Elsevier

Fisheries Research

Volume 248, April 2022, 106222
Fisheries Research

Local fishers experience can contribute to a better knowledge of marine resources in the Western Mediterranean Sea

https://doi.org/10.1016/j.fishres.2021.106222Get rights and content

Highlights

  • Quantitative fisheries data availability prevents describe habitats historical trend.

  • LEK can highlight species and ecosystems at risk when conventional data are scarce.

  • Fishers’ perception match quantitative information from stock assessment analyses.

  • LEK may provide a promising tool for describe VMEs’ distribution and temporal trend.

Abstract

In this study we explore fishers’ perceptions in the Ebro Delta area, Western Mediterranean, throughout structured questionnaires. Specifically, we compare the coherence of information provided by fishers with those resulting by scientific studies in terms of the status of demersal marine resources in the Ebro Delta area; we describe temporal trends of demersal key species in the area with fishers’ perceptions; and we explore the use of Local Ecological Knowledge (LEK) as an alternative data sources to reduce the gap of knowledge on the spatial distribution and temporal trends of sensitive and vulnerable benthic marine species. Our results document important changes in the bottom trawling activity in the study area and in the abundance of commercial species with time according to fishers’ perceptions. Our results mostly match quantitative information from national statistics and stock assessment analyses. In addition, we document important changes in the presence of Vulnerable Marine Ecosystems (VMEs) in the study area due to the by-catch of habitat forming species with time. According to fishers’ perceptions, habitat forming species occur in the area, but were more frequently captured incidentally in the 1980 s and 1990 s. Overall, our study evidences that fisher’s perception represents an important source of complementary information to describe bottom trawling fisheries characteristics and the long-term changes of demersal target species in the Western Mediterranean Sea. Moreover, it highlights that LEK can provide fundamental and additional information on ecosystem changes and it can be a useful tool to increase the knowledge on spatial distribution and on temporal trends of vulnerable benthic species.

Introduction

Fisheries, in particular towed gear fisheries such as otter trawls, dredges, and beam trawls, are considered one of the most destructive practices in the marine environment, impacting commercial and non-commercial stocks, habitats and ecosystems (Clark et al., 2016, Thrush et al., 2016). Moreover, the perennial utilisation of resources, in addition to the multiple impacts on marine ecosystems such as habitat degradation, pollution and eutrophication, climate change, and invasion of non-indigenous species, have an effect on marine biodiversity (Coll et al., 2012, Ferretti et al., 2013), on abundances of marine resources and on marine ecosystems and functioning (Fortibuoni et al., 2017, Danovaro, 2018). The severe effects that bottom gears cause on benthic communities and over hard bottom seabed are well known and include scraping and ploughing of the seabed, sediment resuspensions, destruction of habitats and species (Puig et al., 2012; Clark et al., 2016; Tiano et al., 2019; Mazor et al., 2021).

Despite recent efforts, analytical assessments of the ecological impacts of bottom trawling on benthic communities (e.g., direct changes to substrates and topography, resuspension of sediments caused by fishing gears) are still scant and they mainly focus on shallow waters (Clark et al., 2016; Mazor et al., 2021). Moreover, the availability of pre- and post-impact time-series data, which can provide fundamental information to define the recovery and restoration period of impacted habitats, is scarce (Clark et al., 2016).

The lack of long-term data and biological information impairs the management of marine fish populations, fisheries and the implementation of an ecosystem-base management approach. Benthic megafaunal species, such as sponges and corals, are highly vulnerable to trawling. Since many of these habitat-forming species are exceptionally long-lived and slow growing, their recovery after bottom-towed fisheries is predicted to take decades to centuries once the impact has ceased (Clark et al., 2016). Information about the present and past distribution, together with abundances of key species such as corals, sponges, or sea-pens, is urgently required for the protection and recovery of these communities.

To overcome limitations in data availability and to recover historical information needed to reset the current baseline, fishers’ perceptions (also called Local Ecological Knowledge, LEK) can be used. This approach substantially contributes to improve the historical picture and understanding trends of commercial important species (Azzurro et al., 2011, Damalas et al., 2015a, Coll et al., 2014) and of large marine fauna (Maynou et al., 2011) together with those of discarded or mega-benthic species (Damalas et al., 2015b, Bastari et al., 2017).

Qualitative methodology in fisheries has been gaining importance in recent years with the recognition of the importance of the fishers’ traditional knowledge. UNESCO uses the term “Local and indigenous knowledge” to refer to “the understandings and skills developed by societies with long histories of interaction with their natural surroundings”, as it is the case of fishing communities. Their knowledge includes species seasonal abundance, systems of localisation or fishing gears practices, among others (Herrera and Lizcano, 2012). Moreover, it has been showed that fishers’ observations can provide information of the presence of species and ecosystems at risk when traditional scientific data are scarce or absent (Bastari et al., 2017). The mapping and identification of vulnerable habitats and species is crucial to identify priority areas that need protection and to define efficient fisheries management measures including conservation closures.

