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We present the description of defensive behavior in wild Octopus vulgaris against conger eel (Conger conger) attacks based on three video sequences recorded by recreational SCUBA divers in the eastern Atlantic off the coast of Galicia (NW Spain) and in the Cantabrian Sea (NW Spain). These records document common traits in defensive behavior: (1) the octopuses enveloped the conger eel's head to obscure its view; (2) they covered the eel's gills in an attempt to suffocate it; (3) they released ink; (4) the octopuses lost some appendages because of the fight. In the third video, the octopus did not exhibit the defensive behavior described in the first two videos due to an inability to utilize its arms in defense, and the conger eel's success in capturing octopuses is discussed. Additionally, both the cost that the octopus could face by losing some arms during the fight and whether the experience it acquires can be an advantage for future encounters are analyzed. The defensive behavior exhibited by octopuses in this study highlights their ability to survive in a hostile environment and serves as an example of the extensive repertoire of anti-predator strategies employed by these cephalopods

This study provides the first socio-ecological overview of the Seriola dumerili fishery occurring in the Balearic Islands. This pelagic top-predator is among the five most valued fish resources of the Balearic community. Despite its ecological importance and potential vulnerability to aggregation fishing, few studies address the ecology of this large Carangidae species. Shining a light on its ecology is vital to ensure adequate species conservation and the sustainable and effective management of the fishery. Historical catches from 1950–1999, alongside detailed landing data for the last 21 years, were analysed to identify potential patterns in ecological and socio-economic factors. Significant inter-annual variability among the years was found in historical catches of greater amberjack, while catches and mean prices of the different size categories revealed significant results between seasons and months, respectively. Additionally, the purse seine fleet accounted for the highest percentage of S. dumerili catches. CPUE did not appear to change greatly between months and years after the annual 8-month fishing ban imposed in 2011 and therefore a re-evaluation of the closure was intended. Overall, this study suggests seasonality influences the S. dumerili fishery in the Balearic Islands, within which ecological influences show a higher regulating power than socio-economic factors.

[EN] We present the Terms of Reference for a case study on a Mediterranean eco-region focusing on the environmental component of the Ecosystem Report Card. The objective of this case study is to describe and monitor the variability of environmental processes in the Mediterranean Sea that affect the ecology of large pelagic fishes, with a particular attention on tunas, and the possible role of climate change on this variability. Here we define the objectives and activities of the initiative, the participant roles, primary indicators and the methodological approach, [FR] Ce document présente les termes de référence d’une étude de cas sur une écorégion méditerranéenne consacrée à la composante environnementale de la fiche informative sur les écosystèmes. L'objectif de cette étude de cas est de décrire et de suivre la variabilité des processus environnementaux en mer Méditerranée qui affectent l'écologie des grands poissons pélagiques, en accordant une attention particulière aux thonidés, et de déterminer le rôle possible du changement climatique sur cette variabilité. Nous définissons ici les objectifs et les activités de l'initiative, les rôles des participants, les indicateurs primaires et l'approche méthodologique., [ES] En el documento se presentan los términos de referencia para un estudio de caso sobre una ecorregión mediterránea centrado en el componente medioambiental de la ficha informativa sobre ecosistemas. El objetivo de este estudio de caso es describir y hacer un seguimiento de la variabilidad de los procesos medioambientales en el mar Mediterráneo que afectan a la ecología de los grandes peces pelágicos, con especial atención a los túnidos, y el posible papel del cambio climático en esta variabilidad. A continuación, se definen los objetivos y actividades de la iniciativa, las funciones de los participantes, los indicadores principales y el enfoque metodológico.

