Argyrosomus regius (Asso, 1801) fishery and ecology in portuguese waters, with reference to its relationships to other european and african populations

Tese de doutoramento, Biologia (Biologia Marinha e Aquacultura), Universidade de Lisboa, Faculdade de Ciências, 2014Life history parameters of valuable marine fish remain poorly studied worldwide. The meagre (Argyrosomus regius) is a large sciaenid from European and North African waters that, on its European range, supports regional small-scale and recreational fisheries and is considered a promising candidate species for aquaculture. However, its fisheries and ecology have remained poorly documented. The present work describes (1) progress made on raising scientific and societal awareness on this fish resource, (2) research carried out on the Portuguese fisheries targeting meagre and on the main biological parameters of the species in Portuguese waters. The study of fish remains from archaeological sites showed that both adult and juvenile meagre have been fished in Portuguese estuarine and coastal environments since, at least, the Mesolithic period. Today, two main commercial fisheries on meagre exist: one that targets meagre on the Western coast (within the Tagus estuary and off Peniche); and the other that captures the fish as by-catch in the Southeastern coast of Portugal. Using a new sampling methodology (commercial mark-recapture) a comprehensive set of otoliths and gonads was collected. Analyses of these samples showed that meagre is long-lived (up to 43 years old), displays fast juvenile growth and is reproductively active in spring and summer both in estuaries (Tagus and Guadiana) and adjoining coasts. Furthermore, it shows that both meagre males and meagre females display some signs of precocious maturity and that the meagre females are asynchronous batch spawners that likely have indeterminate fecundity. Moreover, microsatellite work showed that meagre populations in Europe and North Africa are highly fragmented. Finally, a statistical time series methodology is presented (SARIMA) that uses landings under a process control perspective to provided baseline monitoring to fisheries resources currently found in data-poor situation.Fundação para a Ciência e a Tecnologia (FCT, SFRH/BD/12550/2003, POCTI/MAR/15263/1999 - III Quadro Comunitário de Apoio - 2000-2006); Direção Geral das Pescas e Aquicultura, projeto CORV POCTI/MAR/15263/1999

Use of SARIMA Models to Assess Data-Poor Fisheries: A Case Study With A Sciaenid Fishery Off Portugal

Research on assessment and monitoring methods has primarily focused on fisheries with long multivariate data sets. Less research exists on methods applicable to data-poor fisheries with univariate data sets with a small sample size. In this study, we examine the capabilities of seasonal autoregressive integrated moving average (SARIMA) models to fit, forecast, and monitor the landings of such data-poor fisheries. We use a European fishery on meagre (Sciaenidae: Argyrosomus regius), where only a short time series of landings was available to model (n=60 months), as our case-study. We show that despite the limited sample size, a SARIMA model could be found that adequately fitted and forecasted the time series of meagre landings (12-month forecasts; mean error: 3.5 tons (t); annual absolute percentage error: 15.4%). We derive model-based prediction intervals and show how they can be used to detect problematic situations in the fishery. Our results indicate that over the course of one year the meagre landings remained within the prediction limits of the model and therefore indicated no need for urgent management intervention. We discuss the information that SARIMA model structure conveys on the meagre life-cycle and fishery, the methodological requirements of SARIMA forecasting of data-poor fisheries landings, and the capabilities SARIMA models present within current efforts to monitor the world\u27s data-poorest resources

Revidering av miljöövervakningen i trendsjöar : färre nät eller färre provfisken?

