Archive (2018): Assessing fishing effects inside and outside an MPA: The impact of the Galapagos Marine Reserve on the Industrial pelagic tuna fisheries during the first decade of operation

Assessing fishing effects inside and outside an MPA: The impact of the Galapagos Marine Reserve on the Industrial pelagic tuna fisheries during the first decade of operation

Santiago J. Bucaram, ESPOL Polytechnic University, Escuela Superior Politécnica del Litoral, ESPOL, Facultad de Ciencias Sociales y Humanísticas (Guayaquil, Ecuador)
Alex Hearn, School of Biological and Environmental Sciences (Universidad San Francisco de Quito, Ecuador) &Turtle Island Restoration Network (Olema, CA)
Ana M. Trujillo, Yale University (New Haven, CT)
Willington Rentería, Instituto Oceanográfico de la Armada (Guayaquil, Ecuador)
Rodrigo H. Bustamante, CSIRO Ocean & Atmosphere, (QLD, Australia)
Guillermo Morán, Inter-American Tropical Tuna Commission (La Jolla, CA) & TUNACONS (Guayaquil, Ecuador)
Gunther Reck, School of Biological and Environmental Sciences (Universidad San Francisco de Quito, Ecuador)
José L. García, TUNACONS (Guayaquil, Ecuador)

Read the entire publication in Marine Policy (2018) via Science Direct at


The conservation benefits of the Galapagos Marine Reserve (GMR), created in March 1998, have been consistently proved for endemic species and populations with limited movements. Yet, to date, no study has explored its effects on highly-migratory pelagic species, such as tuna. To this end, the impact of the GMR on the behavior and productivity of tuna fisheries in this region is analyzed. After considering other potential factors, which occurred approximately over the same period (i.e. increase of fleet size, changes in fishing technology, and climatic events, among others), it was found that the creation of the GMR increased fishing productivity in both the Galapagos Exclusive Economic Zone (EEZ) surrounding the GMR, as well as inside the marine reserve.

However, the effect was heterogenous among tuna species – the GMR had a positive impact on the fishing productivity of yellowfin tuna (YFT) and skipjack tuna (SKJ) fisheries, but did not have any significant effect on that of bigeye tuna (BET). Then, it is proposed that the GMR effect might be dissipated by the overuse of Fish Aggregating Devices (FADs), especially in the case of BET.

1. Introduction

Many fish species around the world are increasingly threatened with collapsing. Bio-economic models have shown that stock rebuilding leads to increased profits, with maximum economic yield exceeding maximum sustainable yield. Marine Protected Areas (MPAs) and area-based fishery closures have been used to reverse declining trends in marine biodiversity, and have resulted in increased productivity of fisheries. In addition to protection within their boundaries, MPAs may often have the goal, stated or otherwise, to promote sustainability of fisheries outside their borders, which can occur through larval dispersal, or spillover of adult organisms.

The creation of MPAs is often politically and socially controversial, especially when stakeholders are required to make a short-term sacrifice, with the promise of potential long-term gains. In many cases, marine reserves may also result in particular stakeholder groups losing access to resources, which in turn can lead to issues of compliance and enforcement. This is even more challenging when it comes to oceanic MPAs. As pelagic species tend to be highly mobile, oceanic MPAs – designed to protect the species or enhance fisheries – must be either very large, or target specific key life stages of species that display site fidelity. A number of very large MPAs (> 100,000 km2) haven been created in recent years, and many are claiming putative benefits for oceanic species and their related commercial fisheries.

The Galapagos Marine Reserve (GMR) is an example of an oceanic MPA whose protection benefits were expected to be materialized beyond its borderline. The GMR was created in 1998 by the Ecuadorian Government as a multi-use MPA, covering an area of approximately 133,000 km2, measured from a baseline to 40 nautical miles (Nm) offshore. It sought to expand the conservation management of the archipelago’s coastal areas, and to mitigate the impacts of a rapidly growing industrial fleet, while benefiting local small-scale island-based fisheries.

Prior to the creation of the GMR, industrial longliners and purseseiners [1] frequently operated in Galapagos, targeting three tuna species: yellowfin (Thunnus albacares), skipjack (Katsuwonus pelagicus) and bigeye (Thunnus obesus), all of which are highly mobile and able to travel large distances. At the time, the fishing industry – based at the coastal city of Manta – strongly opposed the establishment of the GMR and the subsequent prohibition of industrial fishing within the reserve.

