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Jeg har sett på bestandsutviklingen til hjort og elg i tidligere Halsa kommune. Ved å bruke sett og skutt data fra hjorteviltregisteret så kan jeg se at hjorten har hatt en økning i bestanden de siste 18 årene, mens elgen har hatt en nedgang i antall individer i bestanden. Jeg undersøkte flere momenter for forvaltningen av disse artene og sammenlignet med interkommunale målsettinger fra hjorteviltregion 2 som grunnlag. Hjorten har over flere år blitt forvaltet for å få ned bestanden og har derfor hatt et høyt uttak av hodyr med noe suksess, men fortsatt har ett høyt antall individer. Hos elgen har også målet vert å få ned bestanden, men det ser ut til at avskytningen har vært mer vilkårlig og senere fått konsekvenser med en lav bestand under bestandsmål. Ved sammenligning av de to artene viste det seg at det er et langt høyere antall hjort enn elg i tidligere Halsa kommune. Begge artene hadde en viss synkende gjennomsnittlig vekt hos kalv som kanskje som kanskje kan skyldes en direkte konkurranse om mattilgang mellom artene på grunn av antall uten at dette kan konkluderes. Jeg har også sett på blant annet kjønnssammensetningene, sett dyr per jegerdag samt alderssammensetningen (kun for hjort) for å se på endringene i de to artenes bestander. Jeg har også brukt data fra et pågående viltkameraprosjekt som viste en økende andel sette elg med økende andel sette hjort i utmark. Det motsatte ble vist når jeg sammenlignet antall hjort og elg med sett og skutt data fra hjorteviltregisteret. Dette kan forklares med at flesteparten av hjorten som blir registrert under jakt blir observert på innmark, mens elg kanskje oppholder seg mere i utmark. Abstract I have studied population development of red deer and moose in former Halsa municipality. With the use of seen and shot data from “hjorteviltregisteret.no /register for deer species” I have seen that the population of red deer has increased over the last eighteen years, but the number of moose has decreased. I investigated multiple factors in the management of these two species and compared them to the overall management plans for the deer region 2 (hjorteviltregion 2) in Norway. The population of red deer has over many years been managed to decrease the overall numbers and because of that have had a management plan to take out a big portion of females. This has had some success, but still there is a big number of deer in the area. The management plan for moose has also been to reduce the number of animals in the population. But poor management planning and unrestricted shooting has taken the population to an all-time low compared to the overall plans for the area. Both species has had a decrease in weights for calves, this could be a direct consequence to competition for food between the two species. That could be because of the number of animals in the herds. but in this research, I could not conclude if this was the main cause of lower weights of calves. I have also looked in to among other things the gender composition, seen animals per hunters’ day and the age composition (only for red deer). All this to understand the population development for the two species. I also used data from a local camera trapping project to compare the number of red deer to moose over a period and I found out that with an increase in the number of deer the number of moose also increases. I did the same comparison on the data from seen deer, in this comparison I found the opposite. Whit an increase in number of red deer, the number of moose decreased. This can be explained by the fact that most registered reed deer from seen data gets registered on farmland-areas where the moose do not tend to use the farmlands for grazing as much as the red deer.

Background The Scandinavian wolf (Canis lupus) population is being monitored annually using non-invasive genetic sampling (NGS) and recovery of dead individuals. DNA extracted from faeces, urine, hair, and tissue is used to identify the species, sex, and individual from which each sample originated. These data have been compiled in the Scandinavian large carnivore database Rovbase 3.0 (www.rovbase.se). Approach Using the Bayesian open-population spatial capture-recapture (OPSCR) model developed by RovQuant (Bischof et al., 2019b, 2020), we estimated annual density and vital rates of the Scandinavian wolf population for nine seasons from 2012/13 to 2020/21. The OPSCR model accounts for individual movements, as well as imperfect and variable detection. Results The OPSCR model yielded annual density maps and both total and jurisdiction-specific population sizes for wolves from 2012/13 to 2020/21. The estimated number of wolves for October 1, 2020 (start of the 2020/21 monitoring season) was 460 individuals (CrI: 439 - 483), of which 371 (CrI: 351-392) were located in Sweden and 89 (CrI: 80-99) in Norway. In addition to annual density and jurisdiction-specific abundance estimates, we report estimates of survival, recruitment, and detection probabilities. Bakgrunn Den skandinaviske bestanden av ulv (Canis lupus) blir overvåket årlig ved bruk av ikke-invasiv genetisk prøveinnsamling (NGS) og gjenfunn av døde individer. DNA ekstrahert fra skit, urin, hår og vev brukes til å identifisere art, kjønn og individ for hver enkelt prøve. Denne informasjonen samles og ivaretas i den skandinaviske databasen for store rovdyr; Rovbase 3.0 (www.rovbase.se). Tilnærming Ved bruk av en Bayesiansk åpen romlig fangst-gjenfangst populasjons modell (OPSCR), utviklet av RovQuant (Bischof et al., 2019b, 2020), estimerte vi årlige tettheter og demografiske rater hos den skandinaviske ulvebestanden i ni sesonger fra 2012/13 til 2020/21. OPSCR modellen tar høyde for individers forflytninger, samt variabel oppdagbarhet. Resultater OPSCR modellen gav årlige kart med tetthet av ulv fra 2012/13 til 2020/21, hvor bestandsstørrelsen både totalt og innenfor ulike administrative enheter kunne avledes. Det estimerte antallet ulver for 1. oktober 2020 var 460 individer (CrI: 439 - 483), hvorav 371 (CrI: 351-392) var lokalisert i Sverige og 89 (CrI: 80-99) i Norge. I tillegg til årlige tettheter og områdespesifikke bestandsestimater, gir rapporten estimater på årlig overlevelse, rekrutering og oppdagbarhet i den skandinaviske bestanden av ulv for perioden 2012/13 til 2020/21.

