Investigating the drivers of maturation dynamics in Barents Sea haddock (Melanogrammus aeglefinus)

Changes in size and age at maturation of many exploited fish stocks have been investigated and the influences of environmental factors and exploitation have often been inferred, but not explicitly investigated. Here we determine probabilistic maturation reaction norms (PMRNs) for Barents Sea haddock (Melanogrammus aeglefinus) using generalized linear models (GLMs) and mixed effect models (GLMMs), which account for the correlation among samples within a tow station, and investigate the effects of fishing mortality, environmental factors (NAO, water temperature, and salinity), and potential density dependence or species interaction effects. We found little evidence of a consistent trend in maturation tendencies for Barents Sea haddock for cohorts 1983–2003, ages 4–6 years. Female haddock matured at larger lengths for a given age than males, but overall patterns were similar for both sexes. The GLMM approach gave consistently higher PMRN midpoint estimates than the GLM approach, which indicated that PMRNs that do not account for correlations within the data may bias estimates. Environmental factors, rather than exploitation, density dependence, or species interactions, were responsible for the observed changes in size and age at maturation in Barents Sea haddock during the late 1980s through early 2000s. Little evidence of fisheries-induced evolution was found in these fish over the time period investigated. The lack of a significant temporal trend in maturation may be due to several challenges in estimating representative population parameters for this stock, the trait change being in a period of stasis or reversal, or adaptation by the fish to higher exploitation in the past resulting in negligible evolutionary selection during the study period when exploitation has been more moderate

Evaluating effort regulation in mixed fisheries: a Monte Carlo approach

This paper evaluates whether effort regulation could achieve the goal of protecting low-abundance species in mixed fisheries. We construct a two-species bio-economic model and compare the stock abundance ratio in the end of the fishing season with the ratio prior to the fishing. Fishers’ profit maximization problem is governed by three key factors: (a) the overall efficiency of catching different species (catchability), (b) the price of different species, and (c) their ability to catch the favoured species separately from the less-favoured species (separability). Using a Monte Carlo sampling of feasible parameters space, we show that effort regulation has good chances (87% of the cases) of maintaining the end stock ratio near equal levels ( 1/2 < stock ratio < 2) when the initial stock ratio is equal. If the initial stock ratio is not equal, however, there is a high risk (about 50% of the cases) that effort control increases differences in the relative species abundances, rather than diminishing them. The effects depend on whether the key factors determining fishing profitability are counteracting or reinforcing each other, and their relative strength. Our results warn against placing too much faith on the ability of effort regulation to protect species at low abundances from excessive exploitation.submittedVersio

The latitudinal uniformity of the unique life history of Velia caprai (Heteroptera: Veliidae) and notes to the pre-overwintering period of selected water striders (Heteroptera: Gerridae)

Temperate water striders (Gerridae) overwinter as adults and die after spring reproduction. European water cricket Velia caprai (Veliidae) overwinters concurrently in egg and adult stage in Central Europe. This rare overwintering strategy goes with longevity ofthis species. Adults can survive two winters in Central Europe, unlike other semiaquatic bugs. Scandinavian populations of V. caprai and water striders Gerris lacustris and G. lateralis were examined at the beginning and end of September to determine their life histories. Both gerrids start to overwinter during September, females prior to males and macropterous individuals prior to brachypterous. All females of G. lacustris and G. lateralis enter reproductive diapause before winter. V. caprai overwinters in both adult and egg stage in Norway, and can probably survive two winters. Central European and Scandinavian populations of V. caprai share the same unusual way of overwintering and probably also the whole life history

LabVolt-sarjan aurinkolämmön harjoitusjärjestelmä sekä aurinkolämpöjärjestelmät Suomessa

