Synergizing basic and applied scientific approaches to help understand lamprey biology and support management actions

Lampreys (Petromyzontiformes) are a key component of freshwater ecosystems throughout temperate parts of the world. Of the 44 described species of lamprey, the sea lamprey (Petromyzon marinus) is certainly the most commonly recognized. This species has expanded its range from the Atlantic Ocean basin where it is of conservation concern in North America and Europe into the Laurentian Great Lakes where it is subject to a large-scale international control program. Many other species of lamprey are imperiled and require management intervention to ensure their persistence. These management efforts range from routine assessment and monitoring to active or proposed restoration plans where they have been extirpated. Regardless of whether the goal is to control or conserve a given lamprey population, an understanding of their basic biology is paramount when generating and executing management plans. Here, we take a broad look across core aspects of biology (survival, foraging, and reproduction) that encompass challenges and opportunities in regard to future science-based management of lampreys. We attempt to synergize basic and applied research to highlight where these findings are most applicable to solving management problems and reveal knowledge gaps. We conclude by suggesting future research avenues and questions aimed to stimulate progress in both basic and applied lamprey research

Salinity and Atrazine Sublethal Levels Induce Gill Cells Basolateral Membrane Phospholipids Modulation in Sea Lamprey Downstream Migrants

Conditions experienced by anadromous fishes while in freshwater may be critical to their subsequent survival in the sea. During the trophic migration to the ocean, juveniles of sea lamprey (Petromyzon marinus L.) are exposed to several stress factors, including different types of pollutants. We analyzed gill histopathological biomarkers, characterized the lipid profile of the basolateral membrane (BLM) of gill cells, and determined NKA activity, in order to evaluate if BLM lipid profile system plays a part in modulation of NKA activity and may be involved in the successful acclimation of sea lamprey juveniles during downstream migration

Into the Wild: A New Approach to the Aquaculture Production of Brown Trout (Salmo trutta L.) to Enhance Restocking Success

The brown trout (Salmo trutta L.) is one of the most iconic native species from European river ecosystems and is also one of the main species of interest for recreational fishing activities (e.g., fly fishing). This species has a significant potential to attract anglers and related investment to the main fishing grounds, which are usually located in poorly developed areas and away from main city centers. Due to its environmental and socioeconomic value, this species is often targeted by management programs directed to the protection and sustainable exploitation of this valuable natural resource. One of the most common actions to enhance the abundance and condition of trout populations is the restocking of wild populations with fish from aquaculture facilities. However, most fish come from fishfarms using production methods such as high densities in the tanks, use of commercial food and standardized feeding methods, lack of environmental stimulus, and domestication of breeding stocks, which usually results in poor fitness and very low survival rates after release. This consequently leads to reduced success of these management actions. To contribute to solving these problems and enhancing the success of restocking actions for the recovery and sustainable enhancement of wild trout populations, we propose a novel approach to the production of this species, by testing and implementing a new protocol that aims to produce wild-reared trout. These fish come from wild breeders and will be produced with the least human contact in conditions that mimic their natural habitat. Taking advantage of a recently remodeled and re-equipped aquaculture facility, located in Central Portugal (Posto Aquícola de Campelo, Figueiró dos Vinhos), we are rearing trout in low densities (10–20 trout/m3 ), like the ones observed in natural habitats, using live food (larvae and insects), and subjected to environmental stimuli such as refuges, and water and flow variability, equivalent to those observed in local streams. Accompanied by a pre- and post-restocking monitoring program (e.g., evaluation of trout abundances and habitat in the target stream, dispersion and movement patterns and survival), this study will contribute to enhancing the success of future restocking actions, promoting the sustainable enhancement of wild trout populations, and, thus, increasing the interest of restocked fishing grounds for angling activities and associated incomes

