Sustainable Artisanal Fisheries Under Risk: Is the Min- Imum Legal Size Regulation Working for the Chilean Abalone Concholepas Concholepas ? (Master Thesis, EMBC+)

Pontificia Universidad Católica de Chile Facultad de Ciencias Biológicas - Departamento de Ecologia Estación Costera de Investigaciones Marinas (ECIM)

Sustainable Artisanal Fisheries u nder Risk Is the minimum legal size regulation working for the Chilean abalone Concholepas concholepas ?

Michael Kriegl Miriam Fernández Maria Dulce Subida

Master thesis submitted for the partial fulfilment of the title of Master of Science in Marine Biodiversity and Conservation

within the International Master of Science in Marine Biodiversity and Conservation (EMBC+)

June, 2018

______Las Cruces, Chile. e-mail: [email protected]

Content 1 Introduction & Aims ...... 1 1.1 Artisanal fisheries in Chile ...... 3 1.2 Minimum Legal Size Regulation ...... 4 1.3 The Co-Management of Benthic Resources in Chile...... 6 1.4 Loco fishery and biological knowledge ...... 9 1.5 Aims of this study ...... 11 2 Material & Methods ...... 13 2.1 Geographical, social and ecological setting ...... 13 2.2 Study area, data sources and sampling procedure ...... 16 2.3 TURF density and CPUE ...... 18 2.4 Data analysis ...... 18 3 Results ...... 22 3.1 The influence of management regime on compliance ...... 22 3.2 The influence of TURF density on compliance ...... 29 3.3 Can catch rates help predicting levels of compliance? ...... 30 3.4 Beyond hypothesis: Exploring the sustainability and optimization of the Loco fishery ...... 31 4 Discussion ...... 34 4.1 Management practices affecting compliance ...... 34 4.2 The influence of effort displacement and abundance ...... 37 4.3 Sustainability & optimization within the Loco fishery ...... 38 4.4 Management implications ...... 41 4.5 Study limitations ...... 42 4.6 Conclusion ...... 44 5 Acknowledgements ...... 46 6 References ...... 47 7 Annex ...... 60

“What is common to the greatest number has the least care bestowed upon it.”

Aristotle

I dedicate this manuscript to you, Matthias. For living your passion and accompanying me while living mine. Thank you for being an eternal source of motivation & inspiration.

Executive summ ary

The majority of marine fisheries around the world are overexploited. To protect fished stocks from collapse, resource managers apply several management tools: one of the most common measures is the definition of a minimum legal size of capture (MLS). The MLS aims at preventing the harvest of juveniles and ensuring sufficient levels of reproduction to sustain future catches. The efficiency of such a measure, however, depends on compliance by the resource users.

In this study, focused on central Chile, I investigated fishermen’s compliance with the MLS in the artisanal diving fishery for Chile’s economically most important shellfish, the Chilean abalone Concholepas concholepas (commonly “Loco”). Fishermen harvest this high-priced marine snail i) legally, from areas with exclusive extraction-rights for members of local fishing organizations (“management areas”) and ii) illegally, from fishing grounds without entry-restrictions, where the Loco fishery is, however, permanently banned (“open-access”). I hypothesized a larger fraction of undersized individuals in the catch from open-access areas, where fishermen are prone to think: “If I don’t take it, then the next diver will”. In contrast, fishermen co-operating in management areas are expected to safeguard “their” resource base.

We accompanied fishermen on their fishing trips and recorded the maximum shell length (”size”) of each extracted Loco. In management areas, the fraction of undersized individuals in the catch was 14%. In open-access areas, however, almost half of the individuals (47%) were smaller than the MLS. Furthermore, a significantly larger share of immature individuals was extracted from open-access areas. Despite variable MLS-compliance, these results illustrate the devastating fishing practices in the open-access fishery and emphasize the positive effect management areas entail on sustainable resource use. Altogether, I estimated that one out of three Locos landed in Chile is smaller than the legal size limit. Additionally, the majority of Loco is harvested outside the “optimal length range” that would provide maximum biomass yields and highest financial revenues.

Until now, these insights have remained concealed, as solely data on abundance and bulk biomass is being assessed for this fishery. I therefore propose

III

to extend catch assessments by integrating size-based indicators. Further- more, I suggest complementing existing management regulations in a way that brings together economic incentives and resource conservation by:

• Promoting the extraction of individuals within the optimal length range • Redesigning the management of open-access areas to promote MLS- compliance

The present report provides the base for better-informed management decisions towards an optimal and sustainable resource use.

Abstract

The majority of global marine fisheries, in particular small-scale fisheries, are overexploited or already collapsed. Defining a minimum legal size of capture (MLS) is a common tool to mitigate the consequences of exploitation on fished stocks. Its effectiveness, however, depends on compliance by resource users . The extent of illegal fishing resulting from violations to the MLS was assessed in the artisanal diving fishery for Chile’s highest-value marine mollusc, the Chilean abalone Concholepas concholepas . The fraction of catch below the MLS (shell length) was estimated for two different management regimes operating in central Chile: (a) areas with exclusive extraction-rights for designated fishermen (“management areas”) and (b) areas without entry-restrictions (“open-access”), where the C. concholepas fishery is, however, permanently banned. Almost half (47%) of the individuals extracted in open-access and 14% in management areas were smaller than the MLS. Furthermore, a significantly larger share of immature individuals was extracted from open-access areas. Considerable variability in MLS-compliance was, however, observed among sites. These results suggest that undersized individuals contribute a substantial fraction (almost one-third) to the total C. concholepas landings of Chile. In the light of these findings, the need to develop better-informed management strategies towards “optimal” and sustainable exploitation patterns is discussed.

Keywords: Illegal Fishing, Minimum Legal Size Regulation, Small-scale Artisanal Fisheries, Concholepas concholepas , Chilean TURF system.

No data can be taken out of this work without prior approval of the author and his supervisors.

To cite this thesis: Kriegl, M.A. (2018) Sustainable Artisanal Fisheries under Risk: Is the minimum legal size regulation working for the Chilean abalone Concholepas concholepas ? (Master thesis, EMBC+)

1 Intro duction & Aims

The overexploitation of marine resources first received scientific attention in the 19th century (Huxley, 1883), but the onset of depletion in the ocean realm dates back centuries into the past (Jackson et al., 2001; Lotze et al., 2006). Today, around half of the marine fisheries of the world - including both finfish as well as shellfish species - are overexploited or already collapsed (Jamieson, 1993; Pauly & Zeller, 2017). The unsustainable exploitation of marine resources can derive from (i) the extraction of individuals before the realization of the full growth potential, called growth-overfishing, affecting the yield of a fishery and (ii) a high exploitation rate of the reproductive stock, which greatly reduces the general ability of a population to restock and reproduce, called recruitment overfishing (Beverton & Holt, 1993; Cushing, 1972; Hilborn & Walters, 1992), or iii) simply unregulated fisheries. To help populations to recover and to promote the sustainable exploitation of marine resources, several management rules and regulations are currently in force around the world (Worm et al., 2009). These measures, comprising catch restrictions, closed areas, prohibition of certain gear types and minimum landing sizes, can only be effective under scenarios of compliance by the fishing sector (Gigliotti & Taylor, 1990; Paragamian, 1984). Scientific evidence however suggests that non-compliance is a widespread phenomenon in global fisheries (Kuperan & Sutinen, 1998; McKinlay & Millington, 2000).

Illegal, unreported and unregulated fishing (IUU) is considered a major concern for many of the world’s fisheries as it undermines the sustainable management of marine ecosystems. IUU fishing activities account for about 20% (in some regions >30%) of the total marine landings (Agnew et al., 2009) and can lead to the depletion of marine resources, cause significant environmental damage and have cascading effects on whole ecosystems as well as societies (Cavole et al., 2015). Since 2001, this topic has gained international attention, driving the implementation of the “International Plan of Action to Deter, Prevent and Eliminate Illegal, Unreported and Unregu- lated Fishing” (FAO, 2001). Moreover, IUU has been identified as one of the greatest threats to marine ecosystems by the United Nations General Assembly (Resolution A/66/L.22). Within this framework, the combat

against illegal fishing practices, comprising any kind of marine resource extraction that violates state- or international laws and regulations, has also gained momentum. Mitigating and counter-acting the effects of illegal activities, however, is difficult without detailed information on the character of illegal fishing and reliable estimates of non-compliance rates with existing regulations (Blank & Gavin, 2009). Understanding and quantifying the extent of illegal fishing activities should thus be a priority for effective and sustainable resource management. Despite the recent increase in governmental and scientific interest in illegal activities occurring in global fisheries (e.g. Bray, 2000; Pauly & Zeller, 2016), information on illegal fishing practices in small-scale fisheries is still scarce (Cabral et al., 2018).

The artisanal (or small-scale) fisheries are of global socio-economic importance with an estimated 50 of the world’s 51 million fishermen directly employed within this sector (Berkes, 2001; McGoodwin, 1990; Pomeroy & Rivera-Guieb, 2005). Landings from artisanal fisheries are almost entirely directed towards human consumption (Berkes, 2003). They are thus criti- cally important for global food security, supplying more than half of the global catch designated as food for humans (Pauly, 2006). As such, artisanal fisheries are recognized as a key element for coastal economies and livelihoods (Freire et al., 2002). Understanding the drivers of overexploitation within this sector is thus of crucial importance, but information on the status of small-scale artisanal fisheries is not as readily available as one might believe. In fact, we know little about the status of artisanal fisheries, and therefore, the consequences of fisheries regulations on exploited stocks.

Most unassessed fisheries, which currently comprise 80% of the world’s fisheries (Costello et al., 2012), fall within the small-scale category and are typically located in the developing world. The main constraints to assess fisheries in developing countries range from insufficient data to the enormous costs associated with scientific stock assessment (Costello et al., 2012; Hil- born et al., 2005; Mora et al., 2009). In addition, existing regulations are ineffective, because conventional management tools - usually implemented in a top-down manner - can hardly be enforced in the (in general) spatially scattered nature of these fisheries (Drammeh, 2000; Mora et al., 2009; Worm et al., 2009). As a consequence, unassessed (mostly artisanal) fisheries are - on average - in worse condition than assessed fisheries, with 64% of the

former indicating signs of overexploitation (i.e. stock biomasses below levels of maximum sustainable yield, Costello et al., 2012). The current condition of the unassessed fisheries suggests a large potential for improved management practices. In this context, a profound understanding of illegal fishing practices in small-scale fisheries is particularly critical (Aburto et al., 2013; González et al., 2006; Raemaekers et al., 2011; Salas et al., 2007) and offers the chance to promote sustainability while at the same time increasing legal catch, ultimately leading to higher revenues for fishermen (Neubauer et al., 2013).