In this study we explore fishers’ perceptions in the Ebro Delta area, northern Spain, throughout structured questionnaires. The studied region is within the most productive area of the Mediterranean Sea (Bosc et al., 2004) due to upwelling influenced by wind, freshwater inputs from the Ebro River, and a wide counter-clockwise current running along the continental slope (Agostini and Bakun, 2002, Salat, 1996). The area hosts essential fish habitats such as spawning and nursery areas for small pelagic and demersal fish (Giannoulaki et al., 2011, Giannoulaki et al., 2017, Tugores et al., 2019). The region is also relevant for seabirds’ colonies, marine mammals, marine turtles, and species at risk (Coll et al., 2015).

Since ancient times, the Mediterranean Sea and its ecosystems have been impacted by human activities (Lotze et al., 2011, Ferretti et al., 2008, Ferretti et al., 2013, Coll et al., 2010). Many assessed demersal commercial species in European waters and elsewhere have been classified as fully exploited or overexploited (Colloca et al., 2013: FAO, 2020). The status of Mediterranean and Black Sea fish stocks is worrisome, with 75% of the assessed stocks being overexploited (FAO, 2020) while its ecosystems and benthic communities continue to be highly impacted by fisheries (Pranovi et al., 2000, de Juan et al., 2007, Libralato et al., 2005, Coll and Libralato, 2012, Fortibuoni et al., 2017). Currently, Mediterranean fisheries are mostly poorly managed (Cardinale et al., 2017, Colloca et al., 2017).

Although in the Mediterranean region there is a long history of biological research, marine research was not a top priority (Colloca et al., 2013). Analytical assessment of commercial stocks (i.e. incorporating the effect of fishing on the structure of the population) and the standardised collection of fisheries-independent data (such as MEDITS trawl survey) started relatively late (in the 1990′s) compared to other European countries such as those in the North Atlantic (Colloca et al., 2013). Data availability and analysis for benthic communities, sensitive habitats or vulnerable marine ecosystems and species is even more scattered, both in time and space (Lauria et al., 2017, Bastari et al., 2018, Carbonara et al., 2020). Thus, there is an urgent need to use alternative sources of information to understand the spatial distribution of key habitats and the current population status (stable or declining) and to compare it with available quantitative data to assess its value and potential complementarity.

Specifically, the aims of the study were (i) to compare the coherence of information provided by fishers with those resulting by scientific quantitative studies in terms of the status of demersal marine resources in the Ebro Delta area; (ii) to describe temporal trends of demersal key species in the area with fishers’ perceptions, in order to highlight the key role played by fishers in describing spatial and temporal changes of both target and no target species; and (iii) to explore the use of LEK as an alternative data source to reduce the gap of knowledge on the spatial distribution and temporal trends of sensitive and vulnerable benthic marine species.

Section snippets

Study area

Our study was conducted in the northwestern Mediterranean Sea, between Cape of Salou and Castellon de la Plana (Fig. 1), which includes the area adjacent to the Ebro River Delta. The study covers an extension of ~7000 km2 and a depth range from 40 to 900 m, including the continental shelf and upper slope. In relation to the Iberian Peninsula coast, this area is characterised by having a larger continental shelf, especially in the southern part, which corresponds to the Ebro River delta and the

Characteristics and evolution of the fishing activity

Questionnaires were answered by 49 fishers whose experience was mostly on bottom trawling vessels (SOM, Table S1). The vessels where interviewees were working had a Length Over All (LOA) between 10 and 30 m and bottom trawling was the main gear (SOM, Table S2). The interviewed corresponded to individuals between 23 and 85 years old, and around 65% of them started their fishing activity 30 years ago, with the rest of fishers (with 1 exception) that had been fishing even for a longer period.

Discussion

This study evidences that fishers’ perception represents an important source to describe bottom trawling fisheries characteristics and the long-term changes of demersal target species in the Western Mediterranean Sea. Moreover, it highlights that LEK can provide additional information on ecosystem changes, and it can be a reliable and useful tool to increase the knowledge on spatial distribution and on temporal trends of vulnerable benthic species.

Through fishers’ perceptions we were able to

Conclusions

To understand long-terms changes of marine ecosystems, historical studies are fundamental. LEK can furnish a useful tool to describe the fluctuation of demersal target species and can represent an opportunity to reduce the gap of knowledge on the historical and on the current distribution of VMEs. In highly exploited areas, such as the soft bottoms of the Ebro Delta region, the possibility to use fishers’ perception as complementary source of information to identify the last presence of VMEs

CRediT authorship contribution statement

Azzurra Bastari gave substantial contributions to the conception and design of the work and drafting the work and final approval of the version to be published. Yesmina Mascarell gave substantial contributions to the acquisition and analysis of data. Miquel Ortega gave substantial contributions to the work conception, analysis and interpretation of data, the writing of the article and final approval of the version to be published. Marta Coll gave substantial contributions to work analysis, and

Ethics statement

Ethics approval was not required for this study as per Spanish law and regulations. In compliance with the aforementioned laws and regulations, an oral consent procedure was followed: all participants were provided of the purpose of the study and the usage of the data, and then their consent was obtained. Fishers’ answers were anonymised and it is not possible to link the statements back to individual subjects.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The authors acknowledge the fishers that have provided their knowledge answering the questionnaires. This work acknowledges the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019–000928-S) to the Institute of Marine Science (ICM-CSIC). MC acknowledges partial funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 869300 (FutureMARES).

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