# Redistribution of fisheries catch potential in Mediterranean and North European waters under climate change scenarios

Emna Ben Lamine, Alexandre Schickele, Paolo Guidetti, Denis Allemand, Nathalie Hilmi, Virginie Raybaud

► To cite this version:

Emna Ben Lamine, Alexandre Schickele, Paolo Guidetti, Denis Allemand, Nathalie Hilmi, et al. Redistribution of fisheries catch potential in Mediterranean and North European waters under climate change scenarios. Science of the Total Environment, 2023, 879, pp.163055. 10.1016/j.scitotenv.2023.163055. hal-04659664

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1 Redistribution of fisheries catch potential in Mediterranean and North European waters under climate change

2 scenarios

3 Emna Ben Lamine ¹,²*, Alexandre Schickele³, Paolo Guidetti⁴, Denis Allemand²,⁵, Nathalie Hilmi²,⁵ & Virginie

4 Raybaud¹,²

5 *Corresponding author

6 ¹Université Côte d'Azur, CNRS, ECOSEAS, France

7 ²LIA ROPSE, Laboratoire International Associé Université Côte d'Azur—Centre Scientifique de Monaco, Monaco,

8 Monaco.

9 ³Sorbonne Université, CNRS, UMR 7093 LOV, Villefranche-sur-Mer, France.

10 ⁴Department of Integrative Marine Ecology (EMI), Stazione Zoologica Anton Dohrn-National Institute of Marine

11 Biology, Ecology and Biotechnology, Genoa Marine Centre, Genoa, Italy

12 ⁵Centre Scientifique de Monaco, Monaco, Monaco.

13 Abstract

14 The Mediterranean Sea is a hotspot of global warming where key commercial species, such as demersal and
15 pelagic fishes, and cephalopods, could experience abrupt distribution shifts in the near future. However, the
16 extent to which these range shifts may impact fisheries catch potential remains poorly understood at the scale of
17 Exclusive Economic Zones (EEZs). Here, we evaluated the projected changes in Mediterranean fisheries catches
18 potential, by target fishing gears, under different climate scenarios throughout the 21st century. We show that the
19 future Mediterranean maximum catch potential may decrease considerably by the end of the century under high
20 emission scenarios in South Eastern Mediterranean countries. These projected decreases range between -20 to -
21 75% for catch by pelagic trawl and seine, -50 to -75% for fixed nets and traps and exceed -75% for benthic trawl.
22 In contrast, fixed nets and traps, and benthic trawl fisheries may experience an increase in their catch potential in
23 the North and Celtic seas, while future catches by pelagic trawl and seine may decrease in the same areas. We
24 show that a high emission scenario may considerably amplify the future redistribution of fisheries catch potential
25 across European Seas, thus highlighting the need to limit global warming. Our projections at the manageable scale
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of EEZ and the quantification of climate-induced impacts on a large part of the Mediterranean and European

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fisheries is therefore a first, and considerable step toward the development of climate mitigation and adaptations

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strategies for the fisheries sector.

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Key words: Fisheries, maximum catch potential, Mediterranean, Climate change, species distribution

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## 1. Introduction

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Climate change is rapidly becoming one of the biggest threats to marine habitats and species. It affects
biological traits of marine organisms (e.g., growth and reproduction), resulting in shifts of their biogeography

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(Cheung, 2018; Schickele et al., 2021a; 2021b; Ben Lamine et al., 2022). Moreover, top-predators biomass is
expected to decrease significantly (-17% by 2100), independently of the future radiative forcing scenario

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(Schwalm et al., 2020; Lotze et al., 2019). Consequently, fisheries production patterns are expected to be
modified in the near future (Cheung et al., 2018; Holsman et al., 2020). In addition, overexploitation rate, that is
highly heterogeneous among species and regions (Cheung, 2018; Holsman et al., 2020), is considered as a key
factor accelerating the decline of fishery catches, thus exacerbating the above-mentioned climate change effects

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(Sumaila and Tai, 2020).