The ocean is a key component of the Earth’s dynamics, providing a great variety of ecosys- tem services to humans. Yet, human activities are globally changing its structure and major components, including marine biodiversity. In this context, the United Nations has proclaimed a Decade of Ocean Science for Sustainable Development to tackle the scientific challenges necessary for a sustainable use of the ocean by means of the Sustainable Development Goal 14 (SDG14). Here, we review how Acoustic animal Tracking, a widely distributed methodology of tracking marine biodiversity with electronic devices, can provide a roadmap for implementing the major Actions to achieve the SDG14. We show that acoustic tracking can be used to reduce and monitor the effects of marine pollution including noise, light, and plastic pollution. Acoustic tracking can be effectively used to monitor the responses of marine biodiversity to human-made infrastructures and habitat restoration, as well as to determine the effects of hypoxia, ocean warming, and acidification. Acoustic tracking has been historically used to inform fisheries man- agement, the design of marine protected areas, and the detection of essential habitats, rendering this technique particularly attractive to achieve the sustainable fishing and spatial protection target goals of the SDG14. Finally, acoustic tracking can contribute to end illegal, unreported, and unregulated fishing by providing tools to monitor marine biodiversity against poachers and promote the development of Small Islands Developing States and developing countries. To fully benefit from acoustic tracking supporting the SDG14 Targets, trans-boundary collaborative efforts through tracking networks are required to promote ocean information sharing and ocean literacy. We therefore propose acoustic tracking and tracking networks as relevant contributors to tackle the scientific challenges that are necessary for a sustainable use of the ocean promoted by the United N

A key aspect of the sustainable management of commercially important coastal pelagic fish stocks is the identification of the spatio-temporal dynamics of aggregation behaviour. An exemplary case species is the greater amberjack, Seriola dumerili. This top-predator is an important commercial resource exploited by recreational and commercial fisheries worldwide. Greater amberjack is known to form aggregations during important stages of its life-history, making it highly vulnerable to overfishing with potential consequences to its conservation. To improve the limited knowledge on the spatio-temporal aggregation areas of this important resource, this study combined fishing fleet dynamics (Vessel Monitoring System records), environmental and landing data into a species distribution model to predict such vulnerable events in space and time around the Balearic Islands. Our results indicated that S. dumerili aggregations were generally encountered in coastal areas at shallow depths (<100 m), low salinities, low chlorophyll concentrations, and weak meridional and zonal current velocities around the Balearic Islands. The preference for these environmental variables and processes is probably related to searching for an optimal scenario that maximises the success of larval development and survival of its offspring. Moreover, the distribution model suggested the possibility of a longer spawning period than previously predicted. This research demonstrates the use of a perceptive statistical tool that efficiently combines fisheries-dependent data and environmental data to highlight essential factors that influence the aggregation behaviour of S. dumerili and thus provides essential information for the conservation and sustainable exploitation not only of the greater amberjack, but also for other gregarious species highly-vulnerable to fishing by their aggregation behaviour.

Decadal trends in the zooplankton community were seasonally investigated in multiple monitoring transects of the western Mediterranean Sea during a period of increasing and record-high water temperatures. The transition area around the Baleares archipelago can be separated into two regions: the Alborán Sea and the Balearic Sea. Differences were found in the abundance and structure of the dominant zooplankton groups: the cladocerans and copepods. The highest zooplankton abundances were found during the stratified summer season, when cladoceran numbers peaked. However, copepods were more abundant during the winter. A marked seasonality was found in all groups and the dominant taxa: 114 species of copepods and 5 species of cladocerans were identified, but less than 8 species of copepods and 2 species of cladocerans dominated the populations. During the 2007–2017 study, warm and salty waters were observed in the Balearic Sea. In the Alborán Sea, cool and fresh waters were observed, along with a decline in chlorophyll. Irregular group and species trends were observed in both regions, exhibiting both increases and decreases depending on region and season. Trends differed, often oppositely, for the Alborán versus the Balearic Sea, with the transition region between them mirroring one or the other, switching with the seasons. The most dominant species, including Penilia avirostris and Clausocalanus arcuicornis, but also Evadne spinifera, C. lividus, C. furcatus, Paracalanus parvus, Acartia clausi, Centropages typicus, Subeucalanus monachus, and Calanus helgolandicus, are proposed as biological tracers to be used in further studies on climate and zooplankton community changes in the western Mediterranean Sea.

