Behaviour and body patterns of Octopus vulgaris facing a baited trap: first-capture assessment

This study highlights for the first time individual differences in ethology and vulnerability of Octopus vulgaris (i.e. body postures, movements and skin displays) facing passive baited traps. Common octopus exposed to a baited trap during three consecutive first-capture tests exhibited diverse behavioural and body pattern sequences resembling when the octopus searches for and hunts its wild prey. Overall, they first visually recognized new objects or potential preys and rapidly moved out of the den, exploring, grabbing and approaching the trap with the arms (chemotactile exploration), and capturing the bait with the arms and feeding on top over long periods inside the trap. Simultaneously, O. vulgaris displayed diverse skin textural and chromatic signs, the regular pattern being the most frequent and long-lasting, followed by broad mottle, passing cloud and dark patterns. All individuals (n=8) caught the bait at least once, although only five octopuses (62.5%) entered the trap in all three tests. In addition, high variability among individuals was observed regarding behaviour and body patterns during the first-capture tests, which might evidence different individual temperaments or life-history traits. Differences in behavioural responses at individual level might have population consequences due to fisheries-induced selection, although there is a high necessity to assess how behavioural traits might play an important role in life-history traits of this species harvested by small-scale trap fisheries.IJCI2015-25595info:eu-repo/semantics/publishedVersio

MPA network design based on graph network theory and emergent properties of larval dispersal

Despite the recognised effectiveness of networks of Marine Protected Areas (MPAs) as a biodiversity conservation instrument, nowadays MPA network design frequently disregards the importance of connectivity patterns. In the case of sedentary marine populations, connectivity stems not only from the stochastic nature of the physical environment that affects early-life stages dispersal, but also from the spawning stock attributes that affect the reproductive output (e.g., passive eggs and larvae) and its survivorship. Early-life stages are virtually impossible to track in the ocean. Therefore, numerical ocean current simulations coupled to egg and larval Lagrangian transport models remain the most common approach for the assessment of marine larval connectivity. Inferred larval connectivity may be different depending on the type of connectivity considered; consequently, the prioritisation of sites for marine populations' conservation might also differ. Here, we introduce a framework for evaluating and designing MPA networks based on the identification of connectivity hotspots using graph theoretic analysis. We use as a case of study a network of open-access areas and MPAs, off Mallorca Island (Spain), and test its effectiveness for the protection of the painted comber Serranus scriba. Outputs from network analysis are used to: (1) identify critical areas for improving overall larval connectivity; (2) assess the impact of species' biological parameters in network connectivity; and (3) explore alternative MPA configurations to improve average network connectivity. Results demonstrate the potential of graph theory to identify non-trivial egg/larval dispersal patterns and emerging collective properties of the MPA network which are relevant for increasing protection efficiency.Comment: 8 figures, 3 tables, 1 Supplementary material (including 4 table; 3 figures and supplementary methods

Performance of a novel system for high-resolution tracking of marine fish societies