1.1 Artisanal fisheries in Chile The definition of artisanal or small-scale fisheries - as opposed to mid- and large-scale or industrial fisheries - varies by country (Berkes, 2001; Castilla & Defeo, 2001). In Chile, artisanal fishing describes extractive activities performed in nearshore environments (< 5 nautical miles from the coast) with fishers either operating from shore or using vessels below 18m in size (Moreno & Revenga, 2014). In northern and central Chile, the first nautical mile from the coast is exclusively reserved for artisanal fishermen using boats less than 12m in size (Art. 47bis, FAL 2013). The Chilean artisanal fishing sector is of paramount importance with yearly total artisanal landings con- sistently exceeding industrial landings since 2008 (SERNAPESCA, 2016a). The artisanal fleet responsible for this catch comprises approximately 13.000 vessels, notably outnumbering the 196 industrial ships roaming the country’s territorial waters and the high seas under the Chilean flag (Moreno & Re- venga, 2014). Currently, there are about 100.000 artisanal fishermen registered in Chile of which 12.000 are listed as divers, mainly exploiting benthic shellfish as part of their livelihood (SERNAPESCA, 2016b).

The exploitation of the benthic marine resources in Chile is controlled by a variety of management instruments, usually applied in conjunction with one another. Besides spatial and temporal extraction bans, fishing quotas and a fishermen registration scheme, the main legal instruments controlling benthic artisanal fisheries are species-specific minimum legal size (MLS) regulations and an area-based access-regulating co-management program (TURFs, see below). The two latter management instruments, namely MLS and TURFs, will be the focus of this study and are explained in more detail in the following paragraphs.

1.2 Minimum Legal Size Regulation Size limit regulations, or minimum allowed sizes for the extraction of certain species, have been applied in fisheries management for more than 150 years (Hill, 1990) and are frequently employed in benthic shellfisheries around the world (Donaldson & Donaldson, 1992; Jamieson, 1993). The aim of setting a minimum legal size is increasing the amount of large, sexually mature animals in a population and allowing a sufficient number of individuals to spawn at least once before being extracted (“Let them spawn! - strategy”, (Hill, 1990; Noble & Jones, 1993) . By increasing the reproductive output of a population, it is expected to safeguard healthy spawning stocks (Froese, 2004) and control the two major problems in fisheries management: growth overfishing and recruitment overfishing (Allen et al., 2013; Castello et al., 2011b; Hill, 1990).

The minimum legal size of capture is usually defined based on a set of biological characteristics of a certain species (e.g. life cycle, growth & mortality parameters) and is ideally informed by the size at maturity (e.g. p50, the size at which 50% of a population is sexually mature; González et al., 2012; Somers, 1985). Positive effects of minimum length limits on abundance and mean length of individuals have been documented by the scientific lit- erature (e.g. Cornelius & Margenau, 1999; Pierce, 2010) and based on this, several studies around the world suggest that compliance with measures like the minimum legal size regulation is crucial to ensure the sustainability of exploited resources and forms the basis of rebuilding efforts (Castello et al., 2011a; Mora et al., 2009; Myers & Mertz, 1998; Paragamian, 1984). Never- theless, minimum legal sizes alone are inadequate for stock management (Harrison, 1986) and - in some cases - have proven insufficient to promote larger stock sizes. These outcomes have usually been attributed to short durations of evaluation periods and variability in recruitment (Allen & Pine, 2000; Wilde, 1997).

In order to function efficiently, minimum legal sizes have to be set appro- priately. For species exhibiting sexual dimorphism, e.g. where female individuals significantly outgrow males, an inappropriate minimum length may concentrate the fishing effort on only one sex and subsequently alter the population’s natural male-female ratio (e.g. Australian bass Macquaria aus-

tralasica , Hill, 1990). In most species, sexual maturity is attained at a specific age rather than a specific size (e.g. Nash, 1990). Fast-growing individuals in a population are therefore more likely to reach the minimum size before reaching sexual maturity (Hill, 1990). Size-selective fishing removes these individuals from a population before they get the chance to reproduce. This selection for slower-growing individuals may yield long-term consequences on a population level, leading to smaller sizes at first maturity and finally lower production levels (Fenberg & Roy, 2008; González et al., 2012; Sutherland, 1990). As first maturity is determined by age, geographic variations in growth patterns should also be taken into account when considering minimum sizes (Nash, 1990).

Minimum legal extraction sizes may not always consider biological variables, but can also be based on economic considerations. By altering the size at which individuals are caught, the economic yield and performance of a fishery can be optimized (Hill, 1990; Somers, 1985). In this context the “critical length” (sometimes also called “optimal length”) is an important parameter which describes the size at which a cohort achieves its maximum biomass, i.e. the point where, for an age class, the biomass increase from growth and the biomass loss from natural mortality balance each other (Al- verson & Carney, 1975; Colloca et al., 2013; Ricker, 1945). However, several authors call for precaution when considering this parameter for resource management as there is some uncertainty in the exact determination of the critical lengths (e.g. Ragonese & Svediing, 2017).

In Chile, minimum legal size regulations are currently in place for a variety of benthic marine species (Resolution Nº 630/98, Procedures for the Control of Minimum Sizes). The control of catches and enforcement of regulations is usually performed by SERNAPESCA - aided by the Chilean armada and the police - with a total of ~10.000 enforcement actions focusing on minimum legal size regulations in 2015 (SERNAPESCA, 2015). In a study conducting interviews with Chilean artisanal benthic fishermen, more than 90% of the interviewees claimed to follow the existing size limits for benthic resources (Gelcich et al., 2009), but actual levels of compliance with minimum legal size regulations in the benthic artisanal fishery of Chile are currently un- known. The present study attempts to fill this void in knowledge.

1.3 The Co -Management of Benthic R esources in Chile Territorial use rights for fisheries (TURF) grant local artisanal fishermen associations exclusive extraction rights (tenure) over benthic resources for certain sections of the coastline (Aceves-Bueno et al., 2017). Under this um- brella, a co-management system for near-shore benthic fisheries has been established in Chile in 1991. The areas managed within this system are in- ternationally known as TURFs and locally known as AMERBs (Áreas de Manejo y Extracción de Recursos Bentónicos). These fishing grounds, collo- quially referred to as “management areas ” (MAs), are co-managed by both government and the local fishermen with the aim of promoting the sustainable harvest of benthic resources (Gallardo Fernández, 2008). The idea behind TURFs is based on a common property approach, leading to a collective management and sustainable harvest of shared resources (Ostrom, 1990; Ostrom & Schlager, 1996). The main resources targeted within the Chilean TURF system are the muricid gastropod Loco ( Concholepas concholepas ), key-hole limpets (a set species belonging to the genus Fissurella ) and the red sea urchin ( Loxechinus albus ). More recently, several kelp species have also moved within the fishermen ’s focus of attention (Gelcich et al., 2010, for a full-review of the TURF system see Moreno & Revenga, 2014).

The history of the Chilean TURF system is associated with the collapse of the Loco fishery. In the late 70s, an increasing international demand for Loco led to a sharp increase in C oncholepas concholepas landings in only a couple of years, a period commonly known in Chile as the “Loco fever” (Meltzoff et al., 2002; San Martin et al., 2010). The extensive harvesting of C. concholepas (~30% of the global gastropod catches reported to FAO, Castilla 2008) led to a rapid stock decline, culminating in a government- imposed closure of the Loco fishery from 1989 to 1992 (Castilla & Gelcich, 2008; reviewed in Castilla & McClanahan, 2007). Simultaneously to the closure, informal TURFs (known as the Natural Shellfish Restocking) were established with the aim of counter-acting the depletion of this resource (Castilla et al., 1994; Castilla & McClanahan, 2007). These experimental areas - managed jointly by marine ecologists and fishermen - were exempted from the general closure of the Loco fishery and within these confined coastal patches, signs of stock recovery were soon evident (Castilla et al., 1998).

Based on this success, the Chilean government adopted the strategy on a broader scale and formally implemented the TURF system in 1991 (Ley General de Pesca y Acuicultura 1991). Since then, fisher organizations can apply for unique spatial harvest rights in sections of the coast adjacent to their area of residence (Castilla & Gelcich, 2008). Before being granted a TURF, an initial ecological baseline study is mandatory and annual (sometimes biannual) follow-up stock assessments focusing on the benthic resources in the respective area have to be conducted. A management plan must be defined and resource-specific extraction quotas are set for each TURF by so-called Management committees, assuming compliance with all the national regulations (Chávez et al., 2010; Parma et al., 2001). Non-compliance with the rules (e.g. harvesting during banned periods or extracting individuals below the minimum legal size) may cause an artisanal fisheries organization to lose the special access rights for its TURFs (Castillo Gonza- lez, 2011; van Leuvan, 2013; General Fisheries Law of Chile §110b & §112).

The two main government agencies involved in managing the TURF system are the Undersecretary of Fisheries SUBPESCA and the National Fish- eries Service SERNAPESCA, with the former overseeing the approval and decreeing of TURFs and the latter being responsible for controlling extractive activities and legal sanctioning (van Leuvan, 2013). In a fishery span- ning 38 degrees of latitude that is associated with thousands of fishermen mainly utilizing small boats and operating from hundreds of dispersed and in many cases isolated landing locations, top-down sanctioning is obviously highly impeded. The effective enforcement of fisheries laws by governmental agencies is thus illusionary (Berkes, 2003; Orensanz & Parma, 2010). Never- theless, since the fishermen themselves have a personal interest in protecting the resources within their management areas, several authors suggest that the TURF-approach should contribute to an increased level of compliance with existing regulations (Castilla & McClanahan, 2007; Gelcich et al., 2008b; Jentoft et al., 1998).