Sedan år 2007 utförs standardiserade provfisken med nordiska översiktsnät (SS-EN 14757) i knappt hälften av de så kallade trendsjöarna inom nationell miljöövervakning. 15 sjöar provfiskas varje år och 30 vart 6-e år, med 8-48 bottennät och 0-10 pelagiska nät, beroende på sjöns area och djup. Vi utredde om det går att upptäcka skillnader mellan år med färre nät och trender över tid med glesare än årlig frekvens. I så fall ryms fler sjöar inom oförändrad budget, och nuvarande sjöar kan behållas om budgeten minskar. Dessutom ska svenska myndigheter ska sträva efter att minska onödigt lidande och dödande i förhållande till nyttan vid användningen av försöksdjur, i enlighet med principen 3R (reduce, refine, replace).I denna rapport fokuserade vi på konsekvenser för kvaliteten på insamlade data genom; 1. ett minskat antal lagda nät vid ett givet provfiske, 2. en minskad frekvens till vart annat år för sjöar som idag provfiskas varje år. Dessutom indikerade vi hur kostnader (antal fältdagar) kan påverkas av förändrad nätläggning i tid och rum.Med begränsad tid till punkt 1 analyserades data från en sjö (Stensjön), som grund till senare analyser för andra sjöar. Vi använde en beräkningsmetod ifrån tidigare optimering av kustfiskövervakningen, modifierad för beräkning av artspecifik fångst per ansträngning (antal och biomassa) och de indikatorer som ingår i tre multimetriska fiskindex som används i bedömning av ekologisk status enligt ramdirektivet för vatten. Via bootstrap gjordes 10000 slumpmässiga urval av åtta nät vardera i tre djupstrata (standard för en sjö av Stensjöns storlek), för varje år under 1994- 2021. Därefter upprepades proceduren med sju, sex, fem och fyra nät per djupstratum och år. Med nuvarande nätansträngning uppfylldes målet att särskilja skillnader på 100% mellan år i ansträngning mellan år för de vanligaste fiskarterna i sjön och för alla indikatorer i bedömningsgrunderna. I just denna sjö skulle vi ha upptäckt skillnader mellan år med de lägsta och de högsta observerade värdena även om vi bara hade lagt sex eller fler nät per djupstratum.För punkt 2 analyserades befintliga dataserier från 15 sjöar som nu provfiskas varje år. Ickeparametriska trendtester visade att med provfisken vart annat år var sannolikheten lägre att vi skulle ha upptäckt ökningar eller minskningar över tid jämfört med provfisken varje år. Några åldersbaserade indikatorer kunde dock beräknas för alla år, även på urval av prover tagna vart annat år. Med provtagning vart annat år kunde en ökande trend i abborrens storlek upptäckas för 61% av signifikanta trender med provtagning varje år. För de vanligaste arterna abborre och mört kunde vi i 74 respektive 68 % av jämförelserna upptäcka samma starka eller svaga årsklasser med prover från vartannat som med prover från alla år.Hypotetiska beräkningar indikerade att flest fältdagar (195) skulle frigöras per sexårsperiod om 15 sjöar med årligt provfiske istället provfiskas vart annat år. Det skulle kunna motsvara provfiske en gång vart sjätte år i många av de trendsjöar som idag saknar provfiske. 57 fältdagar skulle frigöras om frekvensen halverades i de fyra sjöar som bara har årliga provfisken sedan 2007. Minskning med en fältdag per provfiske i sjöar med en ansträngning på minst 24 nät motsvarar 68 frigjorda fältdagar.Alla reduktioner av antal lagda nät skulle leda till färre dödade fiskar per sjö och sexårsperiod, i linje med 3R-strategin. Sjöar med årligt provfiske ger viktig information om mellanårsvariation, som behövs för att tolka resultat från sjöar med glesare provfiskefrekvens, i den nationella miljöövervakningen och i program som drivs av andra aktörer. Ur detta perspektiv är det klokast att försöka minska antal nät per provfiske, om det kan göras med godtagbar kvalitetssänkning. En sådan bedömning behöver göras för varje sjö, t.ex. med den metod som i detta projekt anpassades till data från Stensjön

Underwater noise recognition of marine vessels passages: two case studies using hidden Markov models

Passive acoustic monitoring (PAM) is emerging as a cost-effective non-intrusive method to monitor the health and biodiversity of marine habitats, including the impacts of anthropogenic noise on marine organisms. When long PAM recordings are to be analysed, automatic recognition and identification processes are invaluable tools to extract the relevant information. We propose a pattern recognition methodology based on hidden Markov models (HMMs) for the detection and recognition of acoustic signals from marine vessels passages and test it in two different regions, the Tagus estuary in Portugal and the Öresund strait in the Baltic Sea. Results show that the combination of HMMs with PAM provides a powerful tool to monitor the presence of marine vessels and discriminate different vessels such as small boats, ferries, and large ships. Improvements to enhance the capability to discriminate different types of small recreational boats are discussed.info:eu-repo/semantics/publishedVersio