Recent advances in tracking systems have revolutionized our ability to study animal movement in the wild. In aquatic environments, high-resolution acoustic telemetry systems make it technically possible to simultaneously monitor large amounts of individuals at unprecedented spatial and temporal resolutions, providing a unique opportunity to study the behaviour and social interactions using a reality mining approach. Despite the potential, high-resolution telemetry systems have had very limited use in coastal marine areas due to the limitations that these environments pose to the transmission of acoustic signals. This study aims at designing and testing a high-resolution acoustic telemetry system to monitor, for the first time, a natural fish population in an open marine area. First, we conducted preliminary range tests and a computer simulation study to identify the optimal design of the telemetry system. Then, we performed a series of stationary and moving tests to characterize the performance of the system in terms of positioning efficiency and precision. Finally, we obtained a dataset corresponding to the movements of 170 concurrently tagged individuals to demonstrate the overall functioning of the system with a real study case of the behaviour of a small-bodied coastal species. Our results show that high-resolution acoustic telemetry systems efficiently generate positional data in marine systems, providing a precision of few meters, a temporal resolution of few seconds, and the possibility of tracking hundreds of individuals simultaneously. Data post-processing using a trajectory filter and movement models proved to be key to achieve a sub-meter positioning precision. The main limitation detected for our system was the restricted detection range, which was negatively affected by the stratification of the water column. Our work demonstrates that high-resolution acoustic telemetry systems are an effective method to monitor the movements of free-ranging individuals at the population level in coastal sites. By providing highly precise positioning estimates of large amounts of individuals, these systems represent a powerful tool to study key ecological processes regarding the social interactions of individuals, including social dynamics, collective movements, or responses to environmental perturbations, and to extend the studies to poorly studied small-sized species or life-stages.The telemetry system was financed by the German Federal Ministry of Education and Research (grant no. #033W024A). EA was supported by a Margalida Comas postdoctoral grant from the Government of the Balearic Islands and the European Social Fund (Grant No. PD/023/2018). JA was supported by a Ramon y Cajal Grant (Grant No. RYC2018-024488-I) and received funding from the CLOCKS R&D Project (Grant No. PID2019-104940GA-I00) and the intramural research project JSATS (Grant No. PIE 202030E002) funded by the Spanish Ministry of Science and Innovation and the Spanish National Research Council. GFB was supported by a Ph.D. fellowship (FPI-INIA 2015–0013-CPD2015-0084) from the National Institute for Agricultural and Food Research and Technology.Peer reviewe

Updating the National Baseline of Non-Indigenous Species in Spanish Marine Waters

The introduction of new non-indigenous species (NIS) in Spanish marine waters is addressed under Descriptor 2 of the European Union’s Marine Strategy Framework Directive. National baseline inventories of NIS have been compiled and updated for the three subregions (Western Mediterranean Sea, WMED; Bay of Biscay–Iberian Coast, ABI; Macaronesia, AMA) with data from 1800 to 2021. An overall of 574 species were identified with an alien, cryptogenic, crypto-expanding, or debatable status, mostly invertebrates (~65%) and primary producers (~22%). Of 412 alien species, 80.51% were reported in ABI, 67.82% in WMED, and 66.67% in AMA. Cryptogenic species are more abundant in the WMED (25.25%), compared to AMA (19.77%) and ABI (18.46%). ABI harbors more established species (62.56%) than AMA (45.2%) and WMED (43.56%), contrary to casual records (AMA 31.64%, WMED 23.76%, ABI 13.85%). Invasive species are more abundant (14.36%) in WMED. The ‘transport-stowaway’ pathway accounted for 142 (79.33%), 123 (67.58%), and 169 (85.21%) records in WMED, ABI, and AMA, respectively. The second most common pathway was ‘transport-contaminant’ related to mariculture (~10% of the total), prevalently in ABI with 42 species (23.08%). The Canary Islands stand out for species introduced through oil platforms from throughout the world. ‘Unaided’ was a relevant pathway of secondary introduction into the WMED, particularly of Lessepsian species progressing westwards. Temporal trends in newly introduced species show similar behavior among subregions.This research was funded by Ministerio para la Transición Ecológica y el Reto Demográfico, grant number 11_MM_ESMARES2. The APC was funded by the ESMARES2-C3 project

Wide-Geographic and Long-Term Analysis of the Role of Pathogens in the Decline of Pinna nobilis to Critically Endangered Species

