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  • 1. Ah-King, Malin
    et al.
    Elofsson, Helena
    Kvarnemo, Charlotta
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Why is there no sperm competition in a pipefish with externally brooding males? Insights from sperm activitation and morphology2006Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 68, nr 3, s. 958-962Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nerophis ophidion sperm activation and morphology were investigated with the aim of explaining the apparent lack of sperm competition in this syngnathid with externally brooding males. Nerophis ophidion sperm were activated by a mixture of ovarian fluid and sea water, but not by sea water alone. This indicated that sperm were not shed into the water but needed to be released near the eggs, which probably restrained sperm competition.

  • 2.
    Ahnesjo, Ingrid
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Craig, J. F.
    The biology of Syngnathidae: pipefishes, seadragons and seahorses2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1597-1602Artikel i tidskrift (Övrigt vetenskapligt)
  • 3.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Behavioural temperature preference in a brooding male pipefish Syngnathus typhle2008Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 73, nr 4, s. 1039-1045Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the broad-nosed pipefish Syngnathus typhle, brooding males positioned themselves significantly more often towards the warmer part (18 degrees C) of an aquarium. whereas females were indifferent in this respect. This behavioural temperature preference may increase male brooding rate and indirectly influence patterns of mating competition. (c) 2008 The Author Journal compilation (c) 2008 The Fisheries Society of the British Isles.

  • 4.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik.
    Fewer Newborn Result In Superior Juveniles In The Paternally Brooding Pipefish Syngnathus-Typhle L1992Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 41, nr Suppl. B, s. 53-63Artikel i tidskrift (Refereegranskat)
  • 5.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Seahorses and Their Relatives2010Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 77, nr 1, s. 308-309Artikel, recension (Övrigt vetenskapligt)
  • 6.
    Amcoff, Mirjam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Does female feeding motivation affect the response to a food-mimicking male ornament in the swordtail characin Corynopoma riisei?2013Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 83, nr 2, s. 343-354Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Female response to various aspects of male trait morphology and the effect of female feeding motivation were investigated in the swordtail characin Corynopoma riisei, a species where males are equipped with a flag-like food-mimicking ornament that grows from the operculum. Unfed females responded more strongly to the male ornament and showed a stronger preference for larger ornaments than did fed females. Females were shown not to discriminate between artificial male ornaments of either undamaged or damaged shape.

  • 7.
    Andersson, Matilda L.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Sundberg, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Chasing away accurate results: exhaustive chase protocols underestimate maximum metabolic rate estimates in European perch Perca fluviatilis2020Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 97, nr 6, s. 1644-1650Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Metabolic rates are one of many measures that are used to explain species' response to environmental change. Static respirometry is used to calculate the standard metabolic rate (SMR) of fish, and when combined with exhaustive chase protocols it can be used to measure maximum metabolic rate (MMR) and aerobic scope (AS) as well. While these methods have been tested in comparison to swim tunnels and chambers with circular currents, they have not been tested in comparison with a no‐chase control. We used a repeated‐measures design to compare estimates of SMR, MMR and AS in European perch Perca fluviatilis following three protocols: (a) a no‐chase control; (b) a 3‐min exhaustive chase; and (c) a 3‐min exhaustive chase followed by 1‐min air exposure. We found that, contrary to expectations, exhaustive chase protocols underestimate MMR and AS at 18°C, compared to the no‐chase control. This suggests that metabolic rates of other species with similar locomotorty modes or lifestyles could be similarly underestimated using chase protocols. These underestimates have implications for studies examining metabolic performance and responses to climate change scenarios. To prevent underestimates, future experiments measuring metabolic rates should include a pilot with a no‐chase control or, when appropriate, an adjusted methodology in which trials end with the exhaustive chase instead of beginning with it.

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  • 8. Bakke-McKellep, A. M.
    et al.
    Refstie, S.
    Stefansson, S. O.
    Vanthanouvong, Viengphet
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk cellbiologi.
    Roomans, Godfried
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk cellbiologi.
    Hemre, G. -I
    Krogdahl, Å.
    Effects of dietary soybean meal and photoperiod cycle on osmoregulation following seawater exposure in Atlantic salmon smolts2006Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 69, nr 5, s. 1396-1426Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Atlantic salmon Salmo salar juveniles were fed either fishmeal-based diets (FM) or diets in which soybean meal (SBM) partly replaced the FM from first feeding on. The fish were kept at continuous daylight during the juvenile stage. During the last 3 weeks before reaching 100 g body mass, all fish were subjected to 12L:12D. Starting at 100 g body mass, groups of 60 fish from each feeding background were subjected to continuous light for 12 weeks (short winter), or a square-wave photoperiod cycle to stimulate parr to smolt transformation with 8L:16D during the first 6 weeks, and then continuous light during the last 6 weeks (long winter). After the 12 weeks, 20 fish from each treatment were subjected to 0, 24 or 96 h seawater exposure at a water salinity of 34. Hypo-osmoregulatory ability at seawater exposure was assessed by mortality, intestinal pathology, plasma ion concentrations and osmolality, gill Na+/K+-ATPase activity and element concentrations in the cytoplasm of distal intestinal enterocytes using X-ray microanalysis. The hypo-osmoregulatory capacity was higher in fish kept at short winter than at long winter, apparently due to more rapid development of gill Na+/K+-ATPase activity. Fish fed SBM suffered typical soybean meal-induced histological alterations of the distal intestine and apparent reductions in digestive function in the more proximal gastrointestinal regions. The net osmoregulatory capacity of these fish was maintained, as indicated by higher gill Na+/K+-ATPase activity and lower plasma Na+, Ca2+ and osmolality compared to the FM-fed fish. Thus, feeding SBM did not impair the hypo-osmoregulatory ability of the Atlantic salmon following seawater exposure.

  • 9.
    Bergek, Sara
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Sundblad, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Björklund, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Population differentiation in perch Perca fluviatilis: environmental effects on gene flow?2010Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 76, nr 5, s. 1159-1172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Environmental parameters were used to investigate barriers to gene flow and genetic differentiation in the Eurasian perch (Perca fluviatilis L.) at a small geographical scale in an archipelago system. Significant genetic differentiation was found among locations. Distance per se did not play a major role in the reduction of gene flow. Instead, the largest genetic differences between populations correlated with major changes in environmental conditions, such as temperature at time of spawning. The results show that genetic divergence can arise between populations in habitats thought to be highly connected, and that environmental variables can influence the level of gene flow between populations, including those that are at small spatial scales (tens of kilometres). The importance of a landscape approach when investigating genetic differentiation and defining barriers to gene flow is highlighted.

