Aktuality výzkumu

Germ stem cells are the progenitors of gametes that can be isolated and transplanted between phylogenetically related species. The transplantation of these cells presents significant promise in reproductive biotechnology, enabling the production of gametes and offspring of the donor origin through surrogates. Zebrafish are a popular research model due to their beneficial characteristics and extensive genomic resources. Yet, their diminutive size restricts sperm yield.  In our research, we leveraged the technique of surrogate production to enhance sperm production in zebrafish by utilizing the larger Devario species, specifically the giant danio, which is three times its size. We extracted spermatogonial cells from mature zebrafish males and introduced them into sterile giant danio larvae. Half a year after the transplantation, the recipient generated sperm of zebrafish with thrice the volume and tenfold the concentration compared to zebrafish. The presented study is the first of its kind to produce zebrafish donor-derived gametes via a surrogate from different genera.

Detailed information can be found in the original article: Enhancement of zebrafish sperm production via a large body-sized surrogate with germ cell transplantation. Communications Biology 6: 412. https://doi.org/10.1038/s42003-023-04800-7

Picture: Schematic of the study.

Written by: Assoc. Prof. Martin Pšenička

Within the long-term cooperation of the Faculty of Fisheries and Protection of Waters USB with Turkish colleagues in crayfish research and colleagues from Charles University in Prague, we developed a method of artificial incubation of crayfish eggs to reduce the transmission of crayfish plague from infected females to their offspring. In Turkey, the commercial harvesting of crayfish, namely the narrow-clawed crayfish, is a significant part of commercial aquaculture. They are mainly exported and represent an important source of income. These exports grew until the mid-1980s when the accidental introduction of the crayfish plague caused dramatic declines in crayfish populations. Although crayfish densities in some Turkish lakes have recovered to levels where fishing is economically viable, persistent chronic crayfish infections have not allowed full recovery of the local populations. Consequently, considerable financial resources have been invested in developing alternative methods of crayfish farming in closed aquaculture systems.  

However, the development of these farms has been hampered by the high mortality rates of both wild-caught broodstocks and juveniles. This is caused by the onset of crayfish plague symptoms. We have focused on solving this problem. We have shown that the artificial incubation of separated eggs from females held in a flow-through system with plague-free water, in a possible combination of egg disinfection in formaldehyde or peracetic acid, reduces the transmission of infection from mothers to their offspring.

The utilization of this method has significant potential in commercial crayfish farms in regions with crayfish plague presence, potentially resulting in the disease transmission- via infected broodstocks or infected water. This is another particular success of the FFPW USB scientists in protecting native crayfish species and mitigating the negative impacts of the spread of non-native crayfish species and crayfish plague.

More detailed information can be found in the original article: Kozák, P., Erol, K.G., Uzunmehemtoglu, O.Y., Tangerman, M., Mojžišová, M., Özkök, R., Kouba, A., Cinar, S., Petrusek, A., 2023. Short-term artificial incubation before hatching limits vertical transmission of Aphanomyces astaci from chronically infected females of a host species susceptible to crayfish plague. Aquaculture 569: 739373. https://doi.org/10.1016/j.aquaculture.2023.739373

Written by: prof. Pavel Kozák

Central European standing water bodies, the main part of it consisting of carp ponds, suffer from strong eutrophication (an excess of available nutrients, especially nitrogen and phosphorus). This eutrophication is often associated with the currently conducted feeding (farming) management in these fishponds, which does not consider the balanced nutritional needs of the growing fish. Our present study provides an understanding of how to fish nutrition shapes nutrient excretion and eventually eutrophication. The study concludes that in spring and autumn, the status quo diets lead to inefficient resource use and indirectly to poor ecological conditions. Improved ecosystem resource use efficiency and tackling eutrophication may be achieved by ‘bio-manipulating’ these fishponds towards a more balanced fish nutrition. The study calls for balanced pond feeds that optimize resource utilization efficiency and stimulates fish to exploit better the natural food – in such a way that ecosystem services are maintained.

The authors feel future researchers could carry the baton forward with a novel understanding this article offers. Especially the ecological management of these important pond ecosystems and cleaner aquatic food production from pondscapes of Central Europe.