Impact of phlorotannin extracts from fucus vesiculosus on human gut microbiota

Recent studies indicate that plant polyphenols could be pointed as potential prebiotic candidates since they may interact with the gut microbiota, stimulating its growth and the production of metabolites. However, little is known about the fate of brown seaweeds’ phlorotannins during their passage throughout the gastrointestinal tract. This work aimed to evaluate the stability and bioaccessibility of Fucus vesiculosus phlorotannins after being submitted to a simulated digestive process, as well as their possible modulatory effects on gut microbiota and short-chain fatty acids production following a fermentation procedure using fecal inoculates to mimic the conditions of the large intestine. The stability of phlorotannins throughout the gastrointestinal tract was reduced, with a bioaccessibility index between 2 and 14%. Moreover, slight alterations in the growth of certain commensal bacteria were noticed, with Enterococcus spp. being the most enhanced group. Likewise, F. vesiculosus phlorotannins displayed striking capacity to enhance the levels of propionate and butyrate, which are two important short-chain fatty acids known for their role in intestinal homeostasis. In summary, this work provides valuable information regarding the behavior of F. vesiculosus phlorotannins along the gastrointestinal tract, presenting clear evidence that these compounds can positively contribute to the maintenance of a healthy gastrointestinal condition.info:eu-repo/semantics/publishedVersio

Meso- and Micro-Habitat Preferences of European River and Brook Lamprey in a Mediterranean River Basin

The European river (Lampetra fluviatilis Linnaeus, 1758) and brook (Lampetra planeri Bloch, 1784) lampreys are considered ‘paired species’, i.e., they are closely related and morphologically very similar but have distinct modes of adult life (anadromous vs. resident). In the Iberian Peninsula, the southern limit of both species’ distribution, they face different pressures (e.g., barriers, pollution, hydrological stress) that reduce the available habitat, which is exacerbated by the actual climate change context. The main objective of the present study was to evaluate meso- and microhabitat preferences of Lampetra sp. On the mesohabitat scale, the environmental variables that influence these species’ distributions on the watershed scale were identified. On the microhabitat level, besides identifying the fine-scale variables that influence the presence and abundance of Lampetra sp., possible changes in habitat preferences throughout the larval stage (i.e., distinct size/age classes) were also assessed. Mesohabitat results suggest that the relative abundance of Lampetra sp. is related to variables such as pH and riparian vegetation. Regarding the microhabitat, the relative abundance of the size classes’ distribution seems to be associated with variables such as substrate granulometry. The results in terms of habitat preferences on a Mediterranean basin are discussed in the context of a climate change scenario (e.g., decrease in habitat quality and availability) and management and conservation perspective

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

Session D1: Modelling the Efficiency of a Vertical Slot Fishway for Anadromous Fishes

Abstract: Several types of fish passage are increasingly being installed in river barriers to restore the longitudinal connectivity of fragmented riverine habitats. A vertical slot fishway installed in the Açude-Ponte weir at Coimbra (River Mondego, Portugal) was monitored to model the efficiency of this infrastructure for anadromous fishes (i.e., sea lamprey Petromyzon marinus L.; allis shad Alosa alosa L. and twaite shad Alosa fallax Lacépède, 1800) throughout 2013 and 2014 spawning seasons. Fish passage was assessed using a video recording system. Simultaneously, eight abiotic parameters, considered as potential predictors of fishway’s use by anadromous fishes, were continuously recorded during the entire study period. Boosted Regression Trees (BRTs) analysis was applied to relate the use of the fishway by sea lamprey and Alosa spp. with the abiotic predictors. To complement this data, a passive integrated transponder (PIT) antenna system was used to quantify passage efficiency for sea lampreys. Size frequency distribution and total biomass of fishes that successfully transposed the fishway was also estimated. Video data show that in the migratory seasons of 2013 and 2014, 8333 and 21979 sea lampreys passed through fishway, respectively, and a total of 7503 and 3404 Alosa spp. individuals transposed this infrastructure during the same period. About 30% of PIT tagged lampreys transposed the fishway. BRT models identified the river flow as the most important variable to explain use of the fishway by anadromous fishes. The relationships of this variable with the fish passages suggest that sea lampreys and Alosa spp. use the fishway preferentially at relatively low flow conditions that maximize the attraction efficiency of the fishway entrance. Finally, results obtained with this study were used to implement a sub-sampling methodology (video processing) to estimate the total amount of fish (lamprey and shads) that annually use the fishway during their spawning migrations