This document presents the current electronic tagging information available for management strategy evaluation. This information also allows to identify gaps, in sizes and geographical areas, that should be taken into account to plan future tagging activities. It also describes the status of current electronic tag databases, advantages and disadvantages of electronic tags used on Atlantic bluefin tuna and outlines the technological advances that will allow the use of different types of tags (pop-up satellite archival, archival internal and acoustic tags) to improve the description of movements of this species. The conclusions section summarizes the progress needed to develop the use of electronic tagging on Atlantic bluefin tuna.

In cephalopods, it was initially assumed that there is no parental care by males and the only known form in females is egg care. In the case of the loliginids, it was accepted that they deposit their eggs in the seabed and then abandon them to develop on their own. In this work, we present the first evidence of parental care in the European squid, Loligo vulgaris. While scuba diving in Spain, we found a large mass of squid eggs inside a crevice which was visited and filmed 13 times at night in a 50 days’ period. A female and a male of L. vulgaris were found in front of the crevice for two consecutive nights. In the presence of the divers, male and female alternated their approaches to the crevice, repeatedly touching the egg clusters with their arms in an apparent cleaning operation. The next night only the male was found caring for the eggs. Our finding is unexpected because this behaviour differs from the reproductive habits assumed for squids. Furthermore, it is the first evidence of parental egg care by a male in cephalopods

The ocean is a key component of the Earth's dynamics, providing a great variety of ecosystem services to humans. Yet, human activities are globally changing its structure and major components, including marine biodiversity. In this context, the United Nations has proclaimed a Decade of Ocean Science for Sustainable Development to tackle the scientific challenges necessary for a sustainable use of the ocean by means of the Sustainable Development Goal 14 (SDG14). Here, we review how Acoustic animal Tracking, a widely distributed methodology of tracking marine biodiversity with electronic devices, can provide a roadmap for implementing the major Actions to achieve the SDG14. We show that acoustic tracking can be used to reduce and monitor the effects of marine pollution including noise, light, and plastic pollution. Acoustic tracking can be effectively used to monitor the responses of marine biodiversity to human-made infrastructures and habitat restoration, as well as to determine the effects of hypoxia, ocean warming, and acidification. Acoustic tracking has been historically used to inform fisheries management, the design of marine protected areas, and the detection of essential habitats, rendering this technique particularly attractive to achieve the sustainable fishing and spatial protection target goals of the SDG14. Finally, acoustic tracking can contribute to end illegal, unreported, and unregulated fishing by providing tools to monitor marine biodiversity against poachers and promote the development of Small Islands Developing States and developing countries. To fully benefit from acoustic tracking supporting the SDG14 Targets, trans-boundary collaborative efforts through tracking networks are required to promote ocean information sharing and ocean literacy. We therefore propose acoustic tracking and tracking networks as relevant contributors to tackle the scientific challenges that are necessary for a sustainable use of the ocean promoted by the United Natio

Albacore Thunnus alalunga and skipjack tuna Katsuwonus pelamis are highly migratory species that are usually caught together in the Western Mediterranean. These species are top predators that are highly affected by the biomagnification process through the trophic chain. Bioaccumulation pattern of the main metal pollutants (mercury, Hg; lead, Pb; and cadmium, Cd) were analyzed in muscle tissues of 52 individuals (26 T. alalunga and 26 K. pelamis) of these highly consumed species in order to address two objectives: (1) compare the species-specific bioaccumulation between these large-pelagic species, and (2) assess the healthy properties of such valuable resources based on the trace metal limits established by the European Commission Regulation (ECR). Both generalized linear mixed models and redundancy analysis indicated a differential bioaccumulation between these two tuna species. While T. alalunga accumulates higher concentrations of Hg (0.1996 ± 0.0602 mg·kg-1 weight wet-ww), K. pelamis accumulates higher concentrations of Cd (0.0076 ± 0.0049 mg·kg-1 ww) and Pb (0.0031 ± 0.0017 mg·kg-1 ww). Size and trophic ecology support the differences detected in the bioaccumulation pattern. Heavy metal concentrations were below the tolerable limits considered by ECR (1, 0.1, and 0.3 mg·kg-1 ww for Hg, Cd, and Pb, respectively)