This study is the first attempt to quantify the impact of the GMR on the industrial tuna fleet, in terms of the productivity of three commercial tuna species (yellowfin – YFT, skipjack – SKJ, and bigeye – BET), and the displacement of fishing effort, while accounting for several other events which occurred around the same time as the creation of the GMR (increase of fleet size, changes in fishing gear/technology, [2] and possible biological responses to intense “El Niño” and “La Niña” events), and which may have interacted to further alter fishing productivity.

Spatially-explicit time series of catch and effort data, gathered by the observer program run by the Inter-America Tropical Tuna Commission (IATTC) and owned by the Ecuadorian government, for a twenty-year period,[3] were used to assess the impact of the marine reserve on three Ecuadorian tuna fisheries. Size-structure data were employed to explore: (i) whether the GMR is part of a regional area of rearing habitat for juveniles of the three species, and (iii) whether tuna have been caught at greater sizes since the creation of the MPA.

1 The Ecuadorian purse-seine tuna fleet sets on: 1) objects/fish aggregating devices (FADs), 2) dolphin schools, and 3) unassociated tuna schools.

2 The most important change in fishing technology was the adoption of FADs (and its increased use).

3 The data for this study are owned and provided by the Ecuadorian government and are considered confidential.

2. Methods and materials

2.1. Geographic area

Tuna fisheries in the Eastern Pacific Ocean (EPO) operate from USA (California) to Chile, and out to the 150°W meridian. This region is managed by the IATTC, and is divided into 13 length-frequency sampling zones (Fig. 1). This study focuses mainly on the Insular Ecuador’s Exclusive Economic Zone (IEEZ),[4] located in zone 7. For the purpose of this paper, the IEEZ was divided into the two following regions: 1) the GMR, which includes the area within 40 Nm measured from the baseline of the archipelago’s coasts, and 2) the Galapagos Economic Exclusive Zone (which will be referred to as EEZ), that is represented by a belt of 160 Nm wide that surrounds the GMR, and is the part of the IEEZ (where Ecuadorian industrial vessels are allowed to fish). To test for factors unrelated to the GMR effect, data from a large management zone known as “El Corralito”, located approximately 46 Nm West of the EEZ, were used. “El Corralito” is a special management area with a temporal purse-seine closure, extending from September 29th, to October 29th, each year. It is located between the 96°W and 110°W meridians, and the 4°N and 3°S parallels (Fig. 1). Finally, the three study areas (i.e. GMR, EEZ and “El Corralito”) were classified into two groups. The first group is called “interest areas” (includes the GMR and EEZ, which are both inside IATTC zone 7), and the second group is the “control area” (corresponding to “El Corralito”, located inside IATTC zone 9).

4 The UNCLOS defines the Economic Exclusive Zone as a “zone beyond and adjacent to the territorial sea in which a coastal state has: sovereign rights for the purpose of exploring and exploiting, conserving and managing the natural resources, whether living or non-living, of the waters superjacent to the seabed and of the seabed and its subsoil, and with regard to other activities for the economic exploitation and exploration of the zone, such as the production of energy from the water, currents, and winds; jurisdiction with regard to the establishment and use of artificial islands, installations, and structures; marine scientific research; the protection and preservation of the marine environment; the outer limit of the exclusive economic zone shall not exceed 200 nautical miles from the baselines from which the breadth of the territorial sea is measured”. Ecuador’s EEZ has a Continental and an Insular component. This paper focuses on the insular element, referred to as the IEEZ.

2.2. Fleet description

The industrial tuna fleet in Ecuador is made up of several vessel types (including longliners and purse-seiners), as well as gear types. The study focuses on class 6 purse-seiners,[5] given that they are responsible for the largest proportion of tuna catches, and constitute the only class of vessels with full observer coverage. Over the 1990–2009 study period, class 6 purse-seiners employed three different fishing strategies. They set nets on a) man-made Fish Aggregating Devices (FADs), which represent a cheaper and more effective fishing technology, b) unassociated schools, and to a lesser extent, c) dolphins. On average, class 6 purse-seine vessels made up 42.2% of the Ecuadorian tuna purse-seine fleet (with a minimum of 21.2% in 1991, and a maximum of 53.6% in 2008). During the same period, their catch represented, on average, 70.1% of the total catch of the Ecuadorian tuna purse-seine fleet (with a minimum of 42.3% in 1990, and a maximum of 94.1% in 2007) (Fig. 2). [6]

[5] Class 6 purse-seiners are vessels with 363 MT capacity or greater, according to the definition of the IATTC.