Monitoring of wolves (Canis lupus) in Scandinavia is a coordinated effort between Swedish and Norwegian management authorities. Since 2012/13, the size of the Scandinavian wolf population is being estimated indirectly by applying a conversion factor to the number of detected reproductions (Box 1). This conversion factor (CF1) was calculated based on inventory data from 2001-2003. The intent to move from counting reproductions to counting the number of packs (family groups) in Sweden prompted the development of an updated conversion factor, which was published in 2016. This new conversion factor (CF2) was derived with an individual-based model of the wolf population that included social dynamics, information from telemetry studies, and a nearly complete pedigree. Because CF2 differed from CF1 both methodologically and quantitatively, and due to the highly polarized debate surrounding wolf management in Scandinavia, management authorities sought to obtain another assessment via an independent analytical approach to evaluate the new findings. This motivated the analysis detailed in the present report. Specifically, the objective of this new analysis was to generate annual spatially explicit wolf population estimates and then use the results to derive the corresponding factor for converting the number of detected packs to the total number of individuals in the population. We developed a Bayesian open-population spatial capture-recapture (OPSCR) model that incorporates 1) wolf population size and dynamics, 2) the spatial distribution and inter-annual movements of individuals, including dispersal, and 3) a detection process based on a combination of non-invasive genetic sampling (NGS) and recoveries of dead wolves. We then fitted this model to the extensive individual-based wolf monitoring data, which had been collected throughout the Scandinavian wolf range over five seasons (2013/14 to 2017/18) and compiled in the Scandinavian large carnivore database (Rovbase 3.0). The OPSCR model yielded annual density maps, from which both total and jurisdiction specific population sizes were derived. Wolf population size estimates ranged between 368 (95% credible interval, CrI: 344 - 397) and 421 (CrI: 397 - 448) during the 5 year period of this study. The estimated number of wolves for October 1 2017 was 401 wolves (CrI: 392 - 412), of which 310 (CrI: 301-321) were located in Sweden and 91 (CrI: 83-101) in Norway. Based on numbers of observed packs reported for the five monitoring seasons, we arrived at a 5-year-median conversion factor (CF3, packs to total population size, October 1) of 8.8 (CrI: 8.2 – 10.0). Median annual conversion factors ranged from 8.6 to 9.8, with the conversion factor calculated for the 2017/2018 season (9.8; CrI: 9.6 - 10.1) being significantly higher than those during the previous four years. Although CF1 (9.2, uncertainty: 5.8 – 13.8; transformed for conversion from packs to population size), CF2 (8.2, CrI: 6.8 – 10.1, projected to October 1), and CF3 (8.8, CrI: 8.2 – 10.0) result in different point estimates of population size, comparisons between the three conversion factors is challenging, due to methodological differences, reliance on different data sources, and uncertainty reported (see Figure 15 on page 32). The approach used here has several advantages over proxy-based approaches for obtaining estimates of population size. OPSCR models allow direct estimation of annual abundance from non-invasive genetic sampling and dead recovery data, while accounting for spatial and temporal variation in the detection probability of individuals. The resulting estimates are spatially explicit, allowing extraction of abundance estimates and associated measures of uncertainty for any spatial extent desired by the user within the overall study area (e.g. at the country and county level), with October 1 as the reference date. Annual cause-specific mortality and recruitment are also estimated, both useful metrics of the population’s status and trajectory. Importantly, this approach efficiently exploits the data (NGS and dead recoveries) currently collected annually by Swedish and Norwegian management authorities at the population and landscape level. Annual direct estimates of population size also circumvent potential problems arising from applying a fixed conversion factor when population structure or the proportion of detected packs changes over time. For these reasons, and if economically and logistically feasible, we recommend the use of direct means for estimating population size when assessing the status of wolves in Scandinavia and evaluating the impact of management interventions. A transition from the use of proxies to direct population size estimation with the OPSCR model would entail a shift from pack and pair-centered monitoring to a less selective setup where effort is spread evenly enough to collect DNA samples throughout the population regardless of demographic (e.g. age) and social class (e.g. pup, scent-marking adult, vagrant). Whether such a shift is feasible, will depend on the amount of effort required to reach a desired level of precision and whether it allows monitoring of other population parameters that are of importance to managers. The observation process component of our OPSCR model most closely matched the NGS collection pattern during the 2017/18 monitoring season, which was the season with the most intensive data collection. Although such intensive monitoring may not be feasible on a long-term basis, results from a preliminary study, using the 2017/18 season as an example, suggests that reliable and precise population size estimates are still obtainable when monitoring intensity is reduced, as long as collection effort is spread across the landscape and all demographic/social classes. Further study is needed to assess the effort-precision tradeoff and to explore sampling design options that allow managers to obtain other measures of interest. We provide a discussion of the strengths and limitations of our approach, ideas for further development and study, and a series of recommendations for how to adjust the monitoring program to allow effective integration with the OPSCR approach for population size estimation.