Frameless-Finding and Refining A Sampling Frame for Surveying Recreational Fisheries: Lessons from Estimating Swedish Harvest of Western Baltic Cod

To achieve sustainable fisheries, advice to management should be based on reliable science and unbiased data. Attaining quality data (i.e. precise and unbiased) on recreational fishing can be challenging, particularly when prior knowledge of the sector is limited and a proper sample frame of recreational fishers or vessels does not exist. In this study, a registry of access points was constructed for the Swedish south–west coast and used as a spatial sample frame in determining both effort and catches of the private boat fishery. Sampling dates, times for sampling, and access points visited were selected using probabilistic methods, ensuring unbiased results. The final multi-stage sampling design involved multiple strata, clusters, and probability selection methods and enabled first-time estimation of Swedish recreational landings of western Baltic cod by private boats to be used in stock assessment. Concurrent data collection covering aspects such as boat counts at access points, provided additional information on e.g. activity patterns. That additional information opens possibilities to refine the design of the original survey and optimize the sampling effort towards different goals, such as other fished resources. In this paper, we reflect on the challenges that limitations in initial information poses to the design and deployment of a new recreational fisheries survey. We suggest ways, whereby indirect sampling frames can be developed from initially incomplete or limited information to access the fishers and their catch. Our experience shows that, despite initial frame and knowledge limitations, full probabilistic methods are worth considering in data limited scenarios and that the design-based point estimates and variances they provide on recreational fishing effort and catches are useful in guiding initial management and the next steps of survey improvement

Genetic Structure of Meagre (Argyrosomus regius) in Portugal: Implications for Fisheries Management

The meagre Argyrosomus regius (Asso, 1801) is a marine migratory species with a wide distribution range encompassing the north-eastern and central-eastern Atlantic Ocean, the Mediter ranean Sea, and the western Black Sea. A. regius is one of the largest overexploited sciaenids, being a valuable resource for aquaculture and fisheries along its distribution range. The Iberian Peninsula is considered an intermediate area between two genetically distinct groups of A. regius populations, one in the north-eastern Atlantic Ocean and one in the eastern Mediterranean Sea. The current knowledge on the population dynamics and distribution of this species has been derived from commercial and recreational fishery catches; therefore, little is known about the importance of the Iberian Peninsula for the species’ management and conservation. The aim of this study is to evaluate the A. regius population genetic structure along the Portuguese coast taking into consideration the north-eastern Atlantic region. To achieve this goal, the genetic diversity, differentiation, populational structure and demographic history of A. regius populations along the Atlantic coast were analyzed using 15 microsatellite loci. The detected populational structure indicates that A. regius species in Portugal are divided into two distinct stocks, one across the Portuguese western coast, possibly related to the Tagus spawning and nursery area, and another one on the southern coast. This study reveals the need for A. regius-specific fishery management plans in Portugal and underlines the importance of considering the genetic structure of A. regius populations when delineating such management plans

Evidence of Genetic Segregation among Meagre (Argyrosomus regius) Atlantic Spawning Areas

The meagre Argyrosomus regius, one of the largest sciaenidae in the world, is a valuable resource for fisheries and aquaculture. Despite its socioeconomic relevance, knowledge about population dynamics and wild stocks is still scarce, and conservation risks are associated with overexploitation. Two genetic distinct groups, one in the North Atlantic Ocean and one in the eastern Mediterranean Sea, were identified by previous studies. However, little is known about the genetic structure of the Atlantic group, where four important spawning areas have been identified. To assess if each spawning area is an independent breeding unit, the genetic diversity, populational structure, and demographic history of A. regius along the North-East and Eastern Central Atlantic coast were analyzed, using 15 microsatellite loci. Results corroborate the hypothesis tested, suggesting four genetic groups: a first group encompassing individuals from the Gironde spawning area, a second group encompassing individuals from the Tagus spawning area, a third group corresponding to individuals captured in the Algarve region, and a forth group gathering individuals from Morocco and Mauritania. This study reveals the need for specific fisheries management plans considering genetic structure information, and highlights the need for international cooperation