The ocean is a key component of the Earth's dynamics, providing a great variety of ecosystem services to humans. Yet, human activities are globally changing its structure and major components, including marine biodiversity. In this context, the United Nations has proclaimed a Decade of Ocean Science for Sustainable Development to tackle the scientific challenges necessary for a sustainable use of the ocean by means of the Sustainable Development Goal 14 (SDG14). Here, we review how Acoustic animal Tracking, a widely distributed methodology of tracking marine biodiversity with electronic devices, can provide a roadmap for implementing the major Actions to achieve the SDG14. We show that acoustic tracking can be used to reduce and monitor the effects of marine pollution including noise, light, and plastic pollution. Acoustic tracking can be effectively used to monitor the responses of marine biodiversity to human-made infrastructures and habitat restoration, as well as to determine the effects of hypoxia, ocean warming, and acidification. Acoustic tracking has been historically used to inform fisheries management, the design of marine protected areas, and the detection of essential habitats, rendering this technique particularly attractive to achieve the sustainable fishing and spatial protection target goals of the SDG14. Finally, acoustic tracking can contribute to end illegal, unreported, and unregulated fishing by providing tools to monitor marine biodiversity against poachers and promote the development of Small Islands Developing States and developing countries. To fully benefit from acoustic tracking supporting the SDG14 Targets, trans-boundary collaborative efforts through tracking networks are required to promote ocean information sharing and ocean literacy. We therefore propose acoustic tracking and tracking networks as relevant contributors to tackle the scientific challenges that are necessary for a sustainable use of the ocean promoted by the United Natio

The mesozooplankton community was analyzed over a 6-year period (2013-2018) during the post-eruptive stage of the submarine volcano Tagoro, located south of the island of El Hierro (Canary Archipelago, Spain). Nine cruises from March 2013 to March 2018 were carried out in two different seasons, spring (March-April) and autumn (October). A high-resolution study was carried out across the main cones of Tagoro volcano, as well as a large number of reference stations surrounding El Hierro (unaffected by the volcano). The zooplankton community at the reference stations showed a high similarity with more than 85% of the variation in abundance and composition attributable to seasonal differences. Moreover, our data showed an increase in zooplankton abundance in waters affected by the volcano with a higher presence of non-calanoid copepods and a decline in the diversity of the copepod community, indicating that volcanic inputs have a significant effect on these organisms. Fourteen different zooplankton groups were found but copepods were dominant (79%) with 59 genera and 170 species identified. Despite the high species number, less than 30 presented a larger abundance than 1%. Oncaea and Clausocalanus were the most abundant genera followed by Oithona and Paracalanus (60%). Nine species dominated (>2%): O. media, O. plumifera, and O. setigera among the non-calanoids and M. clausi, P. nanus, P. parvus, C. furcatus, C. arcuicornis, and N. minor among the calanoids. After the initial low abundance of the copepods as a consequence of the eruption, an increase was observed in the last years of the study, where besides the small Paracalanus and Clausocalanus, the Cyclopoids seem to have a good adaptive strategy to the new water conditions. The increase in zooplankton abundance and the decline in the copepod diversity in the area affected by the volcano indicate that important changes in the composition of the zooplankton community have occurred. The effect of the volcanic emission