20 Pág.A mass mortality event (MME) affecting the fan mussel Pinna nobilis was first detected in Spain in autumn 2016 and spread north- and eastward through the Mediterranean Sea. Various pathogens have been blamed for contributing to the MME, with emphasis in Haplosporidium pinnae, Mycobacterium sp. and Vibrio spp. In this study, samples from 762 fan mussels (necropsies from 263 individuals, mantle biopsies from 499) of various health conditions, with wide geographic and age range, taken before and during the MME spread from various environments along Mediterranean Sea, were used to assess the role of pathogens in the MME. The number of samples processed by both histological and molecular methods was 83. The most important factor playing a main role on the onset of the mass mortality of P. nobilis throughout the Mediterranean Sea was the infection by H. pinnae. It was the only non-detected pathogen before the MME while, during MME spreading, its prevalence was higher in sick and dead individuals than in asymptomatic ones, in MME-affected areas than in non-affected sites, and it was not associated with host size, infecting both juveniles and adults. Conversely, infection with mycobacteria was independent from the period (before or during MME), from the affection of the area by MME and from the host health condition, and it was associated with host size. Gram (-) bacteria neither appeared associated with MME.This work was funded by: DG Pesca i Medi Mari (GOIB),EsMarEs (order IEO by MITECO, Spanish government), Life UFE IP-PAF INTEMARES (LIFE15 IPE ES 012) “Gestión integrada, innovadora y participativa de la Red Natura 2000 en el medio marino español,” the research project “Estado de conservación del bivalvo amenazado Pinna nobilis en el PNAC” (OAPN 024/2010), the project RECONNECT (MIS 5017160) of the Programme Interreg V-B “Balkan-Mediterranean 2014–2020.” MTES (French Government), DREAL (Direction Régionale Environnement Aménagement Logement) and Région Occitanie (France) for funding research and monitoring of Pinna.GC and PP were contracted under the INIA-CCAA cooperative research programme for postdoctoral incorporation from the Spanish National Institute for Agricultural and Food Research and Technology (INIA) (DOC INIA 8/2013 and 15/2015). MV-L was supported by a Juan de la Cierva-Incorporación postdoctoral contract (ICJI-2016-29329, MICIU Programme). ML-S and EÁ were supported by a Personal Técnico de Apoyo contract MINECO programme (PTA2015-11709-I and PTA2015-10829- I, respectively). CP and GS were supported by the project RECONNECT (MIS 5017160) financed by the Transnational Cooperation Programme Interreg V-B “Balkan-Mediterranean 2014–2020” and co-funded by the European Union and national funds of the participating countries. CP was supported by Sorbonne University.Peer reviewe

Monitoring coastal fish through remote underwater cameras: detectability, abundance, vulnerability and future applications