  • 10.
    Björklund, Mats
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Aho, T.
    Larsson, L.
    Genetic differentiation in the pikeperch (Sander lucioperca): The relative importance of gene flow, drift and common history2007Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 71, nr Suppl. B, s. 264-278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To investigate the relative importance of homogenizing factors, such as gene flow, and diversifying factors, such as drift, genetic variation in pikeperch (Sander lucioperca) in two Fennoscandian regions (North and South) was analysed with microsatellites. Allelic richness and the degree of differentiation were significantly higher in the North (FST= 0·20) than in the South (FST= 0·064). In northern areas, assignments of genotypes were almost exclusively to the population of origin, but in southern areas, the proportion of correct assignments was significantly lower. Most samples exhibited significant heterozygote deficits, and the level of relatedness was higher than expected from randomness. These combined results suggest that there has been more gene flow between populations in southern areas than in northern areas, where the importance of genetic drift has been greater. Effective population sizes were small (c. 100) and did not differ between areas. The effect of a common history appears minor, and thus processes such as genetic drift and gene flow have been more influential in shaping the patterns of genetic diversity in this species.

  • 11.
    Blyth, Samuel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Naturresurser och hållbar utveckling.
    Bower, Shannon D.
    Infin Social & Ecol Solut, Ottawa, ON, Canada.
    After the spawn and on the hook: Sea trout Salmo trutta biophysical responses to different components of catch and release in a coastal fishery2022Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 101, nr 3, s. 464-477Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigated the biophysical responses of sea run brown trout Salmo trutta to catch-and-release in the coastal fishery around Gotland, Sweden. It used information recorded on individual angled S. trutta (n = 162), including fight time, handling time, total air exposure time, injury, bleeding, fish length, body condition, spawning status, water temperature, hook location and difficulty of hook removal. Reflex action mortality predictors (equilibrium, operculum beats, tail grab response, body flex response and vestibular-ocular response), tests of blood glucose and lactate, and observation of hooking injury were used to measure the relative impact of the angling event on the fish's physical state and stress experienced. The results of this study suggest low rates of post-release mortality and generally limited stress responses to angling events, and relatively high post-release survival supported by the recapture of many tagged S. trutta. However, a number of scenarios were identified in which stress responses are likely to be compounded and where anglers should take additional action to reduce sublethal physiological disturbances and the risk of delayed mortality. Particular care should be taken to limit cumulative total air exposure to <10 s, and to reduce handling time and risk of additional injury in angling events with extended fight times, when water temperatures >10 degrees C, or where S. trutta show evidence of being physically compromised by injury or having recently spawned. The results also indicate the importance of using appropriately sized single hooks rather than larger treble hooks to reduce hooking injury and handling time during unhooking.

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  • 12.
    Cooke, Steven J.
    et al.
    Carleton Univ, Dept Biol, Fish Ecol & Conservat Physiol Lab, Ottawa, ON K1S 5B6, Canada;Carleton Univ, Inst Environm & Interdisciplinary Sci, Ottawa, ON K1S 5B6, Canada.
    Twardek, William M.
    Carleton Univ, Dept Biol, Fish Ecol & Conservat Physiol Lab, Ottawa, ON K1S 5B6, Canada;Carleton Univ, Inst Environm & Interdisciplinary Sci, Ottawa, ON K1S 5B6, Canada.
    Reid, Andrea J.
    Carleton Univ, Dept Biol, Fish Ecol & Conservat Physiol Lab, Ottawa, ON K1S 5B6, Canada;Carleton Univ, Inst Environm & Interdisciplinary Sci, Ottawa, ON K1S 5B6, Canada.
    Lennox, Robert J.
    Carleton Univ, Dept Biol, Fish Ecol & Conservat Physiol Lab, Ottawa, ON K1S 5B6, Canada;Carleton Univ, Inst Environm & Interdisciplinary Sci, Ottawa, ON K1S 5B6, Canada.
    Danylchuk, Sascha C.
    Fish Mission, Amherst, MA USA.
    Brownscombe, Jacob W.
    Carleton Univ, Dept Biol, Fish Ecol & Conservat Physiol Lab, Ottawa, ON K1S 5B6, Canada;Carleton Univ, Inst Environm & Interdisciplinary Sci, Ottawa, ON K1S 5B6, Canada.
    Bower, Shannon D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Naturresurser och hållbar utveckling.
    Arlinghaus, Robert
    Humboldt Univ, Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Biol & Ecol Fishes, Berlin, Germany;Humboldt Univ, Fac Life Sci, Div Integrat Fisheries Management, Berlin, Germany.
    Hyder, Kieran
    Ctr Environm Fisheries & Aquaculture Sci, Lowestoft, Suffolk, England;Univ East Anglia, Sch Environm Sci, Norwich, Norfolk, England.
    Danylchuk, Andy J.
    Fish Mission, Amherst, MA USA;Univ Massachusetts, Dept Environm Conservat, Amherst, MA 01003 USA.
    Searching for responsible and sustainable recreational fisheries in the Anthropocene2019Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 94, nr 6, s. 845-856Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recreational fisheries that use rod and reel (i.e., angling) operate around the globe in diverse freshwater and marine habitats, targeting many different gamefish species and engaging at least 220 million participants. The motivations for fishing vary extensively; whether anglers engage in catch-and-release or are harvest-oriented, there is strong potential for recreational fisheries to be conducted in a manner that is both responsible and sustainable. There are many examples of recreational fisheries that are well-managed where anglers, the angling industry and managers engage in responsible behaviours that both contribute to long-term sustainability of fish populations and the sector. Yet, recreational fisheries do not operate in a vacuum; fish populations face threats and stressors including harvest from other sectors as well as environmental change, a defining characteristic of the Anthropocene. We argue that the future of recreational fisheries and indeed many wild fish populations and aquatic ecosystems depends on having responsible and sustainable (R&S) recreational fisheries whilst, where possible, addressing, or at least lobbying for increased awareness about the threats to recreational fisheries emanating from outside the sector (e.g., climate change). Here, we first consider how the concepts of R&S intersect in the recreational fishing sector in an increasingly complex socio-cultural context. Next, we explore the role of the angler, angling industry and decision-makers in achieving R&S fisheries. We extend this idea further by considering the consequences of a future without recreational fisheries (either because of failures related to R&S) and explore a pertinent case study situated in Uttarakahand, India. Unlike other fisheries sectors where the number of participants is relatively small, recreational angling participants are numerous and widespread, such that if their actions are responsible, they have the potential to be a key voice for conservation and serve as a major force for good in the Anthropocene. What remains to be seen is whether this will be achieved, or if failure will occur to the point that recreational fisheries face increasing pressure to cease, as a result of external environmental threats, the environmental effects of recreational fishing and emerging ethical concerns about the welfare of angled fish.

  • 13.
    Demandt, Marnie
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Björklund, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Loss of genetic variability in reintroduced roach (Rutilus rutilus) populations2007Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 70, nr Suppl.B, s. 255-261Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Genetic variation at five microsatellite loci and in mtDNA was surveyed in reintroduced and 'control' populations of roach (Rutilus rutilus) in Sweden. Microsatellite allelic richness and allele size ranges were significantly reduced in reintroduced populations, and mtDNA diversity was nearly significantly reduced in reintroduced populations. These measures of genetic variability were strongly correlated with lake characteristics that influence population size and food availability.

