguez et al.
2006, Forcada 2007, Goñi et al. 2008). Moreover, these
species represent the highest proportion of the catch
and the greatest income for artisanal fisheries (García-
Rodríguez et al. 2006, Forcada 2007, Goñi et al. 2008).
Fig. 6. Trends in catches of: (a) Pagellus acarne, (b) Palinurus
elephas, (c) Mullus surmuletus, (d) Sepia officinalis and (e)
Uranoscopus scaber fished on sandy bottoms at different
distances (see Fig. 1) from the Cerbère-Banyuls Marine
Reserve during the 2 surveys. Error bars = standard error.
Surveys were not conducted in summer due to bad weather
Forcada et al.: Effectiveness of MPA for fisheries enhancement
Therefore, export of fish from the MPAs, even if it is
limited, should provide economic benefits to artisanal
Although fisheries enhancement was detected very
close to MPA borders in general, there were some dif-
ferences between the Tabarca and Carry-le-Rouet
Marine Reserves. They are located in different biogeo-
graphical sectors (Garibaldi & Caddy 1998, Bianchi &
Morri 2000), and one of the most important differences
is that of sea temperature, which ranges at the surface
from 13 to 27°C in Tabarca and from 12 to 24°C in
Carry-le-Rouet. This accounts for the higher abun-
dance at Tabarca of certain species typical of warmer
waters (Sciaena umbra and Dentex dentex), which are
rare in the northern Mediterranean (Harmelin 1991,
Ramos-Esplá & Bayle 1991, Francour et al. 1994).
The other difference between the MPAs is that at
Carry-le-Rouet the increase of the catches was only
detected near the boundaries, whereas at Tabarca
some effects, like the increase of Scorpaena porcus
and Sciaena umbra catches, reached an intermediate
distance, only declining at the fishing ground furthest
from the MPA. This may be interpreted in relation to
the size of each MPA. Carry-le-Rouet is a very small
reserve (85 ha) that has a very limited influence over
the surrounding fished area, while Tabarca is a larger
one (1400 ha) that seems to have a wider exportation
effect. The effect of protection of juveniles and adults
is edge dependent. The probability of fish leaving
a given reserve, and consequently increasing their
vulnerability, will decrease in proportion to the in-
crease in size of the MPA (Kramer & Chapman 1999,
Chapman & Kramer 2000, Roberts et al. 2001b). There-
fore, small MPAs may not support populations effi-
ciently (Edgar & Barrett 1999), especially for mobile
species that often cross reserve boundaries. However,
small MPAs can have an important protective role in
the case of sedentary species or if the the reserves are
situated at crucial locations, such as aggregation sites
for spawning (Beets & Friedlander 1999). There are no
upper limits on reserve size that are relevant to conser-
vation goals, but to achieve an export of fishable stocks
they should not be too large (Roberts et al. 2003). If
reserves are made too large, then spillover to fisheries
will be prevented, while making reserves too small will
yield no benefits. It is difficult to be precise about what
constitutes ‘too large’ because it depends on the mobil-
ity of the species involved and local oceanographic
conditions (Roberts et al. 2003). To determine what
reserve size is too small more empirical study is re-
quired (Edgar & Barrett 1999, Halpern 2003, Gui-
detti et al. 2005). From the results obtained, Tabarca
Marine Reserve and Carry-le-Rouet Marine Reserve
seem large enough to promote population recovery,
and yet are small enough to permit some spillover for
the benefit of local fisheries. Even the small MPA
appears capable of generating increases in catches near
its boundaries; the larger one shows the same effects,
but proportional to its size. For that reason, the
absolute impacts of small and large reserves will be
very different. Although the observations at each MPA
size were not replicated, these results offer some
empirical evidence suggesting that the amount of pro-
tected area is important.
In contrast, there was no clear trend in catches on
sand in Tabarca and Cerbère-Banyuls Marine Reser-
ves. Only a few of the surveys showed higher catches
near the boundaries, and only 2 of the species, Pagel-
lus acarne and Palinurus elephas, evidenced decreas-
ing trends with distance in the Cerbère-Banyuls
Marine Reserve, but neither of these was significant.