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Cheung et al. (2013) investigated the impact of increasing sea temperature on fish catch composition. They
suggested that global warming has already affected global fisheries between 1970 and 2006, as a significant
positive correlation was found between the species thermal preferences, their weight in the catches, and the sea
surface temperature. The suggested impacts include changes on fisheries catch potential and their associated
economic value in the future (Lam et al., 2011; 2016). The Maximum Catch Potential (MCP) of a species is a
prediction of its catch using an empirical relationship considering its trophic level, the primary production, and
other catch related variables gathered into a Generalized Linear Model (GLM) (Cheung et al., 2008). At the global
scale, some studies have evaluated future MCP trends, under climate change scenarios (Cheung et al., 2010; Lam
et al., 2016). The same empirical relationship was used in regional assessments to show a mid-century MCP
decline in west Africa (Lam et al., 2012) and in United Kingdom (Jones et al., 2015), while increasing in the Arctic
(Lam et al., 2014).

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However, no study has yet investigated the projected changes in Mediterranean MCP in details. As global studies showed a decline by more than 50% in MCP in the Mediterranean region (global average for the whole basin; Lam et al., 2016), regional detailed analyses are now needed to improve fisheries management plans in this area. Here, we propose an evaluation of the projected changes in MCP at the scale of Exclusive Economic Zones and by target fishing gear, for the Mediterranean and Atlantic European seas.

In the Mediterranean Sea, the historical trend of reported overall catches (1970–2017) evidences a gradual increase that peaked in mid-1990 at around 1.1 million tons, followed by a continuous decline afterwards (FAO, 2020). According to previous studies on catch dynamics (Pauly and Zeller, 2016), such declining trends are often underestimated due to unreported catches (e.g., discards, recreational catch; Piroddi et al., 2020). While the worldwide average overfishing rate is estimated around 33%, the Mediterranean has the highest overfishing rate with 62% of its fish stocks experiencing overfishing (FAO, 2020), thus increasing their vulnerability to climate change. The Mediterranean fisheries are multi-specific (Calò et al., 2022). The landings are mostly composed by small pelagic (mainly European anchovy *Engraulis encrasicolus* and European sardine *Sardina pilchardus*) and small-to-medium sized demersal fish (e.g., European hake *Merluccius merluccius*, red mullet *Mullus barbatus*, Sparidae) (FAO, 2020).

Therefore, our study aims at quantifying the effects of climate change on fisheries catch potential across the 21st century (2030-2039, 2050-2059 and 2090-2099), under two Representative Concentration Pathways (RCP4.5 and 8.5; i.e. medium to high emission scenarios), at a spatial resolution that is coherent with fisheries management (i.e., EEZ), in the Mediterranean and Atlantic European seas. Considering the distribution shifts from the south Mediterranean countries to the north European ones in small pelagic fish (Schickele et al., 2021a), cephalopods (Schickele et al., 2021b) and demersal and benthic species of high economic value (Ben Lamine et al., 2022), it is substantial to forecast whether they will affect associated fisheries and how. The species considered within our study represent at least 64.6% of the total annual catch in the Mediterranean Sea, and 73.9% of the total economic value, according to the most updated data (FAO, 2020). The originality of our study comes from the predictions of Maximum Catch Potential (MCP) by target fishing gear, that will reflect the gain or the loss in catch for each socio-economic fishers group, that can be very different from one to another. To our knowledge, this is the first study, computing MCP at the species level, and covering multiple climate trajectories,
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at the manageable scale of the Mediterranean and Atlantic European EEZs. Therefore, it provides unprecedented
information to the fisheries managers and decision makers about the future of the stocks of the most exploited
fish species and cephalopods.

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## 2. Methods

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### 2.1. Data collection

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For the 19 fishes and cephalopods (table 1), annual catches from 1960 to 2017, per species and per Exclusive Economic Zone (EEZ) were obtained from the Sea Around Us database (https://www.seaaroundus.org/). These catch data were used for the calculation of the regression coefficients and the intercept of the Generalized Linear Model (GLM). For this study, we considered the species that are targeted by the same gears in a same group (according to Stergiou et al., 2003; Tsagarakis et al., 2012; Grati et al., 2018; Doray et al., 2018) (table 1, see section 2.2.2. for the MCP computation details).

