Arjan P Palstra

• Dr. Ir. Physiology (PhD)
• Senior Researcher at Wageningen University & Research

This study investigated the heart rate (HR) and acceleration (AC) dynamics of Atlantic salmon (Salmo salar) during a swim fitness test in a swim tunnel. Experimental fish were implanted with data loggers equipped with HR and AC sensors. These fish, and controls that were not implanted, were subjected to a swim-fitness test at incremental speeds fro...

Simple Summary Temperature rises, competition for coastal resources, and stricter regulations are forcing finfish farms to move from sheltered shore locations to more exposed open ocean areas. But knowledge is lacking on how the flow conditions in sea pens in these open areas will affect their physiological performance. To evaluate the swimming per...

Simple Summary The yellowtail kingfish is a highly active and fast-growing marine fish with promising potential for aquaculture. In this study, we learned about the energy that these fish spend by measuring heart rate and acceleration during both a test where fish had to swim at increasing speeds and a test where fish were subjected to four steps o...

Ovulation in European eel is induced by injection of 17α,20β-dihydroxy-4-pregnen-3-one (DHP) as the maturation-inducing hormone (MIH). Female eels need to ovulate within 18 h after injection to release good quality eggs. Progesterone (P), as an upstream precursor of DHP, may promote endogenous DHP production and improve egg quality. The purpose of...

To induce oocyte development, eels are weekly injected with salmon or carp pituitary extract (CPE). The weekly handling and hormone peaks result in inferior oocyte quality; therefore, alternative treatments that improve oocyte quality and reproductive success require investigation. The enhancement of early sexual maturation by a single injection wi...

Commonly, female European eels are injected weekly with pituitary extract (PE) from carp (CPE) or salmon (SPE) to induce sexual maturation. However, a PE is a mixture of gonadotropins and other hormones that are not specific for eel and rapidly cleared from circulation. The aim of this study was therefore to test the effects of highly stable eel-sp...

Assisted propagation of the European eel will lead to a closed production cycle supplying the aquaculture industry with juvenile glass eels. Females require long-term weekly treatment with pituitary extract (PE), which is stressful and causes abnormalities in oogenesis. We tested the effects of 17α-methyltestosterone (17 MT), as potent androgen act...

Critical swimming speed (Ucrit) is an important measurement of swimming performance and a good indicator for cardio-respiratory health. It offers a new opportunity to select fish with better fitness. However, the genomic architecture of swimming performance at whole genome level is not clear in Nile tilapia. For this study, swimming performance was...

Nile tilapia is predominantly produced in smallholder ponds without aeration. We hypothesize that Nile tilapia with high oxygen uptake efficiency (O 2 UE) may perform better under these conditions than Nile tilapia with low O 2 UE. Critical swimming speed ( U crit , in cm s ⁻¹ ) is a potential indicator for O 2 UE. Our objectives were to estimate v...

The aim of this study was to investigate swimming performance and oxygen consumption as non−lethal indicator traits of production parameters in Atlantic salmon Salmo salar L. and Gilthead seabream Sparus aurata L. A total of 34 individual fish of each species were subjected to a series of experiments: (1) a critical swimming speed (Ucrit) test in a...

We review knowledge on applications of sustained aerobic swimming as a tool to promote productivity and welfare of farmed fish species. There has been extensive interest in whether providing active species with a current to swim against can promote growth. The results are not conclusive but the studies have varied in species, life stage, swimming s...

This study reports on the first observation of a spontaneously matured female European eel. The 43-year-old eel, together with eleven other females, resided at an aquarium house since their capture in 2002 and stocking as glass eels in 1978. In June 2019, the girth of the belly of the female increased as a sign of oocyte maturation. The specimen ha...

It is well-established that sustained exercise training can enhance brain plasticity and boost cognitive performance in mammals, but this phenomenon has not received much attention in fish. The aim of this study was to determine whether sustained swimming exercise can enhance brain plasticity in juvenile Atlantic salmon. Brain plasticity was assess...

p>This Article contains errors. Since the publication of this Article, the website hosting the assembly data has become inactive. The data has now been re-deposited in the DataverseNO repository. As such, the corrected Data Availability section should be as follows. Data Availability The nanopore sequencing data are available in the European Nucleo...