It appears that biomass is exported through Posido-
nia oceanica meadows (at least for some species and
seasons), while little export occurs through sandy
bottoms. At both Tabarca and Carry-le-Rouet Marine
Reserves, the main habitat, P. oceanica meadow,
extends outside the borders. Rocky and sandy bottoms
are also present in Tabarca Marine Reserve, but are
very limited, ~10 and ~20%, respectively, of the sur-
face protected. Something similar occurs in Cerbère-
Banyuls Marine Reserve, which protects mainly rocky
bottoms, and sandy bottoms start just near the MPA
The types and qualities of habitats, both inside and
outside the reserve, determine how a species responds
to reserve protection (Agardy 1995, Nilsson 1998). It is
desirable that reserves protect habitats where species
feed and reproduce and where they spend a consider-
able portion of time (Kramer & Chapman 1999). In this
sense, habitats can act as surrogates for species in
reserve planning, simplifying the task of deciding
what to protect (Roberts et al. 2001b). On the other
hand, the relative mobility of some species (Chapman
& Kramer 2000) suggests that movement across the
boundary would be much greater if the boundary
divides an area of continuous habitat. It has been
pointed out (Roberts 2000) that habitat continuity
through MPA boundaries is important for biomass
export to open fished areas, and our results confirm
this assessment.
Although we found that the spatial scale of the
spillover-induced density gradient is very localized, it
is, nevertheless, sufficient to provide local benefits to
artisanal fisheries (through juvenile and adult
spillover) and possibly more regional benefits (through
greater larval export). We conclude that spillover
effects are not a universal consequence of marine pro-
tected areas in temperate waters, and that they are
related to the distribution of habitat inside and around
the reserve.
Mar Ecol Prog Ser 379: 197–211, 2009
Acknowledgements. We very much appreciated the help
received from A. Delauney, K. Kawahara, M. Capoulade and
B. Luna during field data collection. We acknowledge the
friendly cooperation of the fishermen of Tabarca, Carry-le-
Rouet and Cerbère-Banyuls. This research was financed by
UE-DG Fisheries through the project BIOMEX (QLRT-2001-
00891), WP5. A.F. was supported by an FPI grant from the
Generalitat Valenciana (CTBPRB/2003/146). We thank the
FAO for providing species drawings for Figs. 3, 4, 5 & 6. We
also thank the anonymous reviewers and the editor for their
useful comments on the manuscript.
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Submitted: November 23, 2007; Accepted: December 16, 2008
Proofs received from author(s): March 13, 2009
... Both aspects contribute to increasing the carrying capacity of the ecosystem including multiple characteristics of physical structure, such as the variation of elements or the size of cavities (Tokeshi and Arakaki, 2012) providing refuge, food, and space. And, at the same time, both are complementary; while heterogeneity favors species richness and diversity (especially if there is some equality in the extension of the different types), vertical complexity is mainly associated with the abundance of individuals (García-Charton and Pérez-Ruzafa, 1998;Forcada et al., 2009;Tokeshi and Arakaki, 2012;St.Pierre and Kovalenko, 2014). The effects of habitat structure manifest at different spatial scales and have effects upon different faunal guilds (nektonic fish, benthic fish, macroinvertebrates, meiofauna...) according to the scale at which they are considered. ...
... Thus, for example, the dominance of medium-sized blocks (between 1 and 2 m in diameter) favors the abundance and richness of benthic or demersal fish and starfish or urchins, while the abundance of stones (<1 m in diameter) favors ophiuroids, small sea urchins, or gobiids (García-Charton and Pérez-Ruzafa, 1998;Entrambasaguas et al., 2008). As a result, habitat structure is a determinant factor for processes like settlement, recruitment, growth, depredation, or successful reproduction (Botsford, 2001;García-Charton and Pérez-Ruzafa, 2001) and can determine the different effectivity of protection on different species (Forcada et al., 2009). ...
... Fishing benefits both from the spread of individuals of commercial species from mature MPAs with high population density, and from the protection of their reproductive function, as demonstrated in the case of fish (Goñi et al., 2008(Goñi et al., , 2010Forcada et al., 2009;Stobart et al., 2009;Vandeperre et al., 2011) and other species such as lobster . From this fishing point of view, an MPA may potentially raise prices due to the variation of fish quantities landed, due to a quality impact based in sizes and species composition of the landings or due to better marketing opportunities and the added MPA brand . ...