A graphical summary of the presented concept. High= beginning of the vegetative season (lacking carbohydrate energy in ponds). Low= end of the vegetative season (lacking some indispensable amino acids in ponds). Balanced= short transition time (beginning-to-mid summer) when zooplankton-zoobenthos is sufficient and cereals are introduced in a pond. Suspended losses= losses through faeces (undigested nutrients). Reactive losses= losses through gills and urine (discarding of digested nutrients). Nutrient loading from fish stock to a pond ecosystem is minimum when the pond diet is balanced.

Detailed information is available in the original article: Roy, K., Vrba, J., Kajgrova, L., Mraz, J., 2022. The concept of balanced fish nutrition in temperate European fishponds to tackle eutrophication. Journal of Cleaner Production 364, 132584. https://doi.org/10.1016/j.jclepro.2022.132584   

Written by: Koushik Roy, Ph.D.

Cover photo courtesy: Dipl.-Ing. Tomáš Kolařík

A large amount of fish is spoilt each year from post-catch to consumption. There is a growing interest in applying essential oils (EOs) as bio-preservatives to control the spoilage of chilled-stored fish. However, piles of information on the EOs’ effects on chilled stored fish cannot provide a clear guide toward the appropriate application of EOs to restrain various spoilage microorganisms. In our recent article, we reviewed and meta-analyzed 180 scientific articles working with chilled stored fish to corroborate the promises of EOs in the chilled-stored fish industry.

We identified six EOs with extraordinary total microflora reduction potential for raw fish – citrus, mentha, origanum, thymus, zataria, and Zingiberaceae. Not all EOs can suppress all groups of specific microbes. Only origanum, Zingiberaceae, and thymus have complete-spectrum efficacy. Noticeably, they should be applied by the correct methods, e.g., hurdle technology, active film nanoemulsion, special packaging. We also exposed the concertation effects of EOs on fish odour and flavour. It is showed that the low level of most EOs imparts little interference on the natural odour of fresh fish. Sensory deterioration in EO treated fish flesh is much slower than normal refrigerated ones. Thus, selected EOs at mild concentrations with the right application method can promote chilled-stored fish' safety, sensory and shelf-life agendas.

The study provides clear-cut strategical support to good EO’s application in chilled stored fish based on metadata analysis.

Detailed information can be found in the original paper Hao, R., Roy K., Pan, J., Shah, B.R., Mraz, J. 2021. Critical review on the use of essential oils against spoilage in chilled stored fish: A quantitative meta-analyses. Trends in Food Science & Technology 111: 175–190.

Heatmap of the anti-microbial efficacy of top 6 essential oils with extraordinary total viable count reduction potential against specific spoilage microbes

Commonly used application methods of essential oils in chill-stored fish

Aquatic invasive species are a major threat to biodiversity, but also the economy. One of the factors facilitating their spread is the construction of canals that connect two previously separated seas. In our paper, we quantified for the first time the economic costs of invasive species facilitated by the three globally most important canals (Suez, Panama, and European Inland Canals) using the most comprehensive database on the economic costs of invasive alien species worldwide (InvaCost).

Despite the high number of invasive species listed to have been facilitated in their introduction and spread by these canals, only for five of them economic costs were reported: the fishhook waterflea Cercopagis pengoi and the zebra mussel Dreissena polymorpha for the European Inland Canals, and the silver-cheeked toadfish Lagocephalus sceleratus, the lionfish Pterois miles, and the nomad jellyfish Rhopilema nomadica for the Suez Canal. However, these species alone accounted for a total cost of $42.2 million ($33.6 for European Inland Canals and $8.6 for Suez, while no costs were reported for the Panama Canal). Considering the high number of ecologically problematic invasive species spreading in these regions, it is obvious that their socioeconomic damage remains almost entirely unknown.

More detailed information can be found in the original article: Balzani, P., Cuthbert, R.N., Briski, E., Galil, B., Castellanos-Galindo, G.A., Kouba, A., Kourantidou, M., Leung, B., Soto, I., Haubrock, P.J., 2022. Knowledge needs in economic costs of invasive species facilitated by canalisation. NeoBiota 78, 207–223. https://doi.org/10.3897/neobiota.78.95050.

Written by: Paride Balzani, Ph.D.

Photo source: EVER_GIVEN_(49643352087).jpg (2934×1640) (wikimedia.org)

In recent decades, new knowledge and evidence have been collected about the negative effects of some substances of anthropogenic origin that enter the environment. These are mainly hormonally active substances that can disrupt the endocrine system of wild animals and humans. These substances have come to be collectively referred to as endocrine disruptors.