Forced sustained swimming exercise at optimal speed enhances growth in many fish species, particularly through hypertrophy of the white skeletal muscle. The exact mechanism of this effect has not been resolved yet. To explore the role of cortisol, we first subjected wild-type zebrafish to an exercise protocol validated for exercise-enhanced growth,...

Seaweeds may represent immuno-stimulants that could be used as health-promoting fish feed components. This study was performed to gain insights into the immunomodulatory effects of dietary seaweeds in Atlantic salmon. Specifically tested were 10% inclusion levels of Laminaria digitata (SW1) and a commercial blend of seaweeds (Oceanfeed®) (SW2) agai...

Background: Male European seabass, already predominant (~ 70%) in cultured stocks, show a high incidence (20-30%) of precocious sexual maturation under current aquaculture practices, leading to important economic losses for the industry. In view of the known modulation of reproductive development by swimming exercise in other teleost species, we a...

We have sequenced the genome of the endangered European eel using the MinION by Oxford Nanopore, and assembled these data using a novel algorithm specifically designed for large eukaryotic genomes. For this 860 Mbp genome, the entire computational process takes two days on a single CPU. The resulting genome assembly significantly improves on a prev...

Ovulation in the European eel can be induced by injection of DHP (17α,20β-dihydroxy-4-pregnen-3-one). The timing of injection is based on the developmental stage of the oocytes. The oocyte stage is determined by invasive biopsy or through external indicators of the oocyte hydration response: body weight index (BWI) and body girth index (BGI). Howev...

Migratory species travelling long distances between habitats to spawn or feed are well adapted to optimize their swimming economy. However, human activities, such as river regulation, represent potential threats to fish migration by changing environmental parameters that will have impact on their metabolism. The main objective of this study was to...

The main aim of this Research Topic is to showcase some of the current studies designed to improve our understanding of the physiological energetic and metabolic requirements of swimming and of the adaptive responses to swimming in fish. A total of 9 articles are presented, covering topics related to swimming performance in wild and aquaculture-rele...

We have sequenced the genome of the endangered European eel using the MinION by Oxford Nanopore, and assembled these data using a novel algorithm specifically designed for large eukaryotic genomes. For this 860 Mbp genome, the entire computational process takes two days on a single CPU. The resulting genome assembly significantly improves on a prev...

Sexual maturation from puberty to adulthood in European eels (Anguilla anguilla) occurs during and/or after the ~. 6000 km reproductive migration from their freshwater habitats to the spawning grounds in the Sargasso sea. This is the first study to simulate an anorexic, mixed-sex, group-wise freshwater migration (2. weeks; 689 km) and subsequent se...

The presence of geosmin in fish products causes an earthy or musty off-flavour. To avoid economic damage resulting from market entrance of off-flavoured fish products, fish farmers utilize the reversibility of geosmin uptake to depurate the off-flavours from their fish crops by holding them in clean water just before harvest. To improve this proces...

Common sole fed with commercial pellets develop anaemia and are restricted in their growth performance. The anaemia can be the result of a difference in feed intake, a nutritional deficiency, an inflammatory response to infection or combinations of these aspects. In this study, it was investigated whether feeding ragworm would alleviate the anaemia...

Reproductive homing migration of salmonids requires accurate interaction between the reception of external olfactory cues for navigation to the spawning grounds and the regulation of sexual maturation processes. This study aimed at providing insights into the hypothesized functional link between olfactory sensing of the spawning ground and final se...

Larval zebrafish was subjected to a methodological exploration of the gastrointestinal microbiota and transcriptome. Assessed was the impact of two dietary inclusion levels of a novel protein meal (NPM) of animal origin (ragworm Nereis virens) on the gastrointestinal tract (GIT). Microbial development was assessed over the first 21 days post egg fe...

Swimming exercise at optimal speed may optimize growth performance of yellowtail kingfish in a recirculating aquaculture system. Therefore, optimal swimming speeds (Uopt in m s⁻¹ or body lengths s⁻¹, BL s⁻¹) were assessed and then applied to determine the effects of long-term forced and sustained swimming at Uopt on growth performance of juvenile y...