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Marine protected areas (MPAs) are globally important environmental management tools that provide protection from the effects of human exploitation and activities, supporting the conservation of marine biological diversity, habitats, ecosystems and the processes they host, as well as resources in a broad sense. Consequently, they are also expected to manage and enhance marine ecosystem services and material, non-material, consumptive and non-consumptive goods, and benefits for humans. There is however certain confusion on what constitutes an ecosystem service, and it is not always easy to distinguish between them and societal benefits. The main nuance is that an ecosystem service is the aptitude an ecosystem has or develops naturally or as consequence of a management action, and that manifests through its own properties (productivity, diversity, stability, quality of its key parameters, etc.), while a societal benefit is the economic or other profitability (emotional, educational, scientific, etc.) that humans obtain from said service or quality. In this work, 268 publications, together with our own experiences in the different investigations carried out in the MPAs that are part of the BiodivERsA3-2015-21 RESERVEBENEFIT European project, have been selected, reviewed and discussed to analyze the knowledge status of the expected ecosystem services of MPAs and the societal benefits derived from them, sometimes providing information on their evidence, when they exist. We define and classify the effects of protection, ecosystem services and societal benefits and elaborate a conceptual model of the cause-effect relationships between them.
... This was the closest distance by water between each survey site and the geographical "centre" of the Reserve (defined as the midpoint between the boundaries of the Integral zone), measured following the depth contour and avoiding crossing sand extensions. This effectively simulated the movement of a fish around the coast (Bell 1983) when following rocky reef habitat (Chapman and Kramer 2000;Forcada et al. 2009). ...
... The CBMR appeared particularly well-suited to investigating the influences of habitat discontinuities on spillover at a scale that is feasible to assess using visual censuses, and in a situation in which spillover has been previously confirmed from studies of fisheries effort and catches (Goñi et al. 2008(Goñi et al. , 2010. While no effect of habitat continuity was found in our study, results of other studies suggest variability in such an effect (Di Lorenzo et al. 2016;Forcada et al. 2008Forcada et al. , 2009). This variability likely arises from numerous factors such as each species' home range size and habitat specificity, the scale of habitat patchiness and fishing pressure and access at each boundary. ...
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The effectiveness of marine protected areas (MPAs) to restore populations of exploited species, both within and outside of their boundaries through net movement of individuals ("spillover"), can potentially be affected by continuity of habitats across the boundaries. Sandy seabeds may reduce movement of reef-associated species across MPA boundaries, thereby increasing the 'reserve effect' while decreasing spillover. Underwater visual censuses were undertaken inside the Cerbère-Banyuls Marine Reserve (CBMR) (France) and adjacent non-protected areas to assess the influence of habitat on spillover. Total fish biomass and mean fish size were significantly higher within the MPA, but rapidly declined across the reserve boundary. Nevertheless, there was no indication of a sharper decline in biomass at the northern boundary where a habitat discontinuity was present relative to the southern boundary with continuous habitat. This result may reflect a number of complicating factors that make assessment of spillover potential difficult, and which may also lead to the uncertainty about which situations and how much spillover may contribute to fished populations outside reserves. In particular, the home range area of the key exploited species relative to the scale of the habitat mosaic, and potentially different levels of fishing pressure at each boundary likely contribute to variability. While the CBMR appeared particularly well-suited to investigating this question, resolving these issues and identifying general principles for where and how much spillover occurs will likely be difficult without a series of specially designed MPAs. This highlights a conundrum facing MPA establishment in the face of pressures to be successful for both biodiversity conservation and to offer fisheries benefits-the latter are clearly not ubiquitous, but a shortage of suitable MPAs that can be used as scientific tools for better understanding how and when these benefits may occur is precluded by a general lack of MPAs designed and managed for this purpose. The results of this study do, however, clearly highlight the biodiversity conservation benefits of the CBMR.
... Even though PLUP can address leakage and ensure permanence (Uisso et al. 2019), it is also important to note that LUPs can always be effective in preventing leakage and/ or ensure permanence if its coverage is widespread rather than implemented on a piecemeal (patchy) basis. This is because the drivers of deforestation and forest degradation in an area with LUPs simply shift to the adjacent area without LUPs (Forcada et al. 2009). Thus, "leakage" and "permanence" issues are core and need to be carefully considered in the process of implementing PLUPs in the context REDD+ initiative. ...