  • 14. Duan, M.
    et al.
    Zhang, T.
    Hu, W.
    Xie, S.
    Sundström, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Li, Z.
    Zhu, Z.
    Risk-taking behaviour may explain high predation mortality of GH-transgenic common carp Cyprinus carpio2013Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 83, nr 5, s. 1183-1196Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The competitive ability and habitat selection of juvenile all-fish GH-transgenic common carp Cyprinus carpio and their size-matched non-transgenic conspecifics, in the absence and presence of predation risk, under different food distributions, were compared. Unequal-competitor ideal-free-distribution analysis showed that a larger proportion of transgenic C. carpio fed within the system, although they were not overrepresented at a higher-quantity food source. Moreover, the analysis showed that transgenic C. carpio maintained a faster growth rate, and were more willing to risk exposure to a predator when foraging, thereby supporting the hypothesis that predation selects against maximal growth rates by removing individuals that display increased foraging effort. Without compensatory behaviours that could mitigate the effects of predation risk, the escaped or released transgenic C. carpio with high-gain and high-risk performance would grow well but probably suffer high predation mortality in nature.

  • 15.
    Eklöv, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Jonsson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Pike predators induce morphological changes in young perch and roach2007Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 70, nr 1, s. 155-164Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The morphological response of two 1 year-old prey species, perch Perca fluviatilis and roach Rutilus rutilus to the presence of predatory pike Esox lucius, was tested in a 6 week aquarium experiment. The growth of perch was higher than that of roach but there was no difference in growth of prey between predator and control treatments. The presence of pike caused morphological changes in both perch and roach. Perch showed an increase in body depth during the experiment whereas the morphological response of roach to pike was more related to a displacement of the dorsal and pelvic fins and width of the anal fin. Differences in morphological responses of perch and roach to pike can be interpreted by their overall differences in antipredator strategies.

  • 16.
    Faulks, L. K.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Östman, O.
    Swedish Univ Agr Sci, Inst Coastal Res, Dept Aquat Resources, Skolvagen 6, S-74242 Oregrund, Sweden..
    Adaptive major histocompatibility complex (MHC) and neutral genetic variation in two native Baltic Sea fishes (perch Perca fluviatilis and zander Sander lucioperca) with comparisons to an introduced and disease susceptible population in Australia (P-fluviatilis): assessing the risk of disease epidemics2016Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 88, nr 4, s. 1564-1583Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study assessed the major histocompatibility complex (MHC) and neutral genetic variation and structure in two percid species, perch Perca fluviatilis and zander Sander lucioperca, in a unique brackish ecosystem, the Baltic Sea. In addition, to assess the importance of MHC diversity to disease susceptibility in these populations, comparisons were made to an introduced, disease susceptible, P. fluviatilis population in Australia. Eighty-three MHC class II B exon 2 variants were amplified: 71 variants from 92 P. fluviatilis samples, and 12 variants from 82 S. lucioperca samples. Microsatellite and MHC data revealed strong spatial genetic structure in S. lucioperca, but not P. fluviatilis, across the Baltic Sea. Both microsatellite and MHC data showed higher levels of genetic diversity in P. fluviatilis from the Baltic Sea compared to Australia, which may have facilitated the spread of an endemic virus, EHNV in the Australian population. The relatively high levels of genetic variation in the Baltic Sea populations, together with spatial genetic structure, however, suggest that there currently seems to be little risk of disease epidemics in this system. To ensure this remains the case in the face of ongoing environmental changes, fisheries and habitat disturbance, the conservation of local-scale genetic variation is recommended.

  • 17. Goncalves, I. Braga
    et al.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kvarnemo, C.
    The relationship between female body size and egg size in pipefishes2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1847-1854Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Comparing five species of pipefish, egg size was significantly larger in species with brood pouches (Syngnathus typhle, Syngnathus acus and Syngnathus rostellatus) than in species without brood pouches (Entelurus aequoreus and Nerophis ophidion). Egg size correlated positively with female body size in species with brood pouches, but was similar across female sizes in the species lacking pouches. These results may reflect differences in offspring competition as a consequence of variable offspring relatedness within a brood, due to the mating systems adopted by the different species and the presence or absence of a brood pouch.

  • 18.
    Herlevi, Heidi
    et al.
    Abo Akad Univ, Fac Sci & Engn Environm & Marine Biol, Turku, Finland..
    Kihlberg, Isa Wallin
    Swedish Univ Agr Sci, Dept Aquat Resources, Oregrund, Sweden..
    Aarnio, Katri
    Abo Akad Univ, Fac Sci & Engn Environm & Marine Biol, Turku, Finland..
    Bonsdorff, Erik
    Abo Akad Univ, Fac Sci & Engn Environm & Marine Biol, Turku, Finland..
    Florin, Ann-Britt
    Swedish Univ Agr Sci, Dept Aquat Resources, Uppsala, Sweden..
    Ljung, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för biologisk grundutbildning, Klubbans biologiska station.
    Lundström, Karl
    Swedish Univ Agr Sci, Dept Aquat Resources, Lysekil, Sweden..
    Mattila, Johanna
    Aland Univ Appl Sci, Mariehamn, Finland..
    Östman, Örjan
    Environmental abundances of the non-native round goby Neogobius melanostomus influence feeding of native fish predators2023Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 102, nr 6, s. 1340-1357Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The authors assessed the importance of the round goby Neogobius melanostomus as prey for three native predatory fish species, Atlantic cod Gadus morhua, European perch Perca fluviatilis and northern pike Esox lucius, in a northern and southern area of the Baltic Proper, using a combination of visual analysis and DNA metabarcoding of predator stomach contents. To explore the influence of environmental abundances of N. melanostomus on predation, they related the occurrence of N. melanostomus in predator diets to its abundance in survey fishing. Gadus morhua and E. lucius in the southern area showed the highest tendency to feed on N. melanostomus when it was abundant, as N. melanostomus occurred in up to 100% of stomachs and constituted up to 88% of the total diet volume proportion. The diet contribution of N. melanostomus was associated with N. melanostomus abundances for G. morhua and E. lucius, and when N. melanostomus was abundant, these predators exhibited lower prey richness and a higher degree of piscivory. G. morhua and P. fluviatilis also fed less on crustacean prey when N. melanostomus was abundant. The high importance of N. melanostomus in diets of native fish predators may modify indirect interactions between N. melanostomus and native prey species in invaded coastal communities.