Background Reliable estimates of population status are a pre-requisite for informed wildlife management. However, abundance estimates can be challenging to obtain, especially for species that are highly mobile, rare and elusive. For nearly two decades, management agencies in Norway and Sweden have been monitoring populations of three large carnivores – brown bear (Ursus ursus), wolf (Canis lupus), and wolverine (Gulo gulo) – using non-invasive genetic sampling (NGS). DNA extracted from fæces, urine, and hair can be used to identify the species, sex, and individual from which each sample originated. Samples thus become evidence of the presence of an individual carnivore in space and time. Project RovQuant was initiated in 2017 with the objective to develop statistical methods that allow a comprehensive assessment of population status and dynamics using NGS data and other sources of information collected by the national monitoring programs in Sweden and Norway. Approach We developed a Bayesian open-population spatial capture-recapture (OPSCR) model that, using a combination of NGS and recoveries of dead carnivores, jointly estimates 1) the spatial variability in the probability of genetic detection, 2) the spatial distribution and interannual movements of individuals and 3) population size and dynamics. We fitted this model to the extensive individual-based monitoring data for bears, wolverines, and wolves, which had been compiled in the Scandinavian large carnivore database Rovbase 3.0 between 2012 and 2019. Results The OPSCR model yielded annual density maps both total and jurisdiction-specific population sizes for each species. The estimated number of bears for April 1, 2018 was 2 757 (95% credible interval, CrI: 2 636 - 2 877), of which 2 615 (CrI: 2 499-2 732) were located in Sweden and 142 (CrI: 124-162) in Norway. The estimated number of wolverines for December 1, 2018 was 1 035 (CrI: 985 - 1 088), of which 660 (CrI: 619-703) were located in Sweden and 375 (CrI: 353-397) in Norway. The estimated number of wolves for October 1, 2018 was 375 wolves (CrI: 352 - 402), of which 297 (CrI: 274-322) were located in Sweden and 79 (CrI: 72-86) in Norway. In addition to density and abundance estimates, the OPSCR models also yielded estimates of survival, recruitment, and space use parameters for each species. Six additional tasks linked to the development of OPSCR model were implemented as either prerequisite technical developments or to address persistent challenges in monitoring and management of large carnivores in Scandinavia. Although this report focuses on the main results from the OPSCR model, findings related to these additional tasks are briefly described as well. Conclusions The unique Scandinavian data set combined with a novel OPSCR model allowed RovQuant to quantify the population status of three large carnivore species at an unprecedented spatial scale (up to 593 000 km2). The approach used here has several advantages over proxy-based approaches for obtaining estimates of population size. The OPSCR model directly estimates annual abundance from NGS and dead recovery data while accounting for spatial and temporal variation in detection probability of individuals. The resulting estimates are spatially explicit, allowing extraction of abundance estimates and associated measures of uncertainty for any spatial extent desired by the user (e.g. management unit). Annual cause-specific mortality and recruitment are also estimated, which are both useful metrics of the population’s status and trajectory. Importantly, this approach efficiently exploits the data (NGS and dead recoveries) currently collected annually by Swedish and Norwegian management authorities at the population level. Although the OPSCR model has been extensively tested, it constitutes a novel approach and is still under development. The ability of the model to produce trustworthy estimates relies on several statistical assumptions and on the suitability of the input data. For example, although the model was able to produce annual density maps and abundance estimates for bears throughout Scandinavia, the current patchy sampling for this species in Sweden means that confidence in the reliability of the results for bear is substantially lower than for the other two species. We discuss the strengths and limitations of our approach and suggest areas for further study and development in order to increase the reliability of the OPSCR model and the cost-efficiency of large carnivore monitoring in Scandinavia.

Heavy positively autocorrelated natural fluctuations in a fisheries stock level are problematic for fisheries management, and collapses in the stock dynamics are difficult to avoid. In this paper, we compare three different har- vesting strategies (proportional harvesting, threshold harvesting, and proportional threshold harvesting) in an autocorrelated and heavily fluctuating fishery — the Norwegian spring-spawning herring (Clupea harengus) — in terms of risk of quasi-extinction, average annual yield, and coefficient of varia- tion of the yield. Contrary to general expectations, we found that the three strategies produce comparable yields and risks of quasi-extinction. The only ob- servable difference was slightly higher yield and variation in the proportional threshold strategy when the yield is optimized. Thus, it remains an open ques- tion as how to characterize the circumstances when it is particularly needful to apply threshold levels in harvest policies.