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Land use planning (LUP) and village land forest reserve (VLFR) have been integral to the Reducing Emissions from Deforestation and forest Degradation plus (REDD+) initiative in Tanzania since its inception in 2008. However, the connection on how LUP and VLFR are taken into consideration in the REDD+ initiative has not been well-synthesised and documented. The link merely appears on piecemeal content in various literature. This study adopted a state-of-art method that employed a documentary review approach to fill the gap. The novelty of this article is that it provides a starting point for filling the gap that exists in literature concerning an extended understanding of the nexus of LUP and VLFR in the REDD+ initiative. The review confirms that LUP, VLFR and REDD+ are interlinked and that LUP and VLFR are crucial components to the pursuit of the REDD+ initiative. It was noted that LUP has evolved from a convectional to a participatory approach commonly known as participatory land use planning (PLUP) and can play an important role to control access to, ownership of and use of VLFR under the REDD+ initiative. PLUP has opportunities for limiting the drivers of deforestation and forest degradation, preventing leakage, and ensuring permanence under the REDD+ initiative. The review recommends the idea of using PLUP as a strategy for safeguarding VLFR under REDD+ in the global debate on climate change issues. This is necessary for the REDD+ practitioners/advocates in Tanzania and beyond, towards sustainable forest management and conservation in the context of climate change.
... Τα τελευταία χρόνια έχει σημειωθεί υπερεκμετάλλευση των ιχθυοαποθεμάτων, με ανησυχητικά αποτελέσματα για την αειφόρο ανάπτυξη της αλιείας (Forcada et al. 2008, Forcada et al. 2009). Πολλές επιστημονικές μελέτες προτείνουν τις Θ.Π.Π., σαν εναλλακτικό και βοηθητικό τρόπο για τη διατήρηση και αύξηση της αλιευτικής παραγωγής (Beverton and Holt 1957, Bohnsack 1993, Sobel 1996, Roberts 1997, Sladek Nowlis and Roberts 1997, Lauck et al. 1998, Γιούργης 2013. ...
... No Brasil, cerca de 26,4% dos ecossistemas marinhos estão protegidos, porcentagem considerada adequada (Ministério do Meio Ambiente, 2020). Entretanto, de acordo com Magris e Pressey (2018) e Giglio et al. (2018), esse percentual vêm sendo atingido sem a cobertura dos ecossistemas mais diversos e vulneráveis, o que torna-o insuficiente para o alcance da sustentabilidade dos recursos marinhos.. (2014), efeitos ecológicos diretos são produzidos com a criação das áreas marinhas protegidas, como o processo de spillover em que ocorre a emigração de adultos e juvenis para além das fronteiras da área protegida (Forcada et al., 2009). Para além desses efeitos, unidades de conservação possuem como função social o incentivo ao uso por outros setores, dando significado à proteção e aumentando seu aproveitamento. ...
... Heavy exploitation caused such a decrease in S. umbra populations that the species is currently classified as endangered in the Mediterranean region [25][26][27] . MPAs have proven to be beneficial to this species, effectively contributing to increase its abundance and biomass within the protected areas 28,29 . Due to the persistent decrease in the number of individuals and scarcity of brown meagre on the French Mediterranean coasts, a moratorium was approved, which bans the capture of S. umbra over the entire French Mediterranean coast until 2023 30 . ...
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The spatio-temporal variability of fish distribution is important to better manage and protect the populations of endangered species. In this sense, the vertical movements of a vulnerable and protected species, Sciaena umbra, were assessed in a marine protected area (the Réserve Naturelle Marine de Cerbère-Banyuls, south of France) to study the variability of their bathymetric distribution at different time scales. Twenty adults were marked with acoustic transmitters and acoustically monitored over 2.5 years. This revealed that some individuals remained at shallow waters (< 8 m) all year round, while others presented vertical segregation at deeper waters during the cold months (mean depth of 22.5 ± 0.04 m) and all aggregated in shallow waters during the warm months. The brown meagre was more active during the night, except in June and July when peaks of activity were observed at dusk. These patterns are likely associated with foraging and reproductive behavior during the cold and warm periods, respectively, and likely regulated by water temperature and the depth of the thermocline. Here, we provide valuable information on when and where in the water column critical periods of S. umbra life cycle are expected to occur, which should be considered in management and protection plans.
... A proxy for proximity to MPAs was calculated based on distance by water to the nearest MPA multiplied by MPA size, since both factors have been shown to affect fish biomass (e.g., Forcada et al., 2009;Friedlander et al., 2017). A proxy for fishing pressure from Koror was based on distance a boat has to travel to the main port. ...