The adult skeletal muscle is a plastic tissue with a remarkable ability to adapt to different levels of activity by altering its excitability, its contractile and metabolic phenotype and its mass. We previously reported on the potential of adult zebrafish as a tractable experimental model for exercise physiology, established its optimal swimming sp...

AMP-activated protein kinase (AMPK) is well known to be induced by exercise and to mediate important metabolic changes in the skeletal muscle of mammals. Despite the physiological importance of exercise as a modulator of energy use by locomotory muscle, the regulation of this enzyme by swimming has not been investigated in fish. We found that susta...

During migration, swimming in schools provides fish with a number of behavioural and ecological advantages, including increased food supply and reduced predation risk. Previous work shows that carangiform and tunniform swimming result in energetic advantages for individuals using a diamond swimming formation. However, little is known about the pote...

Deep RNA sequencing (RNA-seq) was performed to provide an in-depth view of the transcriptome of red and white skeletal muscle of exercised and non-exercised rainbow trout (Oncorhynchus mykiss) with the specific objective to identify expressed genes and quantify the transcriptomic effects of swimming-induced exercise. Pubertal autumn-spawning seawat...

The “Omics” revolution has brought along the possibility to dissect complex physiological processes, such as exercise, at the gene (genomics), mRNA (transcriptomics), protein (proteomics), metabolite (metabolomics), and other levels with unprecedented detail. To date, a few studies in mammals, including humans, have approached this issue by investi...

In light of mounting fishing pressures, increased aquaculture production and a growing concern for fish well-being, improved knowledge on the swimming physiology of fish and its application to fisheries science and aquaculture is needed. This book presents recent investigations into some of the most extreme examples of swimming migrations in salmon...

Salmon has amazing abilities to migrate long distances from the ocean to their natal streams for reproduction. Reproductive homing migration was investigated by two different research approaches from behavioural biology to endocrinology using chum salmon in the north Pacific Ocean as well as two land-locked salmon species. These species are lacustr...

Recently, we have established zebrafish as a novel exercise model and demonstrated the stimulation of growth by exercise. Exercise may also induce cardiac hypertrophy and cardiomyocyte proliferation in zebrafish making it an important model to study vertebrate heart regeneration and improved robustness of fish in aquaculture. Moreover, zebrafish ha...

Swimming is an integral part of the behavior of many species of fish, including trout. Swimming is accomplished through the contractile activity of skeletal muscle that is fueled, in turn, by energy derived primarily from lipids and carbohydrates. On the other hand, swimming alters the skeletal muscle phenotype by increasing fiber hypertrophy and c...

The reproductive biology of the only known intact species flock of large cyprinids, the 16 Labeobarbus species of Lake Tana (Ethiopia), has been extensively studied for the past two decades. Seven species of Labeobarbus are known to migrate >50 km upstream into tributary rivers for spawning during the rainy season (July to October), whereas eight o...

AMPK, a master metabolic switch, mediates the observed increase of glucose uptake in locomotory muscle of mammals during exercise. AMPK is activated by changes in the intracellular AMP:ATP ratio when ATP consumption is stimulated by contractile activity but also by AICAR and metformin, compounds that increase glucose transport in mammalian muscle c...

We examined the effect of temperature in European silver eels during their maturation induced by injections of carp pituitary extract on endocrine parameters: pituitary fshβ and lhβ expression, plasma 17β-estradiol (E2) and vitellogenin, estrogen receptor 1 (esr1), and vitellogenin 2 (vtg2) expression in liver. A variable thermal regime (T10) that...

The onset of downstream migration of European eels is accompanied by a cessation of feeding and the start of sexual maturation which stresses the link between metabolism and sexual maturation, also suggesting an important role for exercise. Exercise has been tested with eels in swim tunnels and was found to stimulate the onset of sexual maturation....

Improved knowledge on the swimming physiology of fish and its application to fisheries science and aquaculture (i.e., farming a fitter fish) is currently needed in the face of global environmental changes, high fishing pressures, increased aquaculture production as well as increased concern on fish well-being. Here, we review existing data on teleo...