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## Table 1

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### 2.2. Maximum Catch Potential calculations

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#### 2.2.1. Generalized Linear Model (GLM) calibration

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Using the published empirical relationship described in Cheung et al. (2008), we calculated the annual maximum catch potential for each of spatial cell. For each species, the empirical relationship estimates its catch potential based on the total primary production within its exploitable range (PP), the area of its exploitable range (A), its trophic level (TROPH) and includes terms correcting the biases from the observed catch potential : (CT) as the number of years of exploitation and (HTC) as the average catch value from the 5 years when the highest catches were recorded (see eq.1) (Cheung et al., 2008; Cheung et al., 2010; Jones et al., 2015, Lam et al., 2012; Lam et al., 2016):

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Predicted catch potential per EEZ = 1,815+0,775 * PP + 0,014 * TROPH – 0,208 * CT - 0,743 * HTC +0,808 * AGR (eq.1)

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PP: the total primary production within its exploitable range for a species t

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AGR: the area of its geographic range
103 TROPH: species trophic level

104 CT: number of years of exploitation

105 HTC: average catch value from the 5 years when the highest catches were recorded

106 Based on the spatially explicit catch data from seaaroundus.org database (https://www.seaaroundus.org/_Pauly et al., 2020), a database freely provided under Creative Commons Attribution Non-Commercial 4.0 International License. This catch data were used for the calibration of the Generalized Linear Model, we calculated the total area where the geographic range of a species was exploited (AGR), i.e., had a non-zero catch. Trophic levels were collected from the Fishbase database (www.fishbase.org) for fishes, and from the Sealifebase database (www.sealifebase.org) for cephalopods.

112 The results of the GLM allowed to determine the coefficient of regression and the intercept, to obtain the equation 1 of the GLM. Then, the contemporary catch potential was first compared to the observed (i.e., realized catch) for the 1990-2017 period, i.e., the most recent data available at the time of the analysis. Then, the future catch potential was calculated using the future geographical distribution ranges published in Schickele et al., 2021a; Schickele et al., 2021b and Ben Lamine et al., 2022 and the future Primary Production extracted from several Earth System Models (ESM, see Table 1 in Schickele et al., 2021a for the list). As the data showed a Gaussian distribution, we used the identity function link. We ran the GLM model specified in Eq. (1) using the software R (package GLM).

120 2.2.2. Estimating contemporary and future Maximum Catch potential (MCP) per group of species

121 For each species time period (t) (contemporary, 2030-2039, 2050-2059 and 2090-2099), geographical cell (i), and Representative Concentration Pathway (RCP4.5 and 8.5), we estimated the Maximum Catch Potential per grid (MCPᵢ,t) using the Catch Potential per EEZ calculated by the GLM (according to Jones et al., 2015):

$$ \text{Maximum Catch Potential}_{i,t} \text{ per grid} = \text{Catch Potential}_{t} \times \frac{\text{ESI}_{i,t}}{\text{ESI}_{t}} \quad (\text{eq.2}) $$

126 The contemporary (1990–2017) and future (2030-2039, 2050-2059 and 2090-2099) spatial distributions of the 19 species were estimated by means of the Environmental Suitability Index (ESI), a spatialized index ranging
from 0 to 1 that reflects suitable environmental conditions, i.e., where a species can live and reproduce. The ESI was estimated per 0.1° x 0.1° grid for each of the 19 species using a multi-model and a multi-scenario approach (see Schickele et al., 2020, 2021a; 2021b, Ben Lamine et al., 2022). The Primary Production (PP) was extracted from several monthly Earth System Models (ESM, see Table 1 in Schickele et al., 2021a for the list), bilinearly interpolated at a 0.1° x 0.1° spatial resolution and averaged for each considered period. The considered climate models were: IPSL (Dufresne et al., 2013; Hourdin et al., 2013), MPI (Giorgetta et al., 2013; Stevens et al., 2013), CNRM (Voldoire et al., 2013), HadGEM (Jones et al., 2011) and GISS (Schmidt et al., 2014).