Prior to the TURF implementation, all small-scale fisheries in Chile oper- ated under a system without spatial access restrictions, where anyone could extract resources from (almost) any part of the Chilean coast (Castilla & Defeo, 2001; World Bank Group, 2006). This traditional open-access regime continues to co-exist alongside the TURF system and still constitutes

an important part of benthic artisanal fisheries in Chile. Despite the unre- stricted access for registered fishermen, management instruments like quotas and/or minimum legal sizes generally apply to those areas. With the ad- vancing of the TURF system, open-access areas (OA) are becoming increas- ingly scarce in certain sections of the coast (e.g. central Chile), which increases the fishing pressure on the remaining OAs and brings along important consequences for the livelihoods of artisanal fishers (Gelcich et al., 2009; Gelcich et al., 2005a; Gelcich et al., 2005b).

Although the number of TURFs is increasing around the world, fisheries managed without spatial-access restrictions are the most common situation globally (Costello, 2012; Defeo & Castilla, 2005). These open-access fisheries do not provide any incentives for fishermen to limit their extractions. Quite one the contrary, the absence of responsibility for marine resources and the lack of individual benefit from complying with conservation rules creates an incentive to fish stocks until depletion, a phenomenon known as “the tragedy of the commons” (Hardin, 1968). As individual fishermen receive all the benefit from overharvesting, while sharing the ecological damage with all other resource users, open-access fisheries are highly prone to overfishing (Israel et al., 2016) . This “tragedy of the commons”-mentality supposedly also contributed to driving the Loco fishery to its collapse (see above, Cas- tilla et al., 1994; Gelcich et al., 2005a). As a consequence, the general fishing law of Chile now prohibits the extraction of C. concholepas in open-access areas (Aceves-Bueno et al., 2017; Parma et al., 2001). Recent studies, however, suggest significant levels of illegal fishing in OAs, consequently impeding resource recovery (Andreu-Cazenave et al., 2017; Hauck & Gallardo- Fernández, 2013; Oyanedel et al., 2017).

To put the area-based management of benthic artisanal fisheries of Chile in a nutshell: Open-access (OA) and management areas (MA) form a spatial mosaic of fishing grounds regulated under contrasting strategies, with MAs being heterogeneously distributed along the coast. This socio-ecological setting opens the interesting opportunity to explore and compare the extent of illegal fishing and its drivers in small-scale artisanal fisheries under different management regimes and varying coverage of management areas (or MA “density”).

1.4 Loco fishery and biological knowledge The high monetary value of some key commercial species provides fishermen with a range of motivations and incentives to extract them despite catch restrictions and beyond levels of sustainability (Pauly et al., 2002). Besides prominent and well-studied examples like the illegal fisheries targeting South African abalone and Cuban spiny lobsters (Alzugaray et al., 2018; Raemaekers et al., 2011), Chile’s highest value mollusc species, the Chilean abalone Concholepas concholepas (Bruguière, 1789) also falls within this category (van Leuvan, 2013). This gastropod superficially resembling true abalone of the genus Haliotis (Fig. 1), is a relatively easy to extract resource that is harvested along the entire coast of continental Chile (San Martin et al., 2010) . Although some of the landings are directed towards national mar- kets and are consumed locally, this species is highly valued in the international seafood trade and most of the Loco catches are exported to Asia, generating a yearly net export profit of 11-16 million US$ (Castilla et al., 2016; Export value: 21.000$/ton Loco). Increasing demand in the last decades lead to the fact that today, Loco is the single economically most important shellfish in Chile (Castilla & McClanahan, 2007).

Figure 1 Two individuals of Concholepas concholepas or Loco. The solid white line represents the peristomal length of C. concholepas .

C. concholepas occurs along the coasts of Chile and southern Peru. While the larval phase of C. concholepas is planktonic, juvenile and adult individuals inhabit rocky shores from the low intertidal to the shallow subtidal (down to approx. 50m depth). In these habitats, Loco is a keystone predator and plays an important role in benthic ecosystem functioning (Castilla, 1981; Castilla et al., 1985; Moreno et al., 1986). This species reaches first sexual

maturity at an age of 3 to 4 years, which is achieved at a peristomal length of about 4-6 cm (although individual growth can vary greatly; Gibson et al., 2007; Herrera & Alvial, 1983; Lozada et al., 1976). For reasons of simplicity, the peristomal length of Loco will be referred to as “size” in this manuscript. While the size of maturity on population level (p50; size where 50% of the male or female population is sexually mature) is highly dependent on latitude (see Manríquez et al., 2008), p50 for the study area (regions IV and V of central Chile) is achieved around 9-10 cm for females and 7-9 cm for males (IFOP, 2017). The comparatively slow growth rate and late maturity of C. concholepas make it particularly vulnerable to high fishing pressures and overexploitation (Rabi & Maravi, 1997) .

Besides the complete ban of Loco extraction outside of the TURF system and annual extraction quotas set for each management area (discussed above), there are two more management instruments controlling the harvesting of this species: a region-specific temporal reproductive ban, prohib- iting Loco extraction inside MAs for certain months (e.g. region IV & V: February - June; Decreto Exento Nº409/2003) and a minimum legal size limit. For most of the Chilean coast (from Region III in the north to Region XII in the south), the MLS of C. concholepas is set at a persitomal length of 10cm (Decreto Exento Nº102, 1987), which is achieved in about 3 to 6 years of benthic life (Manríquez et al., 2008). To account for geographic differences in growth rates, this MLS was more recently adapted for the northernmost regions of Chile (region I, II and XV), where Loco can now be legally extracted from 9cm onwards (SUBPESCA 2008; Resolución Exenta N° 1754, 2008).

Although several management regulations controlling this fishery are established and currently in force, the ability of government agencies to con- duct surveillance and efficiently enforce the law is highly impeded. This leads to low compliance with the existing regulations in both open-access and management areas, which has already been documented on local scales (Andreu-Cazenave et al., 2017; Bandin & Quiñones, 2014; Hauck & Gallardo-Fernández, 2013; Ortiz & Levins, 2011; Salas et al., 2007). The high market values of Loco and high demand in international trade make it especially appealing for illegal harvest (Aburto et al., 2013; Gonzalez et al., 2006; Plagányi et al., 2011) and illicit catches from open-access areas are

estimated to be at least as high or even double the volume of legal catches (Andreu-Cazenave et al., 2017; Bandin & Quiñones, 2014; Meltzoff et al., 2002). C. concholepas therefore constitutes an interesting study object for investigating illegal fishing practices and the effectiveness of management regulations in the small-scale benthic fisheries of Chile.

1.5 Aims of this stud y The global aim of this study was to investigate fishermen’s compliance with the minimum legal size (MLS) regulation in the artisanal fishery for C. concholepas in both management areas (MAs) and open-access areas (OAs). The specific objectives of this study were to: (i) determine the fraction of individuals smaller than the MLS in the Loco fishery (ii) assess the influence of management regime (MA vs. OA), spatial distribution of MAs (MA “density”) and local Loco abundance (based on catch-per-unit-effort estimates; CPUE) on the percentage of undersized individuals in the catch. (iii) analyse the potential impact of violations to the MLS for the Loco fishery The hypothesis to be tested were: 1. The median percentage of undersized Loco in the catch is larger in OAs than in MAs. A larger share of individuals below the minimum legal size is expected for open-access fishing grounds due to the occurrence of a situation known as “tragedy of the commons”. There- fore, I also expect a lower median size of Loco in the catch of OAs compared to MAs (a) for the total regime-specific catch and b) when only considering the undersized (<10cm) catch fraction.

2. For OAs located in regions with high density of MAs, the median percentage of undersized individuals in the catch is larger than for OAs located in regions with low density of MAs. This is based on the rationale that the establishment of MAs reduces the availability of open-access fishing grounds, which in turn increases the fishing pressure for these OAs. Therefore, I also expect a smaller median size of Loco in the catch of OAs in regions with high density of MAs compared to OAs in regions with low density of MAs.

3. The fraction of undersized individuals in the catch is negatively correlated with the local abundance of Loco. This is based on the rationale that by extracting undersized individuals, fishermen can compensate low catch rates (arising from low resource availability), as a fisherman’s income is assumed to primarily depend on the number and only secondarily on the size of Loco sold. CPUE is used as a proxy of Loco abundance.

The results of this study will contribute to narrowing down the knowledge gap on illegal fishing practices in the Chilean artisanal benthic fisheries. The study is part of an overarching project entitled “Sustainable Artisanal Fish- eries under Risk: The Ghost of Illegal Fishing” incorporating a variety of illegal fishing practices and extending the focus of attention to several invertebrate species. Having an understanding of levels of compliance and the extent of illegal fishing of Loco will allow stakeholders to make better informed management decisions and incorporate this newly available information in both stock assessments and the definition of annual quotas as well as facilitate prioritization of enforcement measures. These insights will improve conservation efforts and ensure the sustainability of the Chilean Loco fishery and associated social-ecological systems.

2 Materi al & Methods

2.1 Geographical, social and ecological setting Chile is divided into 15 administrative regions. This study was focused on the regions of Coquimbo (region IV) and Valparaiso (region V) located in central Chile (Fig. 2), which concentrate more than 25% of the reported annual Loco landings of Chile (SERNAPESCA, 2015; SERNAPESCA, 2016a). Artisanal fisheries in Chile are generally organized around officially designated landing areas, called fishing coves ( caletas in Spanish) that serve as operational bases for the local artisanal fleet (Castilla & Gelcich, 2008).

High density caleta (HD) Low density caleta (LD)

Figure 2 Map of the study area in central Chile. Study locations are indicated by circles and col- oured according to the relative coverage of management areas (= MA ”density”) in a 40km coastline interval centred at each location, with light green representing low (<55% MA) and red representing high density ( ≥55% MA) locations. Differentiation of LD and HD was based on the information displayed in the left chart, corresponding to the latitudes of the map and indicating management areas (grey) and open-access areas (white) along the coastline.