[spa] La gestión de la pesca recreativa es un reto particularmente difícil debido a (1) su creciente relevancia, sobre todo a lo largo de la costa mediterránea, y (2) a la escasez de datos disponibles. La relevancia de la pesca recreativa es hoy indiscutible, pero las capturas, la mortalidad por pesca, el esfuerzo pesquero, la abundancia y casi todos los descriptores de esta actividad son desconocidos o poco conocidos en la mayoría de los casos. Dificultando el conocer la dinámica de la población de las especies objetivo. Esta circunstancia impide el diseño, la implementación y la evaluación de cualquier plan de gestión con una base científica. Por lo tanto, es urgente desarrollar métodos de observación que proporcionen datos objetivos, precisos y exactos sobre la pesca recreativa. Esta tesis tiene como objetivo llenar este vacío, explorando las capacidades de las cámaras submarinas para la obtención de estos datos. Los avances tecnológicos experimentados por las cámaras submarinas han sido impresionantes en los últimos años. Actualmente, la calidad de la imagen, la duración de la batería, la durabilidad, la capacidad de memoria o el coste de éstas ya no son factores limitantes para su uso. Sin embargo, las imágenes subacuáticas deben traducirse en datos cuantitativos, necesarios para diseñar planes de gestión adecuados y que estén de acuerdo con los procesos ecológicos subyacentes. La conexión de imágenes y datos está lejos de ser banal. En concreto, he explorado cómo obtener datos para dos variables particularmente difíciles: la abundancia de peces y la vulnerabilidad de los peces a la pesca con caña. En el caso de la abundancia de peces, el primer paso fue combinar cámaras sin cebo y con visionado de campo horizontal con uno de los métodos más populares utilizados para estimar la abundancia de peces costeros: buceadores que cuentan peces a lo largo de transectos (es decir, censos visuales submarinos o UVC). He demostrado cómo combinar cámaras con UVCs para explorar y tener en cuenta cualquier dependencia ambiental o de las características de los peces en la detectabilidad de éstos y, lo que es más importante, he demostrado que una vez estimada la detectabilidad de los peces, la abundancia de éstos puede ser estimada con precisión y exactitud sólo mediante cámaras. Este hecho tan destacable abre la posibilidad de estimar la abundancia de peces a escalas espaciales y temporales relevantes para gestionar la pesca recreativa, siempre que el número de cámaras y el tiempo de implantación de éstas no sean factores limitantes. El siguiente paso fue resolver dos problemas pendientes: (1) el área mostrada por las cámaras sin cebo con visionado de campo horizontal no se puede estimar con precisión y (2) el método estadístico desarrollado para las cámaras proporciona valores de abundancia a la escala del método de referencia, en este caso, los UVC. A pesar de ser el estándar más común, también se reconoce que los UVC pueden introducir algunos sesgos a la hora de estimar la abundancia de peces. En consecuencia, se desarrolló un nuevo diseño de cámaras sin cebo con visionado de campo vertical, un nuevo protocolo de muestreo y un nuevo análisis estadístico. He demostrado que este nuevo marco produce estimaciones de la abundancia de peces de manera más precisa y exacta. Posteriormente, el tercer paso fue demostrar la aplicabilidad y la viabilidad de determinar la abundancia de peces a gran escala, tanto espacial como temporal. Como prueba de concepto, se estimó con éxito la abundancia de una especie de serránido objetivo de la pesca recreativa (Serranus scriba), a lo largo de más de 100 km de la costa sur de Mallorca. Además, este diseño permitió identificar los principales factores ecológicos que se correlacionan con la abundancia de peces. Por ejemplo, demostré que la abundancia de peces se correlaciona negativamente con la exposición a la pesca. En cuanto a la vulnerabilidad de los peces, he utilizado cámaras cebadas para averiguar los patrones de correlación de una variable sustituta (el tiempo de latencia hasta que el pescado muerde el cebo) con diversas variables relacionadas con los complejos procesos subyacentes. Los resultados evidenciaron que las interacciones pez-pez (sociales) juegan un papel relevante en la probabilidad de que un pez específico sea capturado. Los resultados reportados aquí sugieren firmemente que se debería encontrar una explicación mecanicista de los procesos que configuran la vulnerabilidad de los peces con el fin de mejorar el diseño de planes de gestión. En caso contrario, la pesca recreativa puede llegar a generar poblaciones con un gran porcentaje de peces no vulnerables, lo que no sólo es indeseable ecológicamente, sino que también afecta a la satisfacción de los pescadores. Finalmente, hemos explorado en profundidad una de las consecuencias ecológicas de la vulnerabilidad. Los marcos teóricos existentes plantean la hipótesis de que los peces no vulnerables pueden tener un potencial reproductivo menor que el de los peces vulnerables. En consecuencia, he desarrollado un método para cuantificar la vulnerabilidad de los peces y lo he aplicado para diseñar grupos experimentales en cautividad, emulando poblaciones con una vulnerabilidad media diferente. Los resultados demuestran que ni el número de huevos puestos ni el patrón de puesta estacional están relacionados con la vulnerabilidad de los peces. Por el contrario, la calidad de los huevos producidos por los peces no vulnerables parece ser mayor al final de la temporada de puesta que la de los peces vulnerables. Si la calidad de los huevos afecta la capacidad de supervivencia y dispersión de estos, los resultados de este hallazgo se deben explorar y tener en cuenta a la hora de diseñar planes de gestión espacial. Para terminar, esta tesis ha alcanzado su objetivo principal: desarrollar técnicas de muestreo viables y fiables basadas en cámaras subacuáticas, que produzcan datos precisos y exactos ya listos para ser utilizados para la evaluación de la pesca recreativa y de otras pesquerías con carencia de datos.