Then, the mean MCP per target fishing gear was calculated as the sum of MCP weighted by their percentage in the total MCP of the group (eq.3). This calculation method was used since Mediterranean fisheries are multi-specific (Calò et al., 2022), i.e. fish and cephalopods can be caught by more than one fishing gear. Groups of species gathered the target of the most common fishing methods used in the Mediterranean Sea (Table 1). The weighted mean relative difference in MCP under both RCP scenarios was calculated, using the R software, as the difference between the contemporary (1990-2017) and the future MCP (2050ies and 2090ies) for each species, relatively to the MCP in the contemporary period (eq. 4).

$$ \text{MCP}_{i,t} \text{ per target fishing gear} = \frac{\sum (\text{MCP}_{i,t} \text{ species} \times \text{\% of the MCP}_{i,t} \text{ in the group})}{\text{Total number of species in the group (eq.3)}} $$

For a target fishing gear : Weighted relative difference in MCP$_{i,t}$ = (MCP$_{i,t}$ - MCP$_{i,contemporary}$) / MCP$_{i, contemporary}$
(eq.4)

## 3. Results

### 3.1. Correlation between predicted and observed contemporary catch potential

The potential catch of the 19 species of fishes and cephalopods were significantly correlated with annual primary production in the species' exploited range, trophic level, geographic range, and the number of years of records in the catch time-series (1960-2017) (Table 2). Levels of significance for the above terms were high (p-value<0.01). The full model was significant at the 95% confidence level and explained 86% of the variation in the average maximum annual catches of the species (R²=0,86; p-value < 0,001; Figure 1). The effect of total annual primary production from the exploited range, the geographic range and trophic level were positive, whereas the
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effects of the years of exploitation and average catch value from the 5 years when the highest catches recorded
were negative (table 2).

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Table 2

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## 3.2. Maximum Catch Potential (MCP) prediction in the future period by Exclusive Economic Zones (EEZs)

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In all Mediterranean EEZs, and the Atlantic coasts of France and Spain, predictions in MCP expressed in tons per km² by EEZ (Figure 2 A, B & C, figure S2 in appendix 2) show a decrease between the contemporary period (1990-2017) and all the future periods under all scenarios for fish and cephalopods caught by fixed Nets and Traps (NT), and by Benthic Trawl (BT) and by Pelagic trawl and Seine (SP) by at least 0.2 T.km⁻². For some EEZs, the expected loss exceeds 0.5 T.km⁻² (e.g., Morocco, Croatia, Italy, and Atlantic coasts of France). For some Atlantic European EEZs (e.g., Denmark, Sweden, and Norway), fixed Nets and Traps MCP (NT MCP) and Benthic Trawl MCP (BT MCP) are expected to increase by at least 0.5 T.km⁻² (Figure 2 A & B). However, Pelagic trawl and Seine MCP (SP MCP) is expected to decrease in Denmark, remains stable in Sweden and increases in Norway (Figure 2C). In the same Atlantic European EEZs, NT MCP and BT MCP are expected to increase in the future under scenarios RCP4.5 and 8.5. While for SP MCP, it decreases in Denmark, is constant in Sweden, and increases in Norway.

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## Figure 2

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## 3.3. Projected changes in weighted Maximum Potential Catches (MCP)

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### Fixed Nets and Traps (NT) catches

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In the southern and eastern Mediterranean Sea, under RCP4.5 and for the 2050-2059 period, we project a decrease of about 25% for fixed Nets and Traps MCP (NT MCP), reaching 75% in the Gulf of Gabès (Tunisia). These values reach 50% to 75% for the end of the century (Figure 3.1 A, figure S3 in appendix 3). Under RCP8.5, the projected decrease in NT MCP is greater throughout the southern and eastern Mediterranean Sea: between 50 and 75% for mid-century projections and exceed 75% for the end of the century (Aegean Sea and Gulf of Gabès). This projected future NT MCP decrease is alleviated in the northwestern Mediterranean Sea and northern
178 Adriatic Sea, showing a 25 to 50% decrease for 2050-2059 under both RCP4.5 and 8.5 scenarios (figure 3.1 A and 3.2 A).
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180 On the Atlantic European, we project a NT MCP decrease between of 25% from the Portuguese coasts to the Celtic Sea under all scenarios (figure 3.1 A and 3.2 A, figure S3 in appendix 3). In contrast, NT MCP is expected to increase from 25% (under the RCP 4.5 both periods and under RCP 8.5 2050-2059) to +50% under RCP 8.5 by the end of the century (Figure 3.2 B). It could even increase by +100% along the Norwegian coasts under both scenarios for the same future time period (2090-2099).
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185 Benthic Trawl (BT) catches