Currently there are more than 450 caletas in Chile (SERNAPESCA, 2016c). The extractive sector for Loco is of highly heterogenous nature, with some caletas being located in urban areas, offering comparatively greater market opportunities. On the contrary, some caletas are relatively isolated and of quite rural character, equivalenting to small fishing villages with sometimes only a couple of houses situated at a remote section of the coastline. Caletas in different areas of the Chilean coast are thus associated with a range of livelihood characteristics (Castilla et al., 1998; Chávez et al., 2010). Besides seaweed gathering and long-lining for finfish, harvesting shellfish is the main activity in a typical artisanal caleta of central Chile (Gonzalez et al., 2006). Benthic artisanal fishermen manually extract shellfish in the intertidal, through freediving and - most prominently - using ‘hookah’ air compressor diving gears in the subtidal (Fig. 3; Bustamante & Castilla, 1987; Castilla & Defeo, 2001). The latter group is the centre of the territorial use rights for fisheries (=TURF) system in Chile and was the focus of the present study. Hookah diving is usually performed from an open glass-fibre boat generally <10 m in length, equipped with an outboard engine, an air compressor and intermediate pressure tank as well as a diving hose connected with a scuba-regulator. Through the hose (between 50–100 m in length), hookah divers are supplied with pressurized air throughout their diving activities. The fishing crew usually consists of 2-3 fishermen, and besides the diver includes a boatman and/or diving assistant (Fig. 4). Fishing trips are usually performed within a distance of 20km from the caleta and diving usually occurs in multiple immersions not deeper than 25m below the surface, with single immersions generally not exceeding 60 minutes of dive time (Cas- tilla & Defeo, 2001; Castilla & Gelcich, 2008; personal observation).

Figure 3 Artisanal benthic hookah diver collecting Loco

A B

Figure 4 Typical fishing team consisting of A) diver with collection bag, B) assistant with air hose and C) boatman with air compressor.

2.2 Study area, d ata sources and sampling procedure The present study was conducted between October 2017 and May 2018 with sampling sites located in region IV and V along the central Chilean coast. Using a google earth layer provided by SUBPESCA (http://www.subpesca.cl/portal/619/w3-article-79986.html), caletas with operative TURFs that have Loco declared as one of their target resources were identified. Ten of these caletas were then selected, representing rural as well as urban-type fishing coves located in areas with contrasting TURF densities (Fig. 2). The distance between the northernmost caleta Huentelauquen (31.6°S) and the southernmost caleta Algarrobo (33.4°S) was approximately 200 km. For each caleta, the corresponding artisanal fishing associations were identified and the official fishermen representatives approached to present the general idea of the project. In most cases, representatives confirmed their consent to collaborate right away, but in some cases the project had to be presented in front of the general assembly of the fishing organization with all its member present to clarify possible doubts. As the fishermen generally participate in the mandatory annual/biannual stock assessments for their own TURFs, undertaken by biological consultants, most of them were already used to collaborate with scientists.

Upon the organization’s approval and consent to collaborate, individual fishing trips were scheduled depending on favourable oceanic conditions (i.e. a prognostic of <2 m wave height & moderate winds based on modelled environmental predictions from windguru.cz). In about a third of the cases, we could benefit from the fishermen’s regular fishing trips (“non-paid”). When we were requesting a specific fishing trip, the participating fishermen were remunerated for their working day (“paid”). For each fishing trip, at least 200 individuals of C. concholepas were collected by the artisanal fishermen using semi-autonomous diving techniques (hookah), either as part of their normal harvesting routine or during the paid “fishing-simulations”. The minimum sampling size was set based on an additional objective of the overarching project, namely obtaining reliable size frequency distributions to estimate total mortality of the studied species, for which a previous study (Andreu-Cazenave et al., 2017) estimated n = 200 as the minimum sampling size.

For each caleta, at least one open-access area (OA) and one management area (MA) were sampled. In the town of Los Vilos, two distinct caletas exist in close proximity to each other (namely Las Conchas and San Pedro) and sampling trips were conducted with fishermen from both caletas. The sampling procedure was identical for the two management regimes (MA & OA) and organisms were handled directly onboard the fishing boats. While the fishermen proceeded with their harvesting routine, one or two scientists were counting the number of Locos brought up by the divers in each collection bag ( chinguillo in Spanish, see Fig. 4A). Using a Vernier caliper, the peristomal length (= “size”) of each Loco collected was measured to the nearest mm (Fig. 5), as this was believed to be the accuracy limit for on-board size measurements. The size of C. concholepas was measured as the maximum extension of the peristomal opening, equivalent to the distance between the external border of the siphonal canal and the extreme opposite of the shell (Fig. 1), as this is the size relevant for catch inspections by SERNAPESCA (Stotz, 1997; Decreto Exento Nº102, 1987). The size measurements were logged in a water-resistant field book. The GPS coordinates of the specific fishing location, the time divers needed to fill each collection bag as well as the species composition (number of individuals per species) of every chinguillo were recorded. In addition, information about the boat and the fishing team was noted down (names of the fishermen, the boat’s name and unique identifier). All the data was subsequently digitalised in an excel sheet.

Figure 5 Measuring the peristomal length (= size) of a Loco

As explained above, Loco is protected by a spatial extraction ban in open- access areas. Moreover, the sampling campaign partly overlapped with the temporal extraction ban for this species. For the realization of this project,

we were therefore granted a special fishing permit issued by SUBPESCA allowing us to collect Loco only for measuring purposes despite these restrictions. In accordance with the permit, all collected individuals were re- turned to the water after measuring in OAs, during the reproductive ban and during paid fishing simulations.

2.3 TURF density and CPUE I assume that fishermen concentrate their fishing activities in a range of approx. 20km to the north and to the south of their respective caleta and based on this, I calculated the TURF “density” (= relative MA coverage) for each caleta. Using a google earth layer provided by SUBPESCA (http://www.subpesca.cl/portal/619/w3-article-79986.html), the entire coastline of Chile between 31.5°S and 33.5°S was designated as either MA or OA (see Fig. 2). Caletas were classified as high density (HD) if more than 55% of the coastline within a 40km interval centred at the location of the caleta was covered by management areas, and vice versa for low density caletas (LD). For calculation of the catch-per-unit-effort (CPUE), exclusively collection bags with a Loco abundance ≥70% were considered, as I assumed that divers - although extracting multiple species simultaneously - were primarily targeting Loco in these instances. For the CPUE calculation, the number of Locos in a collection bag (= chinguillo) was divided by the time (in minutes) a diver needed to fill each respective chinguillo.

2.4 Data analysis All data treatment and statistical analysis were carried out using the statistical software R v 3.4.1 (R Core Team, 2017). Plots were prepared using the R-package “ggplot2”. An overall size-frequency distribution as well as spatially explicit histograms for each individual sampling location were prepared, allowing visual inspection for extraordinary attributes of the size- frequency data (i.e. in terms of shape, skew, kurtosis or outliers).

Treatment of o utliers

Size measurements were categorized in 0.5cm size bins (i.e. 0.0cm to 0.5cm, 0.5cm to 1cm, etc.; left-closed and right-open). Size classes comprising less than two individuals occurred at the lower extreme of the overall size-fre-

quency distribution and corresponded to the isolated occurrence of excep- tionally small individuals in the dataset. I assumed that those individuals were located on top of bigger individuals at the time of extraction and - based on catch statistics provided by SUBPESCA (Stotz, 1997; Stotz et al., 2010) - I infer that those individuals do not represent sizes that are generally commercialized. The inclusion of those outliers would have interfered with the applied statistics and they were thus excluded from further analysis. This approach had marginal influence on the dataset. Only two of 7205 size measurements (3.4 and 5.3cm, respectively) were removed from the dataset.

The influence of management regime on compliance (Hypothesis 1)

In order to test hypothesis 1 and investigate the influence of the factor management regime on both the catch structure as well as levels of compliance, I performed the following steps. First, the location-specific size data were visualized using boxplots. Then, relative size frequency histograms were prepared for the size data grouped according to management regime, provid- ing a general picture of the regime-specific catch structure. The size data grouped for management (MA) and open-access (OA) areas was visually inspected using Q-Q plots. While data from open-access areas appeared to be roughly following a normal distribution, this was not the case for management areas (exhibiting a left skew; i.e. lower values in the lower extreme than one would expect if samples were to come from a normal distribution). In order to test for differences in median size of Loco between the two management regimes, the non-parametric two-tailed Wilcoxon rank sum test (=Mann-Whitney U test) was applied. The level of illegal fishing resulting from violations to the minimum legal size (MLS) regulation was quantified by calculating the percentage of landed individuals below MLS (<10cm) for each sampling location as well as for the data grouped within MA and OA. In order to test for differences in percentage of undersized Loco in the catch between the two management regimes, the non-parametric two-tailed Wil- coxon rank sum test (=Mann-Whitney U test) was applied, after Q-Q plots indicated non-normal data. A principal component analysis based on the size-frequency distributions of each sampling location (0.5cm size classes as variables; see above) was conducted and the result plotted to visualize regime-specific differences in the catch structure. Permutational multivariate

analysis of variance (PERMANOVA: adonis using Euclidean distances; variables: 0.5cm size classes) was then applied to test for significant effects of two factors: management regime (2 levels: MA, OA) and caleta (10 levels) on the site-specific size frequency distributions. As a prerequisite for the validity of significance in the PERMANOVA results, a test for homogeneity of dispersion among the tested groups was performed (PERMDISP: be- tadisper with permutest). Multivariate analyses and PCA analysis were performed in R using the packages “vegan” and “FactoMineR”. In order to characterize the undersized catches and visually display the distance to the minimum legal size, the median and interquartile range (IQR) of the undersized catch fraction (only including Loco <10cm) was plotted for each sampling location with at least one undersized individual in the catch, together with the 10cm legal size limit. Next, the undersized catch was grouped within regimes and the median was calculated and plotted. To test for differences in median sizes of undersized Loco between OAs and MAs, the non- parametric two-tailed Wilcoxon rank sum test (=Mann-Whitney U test) was applied, after a Q-Q plot indicated non-normal data.

The influence of TURF density on compliance (Hypothesis 2)

Differences in percentage of undersized catch for open-access areas corresponding to high density (HD) and low density (LD) caletas were visualized using boxplots. In order to test hypothesis 2 (difference in median percentage of undersized individuals between high-density and low-density OAs), the non-parametric two-tailed Wilcoxon rank sum test (=Mann-Whitney U test) was applied, after the consultation of Q-Q plots indicated that the assump- tion of normal distribution was not met. Furthermore, a two-tailed Wilcoxon rank sum test (=Mann-Whitney U test) was performed to test for differences in the median size of individuals between high density and low density OAs, after Q-Q plots indicated non-normal data.