A vida no limite: gestão e conservação das populações de salmão do Atlântico em Portugal

O salmão do Atlântico (Salmo salar L.) é uma espécie migradora diádroma emblemática dos ecossistemas aquáticos do hemisfério norte. Em Portugal, que representa o limite sul da distribuição global desta espécie, o salmão encontra-se classificado como Criticamente em Perigo, ocorrendo apenas nas bacias hidrográficas dos rios Minho, a população mais abundante, e Lima, registando-se algumas ocorrências ocasionais nos rios Cávado e Douro. Em Portugal a espécie está sujeita a diversas pressões (e.g., barreiras à continuidade fluvial, legislação pesqueira desadequada, alterações climáticas), e existe um reduzido conhecimento sobre estas populações que impede a definição e concretização de medidas de gestão e conservação adequadas. A presente comunicação tem como objetivo dar a conhecer os objetivos e trabalhos práticos previstos no âmbito de dois projetos científicos atualmente a decorrer e focados nas populações nacionais de salmão, com particular enfoque nas bacias dos rios Minho e Lima. Através de uma parceria entre cientistas e pescadores comerciais e recreativos, o projeto “SalmonLink - Contribuição dos cientistas e pescadores para a conservação e gestão participada das populações de salmão do Atlântico em Portugal”, financiado pelo MAR2020 e coordenado pela Universidade de Évora/MARE, pretende contribuir para aumentar o conhecimento sobre as populações nacionais de salmão e propor medidas que possam promover a gestão sustentável desta espécie. De forma complementar, o projeto internacional “SMOLTrack III - Quantifying smolt survival from source to sea: informing management strategies to optimise returns”, financiado pela Comissão Europeia no âmbito da NASCO (North Atlantic Salmon Conservation Organization), integra vários especialistas europeus num esforço conjunto para estudar a migração para o mar dos juvenis de salmão e os fatores que podem contribuir para a mortalidade destes indivíduos. Em Portugal, este projeto decorrerá ao longo de três anos, nos rios Minho e Lima, igualmente sob a coordenação nacional da Universidade de Évora/MARE. Para além de contribuir para melhorar os programas de gestão e conservação dirigidos ao salmão nas bacias hidrográficas nacionais, o aumento do conhecimento sobre as populações desta espécie que ocorrem no limite sul da sua distribuição global, irá permitir a identificação de eventuais estratégias de vida alternativas, associadas à sobrevivência em locais com condições ambientais sub-ótimas para espécie como são os nossos rios, de extrema importância num contexto de alterações climáticas e aquecimento global

Temporal patterns of the catadromous thinlip grey mullet migration in freshwater

The thinlip grey mullet (Chelon ramada Risso, 1827) is a catadromous fish that performs massive migrations to freshwater habitats for feeding purposes that can assume a structuring role on riverine ecology due to the biomass involved in these movements. Seasonal movements of thinlip grey mullet through a vertical slot fish pass located in River Mondego (Portugal) were continuously monitored between 2013 and 2017. The extent of trophic migration, population size structure, biomass and the environmental triggers of bi-directional species' migratory activity were analysed. Between March and November of 2013/2014, ~2 million and 1 million movements were respectively recorded. From a subsampling approach, the upstream movements between 2015 and 2017 were estimated. Annually, around five hundred thousand upstream movements can occur to provide species access to the upstream freshwater reaches. Movements are exclusively diurnal, and the population composed by young adults in their first year of maturity, yet juveniles and larger fish were present (TL range: 90–540 mm). Upstream movements increased with temperatures above 15°C, reaching a peak at around 20°C coupled with a photoperiod of 15 h. Downstream movements attained the higher rates when temperature dropped from 22°C to 20°C and photoperiod to 13 h. However, under wetter hydrological conditions (as in 2014), discharge flows have a higher influence. These finding provide unique information regarding species migration to freshwater habitats in the Atlantic coast, namely the extended periods spent in such environments, overlapping with the spawning migration period. Additionally, highlights the importance of species' trophic migration both for its life cycle and riverine food-web