186 In the Mediterranean Sea, Benthic Trawl MCP (BT MCP) is expected to decrease by 25% to 50% (Figure 3.1 and 3.2, B, figure S3 in appendix 3). The decrease is expected to reach -75 % in Gulf of Gabès and in the Aegean Sea, for the period 2050-2059 under both scenarios. However, in the Lion Gulf and the Adriatic Sea, BT MCP will keep the same trends under the scenario RCP 4.5 for both time periods, with an expected decrease from 50% to 75% for the mid-century under RCP 8.5. By the end of the century, under the pessimistic scenario RCP 8.5, BT MCP decreases exceed 75% along Tunisian coasts, Adriatic, and Aegean Seas. In the Levantine Sea, BT MCP are expected to keep the same trends in all periods under both scenarios, for future benthic trawling catches.
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193 Along the Portuguese coasts, BT MCP is expected to increase by at least 25% under both scenarios and time periods. In the Celtic Sea, BT MCP is expected to keep increasing by 50% to 75%, reaching 100% in the North Sea and along the Norwegian coasts under both scenarios and time periods (Figure 3.2 B).
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196 Pelagic trawl and seine (SP) catches

197 In the Western Mediterranean Sea, Pelagic trawl and Seine MCP (SP MCP) are projected to slightly decrease (between 0 and -15%) in both RCP4.5 and 8.5 for the mid-century (Figure 3.1C and 3.2C, figure S3 in appendix 3). This value reaches -25% for the end of the century. However, in the Eastern part of the Mediterranean Sea, this projected decrease in SP MCP is greater: it reaches -40 to -50% with RCP4.5 and -50 to -75% with RCP8.5, for the end of the century. On the contrary, an increase by 15 to 20% in the Northern part of the Adriatic Sea and in the Marmara strait is projected under RCP 4.5 (both periods) and under RCP 8.5 for the 2050-2059 period. However, under RCP 8.5 by the end of the century, the SP MCP is projected to decrease by -25%.
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Regarding European Atlantic coasts, SP MCP could decrease until -25% under the scenario RCP 4.5 for 204 205 2050-2059 and until -50% under RCP 4.5 for the end of the century (figure 3.1-C) and RCP 8.5 both time periods, 206 206 along the Portuguese coasts (Figure 3.2-C). However, along the Spanish and French Atlantic coasts, under the 207 207 scenario RCP 4.5 the decrease is more important in the second half of the 21st century. Along the Norwegian 208 208 coasts, SP MCP will increase from +25% to +75% under both scenarios, for both future time periods.

Figure 3.1

Figure 3.2

## 4. Discussion

### Limitations of the empirical relationship

The ecological attributes and related indicators (e.g., trophic level, total primary production, distribution) were 213 used to predict the maximum catch potential (MCP) in the Mediterranean and Atlantic European Seas. The 214 explanatory power of the statistical model (GLM) was high as the correlation between reported and predicted 215 catches was very high, which strengthens the quality of the future MCP predictions. Our results show that, from 216 the data series used for the purpose of this study, the MCP was significantly and positively affected by the 217 primary production and the trophic level. As it is the basis of the marine food web, primary production sustains 218 the whole marine food web and have direct or indirect effects on higher trophic levels (Chassot et al., 2010), 219 resulting in a bottom-up-control of the total catches (Chen et al., 2022) and positive effects on fish stock 220 recruitment (Capuzzo et al., 2018). The primary production could likely decrease with the effect of temperature 221 increase (Capuzzo et al., 2018). In the Mediterranean Sea, primary production decreases from north to south and 222 west to east whilst an opposite trend is observed for temperature (Coll et al., 2010; Costello et al., 2010). 223 Moreover, the primary production is expected to result in an amplification of biomass decline worldwide (Lotze 224 et al., 2019). Our results are consistent with these findings as they show a decreasing MCP from north to south and 225 from west to east, following the primary production trends and inversely with temperature trends. In the 226 meantime, the MCP was negatively affected by the fishing effort (i.e., the number of years with catch data (CT) 227 and the catch from higher taxonomic groups (HTC)). If not controlled, fishing is very likely to result in overfishing 228
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(Chen et al., 2022). Following the suggestions of Sumaila and Tai (2020), ending overfishing would enable more effective conservation of marine resources and more resilient ecosystems to climate change.