[cat] La gestió de la pesca recreativa és un repte particularment difícil a causa de (1) la seva creixent rellevància, sobretot al llarg de la costa mediterrània, i (2) de l’escassetat de dades disponibles. La rellevància de la pesca recreativa és avui indiscutible, però les captures, la mortalitat per pesca, l’esforç pesquer, l’abundància i gairebé tots els descriptors d’aquesta activitat són desconeguts o poc coneguts en la majoria dels casos. Per tant, també es desconeix la dinàmica de la població de les espècies objectiu. Aquest fet impedeix el disseny, la implementació i l’avaluació de qualsevol pla de gestió amb una base científica. Per tant, és urgent desenvolupar mètodes d’observació que proporcionin dades objectives, precises i exactes sobre la pesca recreativa. Aquesta tesi té com a objectiu omplir aquest buit explorant-ne les capacitats de les càmeres submarines. Els avenços tecnològics experimentats per les càmeres submarines han estat impressionants en els darrers anys. Actualment, la qualitat de la imatge, la durada de la bateria, la durabilitat, la capacitat de memòria o el cost d’aquestes ja no són factors limitants. Tot i això, les imatges subaquàtiques s’han de traduir en dades quantitatives, necessàries per dissenyar plans de gestió adequats, d’acord amb els processos ecològics subjacents. La connexió entre imatges i dades és lluny de ser banal. En concret, vaig explorar com generar dades per a dues variables particularment difícils: l'abundància de peixos i la vulnerabilitat dels peixos a la pesca amb canya. En el cas de l’abundància de peixos, el primer pas va ser combinar càmeres sense esca amb visionat de camp horitzontal amb un dels mètodes més populars que s’utilitzen actualment per estimar l’abundància de molts de peixos costaners: bussejadors que compten peixos al llarg de transectes (és a dir, censos visuals submarins o UVC). Vaig demostrar com combinar càmeres i UVC per explorar i tenir en compte qualsevol dependència ambiental o del les característiques dels peixos amb la detectabilitat d’aquests i, el que és més important, vaig demostrar que un cop estimada la detectabilitat dels peixos, l’abundància d’aquests pot ser estimada amb precisió i exactitud només mitjançant càmeres. Aquest fet tan destacable obre la possibilitat d’estimar l’abundància de peixos a escales espaials i temporals rellevants per gestionar la pesca recreativa, sempre que el nombre de càmeres i el temps de desplegament d’aquestes no siguin factors limitants. El següent pas va ser resoldre dos problemes pendents: (1) l’àrea que mostren les càmeres sense esca amb visionat de camp horitzontal no es pot estimar amb precisió i (2) el mètode estadístic desenvolupat per a les càmeres proporciona valors d’abundància a l’escala del mètode de referència, que en aquest cas són els UVC. Tot i ser un dels ’estàndards més comuns, també es reconeix que els UVC poden introduir alguns biaixos a l’hora d’estimar l’abundància de peixos. En conseqüència, es va desenvolupar un nou disseny de càmeres sense esca amb visionat de camp vertical, un nou protocol de mostreig i una nova anàlisi estadística. Vaig demostrar que aquest nou marc produeix estimacions de l'abundància de peixos de manera més precisa i exacta. Després, el tercer pas va ser demostrar l'aplicabilitat i la viabilitat de controlar l'abundància de peixos a gran escala, tant espaial com temporal. Com a prova de concepte, es va estimar amb èxit l’abundància d’un serrànid que és una espècie objectiu de la pesca recreativa (Serranus scriba), al llarg de més de 100 km de la costa sud de Mallorca. A més, aquest disseny va permetre identificar els principals factors ecològics que es correlacionen amb l’abundància de peixos. Per exemple, vaig demostrar que l’abundància de peixos es correlaciona negativament amb l’exposició a la pesca. Pel que fa a la vulnerabilitat dels peixos, he utilitzat càmeres amb esca per esbrinar els patrons de correlació d’una variable sustituta (el temps de latència fins que el peix ataca l’esca) amb diverses variables relacionades amb els complexos processos subjacents. Els resultats van evidenciar que les interaccions peix-peix (socials) juguen un paper rellevant en la probabilitat que un peix específic sigui capturat. Els resultats reportats aquí suggereixen fermament que s’hauria de trobar una explicació mecanicista als processos que configuren la vulnerabilitat dels peixos per tal de millorar el disseny de plans de gestió. En cas contrari, la pesca recreativa pot arribar a generar poblacions amb un gran percentatge de peixos no vulnerables, cosa que no només és indesitjable ecològicament, sinó que també afecta la satisfacció dels pescadors. Finalment, he explorat en profunditat un dels conseqüències ecològiques de la vulnerabilitat. Els marcs teòrics existents plantegen la hipòtesi que els peixos no vulnerables poden tenir un potencial reproductiu menor que els peixos vulnerables. En conseqüència, he desenvolupat un mètode per quantificar la vulnerabilitat dels peixos i l’he aplicat per dissenyar grups experimentals en captivitat, emulant poblacions amb una vulnerabilitat mitjana diferent. Els resultats demostren que ni el nombre d’ous posats ni el patró de posta estacional estan relacionats amb la vulnerabilitat dels peixos. Per contra, la qualitat dels ous produïts pels peixos no vulnerables sembla ser més gran al final de la temporada de posta que la dels peixos vulnerables. Si la qualitat dels ous afecta la capacitat de supervivència i dispersió d’aquests, els resultats d’aquesta troballa s’han d’explorar i tenir en compte a l’hora de dissenyar plans de gestió espaial. Per acabar, aquesta tesi ha assolit el seu objectiu principal: desenvolupar tècniques de mostreig viables i fiables basades en càmeres subaquàtiques, per a produir dades precises i exactes ja llestes per ser utilitzades per l’avaluació de la pesca recreativa i d’altres pesqueries amb mancança de dades.