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  • 19.
    Jaensson, Alia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Ekotoxikologi.
    Olsén, K. Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Ekotoxikologi.
    Effects of copper on olfactory-mediated endocrine responses and reproductive behaviour in mature male brown trout Salmo trutta parr to conspecific females2010Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 76, nr 4, s. 800-817Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present study, the effects of copper (CuSO4) on the ability of mature male brown trout Salmo trutta parr to detect and react both physiologically and behaviourally to female pheromones were studied. The study was composed of two parts. In the first experiment, priming effects of the female pheromone prostaglandin F (PGF) were evaluated by determining the amount of milt produced and the blood plasma levels of 11-ketotestosterone (11-KT) and 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-P) after the PGF exposure. In the second experiment, male parr were placed in a large stream tank together with a group of adult males and ovulated females and their individual behaviours were recorded. In the priming experiment, the amount of expressible milt was significantly lower, less than half, in groups exposed during 4 days to 10 or 100 µg l−1 copper compared with control parr only exposed to water. No significant differences were observed in plasma levels of 11-KT and 17, 20β-P. During the behavioural experiment, exposed parr spent less time with the female and had a lower number of courting events. Blood plasma levels of 11-KT were, however, significantly higher in the group exposed to 100 µg l−1 copper compared with the control group. Furthermore, the exposed group spent significantly less time swimming upstream than did the control group. The present study demonstrates that exposure to copper affects reproductive behaviours and endocrinology of S. trutta male parr.

  • 20. Jansson, Håkan
    et al.
    Wyöni, Per-Ivan
    Fernholm, Bo
    Bredwad, Max
    Mierzykowska, Anna
    Tegelström, Håkan
    Genetic relationships among species of hagfish revealed by protein electrophoresis1995Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 47, nr 4, s. 599-608Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hagfish species of the genera Myxine, Eptatretus and Pnramyxine were analysed for genetic variation by allozyme electrophoresis and isoelectric focusing of general proteins. Large genetic differences were observed between samples of supposed conspecifics of Myxine circifrons from off the Californian coast, and also within one sample of Paramyxine sp. from Sagami Bay, Japan. The results are convincing evidence of the existence of additional sympatric species in these two areas. In general, the highest genetic identities were found between species within the subfamilies Myxininae and Eptatretinae. Within Eptatretinae, the Japanese species Eptatietus burgeri was genetically more similar to Japanese species of Paramyxine than to American species of Eptatretus. Thus, our data indicate that the generic status of Paramyxine should be reconsidered. (C) 1995 The Fisheries Society of the British Isles.

  • 21.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Do egg size and parental care coevolve in fish?2005Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 66, nr 6, s. 1499-1515Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A phenomenon that has attracted a substantial theoretical and empirical interest is the positive relationship between egg size and the extent of parental care in fishes. Interestingly, despite the effort put into solving the causality behind this relationship over the past two decades it remains largely unsolved. Moreover, how general the positive relationship between egg size and parental care is among fishes is also poorly understood. In order to stimulate research exploring egg size and parental care variation in fishes, the potential selective forces from both natural and sexual selection on egg size and parental care are discussed. Recent empirical findings on how oxygen requirements and developmental times may differ between differently sized eggs are incorporated into a critical view of the current theory of this field. Furthermore, it is suggested that the up to now neglected effects of sexual selection, through both mate choice and sexual conflict, can have strong effects on the relationship between egg size and parental care in fishes. In light of the recent developments of comparative and experimental methods, future approaches that may improve the understanding of the relationship between egg size and care in fishes are suggested.

  • 22.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Zooekologi.
    Olsson, Jens
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Limnologi.
    Differential investment in the Banggai cardinalfish: can females adjust egg size close to egg maturation to match the attractiveness of a new partner?2003Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 63, nr S1, s. 144-151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To test whether females can change their egg investment according to the different attractiveness ( i.e. size as measured by standard length, Ls) of a new mate after eggs have already matured in response to an earlier mate, female Banggai cardinalfish Pterapogon kauderni were first allowed to produce eggs for small (unattractive) or large (attractive) males. Then, when spawning was initiated, but prior to actual spawning, their partner was switched to either a significantly larger or a significantly smaller partner, respectively. A strong positive correlation between egg size and days until spawning with the second male was found for the females initially paired to a small and then a large male. Within a few days, these females apparently increased their egg size to match the attractiveness of their new male. No correlation between days until spawning and egg size in females initially paired to a large and then a small male, however was found, so apparently females were unable to adjust egg size in response to a decrease in mate attractiveness. Consequently, it is suggested that females can increase their egg size investment even after the onset of egg maturation and that this change can be quite rapid.

  • 23.
    Kotrschal, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sundström, L. Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Brelin, D.
    Devlin, R. H.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Inside the heads of David and Goliath: environmental effects on brain morphology among wild and growth-enhanced coho salmon Oncorhynchus kisutch2012Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 81, nr 3, s. 987-1002Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transgenic and wild-type individual coho salmon Oncorhynchus kisutch were reared in hatchery and near-natural stream conditions and their brain and structure sizes were determined. Animals reared in the hatchery grew larger and developed larger brains, both absolutely and when controlling for body size. In both environments, transgenics developed relatively smaller brains than wild types. Further, the volume of the optic tectum of both genotypes was larger in the hatchery animals and the cerebellum of transgenics was smaller when reared in near-natural streams. Finally, wild types developed a markedly smaller telencephalon under hatchery conditions. It is concluded that, apart from the environment, genetic factors that modulate somatic growth rate also have a strong influence on brain size and structure.

  • 24. Kvarnemo, C.
    et al.
    Mobley, K. B.
    Partridge, C.
    Jones, A. G.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Evidence of paternal nutrient provisioning to embryos in broad-nosed pipefish Syngnathus typhle2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1725-1737Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In two experiments, radioactively labelled nutrients (either H-3-labelled amino-acid mixture or C-14-labelled glucose) were tube-fed to brooding male Syngnathus typhle. Both nutrients were taken up by the males and radioactivity generally increased in the brood pouch tissue with time. Furthermore, a low but significant increase of H-3-labelled amino acids in embryos was found over the experimental interval (48 h), whereas in the C-14-glucose experiment the radioactivity was taken up by the embryos but did not increase over the experimental time (320 min). Uptake of radioisotopes per embryo did not differ with embryo size. A higher uptake mg(-1) tissue of both H-3-labelled amino acids and C-14-labelled glucose was found in smaller embryos, possibly due to a higher relative metabolic rate or to a higher surface-area-to-volume ratio compared to larger embryos. Uptake in embryos was not influenced by male size, embryonic developmental advancement or position in the brood pouch. It is concluded that brooding males provide amino acids, and probably also glucose, to the developing embryos in the brood pouch.

  • 25.
    Lindqvist, Charlotte
    et al.
    Högskolan på Gotland, Avdelningen för Biologi.
    Sundin, Josefin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rosenqvist, Gunilla
    Högskolan på Gotland, Institutionen för kultur, energi och miljö.
    Male broad-nosed pipefish Syngnathus typhle do not locate females by smell2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1861-1867Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Broad-nosed pipefish Syngnathus typhle were used to investigate whether males used scent in their search for mates. When the males in an experiment had access to olfactory cues only, they did not locate females better than they located males. Thus, S. typhle, was less successful in mate search when visual cues were absent.