Fauchald P, Anker-Nilssen T, Barrett RT, Bustnes JO, Bårdsen B-J, Christensen-Dalsgaard S, Descamps S, Engen S, Erikstad KE, Hanssen SA, Lorentsen S-H, Moe B, Reiertsen TK, Strøm H, Systad GH (2015) The status and trends of seabirds breeding in Norway and Svalbard – NINA Report 1151. 84pp. This report presents the updated sizes, trends and spatial distributions of the breeding populations of 17 seabird species breeding in Norway and Svalbard. The analyses are based on available census and monitoring data from SEAPOP; the Norwegian monitoring and mapping program for seabirds. In addition, the report presents results from a species-specific literature review of the most important prey items and drivers of population change. The report documents large-scale decadal changes in the seabird communities along the coast of Norway and Svalbard. A division of the populations into five geographical regions (North Sea & Skagerrak; Norwegian Sea; Barents Sea; Bjørnøya; and Spitsbergen) was used as a basis for the analyses of population dynamics from 1980 to present. 13 of the 35 regional seabird populations assessed have declined by more than 50% the last 25 years. 5 regional populations increased by more than 100% in the same period, while 8 populations showed large decadal fluctuations. Several populations were not assessed due to the lack of census and/or monitoring data. In order to improve the dataset, it is recommended that a census of breeding seabirds from Vesterålen to the Swedish border is completed. Declining populations were found in all regions and included all major ecological groups (i.e.; Pelagic surface-feeding (Ps), Pelagic diving (Pd), Coastal surface-feeding (Cs), Coastal benthic-feeding (Cb) and Coastal diving (Cd) seabirds). Populations with more than a 50% decline the last 25 years were: Common Gull (Cs), Lesser Black-backed Gull (Ps) and Atlantic Puffin (Pd) in the North Sea & Skagerrak; Great Cormorant (Cd), Common Eider (Cb), Black-legged Kittiwake (Ps) and Common Guillemot (Pd) in the Norwegian Sea; Herring Gull (Cs), Great Black-backed Gull (Cs), Black-legged Kittiwake (Ps) and Brünnich’s Guillemot (Pd) in the Barents Sea; Northern Fulmar (Ps) and Glaucous Gull (Ps) on Bjørnøya; and Brünnich’s Guillemot (Pd) on Spitsbergen. The populations of European Shag and Great Cormorant have shown large fluctuations with a notable increase in the population of Phalacrocorax carbo sinensis in North Sea & Skagerrak. Common guillemot has been increasing in the Barents Sea since the collapse in the population in the 1980s, however the population in the Norwegian Sea has been steadily declining since the early 1980s. Atlantic Puffin is declining in the North Sea and Norwegian Sea, but the population in the Barents Sea is stable or is increasing slightly. The datasets were too small to assess several of the large gull species in the Norwegian Sea. However, extensive monitoring in the North Sea & Skagerrak and recent censuses in the Barents Sea suggest declines by more than 50% in several of the gull populations in these areas. Black-legged Kittiwake has declined in all regions except for Bjørnøya. The large colonies of Brünnich’s Guillemot on Spitsbergen have declined from 1.15 million pairs in 1988 to 522 000 pairs in 2013. The colony on Bjørnøya (about 100 000 pairs) has in the same period been stable or declined slightly, while the small populations on the Norwegian mainland have almost disappeared. Northern Gannet has been increasing in Norway since the establishment of this species on Runde in the 1940s. The species has expanded northward and has recently established a small colony as far north as Bjørnøya. The review of diet studies highlighted the importance of the young age-classes of cod fish, the importance of pelagic forage fish species and in particular the importance of sandeel. However, the differences in diet among ecological groups combined with the fact that declining seabird populations were found in all regions and included all major ecological groups suggest that the recent changes in Norwegian seabird communities cannot be explained by changes in the abundance of a single group of resources alone. On the contrary, this might suggest a combined effect of simultaneous changes in several prey items, possibly involving entire trophic levels. Alternatively, it might suggest that bottom-up regulation through food is less important, and that top-down mechanisms such as anthropogenic stressors and predation are more involved in the present changes. A large number of studies have been conducted to investigate how different anthropogenic and environmental factors affect seabird populations. Factors such as fisheries by-catch, harvest and intentional killing, pollution and disturbance are all anthropogenic stressors with a welldocumented negative impact. Although most of these stressors have been reduced in Norwegian waters due to the implementation of regulatory mechanisms and protection measures, they might still have impact on local populations. For example, the decline in the population of Glaucous Gull on Bjørnøya has been related to high levels of persistent organic pollutants. Several case studies suggest that predation from avian and small mammalian predators in the seabird colonies might be important, and we cannot exclude this driver as an important mechanism behind the observed declines. The large spatial and the relatively long temporal scale of the population changes observed in the present report, might suggest that fluctuations in the marine ecosystems, possibly partly due to climate change and past and present fishing pressures, might be important. This is corroborated by numerous studies documenting a direct impact from food deprivation and an indirect impact from climatic factors on seabird population dynamics. Such factors often involve complex indirect trophic links which make it difficult to point out the ultimate cause of the observed change. We conclude that the two most likely candidates to explain the recent declines in Norwegian seabird populations are 1) increased predation in the seabird colonies from avian and mammalian predators and 2) ecosystem changes affecting the availability of prey. The impact from these drivers might be difficult to document and even more challenging to control. In contrast, more easily managed direct anthropogenic stressors such as fisheries by-catch, pollution, hunting and disturbance have either been constant or have shown a decreasing trend. Although these drivers cannot explain the recent population declines, they still contribute to the cumulative impact on seabird populations and these stressors are therefore especially important to control and minimize in rapidly declining and threatened populations. © Norsk institutt for naturforskning. Publikasjonen kan siteres fritt med kildeangivelse.

Natural populations are affected by a range of factors, including climate and contaminants. In this study, we have used use data from both population monitoring as well as contaminant monitoring to analyse variation in abundance of Atlantic cod on the coast of Skagerrak and black-legged kittiwake in mainland Norway. For Atlantic cod, we found significant effects of both climate (temperature and wind) as well as contaminants (concentrations of HCH-A, HCB and PCB-153 in blue mussels). For black-legged kittiwake, a population model confirms that for the southerly populations Runde and Sklinna, either adult survival is lower than in more northerly populations, or that chicken mortality is extremely high (~95%). Miljødirektoratet

The synergistic effects of fishing, climate and internal dynamics on population fluctuations are poorly understood due to the complexity of these interac- tions. In this paper, we combine time series analysis and simulations to investigate the long-term dynamics of an overexploited population in the Mediterranean Sea, and its link with both fishing-induced demographic changes and hydroclimatic variability. We show that the cyclicity of the catch per unit of effort (CPUE) of Euro- pean hake Merluccius merluccius (EH) vanished in the 1980s, while the correlation between the CPUE and a local environmental index increased. Using simulations, we then show that the cyclicity observed in the EH bio- mass before the 1980s can have an internal origin, while that its disappearance could be due to the fishing- induced erosion of the age structure. Our results suggest that fishing can trigger a switch from internally gen- erated to externally forced population fluctuations, the latter being characterised by an increasing dependency of the population on recruitment and ultimately on envi- ronmental variability. Hydroclimatic modifications oc- curring in the Mediterranean in the early 1980s could have enhanced these changes by leading to a mismatch between early life stages of EH and favorable environ- mental conditions. Our conclusions underline the key effect of the interaction between exploitation and climate on the dynamics of EH and its important consequences for management and conservation.