[6] In the study period, the Ecuadorian class 6 purse-seine fleet more than quintupled: from eight vessels in 1990 to 45 vessels in 2009. This increase translated into an annual growth of 18.03% of the fishing capacity.

3. Results

3.1. Behavior of the relevant variables from 1990 to 2009

3.1.1. Effort levels in the GMR and the EEZ [16]

During the study period, 21.4% of all sets by class 6 vessels were carried out within the IEEZ, which represents approximately 2.1% of the total area of the EPO (the GMR corresponds to 0.3% of this area, and the EEZ 1.8%).[17] The pattern of fishing effort – expressed in number of sets – within the IEEZ varied for each of the two areas that compose it. In the EEZ, there was peak in effort in 1999, followed by a drop back to earlier levels by 2001.

[16] For this and the following sections, fishing effort is defined as number of sets.

[17] The areas were calculated using the Mollweide projection.

Subsequently, it rose steadily until 2007, and then steeply until 2009 (Fig. 3, Panel 3). In the GMR, the 1999 peak was also observed, corresponding to the first full year of operation of the marine reserve. Nonetheless, from 2001 onwards, fishing effort within the reserve reduced to historical minimums. Catch behavior was similar to that of the fishing effort in both areas, in particular the one related to the YFT catch (Fig. 3, Panels 4 and 5). While catches per set steadily increased throughout the 1990s in the IEEZ, there is an overall declining tendency as of 2000 (Fig. 3, Panel 6).

Finally, it can be seen in Panel 1 that the mean sea-surface temperature anomalies reached a peak between 1997 and 1998, corresponding to the “El Niño” phenomenon. Panel 2 shows how the proportion of sets using FADs changed in the EEZ from 1990 to 2009. The use of this gear became predominant by the end of the 1990s. This variable appears to have a fluctuating pattern.

3.1.2. Spatial distribution of the fishing effort

Over the study period, fishing effort of Ecuadorian class 6 vessels expanded westward, from a limit of approximately 115°W, to 155°W; and southward to the extent that, by 2002, it included the continental shelf of Peru (Fig. 4).

In zone 7, following the implementation of the GMR, an instantaneous displacement of fishing effort was expected; however, it did not take place. Rather, its shift out of the GMR was gradual (Fig. 4, right-panel maps). Thus, during the period 1990–1997 (i.e. prior to the establishment of the GMR), effort was highly concentrated inside the area that would later correspond to the marine reserve. Between 1998 and 2001 (phase of initial implementation of the GMR), intense fishing activity was observed inside the southwestern region of the GMR, near the MPA boundary.

It was not until 2002, that fishing effort began to decline definitively in the reserve, and by the maturity of the GMR (2006–2009), effort within its boundaries attained values close to zero.

In fact, during the latter period, a border effect was observable in the southwestern area of the GMR boundary, in what was called the EEZ region.

Over the study period, the frequency distribution of effort shifted from inside to outside the GMR. In the period prior to the creation of the marine reserve (1990–1997), effort distribution displayed a bimodal pattern, with peaks inside and outside of what would later (i.e. from 1998 onwards) correspond to the GMR. From 2002 to 2005, and in particular from 2006 to 2009, effort was displaced outwards of the MPA, and concentrated within the 20–25 Nm belt surrounding the GMR(Fig. 5).

4. Discussion

4.1. Displacement of effort

The main effect of the establishment of the GMR on the industrial tuna fleet was the displacement of fishing effort outside the boundaries of the MPA. It was expected that an instantaneous effort displacement took place immediately after the establishment of the GMR [21]; however, the shift was gradual (Figs. 4 and 5). Furthermore, an unanticipated peak in fishing activity occurred in 1999; that is, one year after the creation of the GMR (Fig. 3, Panel 3).

[21] The GMR was established through the enactment of the Law of the Special Regime for the Conservation and Sustainable Development of the Province of Galapagos on March 18, 1998.

This could be explained by the fact that the (lower hierarchy) regulatory norms for the Law of the Special Regime for the Conservation and Sustainable Development of the Province of Galapagos were not established promptly, which allowed (de facto) the industrial fleet to continue fishing within the marine reserve. The regulatory norms were enacted on January 11th, 2000, which partially reduced the fishing activity of purse-seiners in the GMR.