Palau has a rich tradition of fisheries management and stewardship of its waters, and as in many island nations, small-scale coral reef fisheries are a vital part of the local culture, economy, and food security. However, reef fisheries in Palau are data-poor and there is increasing concern that reef fish stocks are declining. To evaluate the current and future status of these resources, information is needed on the abundance, biomass, and size structure of reef fish resource species. To this aim, the Palau International Coral Reef Center (PICRC) conducted a nation-wide study to investigate the status of commercially important reef fish stocks in 2017. Fishery-independent surveys were conducted by diver operated stereo-video (stereo-DOV) at 94 sites across the archipelago. Results showed that fish biomass varied from 0.13 to 293 g m⁻². Habitat was the most significant predictor of fish biomass, with the highest biomass found at western fore-reef sites and the lowest at inner reef sites. Region also affected fish biomass, with significantly higher biomass found in the Northern Reefs compared to those around Babeldaob (the largest island in Palau). In channel habitats, marine protected area (MPA) proximity, fishing pressure from Koror (Palau’s main population center), and local fishing pressure significantly influenced fish biomass. In western fore-reef habitats, fish biomass was significantly affected by region, with differences observed between the Northern Reefs and Babeldaob, and between the Southern Reefs and Babeldaob. Fishing pressure from Koror had a significant effect on fish biomass in inner reef habitats, with a weak negative relationship observed. Using length frequencies from the stereo-DOV surveys we also estimated spawning potential ratio (SPR) for seven species and found the majority had SPR values between 20 % and 40 %. Overall, the low fish biomass and SPRs suggests that many of Palau’s principal fisheries species have been overexploited. This is the first study to evaluate the status of resource reef fish stocks across the main islands of Palau and provides a baseline to assess changes in fish populations over time.
... Density of P. elephas within the MR at the end of the 20th century was estimated to be 6-20 times greater than in comparable fished areas depending on the season (Goñi et al. 2001) and spillover supplied lobster to the adjacent fishery (Goñi et al. 2006), providing a net annual benefit to the local fishery of 12% of the catch in weight (Goñi et al. 2010)" (Díaz et al. 2016). Spillover effect have been observed in other MRs and commercial species (Goñi et al 2008, Forcada et al 2009. ...
... A synthesis of field studies by Goñi et al. 19 also reported patterns consistent with MPAs replenishing heavily exploited fisheries in which the abundance of target species in fished areas was far below that in no-fishing zones 51 . In addition to heavy fishing pressure, other important elements stimulating high catch outside of MPAs appear to be habitat characteristics that promote the movement of animals across MPAs borders 26,36 , good fishing habitat in close vicinity (e.g., < 800 m) to MPA borders 36,50 , and a behavioral response by the fishery to fish near the borders. ...
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Marine Protected Areas (MPAs) are designed to enhance biodiversity and ecosystem services. Some MPAs are also established to benefit fisheries through increased egg and larval production, or the spillover of mobile juveniles and adults. Whether spillover influences fishery landings depend on the population status and movement patterns of target species both inside and outside of MPAs, as well as the status of the fishery and behavior of the fleet. We tested whether an increase in the lobster population inside two newly established MPAs influenced local catch, fishing effort, and catch-per-unit-effort (CPUE) within the sustainable California spiny lobster fishery. We found greater build-up of lobsters within MPAs relative to unprotected areas, and greater increases in fishing effort and total lobster catch, but not CPUE, in fishing zones containing MPAs vs. those without MPAs. Our results show that a 35% reduction in fishing area resulting from MPA designation was compensated for by a 225% increase in total catch after 6-years, thus indicating at a local scale that the trade-off of fishing ground for no-fishing zones benefitted the fishery.
... In this study, we analyzed the effect of the protected area by comparing the states of large areas surrounding the no-take zone before and after the protection; this strategy used is a markedly different methodology from those used to date to evaluate MPA spillover in the Mediterranean (Forcada et al., 2009;Francini-Filho and Moura, 2008;García-Rubies et al., 2013;Goñi et al., 2008;Harmelin-Vivien et al., 2008;Roberts et al., 2001;Stobart et al., 2009). We provide empirical evidences of changes in the fishing behaviour and landings that do not rule out the possibility that a targeted MPA established for the protection of juveniles, such as Roses', contribute to long term hake fishery sustainability. ...