The number of species of the goatfish genus Upeneus from the western Indian Ocean has increased considerably due to recent taxonomic efforts. Here we describe a new species, Upeneus randalli n. sp., based on body and fin coloration and 50 morphometric and meristic characters of eight specimens from the Persian Gulf, and supported by comparative data from a taxonomic review of western Indian Ocean Upeneus species and additional material from collections. Upeneus randalli is distinguished from congeners by the combination of 8 dorsal-fin spines, 14 pectoral-fin rays, 23 to 25 gill rakers, 28 to 30 lateral-line scales, pectoral-fin width 22 to 26 times in SL, and red bars on both caudal-fin lobes. We provide two identification keys: one key is for distinguishing among four species groups and the morphologically unique U. filifer, accounting for all 28 species of the genus, and the other key is for the six closely related species of the “U. tragula group” from the western Indian Ocean, including U. randalli n. sp. Since the colour patterns fade away soon after collection and can be completely lost during preservation, morphometric and meristic characters are important for correctly identifying U. randalli n. sp. and the closely related U. margarethae. The latter species shows considerable variation in body form in different areas of the western Indian Ocean. We discuss the significance of detailed comparative studies of caudal-fin colour patterns and body-form characters for obtaining a deeper understanding of inter- and intraspecific diversity among Upeneus. El número de especies de salmonetes del género Upeneus del Océano Índico Occidental ha aumentado considerablemente debido a los recientes trabajos taxonómicos. En este trabajo se describe una nueva especie, Upeneus randalli n. sp., en base a la coloración del cuerpo y las aletas y a 51 caracteres morfométricos y merísticos de ocho especímenes del golfo Pérsico, apoyados por datos comparativos de una revisión taxonómica de las especies del océano Índico occidental Upeneus y material adicional de colección. Upeneus randalli es differenciada de sus congeners por la combinación de 8 espinas en la aleta dorsal, 14 radios en la aleta pectoral, 23-25 branquiespinas, 28-30 escamas en la línea lateral, anchura de la aleta pectoral 22-26 veces en LS y barras rojas en ambos lóbulos de la aleta caudal. Se proporcionan dos claves de identificación, una para la distinción entre cuatro grupos de especies y la especie U. filifer, morfológicamente única, que responde por el total de las 28 especies del género y la otra clave para las seis especies estrechamente relacionadas del “grupo U. tragula” del océano Índico occidental incluyendo U. randalli n. sp. A causa de que los patrones de color se desvanecen pronto después de la recolección y que pueden perderse completamente durante la conservación, los caracteres morfométricos y merísticos son importantes para la correcta identificación de U. randalli n. sp. y la especie estrechamente relacionada U. margarethae. Esta última muestra una considerable variación en la forma del cuerpo entre diferentes áreas del océano Índico occidental. En este trabajo se discute si la correlación de estudios comparativos detallados de patrones de color de la aleta caudal y forma del cuerpo es significativa para mejorar el conocimiento de la diversidad inter- e intraespecífica entre Upeneus.

Interactions within and between species complicate quantification of climate effects, by causing indirect, often delayed, effects of climate fluctuations and compensation of mortality. Here we identify direct and indirect climate effects by analysing unique Russian time-series data from the Norwegian Sea–Barents Sea ecosystem on the first life stages of cod, capelin, herring and haddock, their predators, competitors and zooplanktonic prey. By analysing growth and survival from one life stage to the next (eggs–larvae–juveniles–recruits), we find evidence for both bottom-up, direct and top-down effects of climate. Ambient zooplankton biomass predicts survival of all species, whereas ambient temperature mainly affects survival through effects on growth. In warm years, all species experienced improved growth and feeding conditions. Cohorts born following a warm year will, however, experience increased predation and competition because of increased densities of subadult cod and herring, leading to delayed climate effects. While climate thus affects early growth and survival through several mechanisms, only some of the identified mechanisms were found to be significant predictors of population growth. In particular, our findings exemplify that climate impacts are barely propagated to later life stages when density dependence is strong.

Satellite data and operational ocean models provide the necessary inputs for ecosystem models of the lower to mid- and upper trophic levels. One key explanatory variable that is usually missing to understand the dynamics of key exploited or protected marine species is the dynamic of the micronekton that is at the Mid-Trophic Level (MTL) in the ecosystem, and thus being both prey of large predators and predator of eggs and larvae of fishes. We present the development of an operational model of mid-trophic functional groups driven by physical and biogeochemical variables. Once a reasonable prediction of MTL organisms is achieved, the number of applications for near real-time management and monitoring of marine ecosystems and resources should increase rapidly, as illustrated by the examples provided here, and including the prediction and forecast of feeding and spawning habitat of many exploited or protected species, their movements and spatial distributions, and finally their population dynamics under the combined effects of natural (climate variability) and anthropogenic forcings (fishing, climate warming).

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Fishing is often size selective such that the likelihood of capture increases with body size. It has therefore been postulated that fishing could favour evolution of slower growth because smaller size would reduce exposure to fishing gear (e.g. Ricker 1981). A recent study by Swain et al. (2007; hereafter referred to as SSH) makes a valuable attempt to demonstrate such an effect on length-at-age of southern Gulf of St Lawrence cod (Gadus morhua). The strength of their study lies in an innovative combination of three elements. First, as the evolving trait, they used length-at-age 4 years, an age at which cod are representatively sampled but have experienced little fishing mortality. Confounding demographic effects of size-selective fishing were therefore avoided. Second, they had time series of temperature and population density, both possibly affecting length-at-age through phenotypic plasticity. Finally, and as the most innovative element, they linked their approach to quantitative genetics theory. Using a modified breeder's equation, they modelled changes in length-at-age 4 as a function of genetic and environmental components: ΔL4=h2S+βΔE+ϵ. Here ΔL4 and ΔE are differences in length-at-age 4 and environment, respectively, between the focal cohort and its parent generation. S is the selection differential (difference in mean length-at-age 4 between fish observed at age 4 and those observed at reproducing ages). Estimated heritability h2 and parameter β are regression coefficients, and ϵ is a normally distributed error term with zero mean. SSH assumed that the environment can be described by changes in population density Δd and temperature Δt. The key point is that a significant effect of S on ΔL4 would indicate an evolutionary response in length-at-age 4. SSH's statistically favoured regression model was one including both S and Δd; they concluded that the data suggested an evolutionary response to fishing. Of course, as SSH readily pointed out, one cannot rule out the existence of alternative and untested factors. Here, we comment on some caveats in the analysis by SSH. We do not challenge their novel approach, but question some key assumptions and the strength of their conclusions.