Syngnathids are considered as flagship species for marine conservation. Seahorses and pipefish are highly vulnerable to anthropogenic and environmental disturbances, but most species are currently considered Data Deficient by IUCN, requiring more biological and ecological research. Although syngnathids are well known for their unusual breeding biology, some aspects on the ecology of this family have rarely received attention. The knowledge on the factors governing syngnathids distribution is limited to some species and geographical regions. The present study is the first approach to predict syngnathid habitat preference in Spanish coasts, particularly in a marine National Park. In this study, Species Distribution Models (SDMs) were implemented to investigate the preferential habitat and distribution of the pipefish Syngnathus acus in Cíes Archipelago (Atlantic Islands of Galicia National Park, PNIA). Occurrence data of the species obtained from 2016 to 2018 surveys in PNIA were modeled as a function of bathymetric (depth, slope), substrate (sediment texture) and oceanographic (waves exposure) variables, using GAM, Random Forest and Maxent algorithms. From those SDMs, prediction models were built and the ensemble map of predictions was performed. The variables that most determined the distribution of the species were depth and wave exposure. The results of this study provide information on (1) habitat preference in the most dominant species in PNIA, the pipefish S. acus, towards sustainable management of this species in the National Park, and (2) predictive statistical tools for proper spatial conservation plans of this syngnathid species

A mass mortality event is devastating the populations of the endemic bivalve Pinna nobilis in the Mediterranean Sea from early autumn 2016. A newly described Haplosporidian endoparasite (Haplosporidium pinnae) is the most probable cause of this ecological catastrophe placing one of the largest bivalves of the world on the brink of extinction. As a pivotal step towards Pinna nobilis conservation, this contribution combines scientists and citizens’ data to address the fast- and vast-dispersion and prevalence outbreaks of the pathogen. Therefore, the potential role of currents on parasite expansion was addressed by means of drift simulations of virtual particles in a high-resolution regional currents model. A generalized additive model was implemented to test if environmental factors could modulate the infection of Pinna nobilis populations. The results strongly suggest that the parasite has probably dispersed regionally by surface currents, and that the disease expression seems to be closely related to temperatures above 13.5 °C and to a salinity range between 36.5–39.7 psu. The most likely spread of the disease along the Mediterranean basin associated with scattered survival spots and very few survivors (potentially resistant individuals), point to a challenging scenario for conservation of the emblematic Pinna nobilis, which will require fast and strategic management measures and should make use of the essential role citizen science projects can play.

The abundance and composition of zooplankton down to 3000 m depth was studied in the subtropical and tropical latitudes across the Atlantic, Pacific and Indian Oceans (35 °N–40 °S). Samples were collected from December 2010 to June 2011 during the Malaspina Circumnavigation Expedition. Usually, low abundances were observed with the highest values found in the North Pacific Ocean, Benguela, and off Mauritania, and the lowest in the South Pacific Ocean. No significant differences in abundance and zooplankton composition were found among oceans, with depth being consistently the most important factor affecting their distribution. Each depth strata were inhabited by distinct copepod assemblages, which significantly differed among the strata. The contribution of copepods to the zooplankton community increased with the depth although, as expected, their abundance strongly decreased. Among the copepods, 265 species were identified but 85% were rare and contributed less than 1% in abundance. Clausocalanus furcatus and Nannocalanus minor dominated the epipelagic strata. Pleuromamma abdominalis and Lucicutia clausi were of importance in the mesopelagic layer, and Pareucalanus, Triconia, Conaea and Metridia brevicauda in the bathypelagic layer. Our results provide a global-scale assessment of copepod biodiversity and distribution, providing a contemporary benchmark to follow future ocean changes at low latitudes.

Cannibalism refers to consuming a conspecific and is common in many taxa. In addition to conferring advantages for a predator’s growth, reproductive efficiency and survival (e.g. elimination of future competitors, ready supply of high-quality nutrition and of optimal proportions of vitamins, minerals and amino acid), cannibalism is an important link between individual and population-level processes (Claessen et al., 2002). Based primarily on the study of stomach contents, Ibañez & Keyl (2010) have shown that cannibalism is widespread in cephalopods. Cannibalism thus potentially may be an important component of natural mortality (Claessen, De Roos & Persson, 2004), and natural mortality is a key factor in the limitation of populations and management of exploited resources. Cannibalism in octopuses has been recorded only infrequently (Ibañez & Keyl, 2010), and available anecdotal observations of cannibalism in the wild are confined to sexual cannibalism (e.g. Hanlon & Forsythe, 2008; Huffard, Caldwell & Boneka, 2010; Huffard & Bartick, 2014)