In the aquatic environment, most attention has so far been paid to substances with estrogenic effects, which have been shown to be involved in the increased occurrence of hermaphrodite fish or can even cause feminization of males. Relatively recently, it has been shown that some substances interact with progesterone receptors and can thus exhibit progestogenic or anti-progestogenic activity. Progesterone receptors mediate the action of natural gestagens (progestins) in the bodies of all vertebrates. Natural gestagens, such as progesterone, play an essential role especially in reproduction, but they also have other physiological functions. If substances with progestogenic or anti-progestogenic activity enter the aquatic environment, it can be assumed that they will negatively affect the development or fertility of fish that live in the affected localities. Progestogenic and anti-progestogenic activities have already been detected in wastewater and surface water in Europe, including the Czech Republic, in Australia, China and India. These activities were mainly detected using in vitro bioassays with the human progesterone receptor. However, there are quite large differences between the structure of human and fish progesterone receptors. Therefore, we sought to determine to what extent data on progestogenic and anti-progestogenic activities, obtained using in vitro bioassays with the human progesterone receptor, are relevant to fish.

For these purposes, we took samples of wastewaters and receiving surface waters. In these samples, we then measured the (anti-)progestogenic activity in parallel using an in vitro bioassay with the human progesterone receptor and a bioassay with the zebrafish progesterone receptor (which is a model fish species). The analyzes showed that the progesterone receptors of humans and zebrafish are activated or blocked differently by environmental samples. And it is a question whether the blocking or, on the contrary, the activation of the fish progesterone receptor is caused by other substances present in the waters than those to which the human progesterone receptor reacts. In any case, our tests have shown that the results obtained using in vitro bioassays with the human progesterone receptor cannot be used to estimate the potential risk of occurrence of (anti-)progestogenic activity in the aquatic environment for fish.

Kocour Kroupová, H., Grimaldi, M., Šauer, P., Bořík, A., Zálohová, K., Balaguer, P., 2023. Environmental water extracts differentially activate zebrafish and human nuclear progesterone receptors. Science of the Total Environment 859: 160232. doi.org/10.1016/j.scitotenv.2022.160232.

Napsala: Hana Kocour Kroupová

An international team, led by our colleague Phillip J. Haubrock, has examined the costs caused by invasive species in Europe. In their study, published last week in the specialist Journal “NeoBiota”, they showed that in the period from 1960 to 2020, damage of more than 116.61 billion euros was caused by non-native species in European countries. According to the researchers, expenditure has increased tenfold every decade – and the real costs are probably many times higher.

Detailed information can be found in the original article: Haubrock et al., 2021. Economic costs of invasive alien species across Europe. NeoBiota 67: 153–190.

Distribution of invasive species costs in Europe by a)type of cost and b)impacted sector.

Despite voluminous literature identifying the impacts of invasive species of organisms, summaries of their monetary costs remain often limited for many taxonomic groups. Invasive aquatic crustaceans are such a case. Using the InvaCost database, we quantified and analysed reported costs associated with this animal group. Invasive crayfish caused US$ 120.5 million in reported costs just in 2000–2020. These costs were unevenly distributed across countries, with a strong bias towards European economies (US$ 116.4 million; mainly due to the signal crayfish in Sweden), followed by costs reported from North America and Asia. The costs of invasive crayfish have increased considerably over the past two decades, averaging US$ 5.7 million per year. Invasive crabs have caused costs of US$ 150.2 million since 1960 (57% in North America and 42% in Europe). Damage-related costs dominated both crayfish (80%) and crabs (99%), with management costs often very low. Reported costs for invasive amphipods (US$ 178.8 thousand) and lobsters (US$ 44.6 thousand) were considerably lower.

Overall, these costs remain vastly underestimated considering the gaps in reporting at taxonomic (already recognised invasive species with no reported costs), geographic (widely invaded regions without costs), and temporal scales (most of the costs occurring in the 21st century despite often longer introduction histories). Therefore, better reporting is needed to assess better the true magnitude of monetary costs caused by invasive aquatic crustaceans.

Detailed information can be found in the original article: Kouba, A., Oficialdegui, F.J., Cuthbert, R.N., Kourantidou, M., South, J., Tricarico, E., Gozlan, R.E., Courchamp, F., Haubrock, P.J., 2022. Identifying economic costs and knowledge gaps of invasive aquatic crustaceans. Science of the Total Environment 813: 152325.