Annual development of density and mean weight of juvenile plaice Pleuronectes platessa was examined at 2 nursery grounds (Port Erin Bay, Isle of Man, Irish Sea and Admucknish Bay, Firth of Lorne, west coast of Scotland) over a number of years. In both cases there was evidence of 'self-thinning' in the populations when the density was high, although in Port Erin Bay the slope suggested a relationship different from the standard - 4 ⁄3 rule proposed for animal populations. The site specific dynamic thinning lines (dynamic carrying capacities) were consistent with the dynamic thinning line (-4⁄3 rule) for both populations. The 2 nursery grounds were different, with growth rates and densities generally higher on the Ardmucknish Bay nursery ground compared with Port Erin Bay. Similarly, the estimated total biomass of plaice was higher in Ardmucknish Bay than Port Erin Bay, but there was considerable inter-annual variation. Maximum plaice biomass generally occurred from August to September for both sites. In Port Erin Bay this coincided with the maximum consump- tion rates. The size structure was described using the Gini coefficient (G) and the timing of size struc- ture development by the centre of gravity (CG). The size structure of the populations differed and in both cases varied during the season in response to settlement and mortality. Over the study periods, population density was only occasionally high enough to reach the site specific self-thinning line. This suggests that these populations rarely approached the carrying capacity of the nursery grounds.

Selective harvesting regimes are often implemented because age and sex classes contribute differently to population dynamics and hunters show preferences associated with body size and trophy value. We reviewed the literature on how such cropping regimes affect the demography of the remaining population (here termed demographic side effects ). First, we examined the implications of removing a large proportion of a specific age or sex class. Such harvesting strategies often bias the population sex ratio toward females and reduce the mean age of males, which may consequently delay birth dates, reduce birth synchrony, delay body mass development, and alter offspring sex ratios. Second, we reviewed the side effects associated with the selective removal of relatively few specific individuals, often large trophy males. Such selective harvesting can destabilize social structures and the dominance hierarchy and may cause loss of social knowledge, sexually selected infanticide, habitat changes among reproductive females, and changes in offspring sex ratio. A common feature of many of the reported mechanisms is that they ultimately depress recruitment and in some extreme cases even cause total reproductive collapse. These effects could act additively and destabilize the dynamics of populations, thus having a stronger effect on population growth rate than first anticipated. Although more experimental than observational studies reported demographic side effects, we argue that this may reflect the quite subtle mechanisms involved, which are unlikely to be detected in observational studies without rigorous monitoring regimes. We call for more detailed studies of hunted populations with marked individuals that address how the expression of these effects varies across mating systems, habitats, and with population density. Theoretical models investigating how strongly these effects influence population growth rates are also required.

Stock/recruit relationships, describing the relationship between the parental population and the number of offspring produced, are a central tool in population ecology. For fish populations the stock/recruit relationship uses spawning stock biomass (SSB) to represent reproductive potential of the parental population. This assumes that the proportion of SSB comprised of females and the relative fecundity (number of eggs produced per unit mass) are both constant over time. To test these two constancy assumptions female-only spawner biomass (FSB) and total egg production (TEP) were estimated for the Northeast Arctic cod stock over a 56-year time period (1946-2001). During that time period the proportion of females (FSB/SSB) varied between 24 and 68% and the variation was systematic with length such that SSB became more female-biased as the mean length of spawners increased and more male-biased as mean length decreased. Over the same time period, relative fecundity of the stock (TEP/SSB) varied between 115 and 355 eggs g-1 and, like FSB/SSB, was significantly, positively correlated mean length of spawners. Because both FSB/SSB and TEP/SSB covaried with length composition, SSB is systematically biased estimate of reproductive potential. FSB and TEP were evaluated as possible replacements for SSB in stock/recruit relationship. Both indices gave a different interpretation of the recruitment response to reductions in stock size (over-compensatory) compared to that obtained using SSB (either compensatory or depensatory). The threshold level of stock size below which recruitment becomes impaired was estimated for each of the different stock/recruit relationships using piecewise linear regression. There was no difference between SSB and FSB in the assessment of stock status, however, in recent years (1980-2001) TEP fell below the threshold level more frequently than SSB fell below. This suggests that using SSB as a measure of stock reproductive potential may lead to overly optimistic assessments of stock status.