This study compares two alternative indices for quantifying the gross pathology of the swimbladder of eels, Anguilla anguilla (L.), infected with the nematode Anguillicoloides crassus. Two observers recorded twice the scores obtained by the two indices on the same set of 71 wild caught eels (from elver to silver eels, French Mediterranean lagoons)....

Studies on artificial hybridization of different Anguilla species were conducted recently, i.e. female A. australis with male A. dieffenbachii, and female A. japonica with male A. anguilla. The existence of these artificial hybrids was however not demonstrated by independent genetic methods. Two species - A. anguilla and A. australis - that are phy...

Zebrafish has been largely accepted as a vertebrate multidisciplinary model but its usefulness as a model for exercise physiology has been hampered by the scarce knowledge on its swimming economy, optimal swimming speeds and cost of transport. Therefore, we have performed individual and group-wise swimming experiments to quantify swimming economy a...

This movie shows two zebrafish swimming near Ucrit synchronously in the small swim-tunnels that were used for the individual swimming fitness experiment (note that blue light was not used during the actual experiment and oxygen electrodes were connected at the back side). After switching to a higher speed, the fish in the first tunnel fatigues and...

This movie shows the behaviour of zebrafish swimming at Uopt (swim-tunnel foreground) and resting fish (swim-tunnel background) during the group-wise long-term training experiment in Blazka-type 127 L swim-tunnels. Swimmers displayed a typical burst-and-glide swimming pattern. The optimal swimming speed Uopt however is so fast that there is not muc...

Lake Tana (Ethiopia) harbours the only known remaining intact species flock of large (max. 100 cm standard length, SL) cyprinid fishes (15 Labeobarbus spp.). In 'common garden' experiments progeny of the riverine spawning benthivorous L. tsanensis, and of the piscivorous L. truttiformis and L. megastoma was raised under similar environmental condit...

Metabolic processes and sexual maturation closely interact during the long-distance reproductive migration of many fish species to their spawning grounds. In the present study, we have used exercise experimentally to investigate the effects on sexual maturation in rainbow trout. Pubertal autumn-spawning seawater-raised female rainbow trout Oncorhyn...

The European eel migrates 5,000-6,000 km to the Sargasso Sea to reproduce. Because they venture into the ocean in a pre-pubertal state and reproduce after swimming for months, a strong interaction between swimming and sexual maturation is expected. Many swimming trials have been performed in 22 swim tunnels to elucidate their performance and the im...

When European silver eels (Anguilla anguilla) venture into the Atlantic Ocean for their 6,000 km semelparous spawning run to the Sargasso Sea, they are still in a prepubertal stage. Further sexual development appears to be blocked by dopaminergic inhibition of hypothalamus and pituitary activity. Recently, we found that swimming for several weeks i...

Because European silver eels have never been caught during or after their 6000-km reproductive migration to the Sargasso Sea, all existing knowledge on their sexual maturation comes from hormonal stimulation. Silver eels that start their oceanic migration are still immature with pre-vitellogenic oocytes. Hence we assumed that vitellogenesis should...

Organochlorine compounds were widely used after the Second World War because they were cheap to produce and useful for many purposes, such as in agriculture for insecticides, in public health to control disease insect vectors and in industry (Pelletier et al. 2002). It is estimated that 16–30% of the 1 million tons of PCBs produced are still presen...

Every year at the end of the growth season in autumn, the majority of the large European eels cease feeding, become restless and start to mature. Only those with sufficient lipid stores (Larsson et al. 1990; Svedäng and Wickström 1997) will start their reproductive migration to the spawning grounds in the Sargasso. They leave in a prepubertal condi...

A growing number of diseases including infections by parasites are thought to play an important role in the drastic reduction of eel in European rivers and lakes. Until now, the occurrence of about forty parasite species has been reported for the European eel. Bykhovskaya-Pavlovskaya et al. (1962) listed 30 species in this fish. Since then, several...

Energy Requirements of European Eel for Trans Atlantic Spawning Migration Guido van den Thillart, Arjan Palstra, and Vincent van Ginneken An important aspect of the reproduction of European silver eels is the huge distance they have to swim to reach their spawning grounds. After leaving the West European coast they still have to swim 5,000–6,000 km...