Nonetheless, despite the existence of a complete legal body that prevented fishing in the reserve as of January 2000, enforcement remained weak until November 2000, when the Directorate of the Galapagos National Park (DGNP) signed a cooperation agreement with the environmental activist organization, Sea Shepherd, which subsequently sent one of its boats to the Galapagos archipelago to assist in patrolling the MPA. By 2002, agreements were in place with the Ecuadorian Navy, and the DGNP was able to patrol the reserve borders.

This mismatch between regulation and enforcement distorted the incentives of the tuna industrial purse-seine fleet. [. . .] By 2000, the fishing effort started to shift outside the GMR, and fishermen began to cluster at the border of the reserve’s southwestern region. During the period 2006–2009, vessels started to expend a disproportionate amount of fishing effort on the margins of the MPA boundaries (Fig. 4).

It was hypothesized that, through this “border effect” –reconsider use of _—” here related to a “spillover effect” from the GMR to the EEZ–, the Ecuadorian purse-seine fleet was able to capitalize on the positive impact that the GMR had on the productivity of the tuna resource. The latter behavior (i.e. border effect) could be considered as the new fishing strategy for the Ecuadorian fleet.

4.2. Impact of the GMR on fishing productivity

The late 1990s were marked by a series of nearly simultaneous changes that had an impact on the Ecuadorian industrial tuna fleet. First, the number of class 6 vessels more than doubled, from 15 units in 1996, to 33 in 1998 (Fig. 2). Second, the 1997–98 “El Niño” event was one of the strongest on record, and was followed by intense “La Niña” conditions, in late May 1998. The creation of the Galapagos Marine Reserve, and the subsequent exclusion of industrial fishing from an area of 133,000 km2, took place against this backdrop; therefore, any analysis of regional effectiveness must consider these changes, along with other technological and climatological transformations. For that purpose, statistical models were constructed, which incorporated these phenomena as explanatory variables. These models allowed to determine the impact of the establishment of the GMR on the fishing productivity of the three commercial tuna species, in the interest areas (i.e. GMR and EEZ).

Results showed that, since the creation of the GMR, fishing productivity (expressed as catch per set) increased by 104% in the EEZ, and by 83% in the GMR; that is, approximately 99% on average in both areas (i.e. IEEZ) (Table 5). Increased productivity was also observed in the “El Corralito” area, although to a lesser extent, suggesting that the effect of the GMR diluted with distance. However, this might also reveal that other factors (not considered in the proposed models) have contributed to increased catch rates throughout the region. These may include other technological advances, such as the use of satellite imagery, helicopters, computers, improved sonars, among others.

Finally, depth of materials under the FADs also changed from a median of<5 m in the early 1990s, to 25–30 m by 1998. In any case, since it is very likely that the creation of the GMR was orthogonal to all these omitted variables, [23] it can be asserted that, on average, the industrial fleet has seen an increase in catch per set during the years subsequent to the creation of the GMR, despite losing access to approximately133,000 km2 of fishing grounds.

[23] The variables omitted in the statistical models are assumed to be orthogonal to the variable representing the existence of the GMR. The latter assumption is based on the fact that the decision to create the GMR was founded on social, economic and political phenomena that occurred during the decades preceding the establishment of this MPA. Additionally, the process of creating the GMR was convoluted, and was marked by hidden interests and conflictive political agendas; issues that triggered controversies between stakeholders. Therefore, it can be assumed that the decision to establish the GMR is orthogonal to omitted variables related to technological developments, natural phenomena, as well as biological processes occurring in that area. It can be asserted that bias due to omitted variables on the estimated effect of GMR on the productivity of tuna fisheries is negligible or nonexistent.

The effect of the GMR on the three commercial tuna species that are caught by the Ecuadorian purse-seine fleet was significant on the fishing productivity of two of the species only: YFT and, more importantly, SKJ (Tables 4 and 5). The impact of the reserve on the productivity of BET was not statistically different from zero (both for the OLS and GAM specifications) (Tables 4–6). In contrast, the estimator related to the FADs variable was positive and statistically significant for the OLS Species Models and GAM specifications (Tables 4 and 6).[24] In addition, the impact of FADs on the fishing productivity of BET was approximately 135% (Table 5). This result could imply that the use of FADs might have diluted the potential positive effects of the GMR on the productivity of the BET fishery. This is consistent with previous findings that FADs have had a great impact on the mortality of juvenile BET. reinforcing the need for management policies to regulate the use of this fishing gear, in order to protect the species from overexploitation.