Population and community level processes change across multiple spatial scales. Understanding these patterns and the factors that drive them are essential for the development of spatial approaches in fisheries management. Determining appropriately-resolved spatial scales is further complicated in temperate marine ecosystems by the generally high mobility and low site fidelity of temperate species compared to those in tropical reef systems. Spatial variability in per capita vital population rates (e.g., consumption, mortality, growth, survival) can directly affect the population level dynamics of managed species. Benthic habitat characteristics also change across spatial dimensions and may contribute to the differential spatial variability in vital rates. We used a set of bioenergetic equations to compute the daily per capita rate of consumption and mortality for individual groundfish species. These estimates used data from the US National Marine Fisheries Service Northeast Fisheries Science Center bottom trawls and food habits data sets. A geographic information system (GIS) was created to map these vital rates at multiple spatial scales. The spatial variability and spatial independence of vital rates were then explored using geostatistical techniques. Multivariate statistical approaches were also used to examine how habitat characteristics may be influencing spatial patterns in vital rates. Our results demonstrate the challenge of evaluating key population processes at the most appropriate spatial scales. Yet the demonstrated ability to integrate individual, population, and habitat information across multiple spatial scales should enhance our ability to manage our living marine resources. Keywords: spatial statistics, consumption, mortality, groundfish, fisheries management, essential fish habitat, NW Atlantic

Journal home page: http://www.int-res.com/journals/meps/ Through the statistical modeling of monitoring data, we assess the ecological interlinkages between cod Gadus morhua L. in the North Sea, Skagerrak and Kattegat—regions which typically have been considered separate management units. The model includes both within-population density dependence (within and between age classes), as well as density-dependent effects of migration between the North Sea, Skagerrak and Kattegat. Further, the model incorporates the effects of environmental features (such as temperature and the North Atlantic Oscillation). The obtained results are discussed, both with reference to general ecological principles as well as with respect to management implication. Altogether our analysis suggests a unified management regime for the entire region including the North Sea, the open Skagerrak and Kattegat.

Contributors: Mikko Heino, Jens Christian Holst, Dankert W. Skagen, Sigurd Tjelmeland, Reidar Toresen

Journal homepage: http://versita.com/bl/ We analysed exploitation of populations that are partly protected in a marine harvest refuge to prevent their over-harvesting in the remaining unprotected area. We carried out our analysis by introducing the model of ideal free distribution to the population renewal process. In the model, individuals in the target population are distributed so that per capita resource availability becomes matched in the harvested and non-harvested areas. We show that the yield from the harvest effort is strongly affected by the fraction of area protected from harvesting. The harvest effort maximising the yield depends on the relative size of the protected area. Maximum yield is independent of the size of the protected area unless the fraction is > 0.56. If this value is exceeded, annual yield declines rapidly with increasing protected fraction. However, our major - and somewhat surprising - finding is that protected areas can be established without any loss to commercial harvesting if harvesting follows reproduction and population densities are balanced between harvesting seasons according to resource availability.

Harvest control rules (HCR) are sets of well-defined rules that can be used for determin-ing annual fish catch quotas. If a management policy can be expressed as a HCR, then the HCR provides means to determine the total allowable catch unambiguously. In order to improve certain aspects of the performance for these rules, rules of increasing complexity have been suggested for fish stocks both in Europe and in North America. But is this complexity necessarily better? Are simple strategies outdated? “Traditional” harvesting strategies (i.e. constant harvest rate, fixed quota and constant escapement strategies) are simple HCRs with only one control parameter (i.e. target harvest rate, catch and escape-ment, respectively). “Complex” harvest control strategies are here defined as a multi-parameter HCR. In this study, three criteria (average catch and its coefficient of variabil-ity and risk of population abundance below a minimum acceptable level) are used to judge the performance of traditional and complex HCRs, utilizing a set of stochastic age-structured population models that mimic dynamics of fish populations. The traditional and complex HCRs are then evaluated against each other, paying particular attention to the trade-offs among the performance criteria.

Contributors: Lars-Johan Naustvoll, Einar Dahl

It is generally assumed that fish populations are regulated primarily in the juvenile (pre-recruit) phase of the life cycle, although density dependence in growth and reproductive parameters within the recruited phase has been widely reported. Here we present evidence to suggest that density-dependent growth in the recruited phase is a key process in the regulation of many fish populations. We analyse 16 fish populations with long-term records of size-at-age and biomass data, and detect significant density-dependent growth in nine. Among-population comparisons show a close, inverse relationship between the estimated decline in asymptotic length per unit biomass density, and the long-term average biomass density of populations. A simple population model demonstrates that regulation by density-dependent growth alone is sufficient to generate the observed relationship. Density-dependent growth should be accounted for in fisheries’ assessments, and the empirical relationship established here can provide indicative estimates of the density-dependent growth parameter where population-specific data are lacking.

Contributor: Einar Dahl

Contributor: Mette Mauritzen

Contributors: Arne Bjørge, Peter Corkeron, Nils Øien, Hans Julius Skaug

Contributor: Einar Dahl

A coupled 3D hydrodynamic and ecological model has been set up for the Norwegian Sea (i.e. SINMOD). The hydrodynamic model uses the z-coordinates in the vertical direction. The horizontal grid point distance is 6.67 km and covers the northern North Sea, Mid Norwegian Shelf, Lofoten Basin, Faroes Shelf. The western limit is just at the eastern boarder of the Icelandic Shelf. The open boundaries are taken from a regional model using 20 km grid resolution. The models have been forced with atmospheric input from 6 hourly wind and pressure fields. The ecological model has eight state variables in addition to a structured model of Calanus finmarchicus. The state variables are nitrate, ammonium, silicate, diatoms, flagellates, microzooplankton, slow and fast sinking detritus. The Calanus model uses developmental structure for the nauplii and weight structure for the copepodites. Data from Station M (66°N, 2°E) has been used to adjust the mortality rates of Calanus. 10% of the CV’s are allowed to develop into females and start a new generation and the remaining 90% is transferred into an overwintering stage having a depth distribution between 500 and 1500m. The overwintering stock of Calanus at Station M below 600m was taken as an initial distribution for the whole model domain (north of the Scotland-Iceland ridge). The model simulates the pattern of phytoplankton growth, which is in accordance with observational data from several cruises in the region during the year of Calanus. An early start (March/April) in the Coastal Norwegian waters and at the front between the coastal water and the Atlantic waters was found. The spring bloom starts gradually later West and North in the Norwegian Sea. The earliest spawning took place near the shelf break off Norway where ascending Calanus met the spring bloom in surface waters. At Station M the timing of the spring bloom and the successive copepodite stages are simulated correctly. The simulated second generation is two weeks earlier than observed in field data. However, there is a large heterogeneity around this position in the Norwegian Sea on the southwestern slope of the Vsring Plateau. Coastal water and perhaps water from the East Iceland Current may ‘change the property (vertical mixing and nutrient supply) and the history of the Calanus stock entering this geographical region. Two generations are of Calanus simulated in the southeastern part of the Norwegian Sea. Along the shelf break the second generation is advected as far north as the entrance to the Barents Sea. In the Northern North Sea the temperature and the supply of food is sufficient for the model to produce three generations.