Written by: doc. Ing. Antonín Kouba, Ph.D.

Navzdory rozsáhlým znalostem o dopadech různých skupin invazních druhů organizmů zůstává poznání jejich ekonomických škod velmi omezené. Takovou skupinou jsou i invazní vodní korýši. Pomocí databáze InvaCost jsme analyzovali doposud vykázané ekonomické náklady spojené s touto živočišnou skupinou. Pouze v letech 2000–2020 měli invazní raci na svědomí škody ve výši 120,5 milionu amerických dolarů (USD). Tyto náklady byly nerovnoměrně rozloženy se silným sklonem k evropským ekonomikám (116,4 mil. USD, především kvůli raku signálnímu ve Švédsku), následovanými Severní Amerikou a Asií. Náklady invazních raků za poslední dvě desetiletí značně vzrostly, v průměru se jednalo o 5,7 mil. USD ročně. Invazní krabi způsobili od roku 1960 náklady ve výši 150,2 mil. USD (57 % v Severní Americe a 42 % v Evropě). Převládaly především přímé škody způsobené těmito druhy (80 % nákladů hlášených u raků a 99 % u krabů). Naopak náklady na jejich management byly podstatně nižší. Vykázané náklady v případě invazních různonožců (konkrétně blešivců; 178,8 tis. USD) a humrů (44,6 tis. USD) byly výrazně menší.

Z důvodu nedostatečného vykazování však zůstávají zmiňované ekonomické náklady významnou měrou podhodnoceny. Důvody jsou mimo jiné taxonomické, geografické a časové. Pro řadu dobře známých invazních druhů totiž nejsou reportovány žádné náklady. Rovněž existují rozsáhlé regiony či dokonce kontinenty se známým výskytem invazních raků bez hlášených ekonomických škod a navzdory podstatně delší historii výskytu v nově osídlených oblastech jsou náklady invazních vodních korýšů hlášeny především v posledních dvou desetiletích. Pro posouzení skutečných ekonomických nákladů invazních vodních korýšů je proto nezbytné posílit aktivity vedoucí ke kvantifikaci a nahlašování takovýchto škod.

Podrobné informace jsou dostupné v původním článku: Kouba, A., Oficialdegui, F.J., Cuthbert, R.N., Kourantidou, M., South, J., Tricarico, E., Gozlan, R.E., Courchamp, F., Haubrock, P.J., 2022. Identifying economic costs and knowledge gaps of invasive aquatic crustaceans. Science of the Total Environment 813: 152325.

Napsal: doc. Ing. Antonín Kouba, Ph.D.

Mezinárodní tým vedený naším kolegou Phillipem J. Haubrockem zkoumal náklady spojené s invazivními druhy vyskytujícími se v Evropě. Ve své studii publikované minulý týden v odborném časopise „NeoBiota“ ukazuje, že v letech 1960 až 2020 si nepůvodní druhy v evropských zemích vyžádaly náklady ve výši více než 116,61 miliardy eur. Podle vědců se výdaje každých deset let zvýšily desetkrát a upozorňují, že skutečné náklady jsou pravděpodobně mnohonásobně vyšší.

Podrobné informace lze nalézt v původním článku: Haubrock et al., 2021. Economic costs of invasive alien species across Europe. NeoBiota 67: 153–190.

Distribuce nákladů způsobených invazivními druhy v Evropě podle a) typu nákladů a b) poškozeného sektoru.

Invazní druhy vodních organizmů jsou velkou hrozbou nejen pro společenstva původních druhů a jejich ekosystémy, ale způsobují i rozsáhlé ekonomické škody. Jedním z faktorů usnadňujících jejich šíření je výstavba vnitrozemských kanálů a průplavů, které propojují dříve izolovaná moře. V našem článku jsme díky databázi InvaCost jako první kvantifikovali ekonomické škody invazních druhů šířících se s přispěním hlavních evropských vnitrozemských kanálů, popř. Suezského a Panamského průplavu.