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Although the empirical relationship was developed from a wide data set of fish and cephalopod catches with different ecology and life history (Cheung et al., 2008), the original data (catch, geographic range, years of exploitations) remain with high uncertainty, considering the unreported catch (Pauly and Zeller, 2016) and the ecological niche modelling uncertainties (Schickele et al., 2020; Ben Lamine et al., 2022). Another uncertainty comes from the trophic level used in the model, which was assumed to be constant over time. However, change in species distributions and community structure resulting from climate change may affect the trophic level of the species. This would affect the estimated change in MCP and remains a major uncertainty of our projections.

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*The variation between the contemporary and the future MCP by target fishing gear*

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From previous studies, the global picture shows a predicted decrease in MCP in 2050s (relative to 2005), up to -50% in the South and the East of the Mediterranean Sea. Lam et al., 2016 estimated that by 2050, the change in total catches in the Mediterranean Sea will reach -15% to -50% and more than -50% in the North Sea. Our study is the first that estimated MCP for the most caught and valuable Mediterranean fish species, under two RCPs for three future time periods (2030 (see appendices 2 and 3), 2050 and 2090 decades). The originality of our results comes from the predictions of MCP by target fishing gear, that reflects the gain or the loss for each socio-economic fishers group, that can be very different from one to another. Our results suggest that, in the southeastern Mediterranean EEZs, fishers using fixed nets and traps, benthic trawl and pelagic trawl and seine are those who will, very likely, experience the larger decrease in their catches. While in the Northern Atlantic European EEZs (Denmark and Norway), future catch using fixed nets and traps and benthic trawl will increase.

Jones et al. (2015) predicted also future catch potential by species and predicted a decrease for the United Kingdom EEZ in *M. merluccius*, *M. surmuletus*, *S. solea* and a stability for *T. trachurus*, *S. sprattus* and *E. encrasicolus*. These results are close to our results under the scenario RCP 4.5, for the future period 2050. In the Mediterranean region, there is a marked gradient, from the arid climate of north Africa to the temperate climate of south Europe (Giorgi and Lionello, 2008). Furthermore, species movements are geographically limited by the semi-enclosed configuration of the Mediterranean Sea with no escape towards colder waters beyond the northern limit (cul-de-sac effect) (Ben Rais Lasram et al., 2010; Raybaud et al., 2017).

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Moreover, our study shows that, by the end of the century, limiting the climate warming to an intermediate value (RCP 4.5) instead of the intense warming (RCP 8.5) (Macias et al., 2015) could limit the loss in mean MCP by 22% in the Mediterranean and the gain by 3.5% in the Atlantic coasts. This is also consistent with a previous study, where benefits for global fisheries catches from limiting global average temperatures to 1.5°C (RCP 2.6) were highlighted (Cheung et al., 2018).

According to our results, the most impacted EEZs in terms of future catches, are the south and eastern Mediterranean countries, independently of the fishing gears used. This covers an important panoply of livelihood as these fishing gears and target species concerns all Mediterranean fisheries (FAO, 2020).