  • 26. Lohmus, M.
    et al.
    Björklund, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Sundström, L. F.
    Devlin, R. H.
    Effects of temperature and growth hormone on individual growth trajectories of wild-type and transgenic coho salmon Oncorhynchus kisutch2010Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 76, nr 3, s. 641-654Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, individual growth patterns of wild-type and growth-enhanced coho salmon Oncorhynchus kisutch at 8, 12 and 16 degrees C water temperature were followed. Despite large differences among individuals in growth rates, there was generally little variation in the shape of the growth curves among O. kisutch individuals of both genotypes and at all temperatures. Typically, individuals that were relatively large initially were also relatively large at the end of the growth period. The limitation in variation was more pronounced in the growth-enhanced O. kisutch than in the wild type, where the relative size of some individuals reared at 12 and 8 degrees C changed by the end of the trial. As a warmer temperature seems to decrease the plasticity of growth trajectories in wild-type fish, it is possible that global warming will influence the ability of wild fish to adapt their growth to changing conditions.

  • 27. Magnhagen, C.
    et al.
    Backstrom, T.
    Overli, O.
    Winberg, Svante
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Nilsson, J.
    Vindas, M. A.
    Brännäs, E.
    Behavioural responses in a net restraint test predict interrenal reactivity in Arctic charr Salvelinus alpinus2015Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 87, nr 1, s. 88-99Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, a 1 min net restraint test was evaluated as a method to predict stress-coping style in Arctic charr Salvelinus alpinus, by investigating the relationship between behaviour during the test and levels of plasma cortisol sampled after 30 min confinement. In two separate groups of S. alpinus, general linearized model revealed significant correlations between cortisol levels and principal component scores extracted from principal component analysis, combining measures of activity in the tests. With the use of glmulti, the model selection ruled out any effects of size, sex and order of capture on interrenal reactivity. In general, S. alpinus that were more active in the net restraint test also had low levels of circulating cortisol, suggesting a proactive coping style. The results from two repeated runs were not correlated, but both runs, performed eight days apart, show a negative correlation between post-stress cortisol level and activity in the net. The lack of consistency could be explained by different treatments before each run and individual differences in behavioural plasticity. The net restraint test is thus predictive of stress-coping style in S. alpinus, and has the benefit of being less time-consuming than the commonly used confinement stress test.

  • 28. Monteiro, N.M.
    et al.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Vieira, M.N.
    Almada, V.C.
    Reproductive migrations of the sex role reversed pipefish Nerophis lumbriciformis (Pisces;Syngnathidae)2006Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 69, nr 1, s. 66-74Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using an individual identification technique, a population of worm pipefish Nerophis lumbriciformis was followed during 19 months, in order to determine the exact use of the intertidal and, considering the specific movement patterns of males and females, the mating system exhibited by this population. Field observations showed that the number of adults increased during the breeding season, with males arriving 1 month earlier than females. Furthermore, males and females presented distinct permanence periods, showing that the intertidal is used as a mating arena. It was also observed that both male and female worm pipefish mated repeatedly over the span of a reproductive season, but females exhibited shorter remating intervals. Also, females stayed for longer periods on the mating grounds, the intertidal zone, whereas males typically left for the subtidal after mating, usually returning within 2 months. These inter-sexual differences in the occupation of the intertidal suggest that females breed with different males but also that males accept eggs from various females since, on their return, a new group of mating partners was now available. Thus, N. lumbriciformis might be considered polygynandric. It is a clearly dimorphic species in spite of the observed polygynandry, suggesting that differences in remating intervals may be influential in determining the strength of sexual selection along with what may be expected from the polygynandrous mating system alone.

  • 29.
    Nissling, Anders
    et al.
    Högskolan på Gotland, Avdelningen för Biologi.
    Jacobsson, Marie
    Hallberg, Nina
    Feeding ecology of juvenile turbot Scophthalmus maximus and flounder Pleuronectes flesus at Gotland, Central Baltic Sea2007Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 70, nr 6, s. 1877-1897Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Food and feeding of juvenile turbot Scophthalmus maximus and flounder Pleuronectes flesus were studied in five nursery areas at Gotland, Central Baltic Sea, ICES SD 27 and SD 28. Ontogeny involved partitioning of available food resources. The food choice of turbot <30 mm standard length (L sub(S)) included both planktonic-hyperbenthic prey (calanoid copepods and mysids) and epibenthic-endobenthic prey (chironomids and amphipods), whereas turbot greater than or equal to 30 mm L sub(S) fed mainly on hyperbenthic species (mysids and fishes). Conversely, for flounder, epibenthic-endobenthic prey were the most abundant prey items throughout development (harpactocoid copepods, oligochaetes and chironomids for fish <40 mm L sub(S) and oligochaetes, chironomids and amphipods for flounder greater than or equal to 40 mm L sub(S)). Thus, the highest degree of dietary overlap occurred between turbot <30 mm and flounder greater than or equal to 40 mm. Food composition for both turbot and flounder varied, however, according to exposure and predominant wind direction in the nursery area. For example, expressed as the ratio between the biomass of mysids and fishes consumed, the relative importance of mysids v. fishes as food source for turbot, varied from <1 in the most sheltered area to 16 and 27 in the more open areas. Considerable differences in feeding incidence were recorded; mean plus or minus s.d. 58 plus or minus 20% for turbot <30 mm L sub(S) and 83 plus or minus 8% for turbot greater than or equal to 30 mm L sub(S), as opposed to greater than or equal to 85-90% for flounder irrespective of size. The lower feeding success of turbot <30 mm L sub(S) was related to mysid abundance, shown to vary spatially and temporally, and to density of flounder, indicating that food availability, and potentially interspecific competition, influence feeding of early juvenile turbot with implications for survival following settlement. Regarding variability in abundance, hyperbenthic prey, as mysids, are considered more variable than epi- and endobenthic organisms. Hence, in addition to the 'nursery size hypothesis', i.e. the positive relationship between abundance of recruits and extension of nursery areas, variability in food availability may explain the average lower recruitment of turbot as compared to other flatfishes, e.g. flounder.

  • 30.
    Nissling, Anders
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Larsson, Roger
    SLU Aqua, Inst Marine Res, Lysekil, Sweden.
    Population specific sperm production in European flounder Platichthys flesus: Adaptation to salinity at spawning2018Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 93, nr 1, s. 47-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Marine teleosts inhabiting the brackish Baltic Sea have adapted to the less saline water with activation of spermatozoa at low salinity hypo-osmotic conditions but with shorter longevity and lower swimming speed that affect the fertilization capacity. Aiming to elucidate if the fertilization capacity may be maintained by increasing the number of spermatozoa produced, testis size for the euryhaline flounder Platichthys flesus with external fertilization was assessed along a salinity gradient; with spawning at a salinity of c. 7, 10-18 and 30-35. Fulton's condition factor K = 0.881 +/- 0.085 (mean +/- S.D.), 0.833 +/- 0.096 and 0.851 +/- 0.086, for fish spawning at salinities of c. 7, 10-18 and 30-35, respectively, with no difference between areas, i.e. analysed fish were in similar nutritional condition. A general linear model, with testes dry mass as the dependent variable and somatic mass as covariate resulted in a significant difference between areas-populations with larger testes for P. flesus spawning at a salinity of c. 7 but no difference between fish spawning at a salinity of 10-18 and 30-35. The result suggests that adaptation by increasing the number of spermatozoa produced may be a key mechanism for marine teleosts spawning in areas with low salinities to sustain the fertilization capacity as shown here for the euryhaline P. flesus.