Mature eels cannot be obtained from the wild situation since nobody has ever observed migrating and spawning silver eels in the ocean. Our existing knowledge comes from the artificial induction of maturation by hormonal injections with carp or salmon pituitary extract (CPE/SPE; Fontaine et al. 1964) in female European eels and with human chorionic...

A swimming speed of 0.4 meters per second (m s(-1)) is the minimal speed for European female silver eels to reach the spawning sites in the Sargasso Sea in time. As silver eels cease feeding when they start their oceanic migration, the cost of transport (COT) should be minimised and the swimming speed optimised to attain the highest energetic effic...

If European silver eels are prevented from reproductive migration, they remain in a prepubertal stage by dopaminergic inhibition of pituitary activity. Because this inhibition is likely a requirement for an extended female growth stage, we tested if it is sex-specific by subjecting both sexes to stimulation by GnRHa (Gonadotropin-Releasing Hormone...

Infection with the swim-bladder parasite Anguillicola crassus is suggested as one of the principal causes of the collapse of the European eel population. This nematode has been introduced in Europe from Asia in the 80s and parasitized in a short time Anguilla eel species in different geographical regions across the globe. The parasites drain energy...

In this study, we subjected eels from Lake Balaton (Hungary) to a swimming period of 1 week and 2 or 6 weeks. Most eels were silver and were 13–21 years old. Time dependent changes in morphometrical parameters and developmental characteristics of the oocytes were determined. Already after 1 week of swimming, the gonadal mass increased and oocytes b...

The catadromous European eel (Anguilla anguilla L.) undertakes a 6000-km spawning migration from its freshwater habitats to the Sargasso Sea. In large Blazka swim tunnels of 127 l, the physiological effect of such a prolonged swimming performance on sexual maturation in adult female eels was investigated. Two groups of eels were placed in swim tunn...

An important aspect of the reproduction of European silver eels is the huge distance (ca 6000-km) they have to swim to reach their spawning grounds. So, obviously endurance swimming is a major requirement for successful reproduction. As migrating eels don't feed, two major questions should be asked: 1) what are the energy costs to cross the Atlanti...

Eel populations worldwide are dangerously close to collapsing. Our study is the first to show that current levels of dioxin-like contaminants are strong candidates because of their devastating effects on development and survival of eel embryos. Female and male silver eels were artificially stimulated to maturation and reproduction by treatment with...

De Europese aal blijkt bij uitstek een langeafstandsspecialist te zijn. Dit is gebleken uit zwemtesten in 22 zwemtunnels. Het kost schieralen slechts 40% van de vetreserves om de 5500-km naar de paaigronden in de Sargassozee te overbruggen, mogelijk zelfs in slechts drie-en-een-halve maand. Niet alleen dienen vetten als brandstof, ze zijn ook essen...

Attempts on artificial maturation of European eel (Anguilla anguilla) have largely been unsuccessful. The moment of stimulation of final maturation and ovulation is mainly based on weight increase related to the hydration response of the oocytes, which, in the European eel, is irregular. In contrast to Japanese eel, European eels show wide individu...

Gonadal development and spawning behaviour of artificially-matured European eel (Anguilla anguilla L.) was studied. Treatment of males with Human Chorionic Gonadotropin (HCG; 1 IU g/week) resulted in a Gonado-Somatic Index (GSI) of 10.88 ± 3.39 and spermiation. Treatment of females with carp Pituitary suspension (cPs) (20 mg cPs/kg body weight per...

This paper aims at assessing the reproductive segregation within the endemic Barbus (renamed Labeobarbus) species flock of Lake Tana (Ethiopia). Migration, followed by temporal and spatial reproductive segregation in the upstream tributaries of two inflowing rivers was studied systematically over the 1999 and 2000 spawning seasons. Physical events...

Thirty-three androgenetic progeny groups of common carp were analysed using 11 microsatellite markers to (i) verify the homozygous status of the 566 androgenetic individuals, (ii) analyse the microsatellite allele segregation, and (iii) study the possible association of microsatellite alleles with phenotypic traits. In total, 92% of the androgeneti...