As the estimated coefficients for the FADs variable were obtained through OLS (parametric technique) and GAM (non-parametric technique) regressions, they cannot be compared. To analyze the nonparametrical estimation of the impact of the use of FADs on fishing productivity, Fig. 8 was constructed. The use of FADs had a stronger effect on the fishing productivity in the EEZ, than inside the GMR.

Furthermore, although this increased fishing productivity of purse-seiners, there is a level of intensity (approximately at 80% and 90% of the total number of sets respectively for each area) after which it is counterproductive to keep increasing the use of this gear. This is a relevant finding, especially for the BET fishery. Between 2000 and 2009, approximately 81% of BET were caught by sets on FADs.

4.3. Size structure of tuna species in the GMR

Although catch per set was higher in the period following the creation of the GMR, it peaked in 2003 (in both the GMR and the EEZ), and has declined since then, with a particular steep drop between 2008 and 2009 (Fig. 3, Panel 6). This decline was not restricted to the IEEZ, rather it was observed on a region-wide scale. Hall & Roman suggested that this might have been a response either to smaller school sizes, to the fact that FADs are set earlier so schools do not have time to develop, or to the decline in the populations of the target species.

Catches of adult BET from the international longline fleet in the region (i.e. GMR and EEZ) also declined, due to the wide-scale use of FADs. Given the size selectivity, fishing with this gear has had a great impact on mortality of juvenile BET, not only in the EPO. In the Atlantic, the International Commission for the Conservation of Atlantic Tunas (ICCAT) recognized the overfishing of BET due to FADs, which might have also had an effect on YFT and SKJ. Therefore, to protect juveniles, the ICCAT has implemented time-area closures for FADs.

From the results, it would appear that zones 7 (GMR and EEZ) and 9 (“El Corralito”) are characterized for having a high proportion of YOY and sub-adult YFT. It was expected that the reduced mortality resulting from the closure of the GMR would have led to a larger modal size of the catch. However, no change in size structure of YOY catch over time in the GMR or EEZ was observed. The selective nature of FADs towards smaller fish might have masked this effect. Given that industrial fishing is prohibited in part of the GMR, data on artisanal tuna fishing by Galapagos fishers, if properly collected, may help to address this inconvenient.

5. Conclusion

Common criticisms of oceanic MPAs, as outlined by Game et al., include biological, physical, governance and design issues. It is contended that the GMR surmounts several of these challenges. Since the shallow Galapagos Islands platform and surrounding waters (i.e. GMR area) make up a key habitat for juvenile YFT, by preserving these areas, a critical life stage for YFT is protected from industrial fishing, as individuals remain within the MPA boundaries. While it must be remembered that the primary focus of the GMR is to protect endemic and coastal species, there was an underlying expectation from local fishers that the reserve would, in some way, improve fishing yields of pelagic species for them. This has yet to be measured.

In the case of the GMR, enforcement is facilitated by having inhabited islands from which patrolling (both air and sea) can be based, and by having upgraded technology, which now permits satellite tracking of all vessels. In 2007, the Government of Ecuador enacted a legislation which resulted in the mandatory use of Vessel Monitoring System (VMS), tracking devices on all industrial fishing vessels.

Overall, the establishment of the GMR appears to have had a positive effect on the industrial tuna fishery. However, the impact of the GMR was not homogeneous among the three tuna species. While YFT and SKJ catches per set increased in the IEEZ, productivity benefits for BET catch were almost null. In the case of BET, other management tools – such as controlling the use of FADs – may thus be a more appropriate approach. This study was based only on class 6 industrial purse-seiners, and does not necessarily extend to semi-industrial longliners, which were the predominant fishing vessels around the Galapagos archipelago, prior to the creation of the GMR. Finally, the wider ecosystem effects of increased and concentrated effort along the GMR boundaries have not been yet explored; in particular, regarding the protection of threatened migratory species, such as sharks and turtles.


We gratefully acknowledge the support of the Ecuadorian Government and specially of former Director of the Instituto Nacional de Pesca – Ecuador, Edwin Moncayo, who authorized us to use the IATTC observer data for this paper. We are also grateful to participants of the ClimEco5-IMBER workshop, as well as of the V Congreso Internacional de Economía in Ecuador, for their useful insights. We would like to thank Dr. Gonzalo Sánchez, Dr. Maria Grazia Pennino, and an anonymous reviewer for their constructive comments on the manuscript. The statements made, and the opinions expressed in this paper are solely responsibility of the authors.

Funding sources

This research did not receive any specific grant from funding agencies in the public, commercial, or non-profit sectors.

Read the entire publication in Marine Policy (2018) via Science Direct at

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