The analysis of fish spillover from marine protected areas (MPA) is often based on data collected after the implementation of protection. In the present study we used a methodology based on the combination of Vessel Monitoring System (VMS) and landings data before and after the establishment of protection for spillover analysis. We defined areas of similar size to the protected zone in order to compare them over time. In addition to the no-take zone effectiveness, using this methodology, we were also able to analyze the spatiotemporal behavior of the hake population. Our results on the hake distribution were consistent with those of previous studies. The juveniles were concentrated on the continental shelf (0 - 200 m), whereas the adults were found over the shelf and the slope (300 - 500 m). We found evidence suggesting a positive spillover effect for the juveniles on the continental shelf, enhancing its fishing yields. The analysis of longer time series on the performance of the protected area combined with field sampling inside the no-take zone would lead us to confirm effective spillover effect contributing to fisheries’ long-term sustainability in this zone.
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We examined movement patterns of sportfish that were tagged in the northern Indian River Lagoon, Florida, between 1990 and 1999 to assess the degree of fish exchange between an estuarine no-take zone (NTZ) and surrounding waters. The tagged fish were from seven spe cies: red drum (Sciaenops ocella tus); black drum (Pogonias cromis); sheepshead (Archosargus probatocephalus); common snook (Centropomus undecimalis); spotted seatrout (Cynoscion nebulosus); bull shark (Carcharhinus leucas); and crevalle jack (Caranx hippos). A total of 403 tagged fish were recaptured during the study period, including 65 individuals that emigrated from the NTZ and 16 individuals that immigrated into the NTZ from surrounding waters of the lagoon. Migration distances between the original tagging location and the sites where emigrating fish were recaptured were from 0 to 150 km, and these migration distances appeared to be influenced by the proximity of the NTZ to spawning areas or other habitats that are important to specific life-history stages of individual species. Fish that immigrated into the NTZ moved distances ranging from approximately 10 to 75 km. Recapture rates for sportfish species that migrated across the NTZ boundary suggested that more individuals may move into the protected habitats than move out. These data demonstrated that although this estuarine no-take reserve can protect species from fishing, it may also serve to extract exploitable individuals from surrounding fisheries; therefore, if the no-take reserve does function to replenish surrounding fisheries, then increased egg production and larval export may be more important mechanisms of replenishment than the spillover of excess adults from the reserve into fishable areas.
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We investigate the effects of the Columbretes Islands Marine Reserve (CIMR, Western Mediterranean) on the adjacent Palinurus elephas (Fabricius, 1787) fishery. After 9 to 12 yr of no-take protection there was a gradient of lobster density from the interior of the reserve up to a distance of about 4 km from its boundary. Catch and effort data were collected onboard commercial fishing boats in the fishery adjacent to the CIMR, and combined with catch per unit effort (CPUE) data from monitoring surveys conducted annually inside the reserve. Generalized additive (GAM) and linear (GLM) models were employed to examine the relationships of CPUE and catch per unit area (CPUA) as a function of distance to the reserve boundary. CPUE showed a significant non-linear decline with distance from the centre of the reserve, with a depression at the boundary followed by a plateau. This depression was caused by local depletion associated with concentration of fishing effort at the reserve boundary, while the plateau suggests that lobster export from the reserve is sufficient to maintain stable catch rates Lip to 1500 in from the boundary. Commercial catch and effort data were combined to estimate CPUA, which declined linearly with distance from the reserve. Analysis of recaptures of lobsters tagged and released inside the reserve indicates that the density gradient is caused by lobsters emigrating from the reserve.
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The use of no-take marine reserves as fisheries management tools is controversial. A major expectation of marine reserves is that they will become net exporters of adult biomass (the 'spillover effect'), Herein, we show that the biomass of the surgeonfish Naso vlamingii tripled over 18 yr (1983 to 2001) in a reserve at Apo Island, Philippines. Over time, the biomass of N. vlamingii increased by a factor of 40 outside but close to the reserve boundaries (200 to 250 m) but not at greater distances (250 to 500 m). In 2000/2001 hook-and-line catch per unit effort (CPUE) for N. vlamingii was 45 times higher within 200 m of the reserve boundary than for all other fishing grounds combined, with 62.5% of the hook-and-line catch records being recorded within 200 m either side of the reserve, in just 11% of the reef fishing area. This comprises some of the best evidence that reserves can benefit fisheries by spillover.