Can catch rates help predict ing levels o f compliance? (Hypothesis 3)

To investigate a possible interaction between local Loco abundance and levels of compliance, the CPUE [Loco/min] for each collection bag contain- ing more than 70% individuals of Loco (see explanation above) was plotted against the percentage of undersized catch of each respective collection bag.

The difference in the mean CPUE between open-access and management areas was tested for significance using the non-parametric two-tailed Wil- coxon rank sum test (=Mann-Whitney U test), after consultation of Q-Q plots indicated non-normal data. To test hypothesis 3, a linear model was fitted to the data of each management regime and checked for significance.

Beyond hypothesis: Exploring sustainability & optimization of the Loco fishery

Complementary catch assessment was performed using a set of size-based indicators (i.e. sex-specific size at maturity on a population level (p50), critical length and central tendency measures of the catch). To allow for a visual interpretation of the sustainability of fishing practices of the Loco fishery in the study region, the mean size and standard deviation of the catch was plotted for each sampling location together with the site-specific critical lengths (size at which the maximum biomass yield from a cohort can be obtained; available only for management areas), the sex-specific p50 values (size at which 50% of the population is sexually mature; only available for caleta Quintay but assumed to be constant over the whole study region), and the minimum legal size. The critical length values for the management areas of the study region as well as the sex-specific p50 values for caleta Quintay were taken from a recent report, estimating biological parameters as well as growth parameters for the Loco in its most important regions of extraction, published by the Chilean Fisheries Development Institute (IFOP, 2017). The average critical length was calculated as the arithmetic mean of all critical lengths of the study locations. The regime specific fraction of individuals a) larger in size than the male and female p50 values (~ L mat ) and b) within the “optimal size range” of mean critical length ± 10% (Lopt ) was calculated and plotted in form of a bar chart to allow for comparison with the sustainability indicators proposed by Froese (2004). A third indicator, based on the percentage of mega-spawners in the catch, was not considered for this study, as I was lacking information on the influence of individual size on the reproductive output of Loco.

3 Results

A total of 7203 individuals of C. concholepas were measured during 29 fishing trips, of which 16 were performed within MAs and 13 in OAs. Divers collected 4170 individuals inside MAs, whereas 3033 Loco originated from open-access fishing grounds (Table 1). For some caletas, more than one MA was sampled, owing to the high number of areas operating under this regime in certain coastal sections (high density locations). For two of the caletas (Papudo and Quintay), more than one open-access site was sampled (Table 1), as fishermen were willing to take us to different fishing grounds. Each of the sampling locations was treated separately in the analysis.

Table 1 Sampling areas (ordered from north to south) with corresponding category of MA density (HD=high density, LD=low density; cf. explanation in Fig. 2), indicating the number of sampling sites per regime. Number of sampled individuals (ind.) is reported in parentheses.

Caleta MA density # of MA (ind.) # of OA (ind.) Huentelauquen LD 1 (289) 1 (218) Chigualoco HD 2 (548) 1 (240) Los Vilos - Pedro HD 2 (631) 1 (227) Los Vilos - Conchas HD 2 (571) 1 (213) Pichidangui HD 1 (290) 1 (250) Los Molles HD 2 (456) 1 (200) Pichicuy LD 1 (255) 1 (231) Papudo LD 1 (238) 2 (521) Quintay LD 1 (250) 3 (719) Algarrobo HD 3 (643) 1 (215) Total 16 (4170 ) 13 (3033)

3.1 The influence of management regime on compliance Sample sizes for each individual sampling location ranged between 200 and 340 Locos (Fig. 6). The number of individuals measured during each fishing trip varied due to the fisheries-dependent nature of the study. The size of the measured specimen of C. concholepas ranged from 5.8 to 14.0 cm. Different approaches to evaluate the influence of management regime on compliance and test hypothesis 1 are reported.

Figure 6 Size data for each sampling location displayed as 23boxplots for management areas (MA; grey boxes) and open- access areas (OA; white boxes) with median (solid line), mean (triangle), Q1 and Q3 (box), minimum within Q1-1.5*IQR and maximum within Q3+1.5*IQR (whiskers) and outliers beyond this range (circles). The horizontal red line indicates the minimum legal size (MLS) for Loco. Sample size is indicated for each sampling location.

The mean size of the catch ranged between 8.7 and 11.9 cm, with the largest mean size observed in one of the MAs of Los Molles (MA Playa Los Molles) and the lowest in an OA area of Papudo (OA Maitencillo, Fig. 6). For 14 out of the 16 sampled management areas, the inter-quartile-range - representing the middle 50% of the catch - exclusively comprises sizes above the minimum legal size of 10 cm (MLS). Notably, this was the case for only one of the 13 open-access locations (Fig. 6). In fact, statistical analysis showed that significantly larger sized individuals of C. concholepas were extracted in management areas (median=11.0, IQR=1.2) compared to open- access areas (median=10.1, IQR= 1.7) (Wilcoxon rank sum test W= 9150510, p < 0.001; Fig. 7). The modal size class for MAs was 11-11.5 cm, whereas for OAs it was two size classes smaller (10-10.5 cm), indicating a comparatively higher level of reliance on smaller individuals under the open- access regime (cf. Fig. 7). For OAs, 47% (16.8 - 80.8%) of the extracted individuals were smaller in size than the MLS (Fig. 7, Table 2). For MAs, undersized individuals represented 14% (0 - 66.2%) of the catch (Fig. 7, Table 2). The median percentage of individuals below MLS (=undersized

undersized n = 4170 catch = 14%

undersized n = 3033 catch = 47%

Figure 7 Regime-specific relative size frequency distribution of C. concholepas sampled during this study (0.5 cm size bins) based on 4170 Loco from management areas (MA) and 3033 Loco from open-access areas (OA). The red dashed vertical line represents the minimum legal size for Loco in the study region (10cm).

catch fraction) was significantly smaller for management areas compared to open-access areas (Wilcoxon rank sum test, W=15, p < 0.001). Only in two caletas, the percentage of undersized catch was larger in the management areas than in the corresponding open-access areas (MA Pichidangui Sector B and MA Algarrobo Sector B; Table 2).

Table 2 Site-specific indicators of size of individuals in the catch of different caletas, for management areas (MA) and open-access areas (OA). Mean, standard deviation (SD) and size range are reported in cm and the fraction of catch below the minimum legal size (MLS) is given as percentage. Sites are further classified according to MA density.

The contrast in size-frequency distributions between the catches from management areas (characterized by relatively larger sized Loco) and from open-access areas (dominated by smaller sized individuals) is highlighted by the PCA plot (Fig. 8A & 8B). It shows a cluster of samples from OAs in the top right (Los Vilos - San Pedro, Los Vilos - Las Conchas and Papudo), predominantly exhibiting smaller sized individuals (8A). The MAs of Huentelauquen, Chigualoco, Los Vilos - Las Conchas and Los Molles are dominated by larger sized individuals and cluster together in the top left (Fig. 8A). A third cluster in the lower centre of the PCA plot, made up of both MAs as well as OAs, is characterized by intermediate sized individuals (Fig. 8A).

A) B)

Figure 8 A) Principal component analysis (PCA) based on size-frequency distributions of each sampling location with symbols corresponding to the respective caleta and colour indicating management area (MA) in red and open-access areas (OA) in blue. B) Corresponding variables factor map, showing direction and magnitude of the effect of each size class.

Significant differences in size-frequency distributions were found between the two management regimes (Permanova, F=10.66, p=0.001, Table 3), but not among caletas (Permanova, F=1.29, p=0.206, Table 3). No significant difference in the dispersion, using regime or caleta as factors, was found, indicating that size-frequency data is homoscedastic (PERMDISP, # of Per- mutations = 999, regime: F= 0.46, p=0.490, cf. Fig 9; caleta: F=0.49, p=0.873). Dispersion is thus not responsible for the significant outcome of the Permanova. The sampling design of this study was aimed at achieving a broad geographical coverage of sampling sites, which limited the number of replicates at each site and thus compromised the ability to test for interactions between the factors regime and site.

Table 3 PERMANOVA results based on Euclidean distances using size-frequency data

Main Effects D.f. Mean Sq F value R² P value Management regime 1 0. 78 441 10 .6648 0.2 6488 0.001 *** Caleta 9 0.09478 1.2887 0.28806 0.206 Residuals 18 0.07355 0.44706 Total 28 1.00000

Figure 9 Principle coordinate analysis (PCoA) based on Euclid- ean distances using regime as factor (black: MA = management area; red: OA = open -access area).

Considering only the catch fraction below 10cm, the median size of undersized individuals in the catch pooled within management regime was calculated, in order to numerically quantify the distance to the minimum legal size. The median was chosen for comparison due to the negative skew of the data (cf. fraction to left of the dashed red line in Fig. 10). In management areas (median = 9.4, IQR=1.0), the upper 50% of the undersized Locos exhibit sizes within 0.6cm from the MLS, whereas in open access areas (median = 9.1, IQR=1.1) the upper 50% of the catch falls within 0.9cm from the MLS (Fig. 10). Undersized individuals were significantly larger in management areas compared to open-access areas (Wilcoxon rank sum test, W=487673.5, p-value < 0.001).

Figure 10 Median (dots) and IQR (horizontal line) for the undersized fraction (<10cm) in the catch for management areas (MA) and open access areas (OA) for each sampling location with at least one individual below the minimum legal size. The percentage (rounded to integers) indicates the contribution of undersized individuals to the catch of each respective location. The vertical lines represent the median size for individuals <10cm grouped according to management regime (MA=solid line; OA=dashed line).

3.2 The influence of TURF density on compliance This analysis is based on the rationale that the establishment of management areas reduces the availability of open-access fishing grounds, which in turn increases the fishing pressure for these OAs. The percentage of individuals below MLS in the catch for high density OAs ranged from to 26.5% to 80.8% and from 16.8% to 80.6% for low density OAs (Table 2). Despite a tendency towards higher percentages in high density OAs, no significant difference in the median percentage of undersized individuals in the catch between open-access areas from high density (HD) (median=42.2, IQR=36.6) and low density (LD) locations (median=33.5, IQR=24.5) was detected (Wilcoxon rank sum test, W=24.5, p=0.668; Fig. 11). No significant difference in the median Loco size between high density OAs (median=10.2, IQR=1.1) and low density OAs (median=10.4, IQR=0.7) was found (Wil- coxon rank sum test, W=18.5, p=0.774).