## Economic consequences of MCP in the projected redistribution of MCP

The predicted loss in MCP is likely to have important economic consequences on the fisheries economy and associated livelihood. For example, the estimated loss in MCP predicted in our study will certainly result in an important economic loss for fisheries livelihoods using fixed nets and traps, benthic trawl and pelagic trawl and seine. Some economic estimations were performed assuming constant fish price over future periods (Lam et al., 2016). However, fish prices (markets or ex-vessel prices; Lam et al., 2011; Calò et al., 2022) can be very different from one country to another and the worldwide inflation of gas and employment costs suggests major inter-annual volatility in fisheries income (Abernethy et al., 2010; Guillen and Maynou, 2016). To fully examine the economic impacts of climate change on society through fisheries, future studies should include analysis of both consumer and producer surpluses (Piroddi et al., 2020). Recent studies examined the impacts of climate change and management reforms on fisheries, using climate-linked bioeconomic model (Gaines et al., 2019; Free et al., 2020). They found that climate-adaptive management reforms could minimize negative climate change impacts in many countries (Free et al., 2020). Other human and socio-economic responses to climate change may also affect future economic impacts of climate change on fisheries studied in here. For example, adaptation responses of the fisheries such as the development of new fisheries that target non-indigenous thermophilic species invading the Mediterranean basin may modify the future catches potential (Schickele et al., 2021c; Frid et al., 2023). Thus, changes in fleet size and fishing effort dynamics, and the variability in ex-vessel prices of marine species, under changing oceans thus need to be further explored.
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290 Calò, A., Di Franco, A., Quattrocchi, F., Dimitriadis, C., Ventura, P., Milazzo, M., Guidetti, P., 2022. Multi-specific small-scale fisheries rely on few, locally essential, species: Evidence from a multi-area study in the Mediterranean. Fish and Fisheries 23, 1299–1312. https://doi.org/10.1111/faf.12689

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406 Figures captions

407 Figure 1. Regression between predicted catch and real catch (in Log₁₀). Real catch dots concerns all previously cited fish species and cephalopods catch (see table 1) from 1990 to 2017 (i.e., the most recent data) from all Mediterranean and Atlantic European EEZs. Predicted catch concerns the predictions for the same fish and cephalopods in the same EEZs for the same contemporary period.

411 Figure 2. Maximum Catch Potential (MCP) in T.km⁻² between the present and the future by EEZ for target fishing gears: (A) coastal: fixed nets and traps, (B) offshore: benthic trawl, and (C) offshore: pelagic trawl and seine. EEZs with MCP under 0.1 T.km⁻² are not shown. Countries are: MAR: Morocco, DZA: Algeria, TUN: Tunisia, LBY: Libya, EGY: Egypt, ISR: Israel, LEB: Lebanon, SYR: Syria, TUR: Turkey, GRC: Greece, ALB: Albania, MNE: Montenegro, HRV: Croatia, SVN: Slovenia, ITA: Italy, FRA MED: France in the Mediterranean, ESP MED: Spain in the Mediterranean, POR: Portugal, ESP ATL: Spain in the Atlantic, FRA ATL: France in the Atlantic, BEL: Belgium, DEU: Germany, GBR: United Kingdom, NLD: Netherlands, DEN: Denmark, SWE: Sweden, NOR: Norway. (See figure S2 in Appendix 2 for the 2030-2039 future time period)

418 Figure 3.1. Projected changes (in percentage) in weighted Maximum Potential Catches (MCP) per target fishing gear (i.e., (A) fixed Nets and traps, (B) Benthic trawl, and (C) Pelagic trawl and Seine), for the Representative Concentration Pathways (RCP) 4.5 over the future periods 2050-2059 and 2090-2099. (See figure S3 in Appendix 3 for the 2030-2039 future time period)

422 Figure 3.2. Projected changes (in percentage) in weighted Maximum Potential Catches (MCP) per target fishing gear (i.e., (A) fixed Nets and traps, (B) Benthic trawl, and (C) Pelagic trawl and Seine), for the Representative Concentration Pathways (RCP) 8.5 over the future periods 2050-2059 and 2090-2099. (See figure S3 in Appendix 3 for the 2030-2039 future time period)
<figure><img src="image_2.png" /></figure>
Atlantic EEZs