Contributors: Agnes C. Gundersen, Roald Sætre, Arild Folkvord, C. Tara Marshall, Kristin Heller, G. Bløm, Per Solemdal

Contributors: Harald Loeng, Tara Marshall, Geir Ottersen, Stig Skreslet

Contributors: Arne Bjørge, Kjell Nilssen

Contributor: Brit Hjeltnes

Contributors: Kjell Tormod Nilssen, Nils Øien

Norsk: Vi har utformet en skisse for et prosjekt som skal gi svar på om elgbestanden i Stor-Elvdal kan gi grunnlag for en økonomisk levedyktig, og økologisk bærekraftig, næringsvirksomhet. Prosjektet er delt i økologiske delprosjekt som skal gi informasjon til utarbeiding av bioøkonomiske modeller. Til tross for at elgen er en godt studert dyreart trenger vi grundigere studier av effekten av landskapsformer, vilttiltak og rovdyr på bestandsutvikling og forflytningsmønster, og dermed på skogskader og elgpåkjørsler. Vi trenger avskytingsmodeller som inkorporerer tap til rovdyr, påkjørsler og tilfeldige variasjoner i demografi. Den økologiske og økonomiske informasjonen skal nyttes av samfunnsvitere for å utarbeide alternative modeller for forvaltning av viltstammer som trekker over eiendomsgrenser. Skissen skal brukes som et underlag for videre arbeid med å finansiere og gjennomføre prosjektet Elg som næring. English: We have outlined a project to evaluate if an ecological and economical sound enterprise may be based on the moose population of Stor-Elvdal municipality. The project is composed of ecological units that shall give information to make economical models. Even though the moose is a well-studied species, we need more thorough studies of the effect of landscape, management programs and carnivores on population development and movements of moose, and on forest damage and moose-traffic accidents. We need harvesting models that incorporate movement patterns and losses to carnivores and traffic. The ecological and economical information must be used by social scientists to make models of how populations which cross property borders may be managed. Statens landbruksbank. Enkelte studier som rapporten bygger på er også støttet av Kirke, Undervisnings og Forskningsdepartementet (KUF), Jernbaneverket, Stor-Elvdal kommune, Glommen skogeierforening, grunneiere i Stor-Elvdal, Direktoratet for naturforvaltning (DN), Rentemiddelutvalget i Stor-Elvdal, Ytre Rendalen Grunneierforening, Øvre Rendalen Utmarksråd og Høgskolen i Hedmark (HH).

Contributor: Einar Dahl

Contributor: Einar Dahl

The entrance region to Tysfjorden was acoustically surveyed a total of eleven times during the December 1996 abundance survey of the spawning stock of Norwegian spring-spawning herring (Clupea harengus). The observations are summarized through maps of the distribution, vertical sections, and statistical measures of acoustic density in each of two strata. Experimental variograms are modeled, yielding parameter values that summarize the major properties of aggregation. The collective measures of density and aggregation portray a highly dynamic situation with strong diel variation but a general persistence of the fish distribution over the eleven days of its repeated observation.

Contributor: Einar Dahl

Herring are long-lived multiple spawners exhibiting strong variation in reproductive and recruitment success between years. They tend to adopt low-risk, preferred-conservative strategies; for example, shifts to alternative overwintering areas do not take place until there are large benefits. At the same time, herring is an extremely flexible species, displaying considerable plasticity in migratory behaviour. Migration patterns of herring have been investigated over many years. Most studies are however, descriptive and little is published that analyses the factors and mechanisms that govern spatial dynamics. In this paper we try to interpret the existing observations from an ecological and evolutionary perspective, emphasising proximate mechanisms that restrict the extent to which herring are capable of attaining an optimal distribution. Focus is directed to observations and literature on the Norwegian spring spawning herring.

Contributors: Dag Aksnes, Kenneth G. Foote, Hein Rune Skjoldal

Contributor: Einar Dahl

Contributors: Dag Aksnes, Johan Blindheim, Stein Kaartvedt, Hein Rune Skjoldal, Dag Slagstad, Svein Sundby, Kurt Tande

HERMOD is a model for the population dynamics and migration of the Norwegian Spring spawning herring that is being developed with the double purpose of being an independent single species model and of being integrated into the Multispecies Model for the Barents Sea (MULTSPEC). This paper describes and discusses the presently used algorithms for maturation, recruitment, growth and migration, as well as the model's input and output options. A brief outline is given of the plans for further development.

Final Report on contract F278-93-008, CEES 07-4-30351, October 1, 1992, to September 30, 1993

Contributors: Dag L. Aksnes, Einar Svendsen

Contributor: Nils Øien

Contributors: Lars Petter Hansen, Knut Eirik Jørstad, Gunnar Nævdal

Contributor: Tore Jakobsen.