Figure 11 The boxplot shows the median (solid line) and mean (triangle) percentages of undersized catch for high (HD) and low density (LD) open access areas, with Q1 and Q3 (box) as well as the minimum within Q1-1.5*IQR and maximum within Q3+1.5*IQR (whiskers). The mean percentage and standard deviation (SD) is indicated.

3.3 Can catch rate s help predict ing levels of compliance? I hypothesized a negative correlation between the fraction of undersized individuals in the catch and local Loco abundance (approximated by CPUE). The underlying rationale is that by extracting undersized individuals, fishermen can compensate low catch rates (arising from low resource availability). In fact, I found that the average CPUE observed for management areas (mean=6.1, SD=4.4) was significantly larger than the average CPUE in open access areas (mean=4.0, SD=3.0) (Wilcoxon rank sum test, W=442, p=0.016). A linear regression analysis was performed to analyse the relationship between the percentage of undersized individuals in the catch and the catch per unit effort (CPUE) per collection bag. For management areas, a significant linear regression with a negative slope (F(1,40)=5.369, p=0.0257, R ²=0.118) between CPUE and percentage of undersized catch was found (Fig. 12). The predicted percentage below MLS for a collection bag was equal to 19.5 - 0.891*CPUE % (CPUE reported as Loco/minute). The percentage of undersized catch thus decreased roughly 1% as CPUE increased by one unit. For open access areas, CPUE showed no significant relationship with the percentage of undersized catch (F(1,28)=0.0035, p=0.9533; R²= 0.0001).

30 Figure 12 For management areas (MA) and open-access areas (OA), catch-per-unit-effort (CPUE) as

[Loco/min] is plotted against the percentage of undersized catch. Regime-specific linear regressions (blue lines) and 95% confidence intervals (dark grey shadow) are shown.

3.4 Beyond hypothesis: Exp loring the sustainability and optimization of the Loco fishery

Figure 13 Mean individual size and standard deviation plotted for each sampling location and sampling locations pooled within regime (Total), with grey circles indicating management areas (MA) and white circles indicating open-access areas (OA). The blue and green line indicate the p50 for the male and female population, respectively and the minimu m legal size (MLS) is represented by the red line. The small black dots indicate the site-specific critical length (IFOP, 2017) and the black line indicates the critical length averaged over the site-specific values.

The mean Loco size and standard deviation range, representative for the range of variation of the size measurements, for each sampling location were plotted together with the p50 (size at which 50% of a population is sexually mature) for males (8.4cm) and females (9.3cm), the MLS (10cm) as well as the site-specific critical length (Fig. 13). The p50 (available only for Quintay;

IFOP, 2017; assumed to be constant over the whole coastal section of the study region) for both male and female population were compared with the mean ± standard deviation range. For all but two of the MAs (87.5% of the MAs), the mean ± standard deviation range falls above the p50 value for the female population (only Pichidangui and Algarrobo Sector B, which showed the highest percentages of individuals below MLS among MAs, extend below) and all are above the p50 for males. For OAs on the other hand, the mean size ± standard deviation range of 7 out of 13 (54% of the OAs) locations extend below the p50 for females, whereas three (23% of the OAs) even extend below the p50 for males. For management areas, the spatially explicit catch data was compared with the critical length (the size at which a cohort reaches its maximum biomass; provided by IFOP, 2017). Only for two of the management areas, Los Molles and Algarrobo Sector B, the site-specific range provided by mean Loco size ± standard deviation overlaps with the critical value. However, these locations also exhibit critical lengths values that are among the lowest for the study sites. When compared with the critical length averaged over all the study sites (12.8cm; black line), no range of mean size ± standard deviation reaches this value.

The proportion of mature Loco in the catch (approximated by applying the sex-specific p50 values) was calculated for each sampling location. The proportion of individuals above the p50 for males ranged between 85.9% and 100%, with an average of 97.9% (SD=4.3) for management areas, and 48.9% to 100%, with a mean of 89.3% (SD=14.9) for open-access areas. Considering the p50 for females, the proportion of individuals above this value varied between 58.3% and 100% (mean=93.6, SD=10.9) for MAs, and 27.6% and 98.8% (mean=72.3, SD=23.2) for OAs. A significantly larger proportion of mature individuals (above either p50 value) was extracted by fishermen in management areas (mean=93.6, SD=10.9) compared to open-access areas (mean=72.3, SD=23.2) (Wilcoxon rank sum test, W=28.5, p <0.001; Fig. 14). The percentage of the catch within the size interval of ±10% of the average critical length (=”optimal length range ”) ranged between 1.0% and 65.2% (mean=26.7, SD=19.2) for MAs. For open-access areas, the percentage within the optimal length range varied between 0.4% and 25.7% (mean=11.0, SD=8.6). A significantly larger proportion of individuals within the optimal length range was extracted by fishermen in management areas compared to open-access areas (Wilcoxon rank sum test, W=50, p=0.009).

The majority of Loco caught by fishermen was, however, not within the critical length ±10% (Fig. 14).

Figure 14 Bar chart displaying the average percentage of individuals larger than the p50 for males and females as well as within ±10% of the critical length for the catch grouped as management areas (MA) and open-access areas (OA). The horizontal dashed line indicates the “target” value of 100% (as proposed by Froese, 2004).

4 Discussion

4.1 Management practices affecting compliance The present study revealed that undersized individuals contribute a considerable share to the catches of C. concholepas in the studied locations. Therefore, a substantial degree of non-compliance with the minimum legal size regulation in central Chile can be inferred. The pattern of fishermen ’s compliance, however, was not homogenous and results differed significantly among management regimes. It is remarkable that undersized individuals constituted approximately half of the catch (47%) in open-access areas (OAs). In contrast, higher levels of compliance were observed in management areas (MAs), where only 14% of the catch corresponded to individuals below the MLS. The low levels of compliance with the MLS in OAs seem to occur because of fishermen thinking: ““ If I don ’t take it now, then the next diver will do so! ” (the rationale behind Hardin ’s “Tragedy of the Commons ”; 1986). Fishermen in MAs seem to be complying rather well with the minimum size limit, when compared with MLS-related non-compliance rates of 23% and 33% in the red abalone ( Haliotis rufescens ) fishery in California (Blank & Gavin, 2009) and the Caribbean spiny lobster (Panulirus argus ) fishery in Turks and Caicos Islands (Tewfik & Béné, 2004), respectively. However, the situation in the open-access fishery appears alarming, considering the extent of violation with the minimum size regulation. Yet, this is only on dimension of the illegal fishery for Loco in Chile. Fishermen extracting undersized Loco from open-access fishing grounds (Andreu-Cazenave et al., 2017) are in fact violating two fishing regulations: the minimum legal size regulation and the spatial extraction ban. In Chile, open-access fishing grounds are (contrary to what the name implies) supposed to be fully closed for extraction of C. concholepas. Nevertheless, recent estimates suggest that the contribution of illegal catches of Loco in OAs equals the reported landings legally extracted from management areas (Andreu-Cazenave et al., 2017; Bandin & Quiñones, 2014; Gonzalez et al., 2006). Adopting this (rather conservative) estimate and incorporating the presented information on compliance with the MLS for both management regimes, I estimated an almost one-third (30.5%) contribution of undersized individuals to the total Loco landings of Chile, corresponding to roughly 5 million individuals or 1500 - 2000 metric tons (weight with shell) of undersized Loco annually (annual estimates based on official landing statistics: SERNAPESCA, 2016a; and

average weight of landed Loco: https://www.ifop.cl/indicadores_ben- tonicos).

Even considering the disappointing situation of illegal fishing for Loco in central Chile, there is still an opportunity for a “seascape of hope ” (Gallardo Fernández, 2008). One the one hand, the mean size of landed Loco originating from open-access areas is still within the same range as ~20 years ago (10.2 - 10.6 cm for OAs Algarrobo and Las Cruces; Castilla et al., 1998). Therefore, I can assume that - at least - there has not been a gradual dete- rioration of the Loco stock in OAs within this timeframe (potentially attributed to the extremely high productivity of the coastal ecosystems in central Chile; Thiel et al., 2007). On the other hand, I present clear indica- tions of the importance of the TURF system established nearly three decades ago in terms of management and compliance, as in almost all sampled caletas, the percentage of compliance with the MLS was higher in MAs than in their respective OAs. Furthermore, individuals caught within management areas were on average bigger in size (cf. Gonzalez et al., 2006) and the median size of undersized individuals is significantly closer to the MLS in management areas compared to open-access areas. The presented size-based distinction of the undersized catch provides interesting insights, as a Loco just below the MLS may be officially illegal, but - ecologically speaking - there may not be much difference in terms of reproductive potential between a Loco slightly above or below the size limit (bearing in mind the large variations in individual growth rate, Manr íquez et al., 2008). Thus, considering both the undersized catch fraction as well as the legal-sized catch, management areas seem to be performing better than open-access areas in the context of sustainable harvesting practices. This finding emphasizes the importance of the co-management approach in benthic artisanal fisheries in Chile.

Compliance varied considerably among individual MAs (and among OAs, respectively). These differences may be explained by regional socio-economic conditions like e.g. internal enforcement and level of organization inside fishing associations, numbers of tourists and/or market opportunities. Two pop- ular tourist destinations, Los Vilos and Papudo, exhibited the smallest average sizes of Loco in their open-access catches. Moreover, in these sites, the contribution of undersized individuals to the catch even exceeded 80%, indicating intense pressure on the Loco stock. As shown by Oyanedel et al.