Maërl is a benthic community composed of accumulations of coralline red algae with an essential eco‐biological role in marine ecosystems. This low‐resilience community has acquired a high conservation status as many anthropogenic impacts threaten this globally distributed ecosystem. Some of the potentially more important but less studied impacts are those caused by fishing activities due to the lack of proper controls. This study investigates the potential fishing impacts and depth‐related differences on the rhodolith morpho‐demographic traits of two maërl‐forming algae, Lithothamnion corallioides and Spongites fruticulosus, with distinct morphologies (ramified vs nucleated). Rhodolith size and shape (roundness and solidity) indicators were assessed in maërl beds protected from fishing inside a large 25‐year old no‐take marine protected area (MPA), in a contiguous 6‐year old no‐take zone and in adjacent beds open to fishing. Rhodoliths of both species were bigger, rounder (spherical) and more solid (structurally less complex) in shallow than in deep beds of the long‐term protected area, which was probably a result of a more active hydrodynamic regime and higher irradiance in shallow beds. Fishing effects manifested differently depending on the morphological properties of rhodoliths, which resulted in a decrease in size and complexity in L. corallioides and roundness in S. fruticulosus. Such fishing impacts were significant only inside the short‐term 6‐year protected area. The most plausible cause of this unexpected observation is the highly localized trammel‐net fishing effort with long soak‐times along the boundary of the contiguous 25‐year MPA, where before closure, fishing effort was concentrated in expectation of greater catches from spillover (i.e. fishing the line). This is the first study to document the impacts of fishing the line on structural species and indicates that boundaries of successful MPAs could be zones of maximum disturbance, a fact that should

Mediterranean small-scale fleets catch a substantial amount of untargeted fish that are sold at a low market price. Most of these catches are pooled into mixed-fish boxes (MFBoxes), which are usually labeled and sold as mixed-fish commercial categories (MFCategories). In this paper, we describe the MFBoxes and the MFCategories from the small-scale fleet of Mallorca Island in terms of species composition, size distribution and economic value. We used (i) daily sales records of MFCategories between 2004 and 2015 and (ii) a sample of 141 photographs of MFBoxes, collected over one year (2009–2010). MFCategories represent a non-negligible fraction of the landings, between 18 and 51 tons/year which represents 100–300 K€/year. Some of the sampled MFBoxes were sold as one of the three identified MFCategories, which differ in species composition, size and average price (3.9 €/kg for the category LARGE MORRALLA, 2.2 €/kg for SMALL MORRALLA and 7.0 €/kg for VARIAT). However, more than half (52%) of the sampled MFBoxes were actually labeled and sold not as MFCategories but as one of the most abundant species in the box. This strategy might seem unprofitable because the market price is lower for MFBoxes sold as non-mixed categories than for non-mixed boxes of the same category. However, we observed that the label itself does not affect the selling price, but species composition does. Therefore, when sorting fish into boxes, fishers may be trying to optimize the tradeoff between not selling some low-priced fish and mixing them with other more valued fish. This alternative marketing strategy should be explored in depth and properly assessed, not only to maximize profits but also to promote a zero-discard European policy.