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Most mangroves occur in tropical estuaries and generally contain higher densities of fish than adjacent habitats such as seagrass beds and sand flats. The question of whether these fishes depend on estuaries per se has given rise to the concept of estuarine-dependence. On several Caribbean islands, mangroves are only found in non-estuarine bays and lagoons. To test whether fishes also depend on mangroves in non-estuarine conditions we determined juvenile and adult densities of a complete reef fish community in 4 bay habitats (mangrove, seagrass bed, channel, sub-titdal mud flat) in the Spanish Water Bay and 4 depth zones (2, 5, 10 and 15 m depth) on the adjacent coral reef of the Caribbean island of Curacao (Netherlands Antilles), using a single visual census technique in all habitats. The results showed that non-estuarine mangroves did harbour a much higher total juvenile fish density, density of juvenile temporary bay residents (i.e. nursery species), and density of juvenile permanent bay residents (i.e. bay species) than adjacent seagrass beds, channel and mud flats, but a similar total juvenile fish density as the coral reef. The different patterns of abundance of juvenile fish are probably related to the degree of structural habitat complexity. For a number of nursery and bay species, juvenile fish were found almost exclusively in the mangroves and sometimes to a lesser extent in other bay habitats, but rarely on the coral reef, giving rise to the concept of 'bay habitat dependence'. Juvenile and adult habitats differed for at least 21 of the 50 most common reef species, suggesting partial or complete ontogenetic habitat shifts from the mangroves to the reef, from the channel to the reef, and from the shallow to the deeper coral reef. Different associations with habitat type were also found at the level of fish families.
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A frequent expectation of the use of marine reserves in management of coral reef fisheries is maintenance or enhancement of yields to areas adjacent to reserves by adult (post-settlement) movements from reserve to fished areas (the so-called 'spillover effect'). Demonstration of this effect has been rare. This paper reports on some circumstantial evidence derived from underwater visual census monitoring of densities of large predatory coral reef fish [Serranidae (Epinephelinae), Lutjanidae, Lethrinidae and Carangidae as a group] inside and adjacent to a small marine reserve at Apo Island in the central Philippines over a 10 yr period (1983 to 1993). The marine reserve (sanctuary) at Apo Island was established in 1982 and was protected from fishing for the duration of the study. The non-reserve area was open to fishing by up to 200 municipal fishers using traditional fishing gear (bamboo traps, hooks and lines, gill nets and spears). Significant positive correlations of both mean density and species richness of large predatory fish with duration of reserve protection (from 1 to 11 yr) were observed in both the reserve and non-reserve areas surveyed. The minimum distance from the boundary of the reserve to the non-reserve area surveyed was 200 m. During the first 8 yr of reserve protection combined, the density of large predatory fish at distances 200 to 300, 300 to 400 and 400 to 500 m from the reserve boundary did not differ significantly from an even distribution (chi-squared test, p > 0.05). During the period of 9 to 11 yr of protection combined, there was a significantly higher density of these fish in the area closest to the reserve (i.e. in the 200 to 300 m area, chi-squared test, p < 0.05). This visual census data is consistent with a proposed model of adult fish export from the reserve to the non-reserve areas. Along with interview data collected in 1986 and 1992 that showed that fishers were unanimous that their yields had increased since the reserve was implemented, this study provides evidence for export of adult fish from reserve to fished areas.
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Despite being one of the most common pieces of information used in assessing the status of fish stocks, relative abundance indices based on catch per unit effort (cpue) data are noto- riously problematic. Raw cpue is seldom proportional to abundance over a whole exploita- tion history and an entire geographic range, because numerous factors affect catch rates. One of the most commonly applied fisheries analyses is standardization of cpue data to re- move the effect of factors that bias cpue as an index of abundance. Even if cpue is standard- ized appropriately, the resulting index of relative abundance, in isolation, provides limited information for management advice or about the effect of fishing. In addition, cpue data generally cannot provide information needed to assess and manage communities or ecosys- tems. We discuss some of the problems associated with the use of cpue data and some methods to assess and provide management advice about fish populations that can help overcome these problems, including integrated stock assessment models, management strat- egy evaluation, and adaptive management. We also discuss the inappropriateness of using cpue data to evaluate the status of communities. We use tuna stocks in the Pacific Ocean as examples.