[eng] Managing recreational fishing is particularly challenging because of (1) its growing relevance, particularly along the Mediterranean coast, and (2) the scarcity of data available. The relevance of recreational fishing is nowadays indisputable, but catches, fishing mortality, fishing effort, abundance and almost all the descriptors of this activity are unknown or poorly known in most of the cases. Thus, population dynamics of the target species remains unknown too. This fact precludes the design, implementation, and evaluation of any scientifically based management plan. Therefore, there is an urgent need for developing observation methods that supply objective, precise, and accurate data on recreational fishing. This thesis is aimed to fulfil this gap by exploring the capabilities of underwater cameras. The technological advances experienced by underwater cameras has been impressive in the recent years. Nowadays, image quality, battery life, durability, memory capability or cost are no longer limiting factors. However, the underwater images must be distilled into the quantitative data needed for designing proper management plans in accordance with the underlying ecological processes. Connecting images and data is far to be trivial. Specifically, I explored how to deliver data for two particularly challenging variables: fish abundance and fish vulnerability to angling. In the case of fish abundance, the first step was to combine unbaited cameras with horizontal field view with one of the most popular methods currently used for estimating abundance of many costal fish: scuba divers counting fish along transects (i.e., underwater visual censuses, or UVCs). I demonstrated how to combine cameras and UVCs for exploring and accounting for any environmental or fish dependencies on fish detectability and, more important, I proved that once fish detectability has been estimated, fish abundance could be precisely and accurately estimated using only cameras. Provided that the number of cameras and the deployment time are not limiting factors, this fact opens the possibility of estimating fish abundance at spatial and temporal scales relevant for managing recreational fisheries. The second step was to solve two pending problems: (1) the area surveyed by unbaited cameras with horizontal view cannot be precisely estimated and (2) the statistical method developed for the cameras renders abundance values at the scale of the reference method, which is, in this case, UVC. In spite of being the common standard, it is also recognized that UVC may introduce some biases when estimating fish abundance. Accordingly, a new design of unbaited cameras with vertical view, a new sampling protocol, and a new statistical analysis were developed. I demonstrated that this new framework produces estimates of fish abundance more precise and more accurate. The third step was to demonstrate the applicability and feasibility of monitoring fish abundance at large spatial and temporal scale. As a proof-of-concept, the abundance of a small serranid targeted by recreational fishers (Serranus scriba) was successfully estimated along more than 100 km of the South coast of Mallorca. Moreover, this design allowed identifying the main ecological drivers that are correlated with fish abundance. For example, I demonstrated that fish abundance is negatively correlated with exposure to fishing. Concerning fish vulnerability, I used baited cameras for disentangling the correlational patterns of a surrogate variable (latency time until a fish attacks the bait) with several variables related with the complex underlying processes. The results evidenced that fish-fish (social) interactions play a relevant role in the odds a specific fish has of being captured. The results reported strongly suggest that a mechanistic understanding of the processes shaping fish vulnerability should be unravelled in order to improve the design of appropriate management plans. Otherwise, recreational fishing may lead to populations with a large percentage of non-vulnerable fish, which is not only ecologically undesirable but also affects fisher’s satisfaction. Finally, I have in-depth explored one of the ecological outcomes of vulnerability. The existing theoretical frameworks hypothesize that non-vulnerable fish may depict smaller reproductive potential than vulnerable fish. Accordingly, I have developed a method for scoring fish vulnerability, and I have applied it to design experimental groups in captivity, emulating populations with a different average vulnerability. The results demonstrate that neither the number of eggs laid, nor the seasonal spawning pattern is related with fish vulnerability. Contrasting, the quality of the eggs quality of non-vulnerable fish seems to be higher toward the end of the spawning season than that of vulnerable fish. Provided that egg quality is affecting survival and dispersal capability, the outcomes of this finding should be explored and accounted for when designing spatial management plans. Overall, this thesis has achieved its primary objective: to develop feasible and reliable sampling frameworks based on underwater cameras that produce accurate and precise data ready to be used for assessing recreational fishing and other poor-data fisheries