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  • 31.
    Nissling, Anders
    et al.
    Högskolan på Gotland, Avdelningen för Biologi.
    Muller, Alajos
    Institute of Marine Research, University of Kiel, Germany.
    Hinrichsen, Hans-Harald
    Institute of Marine Research, University of Kiel, Germany.
    Specific gravity and vertical distribution of sprat eggs in the Baltic Sea2003Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 63, nr 2, s. 280-299Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During peak spawning of sprat Sprattus sprattus in the Baltic Sea in May-June egg specific gravity averaged plus or minus s.d. 1 times 00858 plus or minus 0 times 00116 g cm super(-3) but was significantly higher in the beginning and significantly lower towards the end of the spawning season. A close relationship was found between egg diameter and egg specific gravity (r super(2) = 0 times 71). This relationship, however, changed during the spawning season indicating that some other factor was involved causing the decrease in specific gravity during the spawning period. The vertical egg distribution changed during the spawning season: eggs were distributed mainly in the deep layers early in the season, occurred in and above the permanent halocline during peak spawning, and above the halocline towards the end of the spawning season. Consequently, poor oxygen conditions in the deep layers and low temperatures in layers between the halocline and the developing thermocline may affect egg development. Thus, opportunities for egg development vary over the spawning season and among spawning areas, and depending on frequency of saline water inflows into the Baltic Sea and severity of winters, between years.

  • 32.
    Nissling, Anders
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Thorsen, A.
    Inst Marine Res, POB 1870, N-5817 Bergen, Norway..
    da Silva, F. F. G.
    Inst Marine Res, POB 1870, N-5817 Bergen, Norway.;Tech Univ Denmark, Natl Inst Aquat Resources, Alle 1, DK-2920 Charlottenlund, Denmark..
    Fecundity regulation by atresia in turbot Scophthalmus maximus in the Baltic Sea2016Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 88, nr 4, s. 1301-1320Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Down-regulation of fecundity through oocyte resorption was assessed in Baltic Sea turbot Scophthalmus maximus at three locations in the period from late vitellogenesis in April to spawning during June to July. The mean +/- s.d. total length of the sampled fish was 327 +/- 31cm and mean +/- s.d. age was 62 +/- 15years. Measurements of atresia were performed using the profile method' with the intensity of atresia adjusted according to the dissector method' (106% adjustment; coefficient of determination was 0675 between methods). Both prevalence (portion of fish with atresia) and intensity (calculated as the average proportion of atretic cells in fish displaying atresia) of atresia were low in prespawning fish, but high from onset of spawning throughout the spawning period. Atretic oocytes categorized as in early alpha and in late alpha state occurred irrespective of maturity stage from late prespawning individuals up to late spawning fish, showing that oocytes may become atretic throughout the spawning period. Observed prevalence of atresia throughout the spawning period was almost 40% with an intensity of c. 20%. This indicates extensive down-regulation, i.e. considerably lower realized (number of eggs spawned) v. potential fecundity (number of developing oocytes), suggesting significant variability in reproductive potential. The extent of fecundity regulation in relation to fish condition (Fulton's condition factor) is discussed, suggesting an association between levels of atresia and fish condition.

  • 33.
    Norrgård, Johnny R.
    et al.
    Department of Biology, Karlstad University, 651 88 Karlstad, Sweden.
    Bergman, E
    Department of Biology, Karlstad University, 651 88 Karlstad, Sweden.
    Greenberg, L.A.
    Department of Biology, Karlstad University, 651 88 Karlstad, Sweden.
    Schmitz, Monika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Jämförande fysiologi.
    Effects of feed quality and quantity on growth, early maturation and smolt development in hatchery-reared landlocked Atlantic salmon Salmo salar2014Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 85, nr 4, s. 1192-1210Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of feed quality and quantity on growth, early male parr maturation and development of smolt characteristics were studied in hatchery-reared landlocked Atlantic salmon Salmo salar. The fish were subjected to two levels of feed rations and two levels of lipid content from first feeding until release in May of their second year. Salmo salar fed high rations, regardless of lipid content, grew the most and those fed low lipid feed with low rations grew the least. In addition, fish fed low lipid feed had lower body lipid levels than fish fed high lipid feed. Salmo salar from all treatments showed some reduction in condition factor (K) and lipid levels during their second spring. Smolt status was evaluated using both physiological and morphological variables. These results, based on gill Na+, K+-ATPase (NKA) enzyme activity, saltwater tolerance challenges and visual assessments, were consistent with each other, showing that S. salar from all treatments, except the treatment in which the fish were fed low rations with low lipid content, exhibited characteristics associated with smolting at 2 years of age. Sexually mature male parr from the high ration, high lipid content treatment were also subjected to saltwater challenge tests, and were found to be unable to regulate plasma sodium levels. The proportion of sexually mature male parr was reduced when the fish were fed low feed rations, but was not affected by the lipid content of the feed. Salmo salar fed low rations with low lipid content exhibited the highest degree of severe fin erosion.

  • 34.
    Norrgård, Johnny. R.
    et al.
    Department of Biology, Karlstad University, 651 88 Karlstad, Sweden.
    Bergman, E.
    Department of Biology, Karlstad University, 651 88 Karlstad, Sweden.
    Schmitz, Monika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Jämförande fysiologi.
    Greenberg, l.A.
    Department of Biology, Karlstad University, 651 88 Karlstad, Sweden.
    Effects of feeding regimes and early maturation on migratory behaviour of landlocked hatchery-reared Atlantic salmon Salmo salar smolts2014Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 85, nr 4, s. 1060-1073Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The migratory behaviour of hatchery-reared landlocked Atlantic salmon Salmo salar raised under three different feeding regimes was monitored through the lower part of the River Klarälven, Sweden. The smolts were implanted with acoustic transmitters and released into the River Klarälven, 25 km upstream of the outlet in Lake Vänern. Early mature males, which had matured the previous autumn, were also tagged and released. To monitor migration of the fish, acoustic receivers were deployed along the migratory route. The proportion of S. salar that reached Lake Vänern was significantly greater for fish fed fat-reduced feed than for fish given rations with higher fat content, regardless of ration size. Fish from the early mature male group remained in the river to a greater extent than fish from the three feeding regimes. Smolt status (degree of silvering), as visually assessed, did not differ among the feeding regime groups, and moreover, fully-silvered fish, regardless of feeding regime, migrated faster and had a greater migration success than fish with less developed smolt characteristics. Also, successful migrants had a lower condition factor than unsuccessful ones. These results indicate that the migration success of hatchery-reared S. smolts released to the wild can be enhanced by relatively simple changes in feeding regimes and by matching stocking time with smolt development.