Mediterranean small-scale fleets catch a substantial amount of untargeted fish that are sold at a low market price. Most of these catches are pooled into mixed-fish boxes (MFBoxes), which are usually labeled and sold as mixed-fish commercial categories (MFCategories). In this paper, we describe the MFBoxes and the MFCategories from the small-scale fleet of Mallorca Island in terms of species composition, size distribution and economic value. We used (i) daily sales records of MFCategories between 2004 and 2015 and (ii) a sample of 141 photographs of MFBoxes, collected over one year (2009–2010). MFCategories represent a non-negligible fraction of the landings, between 18 and 51 tons/year which represents 100–300 K€/year. Some of the sampled MFBoxes were sold as one of the three identified MFCategories, which differ in species composition, size and average price (3.9 €/kg for the category LARGE MORRALLA, 2.2 €/kg for SMALL MORRALLA and 7.0 €/kg for VARIAT). However, more than half (52%) of the sampled MFBoxes were actually labeled and sold not as MFCategories but as one of the most abundant species in the box. This strategy might seem unprofitable because the market price is lower for MFBoxes sold as non-mixed categories than for non-mixed boxes of the same category. However, we observed that the label itself does not affect the selling price, but species composition does. Therefore, when sorting fish into boxes, fishers may be trying to optimize the tradeoff between not selling some low-priced fish and mixing them with other more valued fish. This alternative marketing strategy should be explored in depth and properly assessed, not only to maximize profits but also to promote a zero-discard European policy.

Maërl is a benthic community composed of accumulations of coralline red algae with an essential eco-biological role in marine ecosystems. This low-resilience community has acquired a high conservation status as many anthropogenic impacts threaten this globally distributed ecosystem. Some of the potentially more important but less studied impacts are those caused by fishing activities due to the lack of proper controls. This study investigates the potential fishing impacts and depth-related differences on the rhodolith morpho-demographic traits of two maërl-forming algae, Lithothamnion corallioides and Spongites fruticulosus, with distinct morphologies (ramified vs nucleated). Rhodolith size and shape (roundness and solidity) indicators were assessed in maërl beds protected from fishing inside a large 25-year old no-take MPA, in a contiguous 6-year no-take zone, and in adjacent fished beds. Rhodoliths of both species were bigger, rounder (spherical) and more solid (structurally less complex) in shallow than in deep beds of the long-term protected area, which was probably a result of a more active hydrodynamic regime and higher irradiance in shallow beds. Fishing effects manifested differently depending on the morphological properties of rhodoliths, which resulted in a decrease in size and complexity in L. corallioides and roundness in S. fruticulosus. Such fishing impacts were significant only inside the short-term 6-year protected area. The most plausible cause of this unexpected observation is the highly localized trammel-net fishing effort with long soak-times along the boundary of the contiguous 25-year MPA, where before closure, fishing effort was concentrated in expectation of greater catches from spillover (i.e. fishing the line). This is the first study to document the impacts of fishing the line on structural species and indicates that boundaries of successful MPAs could be zones of maximum disturbance, a fact that should be taken into account in management

Although some stocks are being severely exploited by recreational fishing, estimating the biomass extracted (harvest, H) by recreational fisheries is difficult, especially for marine recreational fisheries. One way to estimate H by recreational fisheries is to combine the fishing effort (E) with catch-per-unit-of-effort (CPUE) data. However, naively ignoring heterogeneity in E and CPUE may result in biased and imprecise estimates of H. We propose a framework to address three relevant heterogeneity levels: the spatial and temporal heterogeneity of recreational E, environmental effects on recreational CPUE, and the variability in angler skills (between-angler heterogeneity). Specifically, we combine (i) space-time model predictions of E (number of boats per km2) on the day scale (i.e., fishing trips), (ii) environmentally driven model predictions of daily catch (number of squid per fishing trip), and (iii) off- and on-site sur-veys to account for angler heterogeneity. The precision of the H estimates was assessed using bootstrap confidence intervals. This framework was applied to the recreational fishery for the squid Loligo vulgaris at Palma Bay (Mallorca Island, western Mediterranean). The estimated effort was 15,750 angler-fishing trips (95% CI: 13,086 to 18,569), which yielded an annual harvest of 20.6 tons (95% CI: 16.9–24.5). This harvest was estimated to represent 34% of the total commercial landings in Mallorca, which highlights the importance of recreational harvesting and the need to account for recreational fisheries to improve squid stock management. The framework proposed here provides a promising tool for estimating H in other heterogeneous recreational fisheries and may be the first step toward assessing the actual impact of recreational fisheries on squid populations