Dataset: Mesoscale assessment of sedentary coastal fish density using vertical underwater cameras

Version 6.-- The script.R file contains the code for the analysis. The input.RData file is the data to run in the script and the estimates.RData file contains the results of the analysis.Accurate and precise monitoring of the absolute density (i.e., number of fish per area or volume unit) of exploited fish stocks would be strongly advisable for deriving stock status and for designing proper management plans. Moreover, monitoring should be achieved at relevant (i.e., sufficiently large) temporal and spatial scales. This objective is particularly challenging for data-poor fisheries, as is often the case for recreational fisheries. Therefore, the feasibility of underwater video monitoring (vertical unbaited cameras) for estimating, as a proof of concept, the absolute density (and its ecological drivers) of a coastal sedentary fish species is demonstrated. The absolute density of a small serranid (Serranus scriba) targeted by recreational fishing was estimated along the southern coast of Mallorca Island (nearly 100 km). The median fish density ranged between 111 ind/km2 (Es Molinar) and 14,110 ind/km2 (Cabrera). Absolute density was correlated with fishing exposure, habitat, and depth. Site specific, seemingly long-term, effects of fishing exposure were negatively correlated with fish density, but short-term effects (assessed by the interaction between fishing exposure and before/after the season when recreational fishing occurred in the study area) were not detected. We suggest that the short-term effects of fishing may remain undetected because highly exploited sites could contain fish that are already not vulnerable to recreational fishing gear, irrespective of the short-term fishing pressure exerted. Such a process may explain some hyper-depletion patterns and should preclude the use of fisheries-dependent data for monitoring fish density. The results reported here indicate that monitoring fish abundance with vertical unbaited cameras at large spatial and temporal scales can be a reliable alternative for many species.Peer reviewe