(2017), the principal buyers for illegally extracted Loco are restaurants, ho- tels and most importantly the general public. Manifold market opportunities and high demand for Loco in these two touristic locations may thus have led to the extreme levels of non-compliance rates observed (cf. Winstanley, 1992). The touristic town Los Molles, however, did not show particularly high levels of non-compliance. The mean and median size of Loco in the open-access catches were above the MLS and the management area Playa Los Molles even exhibited the largest mean size of Loco in this entire study, without a single individual below the legal size limit. The difference in compliance between sites, even under similar market and tourism opportunities might be related to the level of organization of the fishermen. Recent studies showed that fishermen’s behaviour is significantly correlated with the characteristics of the fishing association they belong to (based on a “co-management performance index ” incorporating information about internal enforcement, general compliance with association ’s norm as well as cooperation among the members of an association; Gelcich et al., 2013). In a fishing- game setting, fishermen from “high-performing ” caletas showed higher levels of cooperation and refrained from overfishing, while fishermen from “low- performing caletas ” acted in a more selfish manner (Gelcich et al., 2013). In fact, fishermen belonging to the fishing organization of Los Molles are noto- rious for their remarkable compliance with fishing regulations and for having a close relationship with the controlling authority SERNAPESCA (personal observation). An additional influence of resource dependency may also provide a plausible explanation for the observed results (cf. Gelcich et al., 2007), as fishermen from Los Molles are extensively extracting algae, besides diving for benthic invertebrates (personal observation).

Nevertheless, I want to emphasize that a variety of factors and their potential interactions may contribute to the observed results, starting at the level of local productivity, incorporating individual fishermen ’s attitudes as well as characteristics of fishing organizations, reaching up to the economic condition at the regional level (cf. Gallardo Fernández & Friman, 2011). The limited availability of socio-ecological data for the study locations impedes an in-depth understanding of the underlying processes. An array of socio- ecologic descriptors will therefore be considered at the next step of the overarching project, with an expanded data acquisition approach that additionally integrates social-science techniques like questionnaires.

4.2 The influence of effort displacement and abundance In the light of the present work and other recent studies as well as from a conservation perspective, it seems beneficial that management areas are in- creasingly replacing the remaining open-access areas along the Chilean coast. An increase in MA coverage, however, may have ancillary consequences. A decrease in area of open-access fishing grounds, may imply a displacement of fishing effort that in turn results in an augmentation of fishing effort per unit area, as fishermen - besides harvesting Loco inside “their ” MAs - commonly continue to dive for shellfish in the remaining OAs (Gelcich et al., 2005b). Based on this rationale, I hypothesized that the regional density of management areas has an influence on compliance rates in open-access areas. My analysis, however, did not provide support for this hypothesis. Still, a trend - although not significant - towards higher percentages of undersized individuals in the catch in high density open-access areas seems to occur. A larger study, that incorporates a more extensive sampling of OAs, and a wider contrast of management area densities, might reveal a clearer picture.

A possible effect of high fishing pressure may nevertheless be observable at individual sites: Los Vilos, an area where my analysis revealed more than 2/3 management area coverage within a 40km coastline interval centred at the caleta (ranked 2 nd in terms of MA density) showed non-compliance rates around 80% in its open-access sites Punta Chungo and Las Mirgas. In the town of Los Vilos, four different fishing organizations with their corresponding management areas are located in a geographically confined place. Within this seascape, Punta Chungo and Las Mirgas seem to be among the only places still available for the open-access fishery, suggesting potentially high fishing pressure on benthic resources at these locations. In addition to the low levels of compliance, the observed CPUE in these locations were also comparatively low (<3 Loco/min), additionally suggesting low levels of resource abundance. An individual fisherman would most probably prefer a larger and more valuable Loco (Castilla et al., 1998; Oyanedel et al., 2017) over an undersized individual. The high non-compliance rates observed may thus be an effect of local resource depletion (potentially influenced by the socio-economic factors mentioned above).

At least for management areas, resource abundance (approximated by CPUE) correlated significantly with the observed levels of non-compliance.

Lower catch rates led to substantially higher fractions of undersized catch, and resource abundance thus seems to be a reasonable descriptor for illegality related to size limits. We may not forget, however, that local depletion is a common long-term consequence of non-compliance with existing regulations (e.g. Hauck, 2009), culminating in a vicious circle of overfishing. The fact that no clear relation between CPUE and non-compliance rates was found for open-access areas, could potentially be related with a relatively larger influence of individual fishermen’s attitudes in a less-regulated management regime (cf. Gelcich et al., 2013), reflected by higher variability in the observed non-compliance rates. The comparatively lower mean CPUE in OA (being approximately two units smaller than in MA; and emphasized by a 30% lower maximum CPUE) may indicate a general depletion of Loco in open-access fishing grounds, confirming the situation observed in several other studies (Gelcich et al., 2012; Gelcich et al., 2008a). It could, however, also reflect the fact that management areas were preferentially claimed by fishermen in naturally productive areas and the remaining (less productive) fishing grounds were simply left over as OAs (as suggested by Gonzalez et al., 2006). In any case, differences in levels of resource abundance may stand at the root of the observed differences in compliance between the two management regimes. Directly assessed (and not only inferred) size-specific abundance data for Loco within MAs as well as OAs might allow deeper insights into this question. For management areas, this data is - in principle - already being assessed within the framework of the annual stock assessments, but has, however, proven rather difficult to obtain. The situation of the Loco stock in OAs, on the contrary, is notoriously under-researched.

4.3 Sustainability & optimization within the Loco fishery To answer the initial question whether the minimum legal size regulation is working for the Loco fishery, one must go beyond the understanding of compliance and enter into a discussion of the adequacy of a 10cm minimum legal size limit. A simple way of approaching this question, may be at hand by applying Froese ’s “indicators to deal with overfishing ” (Froese, 2004). To assess the sustainability of fisheries, he proposes to look for the percentage of mature individuals in the catch (target: 100%) as well as the percentage of specimens within the optimal (=critical) length range (target: 100%) (as demonstrated by e.g. Babcock et al., 2013; Erisman et al., 2014).

To restore and maintain healthy spawning stocks, an adequate number of individuals of a population should be allowed to spawn at least once before being extracted (Myers & Mertz, 1998). When applying Froese ’s maturity indicator to the catch data of this study, I observe that almost all of the individuals originating from management areas (>90%) and the majority of individuals from open-access areas (>70%) are larger in size than both p50 values (sex-specific sizes at which 50% of the population is sexually mature). The goal of permitting individuals to reproduce at least once thus seems to be almost fully achieved in management areas, but less so in OAs. With approximately one-quarter of landed individuals in open access areas potentially being excluded from reproduction, recruitment overfishing seems to become a relevant factor.

Nevertheless, one has to be cautious as the p50 values utilised in this study were available only for Quintay and might not be valid over the whole range of the study region. I think, however, that adopting the p50 values of Quin- tay for the whole study region is appropriate as the study sites are located within the same biogeographic region, characterized by coastal upwelling (Thiel et al., 2007; Wieters, 2005). Nevertheless, exploring variations in size- at-maturity of Loco along the latitudinal gradient of Chile ’s coastline may prove insightful in this regard. I therefore propose to include simple approaches to estimate size-at-maturity in the protocol for the annual stock- assessments for MAs conducted by biological consultants, as a standardized method for these assessments is currently being established. One should keep in mind, however, that reaching maturity does not necessarily coincide with getting the chance to spawn, as reproduction of Loco is limited to a certain time of the year. This underlines the importance of the established 5-month reproductive ban in this fishery. Moreover, Froese ’s reproduction indicator calls for an estimation of the percentage of mature individuals in the catch. With the approximation of applying the p50, the share of immature individuals landed is underestimated.

Under both management regimes, the fraction of individuals within the optimal size range (= critical length ±10%; MA: 27% and OA: 11%) is far away from the 100% target. This provides strong evidence that the whole Loco fishery in the study region is impacted by growth overfishing, implying that the local biomass potential of this fishery is far from being optimally

utilized. Assuming that the critical length of management areas can - given the geographical proximity - be adopted for the corresponding open-access areas, the situation looks even more daunting. But, even well below the 100% target of optimally sized individuals in the catch, stocks can theoreti- cally be sustainably fished, as pointed out by Cope & Punt (2009). Never- theless, even the national fisheries service of Chile (SERNAPESCA) states that a minimum legal size should never be inferior to the critical length (http://www.sernapesca.cl/index.php?option=com_cotent&view=article& id=205&Itemid=365), which is obviously the case in the Loco fishery of central Chile.

Summarising this simple sustainability analysis, it appears that the current approach to harvest Loco is wasting the biomass potential of this fishery, while adequate levels of reproduction (at least in management areas) seem to be guaranteed. A certain degree of recruitment overfishing is evident in open-access areas, possibly impeding resource recovery under this management regime, but most likely not entailing the risk of collapse.

A way out of this dilemma

Bringing together economic incentives and resource conservation has been identified as a critical component for successful rebuilding efforts for fisheries (Beddington et al., 2007) and may potentially prove beneficial in the case of the Loco. Under the current situation, fishermen are not attaining the maximum economic return they could expect from the Loco fishery. In a potentially highly size selective fishery (collection by hand!), it is indeed possible to work in the small window of optimal size. Considering the existing evidence that compliance within management areas is feasible, the present study suggests the possibility to complement the already existing management measures on a local scale by postponing extraction of individuals until the optimal length window. Therefore, convincing fishermen that letting Loco attain the critical size would augment their monetary incomes (as bigger individuals obtain higher prices; Oyanedel et al., 2017, personal observation) seems like a promising opportunity to increase yields in the Loco fishery. As - for once - conservation and economic considerations call for similar fishing behaviour, voluntary self-imposed length limits for interested

fishing organizations may constitute a fruitful model for the long-term con- duct of management areas. This process may be facilitated by biological consultants acting as barefoot ecologists (Prince, 2003). In any case, a pre- ceding in-depth (economic) analysis of possible scenarios of landings biomass trajectories and impacts on catch rates over several years may be useful (as demonstrated in Mayfield & Ward, 2002 and Tschernij et al., 2004).

The calculation and application of Froese ’s indicators, easily understand- able and tangible by all stakeholders (from fisherman to politician), to the Loco fishery, has proven highly insightful. Propagating this approach may potentially increase the interest of stakeholders to engage in fisheries management and get them on the train to sustainable resource management (“bringing common sense to fisheries management ”; Froese, 2004).