  • 35.
    Petersson, Erik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Järvi, T.
    Characteristics of brown trout males influence growth and survival of their offspring2007Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 71, nr 2, s. 493-509Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Half-sib groups of juvenile brown trout Salmo trutta (0+ years) having fathers with different characteristics were compared in several respects. Two kinds of experiments were performed, aquarium observations in the laboratory and stocking in a semi-natural stream. It was found in the aquarium experiments that the offspring of fathers with larger adipose fins were more active and were probably better at defending territories. Offspring of males chosen by females had higher growth rate. The feeding rate was higher in juveniles having a less aggressive father or a father that was chosen by the mother. The stream experiments showed that offspring of dominant males had higher growth rates, and that offspring of less aggressive fathers had higher survival. Thus, characteristics of the males (fathers) influences the quality of the offspring, and there seem to be benefits for the females both to choose among potential mates and to spawn with the most dominant male. As these male characteristics are never regarded during the process of artificial breeding in hatcheries, the results indicate a basis for divergence between hatchery and wild populations.

  • 36.
    Quevedo, Mario
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Olsson, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    The effect of small-scale resource origin on trophic position estimates in Perca fluviatilis2006Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 69, nr 1, s. 141-150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of small-scale differences in resource origin on trophic position estimates was evaluated with the stable isotopes method. Perch Perca fluviatilis, a widespread freshwater predator, was used as a model organism. High individual variability was found in the contribution of benthic resources to the isotopic signatures of perch caught in the littoral zone, suggesting substantial within-habitat individual specialization. Small-scale resource origin and delta C-13 enrichment should be accounted for to avoid misleading estimates of both the absolute values and the ontogenetic trajectories of trophic position. A conceptual framework using end-member pathways is proposed to estimate trophic position with the stable isotope technique, particularly when marked ontogenetic niche shifts are expected.

  • 37.
    Raby, Graham D.
    et al.
    Univ Windsor, Great Lakes Inst Environm Res, Windsor, ON, Canada;Carleton Univ, Dept Biol, Fish Ecol & Conservat Physiol Lab, Ottawa, ON, Canada.
    Sundin, Josefin
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Jutfelt, Fredrik
    Norwegian Univ Sci & Technol, Dept Biol, Trondheim, Norway.
    Cooke, Steven J.
    Carleton Univ, Dept Biol, Fish Ecol & Conservat Physiol Lab, Ottawa, ON, Canada.
    Clark, Timothy D.
    Deakin Univ, Sch Life & Environm Sci, Geelong, Vic, Australia.
    Exposure to elevated carbon dioxide does not impair short-term swimming behaviour or shelter-seeking in a predatory coral-reef fish2018Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 93, nr 1, s. 138-142Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Adult bluespotted rockcod Cephalopholis cyanostigma, a coral-reef grouper, were acclimated to either ambient (mean +/- s.d. 406 +/- 21 atm; 1 atmos = 101325 Pa) or high pCO(2) (945 +/- 116 atm) conditions in a laboratory for 8-9 days, then released at the water surface directly above a reef (depth c. 5 m) and followed on video camera (for 191 +/- 21 s) by scuba divers until they sought cover in the reef. No differences were detected between groups in any of the six measured variables, which included the time fish spent immobile after release, tail beat frequency during swimming and the time required to locate and enter the protective shelter of the reef.

  • 38.
    Rosenqvist, Gunilla
    et al.
    Högskolan på Gotland, Institutionen för kultur, energi och miljö.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sexual signals and mating patterns in Syngnathidae2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1647-1661Artikel i tidskrift (Refereegranskat)
    Abstract [sv]

    Man graviditet i familjen Syngnathidae (pipefishes, sjöhästar och seadragons) predisponerar hanar att begränsa kvinnliga reproduktiva framgång, sexuell selektion kan då arbeta mer på kvinnor och kvinnliga sexuella signaler kan utvecklas (sex-roll vändning). En förvirrande mängd kvinnliga signaler har utvecklats i Syngnathids, t.ex. hudveck, stor kroppsstorlek, färgning, märkning på kroppen och utarbeta uppvaktning. Dessa kvinnliga sexuella signaler verkar inte kvantitativt eller kvalitativt skiljer sig från dem som utvecklas hos män i arter med konventionella könsroller där män ger honor eller avkomma med direkta fördelar. I flera syngnathid arter, män också utvecklas ornament, kvinnor är kräsna förutom att vara konkurrenskraftiga och män tävlar samt välja partner. Således könsrollerna bildar ett kontinuum, som spänner från konventionella till återförda inom denna grupp av fiskar. Fall presenteras här tyder på att en starkare sexuell selektion på honor kan vara mest extrem i arter som visar klassiska polyandri (en hane parar sig med flera honor, som många arter där hanar ruva sina ägg på bålen), intermediära i polygynandrous arter (män och kvinnor både parar sig med mer än en partner, som i många arter där hanar ruva sina ägg på svansen) och minst extrema, till och med uppvisar konventionella könsroller i monogama arter (en hane parar enbart med en kvinna, som i många sjöhästar och tropiska pipefishes). Samtidigt måste försiktighet iakttas innan enhälligt upprättandet detta mönster: för det första är sambandet mellan parningen mönster, styrka sexuell selektion, könsroller och prydnad uttryck långt ifrån enkel och okomplicerad, dels kunskap om de faktiska morfologi, ekologi och beteende de flesta syngnathid arter är knapphändig. I grund och botten bara ett fåtal Nerophis, Syngnathus och arter Hippocampus har studerats i detalj. Det är dock känt att denna grupp av fiskar uppvisar en anmärkningsvärd variation i könsroller och ornamentik, vilket gör dem till en idealisk grupp för studiet av parningen mönster, sexuell selektion och sexuellt utvalda signaler.