Common octopus settled in human-altered Mediterranean coastal waters: From individual home range to population dynamics

A spatially explicit capture-recapture (SCR) model was applied to estimate simultaneously population parameters and individual activity (i.e. home range size) of O. vulgaris, based on experimental mark-recapture data in a human-altered Mediterranean coastal area. Seventy-two octopuses were captured, tagged with subcutaneous PIT-tags and released. Nineteen tagged individuals were recaptured (recapture rate: 26.4%) in the same area over the study period, which spanned over 6 months. Population sizes and densities decreased over the study period, from 337 octopuses (8 ind. ha -1) in September-October to 105 octopuses (2.5 ind. ha -1) in February-March. The highest recruitment probability was estimated to occur at the beginning of the study but it clearly decreased over time, while mortality probability during a fishing period slightly increased. Mean specific growth rate was 0.82 ± 0.11 day -1. Individual home range or activity area ranged from 2.8 ha to 7.3 ha (median home range radius: 121.8 m). Overall, these results suggest that human-altered coastal habitats, which are characterized by abundant shelters, abundant food and absence of predators, can act as settlement and growth areas for juveniles and adults of O. vulgaris. Furthermore, the methodologies applied in this study are recommended as innovative tools to improve management actions of coastal resources.P.A.L. was supported by a post-doctoral grant (Juan de la Cierva–Incorporación: IJCI-2015-25595) from the Spanish Ministry of Economy, Industry and Competitiveness; and G.F.B. was supported by a pre-doctoral fellowship (FPI-INIA) from the National Institute for Agricultural and Food Research and Technology (INIA).N

Total nitrogen, carbon and phosphorus digestibility in gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) fed with conventional and organic commercial feeds: implications for particulate waste production

Organic fish farming is postulated as a more environmentally friendly activity than conventional activities. However, environmental sustainability as regards waste output has not been addressed. In this respect, the most important environmental problems associated with fish farming are those related with the discharge of particulate wastes. In this study, total nitrogen, carbon and phosphorus digestibility was estimated in a wide size range of gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) fed a commercially available conventional diet and an organic feed, as a previous step to assessing particulate waste output. Neither fish size nor feed nutrient content was seen to influence nutrient digestibility in either species. The organic diet provided higher carbon but lower nitrogen and phosphorus digestibility than conventional feed in both species. Simulations under real ongrowing conditions resulted in lower values for nitrogen and higher values for carbon particulate wastes when conventional feed was supplied to both species. Particulate phosphorus wastes were 2.6- to 3.4-fold higher for fish fed the organic diet. Restrictions concerning NO the raw materials used for organic diet formulation and differences in nutrient bioavailability between the diets seemed to be the underlying reason for the differences found.This research was funded by the Spanish Institute of Agro-Forestry Research (INIA; Ministry of Economy and Competitiveness; Project RTA2011-00088-00-00). The study was also partially sponsored by the Sub-Programme of Researcher Formation of the Spanish Institute of Agro-Forestry Research (FPI-INIA)

Total nitrogen, carbon and phosphorus digestibility in gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) fed with conventional and organic commercial feeds: implications for particulate waste production

[eng] Organic fish farming is postulated as a more environmentally friendly activity than conventional activities. However, environmental sustainability as regards waste output has not been addressed. In this respect, the most important environmental problems associated with fish farming are those related with the discharge of particulate wastes. In this study, total nitrogen, carbon and phosphorus digestibility was estimated in a wide size range of gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) fed a commercially available conventional diet and an organic feed, as a previous step to assessing particulate waste output. Neither fish size nor feed nutrient content was seen to influence nutrient digestibility in either species. The organic diet provided higher carbon but lower nitrogen and phosphorus digestibility than conventional feed in both species. Simulations under real ongrowing conditions resulted in lower values for nitrogen and higher values for carbon particulate wastes when conventional feed was supplied to both species. Particulate phosphorus wastes were 2.6- to 3.4-fold higher for fish fed the organic diet. Restrictions concerning NO the raw materials used for organic diet formulation and differences in nutrient bioavailability between the diets seemed to be the underlying reason for the differences found