Navzdory vysokému počtu známých invazních druhů v daných regionech byly prozatím pouze u pěti z nich zdokumentovány i ekonomické škody. Jedná se o  perloočku Cercopagis pengoi a slávičku mnohotvárnou Dreissena polymorpha v evropských vodách a čtverzubce stříbropásého Lagocephalus sceleratus, perutýna ďábelského Pterois miles a medúzu Rhopilema nomadica v případě Suezu. Pro tyto druhy byly celkově zdokumentované náklady vyšší než 42,2 milionu milionu amerických dolarů (33,6 milionu pro evropské vnitrozemské kanály a 8,6 milionu pro Suez, zatímco v případě Panamského průplavu nebyly doposud hlášeny žádné škody). Vzhledem k vysokému počtu ekologicky problematických invazních druhů šířících se v těchto oblastech je zřejmé, že jejich socioekonomické dopady zůstávají téměř zcela nepodchyceny.

Podrobné informace jsou dostupné v původním článku: Balzani, P., Cuthbert, R. N., Briski, E., Galil, B., Castellanos-Galindo, G.A., Kouba, A., Kourantidou, M., Leung, B., Soto, I., Haubrock, P.J., 2022. Knowledge needs in economic costs of invasive species facilitated by canalisation. NeoBiota 78: 207–223. https://doi.org/10.3897/neobiota.78.95050.

Napsal: Paride Balzani, Ph.D.

Zdroj úvodní foto: EVER_GIVEN_(49643352087).jpg (2934×1640) (wikimedia.org)

Vertebrates are characterized by formation of outer surface by a sheath of cells called ectoderm, while the inner lining of the primitive gut is made from endoderm. These two layers get together in the anterior part of digestive tract, so called farynx. The team of Rober Černý with Martin Minařík as the first author (Charles University in Prague, Faculty of Science, Czech Republic) came with findings, which rewrite the present opinions of developmental and evolutionary biology. The basal ray-finned fishes such as bichirs, gars and sturgeons, sometimes considered living fossils, have a facial part of head composed of endodermal cells of a pre-oral part of the gut, which is very archaic characteristic expected only in ancestors of vertebrates.
Our Faculty of Fisheries and Protection of Waters supplemented the study with a representative of sturgeons and with two co-author positions (Martin Pšenička and David Gela) and two other colleagues mentioned in acknowledgement (Marek Rodina and Martin Kahanec) became inscribed in the prestigious journal Nature.
For more info see a press release here: https://www.natur.cuni.cz/fakulta/aktuality/stara-tajemstvi-nove-hlavy-obratlovcu or the manuscript on the official web page of Nature: http://www.nature.com/nature/journal/v547/n7662/full/nature23008.html, or a publicly accessible view-only version: http://rdcu.be/tXoa

TV interview on ČT24 starts at 15:34 minute:
http://www.ceskatelevize.cz/ivysilani/10101491767-studio-ct24/217411058290719

Full reference: Minarik, M., Stundl, J., Fabian, P., Jandzik, D., Metscher, B.D., Psenicka, M., Gela, D., Osorio-Pérez, A., Arias-Rodriguez, L., Horácek, I., Cerny, R. Pre-oral gut contributes to facial structures in non-teleost fishes. Nature, 547: 209-212. doi:10.1038/nature23008 (IF=40.137)

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Picture legend: SEM images of sturgeon head with endodermal contribution pseudocoloured yellow. Antero-ventral views, 10 days post hatching; mb, medial barbel; lb, lateral barbel; ao, ampullary organs; rb, rostrum; llo, lateral line organs; ll, lower lip.

When fishermen catch fish, they often catch birds instead... that's how one could describe one of the secondary, unfortunately often overlooked, negative impacts of anglers´s leisure activities on the banks of our waterways, ponds or sand pits. This is an often unwanted, but not exactly rare phenomenon.

This is the creation of "traps" in which wild animals (most often birds) inhabiting the area around our waters are caught. Unnecessary severe injuries then occur, often ending in permanent disability or death. In the case of the Czech Republic, there are hundreds of reported cases of injured animals per year. And what are the "traps"? These are the remains of fishing lines, including rigging material (lines, cords, cables) "decorated" with various jewelry, including rubber bands, beads, feeders, hooks, lures, spinners or wobblers. Everywhere around the waters we can observe kilometers of lines and cords hanging from the branches, roots of bushes and trees and grasses, or coiled in the bushes. And how many such luxurious "traps" for wild animals are located under the water surface, no one dares to guess.