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The artisanal fishery of the Alicante Gulf was analysed from data collected at the port of Santa Pola using multivariate analysis and generalised linear models. Daily landings by boat from 1994 to 2003 were used: (i) to describe the activity groups; (ii) to identify the target species; (iii) to characterise the catch composition by gear and (iv) to obtain a derived abundance index for the selected species. This is a multispecies and multigear fishery mainly based on the exploitation of Mullus spp. (especially M. surmuletus), Merluccius merluccius, Octopus vulgaris, Sepia officinalis and some Sparidae species. Many other species are landed either individually or as mixed categories. The main gear is the trammel net, followed by the long line, the gill net and others, all exhibiting a high monthly variability in landings. More generally, there is an annual stability in landings joined to a high annual and monthly variability in the abundance index of the main target species.
In 1995, in collaboration with local Bedouin fishermen, five no-take fisheries reserves were established within the Nabq Natural Resource Protected Area, South Sinai, Egyptian Red Sea. The abundance, size structure and catch of commercially targeted groupers (Serranidae), emperors (Lethrinidae) and snappers (Lutjanidae) were investigated before the establishment of these reserves, then in 1997 and again in 2000. By 1997, these fish had shown a significant increase in mean abundance within two of the no-take reserves. By 2000 each family and three individual species (Lethrinus obsoletus, Cephalopholis argus and Variola louti) had increased in abundance in the reserves. There were significant increases in mean individual length of the serranids Epinephelus fasciatus and C. argus and of the lethrinids L. nebulosus and Monotaxis grandoculis. Meanwhile, mean recorded catch per unit effort (CPUE) within the adjacent fished areas increased by about two-thirds (P <0.05) during the 5 years. The establishment of the no-take reserves appears to have played a key role in maintaining the sustainability of the fishery. The involvement of local Bedouin and fishermen in the co-management of fisheries resources was critical to the success of this initiative.
High population densities of larger fish within reserves could result in emigration of fish to surrounding non-reserve areas, producing a gradient of abundance and mean size across the reserve boundaries. The difference in fish abundance and size between reserve and non-reserve should be higher for sedentary than for mobile species and for highly catchable than for less catchable species. To test these hypotheses we estimated the abundance and size of fishes by trapping and visual census on fringing reefs in Barbados: 5 reefs within the 2.2 km of the Barbados Marine Reserve (BMR) and 8 reefs in the non-reserve (NR) area within 4 km of the reserve boundaries. The abundance of large, trappable size fish of all species combined was higher in the BMR than in the NR, but abundance of small, nontrappable fish did not differ between BMR and NR. Trap catches decreased gradually with distance from the BMR center, but this gradient of abundance was less evident in visual census counts of trappable size fishes of all species combined, and not apparent in trap or visual census estimates of abundance for individual species. Mean size was larger in the BMR than in the NR for 18 out of 24 species. The relative differences in both abundance and size between BMR and NR did not differ between mobile and sedentary fish taxa. However, for sedentary taxa, the relative differences in abundance and size increased with trappability (the vulnerability to traps, which are the most common fishing method). These patterns suggest that the BMR does protect the fish community from fishing mortality and that emigration rates are generally low. Trappability and mobility depend on complex behavioral characteristics of fishes and are potentially important for the functioning of marine reserves.
Mediterranean marine biodiversity has received only a fraction of the attention accorded to its terrestrial counterpart, despite the great cultural and economic importance that the sea has been having for the Mediterranean countries. A rough estimate of more than 8500 species of macroscopic marine organisms should live in the Mediterranean Sea, corresponding to somewhat between 4% and 18% of the world marine species. This is a conspicuous figure if one considers that the Mediterranean Sea is only 0.82% in surface area and 0.32% in volume as compared to the world ocean. The high biodiversity of the Mediterranean Sea may be explained by historical (its tradition of study dates older than for almost any other sea), paleogeographic (its tormented geological history through the last 5 my has been determining the occurrence of distinct biogeographic categories), and ecological (its variety of climatic and hydrologic situations within a single basin has probably no equals in the world) reasons. Present-day Mediterranean biodiversity is undergoing rapid alteration under the combined pressure of climate change and human impact, but protection measures, either for species or ecosystems, are still scarce. To understand the role and patterns of Mediterranean marine biodiversity, marine ecological research should: first, re-value those scientific areas currently unfashionable with funding agencies (systematics, biogeography and taxonomy); second, start monitoring biodiversity with a long-term approach at a whole Mediterranean scale, possibly through an internationally co-ordinated network of marine protected areas.