4.4 Management implications The clandestine “open-access” fishery for Loco is a reality (Oyanedel et al., 2017). We now also know that, in central Chile, this fishery doesn’t respect size limits (a situation that may well extend along the whole Chilean coastline). The comparatively higher compliance with the MLS in management areas, seems to confirm the paradigm that conservation measures are effective when perceived as beneficial by resource users (Meltzoff et al., 2002) and - given the right incentives - are readily adopted by fishermen (Parma et al., 2001; Parma et al., 2006). The presented findings could thus provide a basis for adapted management practices for artisanal fisheries facing illegal fishing activities around the world.

With global demand for seafood - especially from small-scale fisheries - on the rise (Mora et al., 2009), the pressure on marine ecosystems is likely to increase while the demand for marine molluscs will presumably remain high. If adherence with sustainable management practices is ensured, a bright future for the Chilean Loco fishery appears well within reach. Nonetheless, this picture might be darkened by illegal fishing activities. The spatial extraction ban for open-access areas was only recently prolonged for another 5-years, which indicates that - even after an 18-year official fishing closure - resource recovery in OAs is still insufficient. This situation can in fact only be explained by extremely high levels of illegal extraction. The question remains, whether to proceed with this sequence of fishing closures or to lift

off “the coat of illegality” from the clandestine open-access fishery and pave the way for proper fisheries management. Despite the comparatively better compliance with the MLS in MAs, poaching within management areas has been identified as a common activity among fishermen in central Chile (Oya- nedel et al., 2017), adding yet another dimension of illegality to the Loco fishery.

It is known that management areas and open-access areas are connected by the large-scale biological process of larval dispersal (Gonzalez et al., 2006; Orensanz et al., 2005). This fact calls for integrated management actions in a de-facto dual management system. Despite the fact that a large portion of the Loco resource is already under elevated protection within the Chilean TURF system (Gonzalez et al., 2006), an adapted management of the Loco extraction in open-access areas could be beneficial and potentially increase the efficiency of this fishery. Both fishermen representatives as well as the fishing administration have already shown interest to further develop this idea and establish management plans for the open-access fishery for Loco (SUBPESCA, 2017).

Another option to potentially alleviate the pressure on the Loco is to further promote the establishment of management areas (i.e. increasing the MA “density”), which seems to provide fishermen with the right incentives to “protect their resources”. The present study provides further evidence that the co-management system can positively affect sustainable fishing practices (Gelcich et al., 2009; Gelcich et al., 2013), illustrated by the observed difference in compliance rates between management regimes. I want to call for caution, however, as this scenario might disfavour those resource users that do not pertain to the established fisher organizations (due to a multitude of reasons) and may thus result in social conflicts. In any case, it is obvious that enforcement along the extensive Chilean coast is extremely difficult and effective resource management relies heavily on intrinsic compliance by the resource users (Colding & Folke, 2001; Kuperan & Sutinen, 1998).

4.5 Study limitations The approach of the present investigation relies on one important assump- tion: the fishermen participating in this study exhibited a fishing behaviour that is representative of their normal fishing activities. Fishermen, however,

might alter their fishing behaviour in the presence of scientists (with the intention to measure the size of collected individuals), potentially compro- mising the obtained results. A possible alteration in fishing behaviour would most likely result in an underestimation of non-compliance rates (i.e. higher compliance under the presence of observers) and I therefore suggest inter- preting the presented results as conservative non-compliance estimates. Alt- hough relatively unlikely, the possibility that the presence of scientists might unexpectedly lead fishermen to extract more undersized individuals than usually cannot fully be ruled out. Fishermen are commonly contracted by biological consultants to participate in the diving activities of the follow-up stock assessments, where they are asked to extract Loco of all the available size classes. The presence of scientists might potentially invoke this distinct fishing behaviour and consequently affect the obtained results.

To my knowledge, the only publicly available data on size structure of Loco catches is provided by the Chilean Fisheries Development Institute (IFOP): scattered over a period of 15 years, the average individual size for the Loco landings from a handful of MAs was - extremely sporadically - assessed (source: https://www.ifop.cl/indicadores_bentonicos). The fact that the mean size of landed Loco provided by IFOP (11.0 cm; both overall, as well as only considering the fishing coves included in this study) corre- sponds precisely with the mean size of MAs presented in this manuscript, suggests that the fishermen ’s extraction behaviour during this investigation can in fact be considered as representative of the actual fishing behaviour of the benthic artisanal fishermen of Chile.

The fisheries sustainability indicators by Froese (2004) were originally proposed for fish stocks and not invertebrates. Nevertheless, I believe that the application of these simple criteria can provide highly interesting insights for the Loco fishery. I acknowledge that the adequacy of length-at-maturity values and the site-specific growth parameters used by IFOP (2017) to cal- culate the critical length affect the absolute “sustainability ” values presented in this study.

4.6 Conclusion The present study showed how the application of easily collectable size data of landed individuals can provide interesting insight into both management-related as well as ecological aspects of an artisanal fishery. Contrary to the data acquisition of abundance and bulk weight for Loco landings in Chile, size parameters are not being systematically assessed in this fishery and seem to be only utilized for penalization of fishermen. Assessing the size of caught individuals, however, can be highly insightful for evaluating the performance a fishery (as demonstrated above) and potentially inform resource management. It would therefore be recommendable to integrate size- frequency sampling in the framework of catch reports (but keep the potential influence of misreporting in mind; cf. Ruano-Chamorro et al., 2017).

The effectiveness of any fisheries management regulation depends on compliance by the resource users (Bohnsack, 2000). The present study allowed an insight into fishermen ’s compliance behaviour in the Loco fishery in central Chile. Covering a coastal section that spans almost two degrees of latitude, it is the geographically most extensive study of illegal fishing practices in the Chilean artisanal benthic fishery. Moreover, it is - to my knowledge - the first attempt to experimentally address and quantify compliance with the minimum legal size regulation in the Chilean Loco fishery. Despite possible uncertainties in terms of absolute levels of illegal fishing, the presented compliance rates with the MLS should be adequately considered in management plans as well as the determination of quotas, applying the precautionary principle. Based on the results of this study, resource managers are now in the position to make better-informed management decisions and promote a more sustainable use of the Loco resource. It is not my intention to point the finger at fishermen, but to create a framework and knowledge base that permits a sustainable use of marine resources for the future. Economically speaking - the worst thing that could happen to a fisherman is losing the resource he most depends on. Let ’s use science in a clever way to prevent this from happening in the Loco fishery.

Considering the extent of the Chilean coast with its tremendous number of landing sites, it seems that adequate enforcement by government authorities to effectively prevent illegal fishing is not within reach. A solution for the struggle against illegal fishing thus seems to depend on the involvement

of fishermen as well as society as a whole. Alternative strategies to improve compliance with the MLS regulation should consider every component of the supply chain, from fishermen to the final consumers. In a commercial environment without adequate product traceability (personal observation), consumer education towards better-informed buying decisions might emerge as a powerful tool to enforce MLS regulations (for additional information see Annex). I therefore strongly suggest to generate wide communication strategies to reach out to the public and effectively diminish market opportunities for illegal catches.

Ethical considerations

In order not to expose any of the participating fishermen to penalization by enforcement authorities, I chose not to disclose information on the circumstances under which individual fishing trips were conducted (paid vs. non-paid).

5 Acknowledgements

First and most importantly, I want to thank my parents Ingrid and Ger- hard for their loving, unconditional and extremely powerful support at all times and under any imaginable circumstances. Thank you for being who you are and doing exactly what you do. To keep it simple: You are wonderful!

Miriam Fernández and Dulce Subida supported me in an extraordinary manner with their wealth of knowledge. Thank you for always (always!) having an open ear for my concerns. Your dedication on so many different levels has left a lasting impression on me and I am now leaving Chile with two unique role models for my future.

I want to thank my colleagues Ainara Aguilar, Vladimir Garmendia and Sebastián López for their never-ending dedication when it came to planning, conducting and enjoying fieldwork. I benefited immensely from our discus- sions and really enjoyed laughing with you. I am convinced that sooner or later our paths will cross again. In the meantime, I wish you three all the best for your future, wherever it may take you!

I want to thank Carolina Ezquer for her support with preparing the “Sus- tainability Ruler”, but more importantly for her dedication in educating the next generation of marine enthusiasts and reminding me every day - through actions & words - of a scientist’s fundamental role in spreading knowledge.

Thank you to all my friends at ECIM and in Las Cruces who supported me in a variety of ways and made my stay in Chile an unforgettable experience. I hope to see you all again soon!

Last but definitely not least, I want to thank the artisanal fishermen of central Chile, without whose participation, this study would not have been feasible. Thank you for your honesty in sharing your unique knowledge and extraordinary wisdom about the ocean realm and its inhabitants with us.

This research was supported by FONDECYT project 1171603 (CONICYT, National Commission of Science and Technology, Ministry of Education, Chilean Government).

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Online documents

Google earth layer displaying TURFs along the Chilean coast. provided by SUBPESCA [last accessed: 15.4.2018] http://www.subpesca.cl/portal/619/w3-article-79986.html

Database indicating the average weight of landed Loco. provided by IFOP [last accessed: 23.5.2018] https://www.ifop.cl/indicadores_bentonicos

Website of SERNAPESCA stating that a minimum legal size should never be inferior to the critical length. [last accessed: 13.5.2018] http://www.sernapesca.cl/index.php?option=com_cotent&view=article&id=205&Itemid=365

Figure 1 is kindly provided by Jorval [CC BY-SA 4.0 (https://crea- tivecommons.org/licenses/by-sa/4.0)], from Wikimedia Commons (https://commons.wikimedia.org/wiki/File:Loco_concha.jpg).

Figure 3, beautifully illustrated by Andrés Jullian, is reproduced with permission from the copyright-holder “Chile es Mar”.

Figure 5 is reproduced with permission from Vladimir Garmendia, who holds the full copyright.

The author of this manuscript holds the copyright for the remaining photos.

7 Annex

This “sustainability ruler” was prepared as an outreach component of the present study and calls the attention to the minimum legal sizes of three invertebrates commonly consumed in Chile. The slogan “Measure your food!” invites users to reflect on the power of consumer choice in promoting sustainable resource management. It is currently being distributed to school kids as part of guided visits to the marine research station ECIM in Las Cruces, where the present study was realized. I am convinced that raising awareness for the consequences of extracting undersized individuals is the key to promoting sustainability in the benthic artisanal fishery of Chile.