The issue of "traps" can be divided into three areas of emerging problems. The first of them arises purely from the sloppiness, laziness, or indifference of the angler. This is the issue of rigging materials such as waste thrown on the shore, in bushes, reeds, grasses or straight into the water. When birds find such traps, strangulation, necrosis, or amputations occur. As a result, we can see around our waters birds without wings, legs, fingers or with a partially or completely missing beak. Of course, if these animals do not find adequate help, they logically die, often in great pain. And even if they survive, they spend the rest of their lives as severely handicapped individuals with no chance of returning to the wild. This type of "traps" can also be eaten by animals, swallowed when consuming natural food (plants). In this case, the result is clear - death.

The second range of problems lies in the natural curiosity of animals, most often when searching for food and its intake. That's when the animals encounter fishing rods and rigs, both those actively baited and those that have been torn off or cut off, which remain here as a memento of a failed hunt. The birds then swallow the fishing lines, including the jewelry and hooks, and a serious problem arises. As a rule, everything gets stuck in the esophagus and the digestive system and surrounding soft tissues are ruptured, and the hook often peeks out of the bird's throat. If the bird does not find adequate help from a veterinarian, it will die. Even worse than the hooks are the cords and lines themselves, because they can't be seen on an X-ray and the vet doesn't know exactly what's going on. A tangle of fishing line or cord clogs the digestive system and the bird then gradually dies of hunger.

The third group of problems consists of rigs and fishing rods torn off during unsuccessful casting or catching fish, which are suspended from coastal vegetation, most often trees. Related to this is the issue of birds hanging by their wings and legs on bushes and trees around water. If these birds do not find timely help, then logically, like decorations hung on a Christmas tree, they will perish.

The issue of dangerous "traps" does not only concern "ordinary, common" waterfowl, but also highly endangered species. The most common victims of "traps" are swans, then various types of herons (grey and white heron), ducks (mallards, pochards), grebes (great crested and little grebe), as well as cormorants, gulls, coots, terns, cormorants, grebes, storks (most often white stork) or sea eagle or kingfisher. However, primarily "non-aquatic" birds such as owls, ospreys and hawks often get caught in the traps.

More information on the issue of "fishing traps" can be found in the original article intended for the angling public: Drozd, B., 2023. Fishing lines, lines and hooks around the waters: deadly "traps" for birds. Fisheries 127(3): 58–61. (in Czech only)

Photo captions:

• 01: Bird trap: so who will get caught in it? (source: author's archive)
• 02: Drooping lower jaw of the beak due to strangulation, death of the jaw muscles and dislocation of both lower jaw bones in a swan with a line wrapped around the beak. Permanent handicap. (source: Archive DES OP Pilsen)
• 03: Muscle necrosis and near-complete amputation of a black coot's leg wrapped in a fishing line. Black coot did not survive. (source: Archive DES OP Pilsen)
• 04: A baby of stork with a leg amputated by a fishing line. Permanent handicap. (source: Archive DES OP Pilsen)
• 05: Not even a gray heron deserves such a horrible death. (source: ZO ČSOP Vlašim Archive)
• 06: A swallowed fishing rig with a hook and bijouterie caused perforation of the esophagus and soft tissues in a swan. Left: X-ray image. Right: It went well. The assembly was professionally removed, the wound was sutured and disinfected. The patient survived. (source: Archive DES OP Pilsen)
• 07: A cormorant with a broken fishing rig stuck in the esophagus. (source: Archive of Helena Tomšíková)
• 08: Removal of a swallowed coil of fishing line wrapped in plant food, which blocked the digestive system (source: Archive DES OP Pilsen)
• 09: Fishing feeder and rig with a hook stuck in the leg of a swan while wading through the coastal zone of the pond. (source: Archive DES OP Pilsen)
• 10: An exhausted long-eared owl caught in a bird trap (fishing rig with line and hook) on a tree. He survived only thanks to timely rescue. (source: Archive DES OP Pilsen)
• 11: Unfortunately, the black-head gull did not survive hanging on the reeds caught into the “bird trap” (source: Archive DES OP Pilsen)
• 12: Consequence of absence at the rod. A baby swan caught while fishing for carp on a float (source: Archive DES OP Pilsen)
• 13: A very rare "catch". A little grebe caught into the “bird trap” (source: Archive DES OP Plzeň)
• 14: Critically endangered “hang man”. A 15-year-old female of sea eagle originally from Poland found her death near the Kružberk water reservoir in December 2022, when a fishing line with lead wrapped around her neck and subsequently hung herself from a tree while flying through the forest and died (source: Archive of the ZO ČSOP Nový Jičín)

Written by: RNDr. Bořek Drozd, Ph.D.