Evidence of Genetic Segregation among Meagre (Argyrosomus regius) Atlantic Spawning Areas

The meagre Argyrosomus regius, one of the largest sciaenidae in the world, is a valuable resource for fisheries and aquaculture. Despite its socioeconomic relevance, knowledge about population dynamics and wild stocks is still scarce, and conservation risks are associated with overexploitation. Two genetic distinct groups, one in the North Atlantic Ocean and one in the eastern Mediterranean Sea, were identified by previous studies. However, little is known about the genetic structure of the Atlantic group, where four important spawning areas have been identified. To assess if each spawning area is an independent breeding unit, the genetic diversity, populational structure, and demographic history of A. regius along the North–East and Eastern Central Atlantic coast were analyzed, using 15 microsatellite loci. Results corroborate the hypothesis tested, suggesting four genetic groups: a first group encompassing individuals from the Gironde spawning area, a second group encompassing individuals from the Tagus spawning area, a third group corresponding to individuals captured in the Algarve region, and a forth group gathering individuals from Morocco and Mauritania. This study reveals the need for specific fisheries management plans considering genetic structure information, and highlights the need for international cooperation.info:eu-repo/semantics/publishedVersio

Acoustic Telemetry Unravels Movements and Habitat Use Patterns of Juvenile Meagre (A. regius) in the Tagus Estuary

The meagre is among the largest Sciaenidae in the world (max: 230 cm, 103 kg), with a wide distribution range encompassing the NE and CE Atlantic Ocean and the Mediterranean Sea. The life cycle in Atlantic waters includes migratory movements from feeding and overwintering areas at sea to spawning and nursery areas in estuaries and coastal waters. However, significant spawning aggregations are only observed in five locations, among which is the Tagus estuary (Portugal). The meagre fishery that takes place within the Tagus estuary is significant, accounting for approximately two-thirds of Portuguese meagre catches. Despite its economic relevance, the meagre movements in that region remain largely unknown. The existence of a target fishery inside the estuary alongside a lack of routine biological data collection targeting the species and incipient fisheries control in the area, highlight an urgency to adopt innovative methodologies to unravel meagre migrations and its use of critical areas. We present the first insights of movement patterns and habitat use in the Tagus estuary using acoustic biotelemetry data collected between 2019 and 2021. The acoustic receiver array obtained a total of 142.183 registers from a total of 34 individuals tagged. From the tagged specimens, 33% revisited the Tagus estuary in subsequent years at least once, during the spring and summer, and 49% remained in the Tagus at least until autumn. Further analysis was conducted with juveniles tracked over 3 years to identify critical nursery areas using dynamic Brownian bridge movement models (utilization distribution estimations). The effects of abiotic conditions on the meagre behaviour were assessed using in situ sensor data (e.g., temperature and salinity) and other environmental predictors (e.g., photoperiod and tide cycle) and an explanatory model was developed that helps to understand the use of the Tagus estuary by juveniles. The information collected will be discussed in light of possible applications to promote sustainable management of meagre fisheries in the Tagus estuary and adjacent coastal areas

STRENGTHENING REGIONAL COOPERATION IN FISHERIES DATA COLLECTION

fishPi was a research project with the aim of “Strengthening regional cooperation in the area of fisheries data collection”. The project brought together over 40 experts from 13 scientific institutes in 12 countries (10 member states (MS)) and two internationally recognised survey design experts. It was funded by EU MARE grant MARE/2014/19, with a 14 month timeline commencing in April 2015. This project has trialled the way sampling designs would be developed in a regional setting and showed that collaboration and consultation is required at face to face meetings through regional groups that focus on a particular group of fisheries. The project was the first step in this process and one of the main outcomes is the framework to take the process forward; developing data formats, data sharing agreements and easily accessible software for data sharing, checking and analysis, and for the simulation testing of sampling designs.European Unio