  • 39.
    Rowinski, Piotr K.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi. Stockholm Univ, Dept Zool, S-10691 Stockholm, Sweden..
    Mateos-Gonzalez, Fernando
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sandblom, E.
    Univ Gothenburg, Dept Biol & Environm Sci, S-40530 Gothenburg, Sweden..
    Jutfelt, F.
    Norwegian Univ Sci & Technol, Dept Biol, N-7491 Trondheim, Norway..
    Ekstrom, A.
    Univ Gothenburg, Dept Biol & Environm Sci, S-40530 Gothenburg, Sweden..
    Sundstrom, L. F.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Warming alters the body shape of European perch Perca fluviatilis2015Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 87, nr 5, s. 1234-1247Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The consequences of elevated temperature on body shape were investigated by comparing European perch Perca fluviatilis from the Forsmark area of the Baltic Sea to P. fluviatilis from a nearby Biotest enclosure. The Biotest is a man-made enclosure within the Baltic Sea that has received warm water from a nuclear power plant since 1980, resulting in temperatures that are elevated 5-10 degrees C relative to the surrounding Baltic Sea. Sampled fish ranged from young-of-the-year to 14years. Geometric morphometrics and multivariate statistical analysis revealed significant morphological differences between individuals of P. fluviatilis from these two habitats. Most importantly, relative shape changed with size, with small individuals of P. fluviatilis from Biotest being characterized by a deeper body shape and a larger caudal peduncle than the smaller Baltic individuals. In large specimens, smaller differences were found with Biotest individuals being more slender than Baltic individuals. These results show that, in order to have a full understanding of the biological effects of elevated temperatures, studies that cover the entire size range of organisms will be important. Apart from the direct influence of temperature on growth rate and body shape, other ecological factors affected by temperature are discussed as possible contributors to the observed differences between the two populations.

  • 40.
    Scharnweber, Kristin
    et al.
    Department of Biology and Ecology of Fishes, Leibniz Institute of Freshwater Ecology andInland Fisheries, Berlin.
    Plath, Martin
    Winemiller, Kirk
    Tobler, Michael
    Dietary niche overlap in sympatric asexual and sexual livebearing fishes Poecilia spp.2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 79, nr 7, s. 1760-1773Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present study investigated the spatiotemporal patterns in trophic resource use in a system of a gynogenetic poeciliid fish, the Amazon molly Poecilia formosa, and its sexual congeners the sailfin molly Poecilia latipinna and the Atlantic molly Poecilia mexicana using gut contents analysis. No statistically significant differences in trophic resource use were found between sexual and gynogenetic species, but gut contents varied significantly across sites and over time. In addition, variation in trophic morphology (i.e. gut length) was significant across sites but not species, and laboratory experiments indicated that gut length is phenotypically plastic. Overall, trophic differentiation between coexisting asexual and sexual Poecilia appears to be minimal, and it is unlikely that niche differentiation contributes to a stable coexistence of the two reproductive forms.

  • 41.
    Schjolden, Joachim
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Jämförande fysiologi.
    Pulman, Kim
    Metcalfe, Niel
    Winberg, Svante
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Jämförande fysiologi.
    Divergence in locomotor activity between two strains of rainbow trout Oncorhynchus mykiss with contrasting stress responsiveness2006Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 68, nr 3, s. 920-924Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Individuals of rainbow trout Oncorhynchus mykiss with a low cortisol response to stress showed higer locomotor activity compared to individuals with a high cortisol response.

  • 42. Sjöberg, N. B.
    et al.
    Petersson, E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Wickström, H
    Hansson, S
    Effects of the swimbladder parasite Anguillicola crassus on the migration of European silver eels Anguilla anguilla in the Baltic Sea2009Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 74, nr 9, s. 2158-2170Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a mark-recapture study in 2006, migrating European Anguilla anguilla silver eels were caught, tagged and released in the Baltic Sea and recaptures in commercial pound nets examined for possible effects on migration of infection with the swimbladder parasite Anguillicola crassus. The overall recapture rate was 36%. The prevalence of infection was lowest at the northernmost sampling site. There were no significant differences between infected and uninfected A. anguilla in condition indices, body fat content and estimated migration speeds. Parasite infection intensity levels were significantly negatively correlated with times and distances covered between release and recapture, but did not correlate with migration speed. It appears that more heavily infected A. anguilla were relatively more vulnerable to recapture in pound nets. It is hypothesized that parasite-induced damage to the swimbladder inhibited vertical migrations and infected A. anguilla tended to migrate in shallower coastal waters, relatively close to the shore.

  • 43. Sogabe, A.
    et al.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    The ovarian structure and mode of egg production in two polygamous pipefishes: a link to mating pattern2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1833-1846Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the ovarian structure and mode of egg production were examined in two pipefishes, the broad-nosed pipefish Syngnathus typhle and the straight-nosed pipefish Nerophis ophidion, which show different types of polygamous mating patterns. Syngnathus typhle showed an ovary with one germinal ridge and asynchronous egg production, corresponding to previous findings in other polygamous Syngnathus pipefishes. In contrast, the ovary of N. ophidion had two germinal ridges and eggs were produced synchronously in groups, similar to what has been observed in monogamous syngnathids. The egg production of N. ophidion, however, is clearly distinguished from that of monogamous syngnathids by the additional egg production after an ovulation. It is suggested that the differences in female mating strategies result from the difference in egg production process and that this is related to the difference in mating pattern between these two polygamous species.

  • 44.
    Sundin, Josefin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Jacobsson, Örjan
    Högskolan på Gotland, Institutionen för kultur, energi och miljö.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rosenqvist, Gunilla
    Högskolan på Gotland, Institutionen för kultur, energi och miljö. Norwegian University of Science and Technology, Trondheim.
    Straight-nosed pipefish Nerophis ophidion and broad-nosed pipefish Syngnathus typhle avoid eelgrass overgrown with filamentous algae2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1855-1860Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a habitat choice experiment straight-nosed pipefish Nerophis ophidion and broad-nosed pipefishSyngnathus typhle avoided eelgrass Zostera marina covered with filamentous algae. Both juvenilesas well as brooding adult males of the two species clearly preferred to position themselves inZ. marina without growth of filamentous algae.

  • 45. Tiira, K
    et al.
    Laurila, Anssi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution.
    Enberg, K
    Piironen, J
    Short-term dominance: stability and consequences for subsequent growth2009Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 74, nr 10, s. 2374-2385Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dominance status was determined among groups of four fish by using individuals from eight brown trout Salmo trutta populations. Subsequent growth of the fish was later recorded in larger groups. Seven months after the first set of trials, an additional set of dominance trials was performed by using the same fish. Social status affected subsequent growth; individuals having the lowest ranks grew less when compared to the higher ranking fish. Furthermore, the short term dominance hierarchy was rather stable between the two trials. This was especially the case with the lowest ranking fish, which tended to remain in the lowest position also in the second trial. The results suggest that the short term dominance trials done among few conspecifics reflect relatively well not only the subordinates' relative but also absolute social status. (C) 2009 The Authors Journal compilation (C) 2009 The Fisheries Society of the British Isles

  • 46.
    Westin, Lars
    et al.
    Högskolan på Gotland, Avdelningen för Biologi.
    Limburg, Karin E.
    College of Environmental Science & Forestry, State University of New York.
    Newly discovered reproductive isolation reveals sympatric populations of Esox lucius in the Baltic2002Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 61, nr 6, s. 1647-1652Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two populations of pike Esox lucius have been identified on the eastern coast of Sweden, in the Baltic Sea. These live together, but separate into two different populations during the spawning season. One is an obligate freshwater spawner and the other not only reproduces in ambient Baltic salinities, but appears not to enter fresh water at all.

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