Mediterranean EEZs

<figure><img src="image_3.png" /></figure>

<figure><img src="image_4.png" /></figure>
RCP 4.5

2090-2099 period

<figure><img src="image_5.png" /></figure>

2050-2059 period

<figure><img src="image_6.png" /></figure>

(A) Fixed nets and traps

(B) Benthic trawl

(C) Pelagic trawl and seine

<figure><img src="image_7.png" /></figure>

<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>
RCP 8.5

2090-2099 period

<figure><img src="image_10.png" /></figure>

2050-2059 period

<figure><img src="image_11.png" /></figure>

(A) Fixed nets and traps

(B) Benthic trawl

(C) Pelagic trawl and seine

<figure><img src="image_12.png" /></figure>
<table><caption>Table 1. Fish and cephalopod species considered for this study, gathered by target fishing gears: (A) coastal: fixed nets and traps; (B) offshore: benthic trawl, and (C) offshore: pelagic trawl and seine.</caption><thead><tr><th></th><th>Target species</th><th>(A) Coastal: fixed<br>Nets and traps</th><th>(B) Offshore:<br>Benthic trawl</th><th>(C) Offshore:<br>Pelagic trawl<br>and seine</th></tr></thead><tbody><tr><td rowspan="12">Fish species</td><td>Lophius budegassa</td><td></td><td>X</td><td></td></tr><tr><td>Lophius piscatorius</td><td></td><td>X</td><td></td></tr><tr><td>Mullus surmuletus</td><td>X</td><td></td><td></td></tr><tr><td>Mullus barbatus</td><td>X</td><td>X</td><td></td></tr><tr><td>Merluccius merluccius</td><td></td><td>X</td><td></td></tr><tr><td>Solea solea</td><td>X</td><td>X</td><td></td></tr><tr><td>Pagellus erythrinus</td><td>X</td><td>X</td><td></td></tr><tr><td>Dicentrarchus labrax</td><td>X</td><td></td><td></td></tr><tr><td>Sparus aurata</td><td>X</td><td></td><td></td></tr><tr><td>Trachurus mediterraneus</td><td></td><td></td><td>X</td></tr><tr><td>Trachurus trachurus</td><td></td><td></td><td>X</td></tr><tr><td>Sardina pilchardus</td><td></td><td></td><td>X</td></tr><tr><td>Sardinella aurita</td><td></td><td></td><td>X</td></tr><tr><td>Sprattus sprattus</td><td></td><td></td><td>X</td></tr><tr><td>Engraulis encrasicolus</td><td></td><td></td><td>X</td></tr><tr><td>Boops boops</td><td></td><td></td><td>X</td></tr><tr><td rowspan="3">Cephalopods</td><td>Octopus vulgaris</td><td>X</td><td>X</td><td></td></tr><tr><td>Sepia officinalis</td><td>X</td><td>X</td><td></td></tr><tr><td>Loligo vulgaris</td><td>X</td><td></td><td></td></tr></tbody></table>
<table><caption>Table 2. Statistical tests of the full GLM as specified in Eq. (1). P: annual primary production from exploited range; TROPH: trophic level; CT: number of years with catch data; HTC: catch from higher taxonomic groups; AGR: geographic range.</caption><thead><tr><td>Variable</td><td>Estimate</td><td>SE</td><td>t</td><td>p</td></tr></thead><tbody><tr><td>Intercept</td><td>1,815</td><td>0,765</td><td>2,368</td><td>&lt;0,001</td></tr><tr><td>Log<sub>10</sub>(P)</td><td>0,775</td><td>0,136</td><td>5,702</td><td>&lt;0,001</td></tr><tr><td>TROPH</td><td>0,014</td><td>0,012</td><td>1,173</td><td>&lt;0,01</td></tr><tr><td>Log<sub>10</sub>(CT)</td><td>-0,208</td><td>0,071</td><td>-2,923</td><td>&lt;0,01</td></tr><tr><td>Log<sub>10</sub>(HTC)</td><td>-0,743</td><td>0,013</td><td>4,141</td><td>&lt;0,001</td></tr><tr><td>Log<sub>10</sub>(AGR)</td><td>0,808</td><td>0,123</td><td>6,525</td><td>&lt;0,001</td></tr></tbody></table>
# How much remains in the fishing catch under climate change scenarios?

## 19 Fish and cephalopods representing

~65 % of Mediterranean landing value and ~74 % of Mediterranean landing value, and fished by :

<figure><img src="image_13.png" /><figcaption>Nets and traps</figcaption></figure>

<figure><img src="image_14.png" /><figcaption>Pelagic trawl and Seine</figcaption></figure>

<figure><img src="image_15.png" /></figure>

High warming scenario
2090'

<figure><img src="image_16.png" /></figure>

<figure><img src="image_17.png" /></figure>

<figure><img src="image_18.png" /></figure>

By 2090', limiting the climate warming to the RCP 4.5 instead of the RCP 8.5 could limit the loss in mean Maximum Catch Potential by 22% in the Mediterranean Sea

Better anticipate future fisheries management policies