Tämän insinöörityön tarkoituksena on esitellä lämmönkeräysmenetelmiä yleisellä tasolla, käydä läpi erilaisia keräintyyppejä ja erilaisia aurinkolämpöjärjestelmiä sekä perehtyä Metropoliaa varten Feston LabVolt-sarjan aurinkolämmön harjoitusjärjestelmään. Työn käynnistävänä tarkoituksena oli käyttökokemusten kerääminen harjoitusjärjestelmästä ammatti-korkeakoulu Metropolialle sekä harjoitustöiden työohjeiden laatiminen tulevaa opetuskäyttöä varten. Tässä insinöörityössä esittelen Solar thermal energy systems -kirjan koejärjestelyt, kokeiden aurinkolämpöjärjestelmät sekä analysoin niiden käyttömahdollisuuksia Suomessa. Lopuksi esittelen kokeista saadut mittaustulokset. Harjoitusjärjestelmään perehtyminen tapahtui järjestelmän mukana tulleiden harjoitustöiden perusteella. Aurinkolämmön teori-aan perehtyminen tapahtui erinäisten kirjallisten lähteiden perusteella. Niiden perusteella on esitelty erilaiset aurinkokeräimet, aurinkolämpöjärjestelmät ja niiden käyttömahdollisuudet Suomessa. Harjoitusjärjestelmä soveltuu sellaisenaan opetuskäyttöön, ja sen avulla onkin hyvä tutustua aurinkolämpöön. Sillä pääsee helposti tutustumaan aurinkolämmityksessä käytettäviin komponentteihin ja toimintaperiaatteisiin. Tehtyjen töiden perusteella aurinkolämpöjärjestelmät eivät kuitenkaan anna aivan täyttä kuvaa Suomessa käytössä olevista aurinkolämpöjärjestelmistä. Insinöörityöstä saa kattavan kuvan erilaisista aurinkokeräimistä ja niiden käyttömahdollisuuksista ja tulevaisuuden näkymistä Suomessa. Näiden lisäksi Metropolia ammattikorkeakoulu saa työohjeet aurinkolämmön harjoitusjärjestelmästä opetuskäyttöä varten.The purpose of this bachelor’s thesis was to present different solar thermal energy systems, solar energy collection methods and different solar collectors in Finland. Furthermore, one of the main objectives was to introduce the Festo’s solar thermal training system and create instructions for it for future teaching purposes for Metropolia University of Applied Sciences. The training system was studied by performing training exercises in the training material for the Festo system. General information regarding solar thermal energy was gathered from relevant literature and internet based sources. The training exercises showed that the training system is a useful tool for teaching solar thermal energy in general. The components or solar thermal systems were easy to learn and comprehend by performing the training exercises. However, the solar thermal systems presented in the exercises do not fully reflect the different thermal systems that are used in Finland. This bachelor’s thesis can be used to provide a cross-section of the various solar thermal energy forms in Finland. The instructions for the training system are also given to the Metropolia University of Applied Sciences

Ecological and evolutionary effects of harvesting: lessons from the candy-fish experiment

Understanding the challenges of sustainable fisheries management is not easy for non-specialists, and even many specialists fail to appreciate the potential evolutionary consequences of harvest. We propose candy-fish experiments as a savoury approach to teaching and disseminating the key principles of applied ecology and evolution to students, practitioners and the general public. We performed a simple experiment where the resource was represented by fish-shaped candy of distinct colours and flavours (strawberry and liquorice). Typically, harvesting was neither ecologically sustainable (55% of the populations were extinct by the end of the experiment) nor evolutionarily sustainable (most surviving populations had liquorice fish only). This harvest-induced evolution went apparently unnoticed. Somewhat encouragingly, the harvest was most likely ecologically sustainable when a person spontaneously took the role of a stock manager.acceptedVersio

The importance of social dimension and maturation stage for the probabilistic maturation reaction norm in Poecilia reticulata

Maturation is an important event in an organism's life history, with important implications on dynamics of both wild and captive populations. The probabilistic maturation reaction norm (PMRN) has emerged as an important method to describe variation in maturation in wild fish. Because most PMRNs are based on age and size only, it is important to understand limitations of these variables in explaining maturation. We experimentally assessed (i) the sensitivity of age- and size-based PMRNs to unaccounted sources of plasticity, (ii) the role of social environment on maturation and (iii) the significance of estimating PMRNs early and late in the maturation process (initiation and completion of maturation, respectively). We reared male guppies (Poecilia reticulata) under laboratory conditions, subjected to two food levels and three different social cues. We found that growth and social environment affected the maturation in a way that could not be accounted for by their effect on age and size. PMRNs estimated for the initiation stage were less plastic (growth differences and social cues influenced the PMRN shape only little) than those for completion. The initiation of maturation is probably closer to the maturation ‘decision’ and allows determining factors influencing maturation decision most accurately.acceptedVersio

The importance of social dimension and maturation stage for the probabilistic maturation reaction norm in Poecilia reticulata

Maturation is an important event in an organism's life history, with important implications on dynamics of both wild and captive populations. The probabilistic maturation reaction norm (PMRN) has emerged as an important method to describe variation in maturation in wild fish. Because most PMRNs are based on age and size only, it is important to understand limitations of these variables in explaining maturation. We experimentally assessed (i) the sensitivity of age- and size-based PMRNs to unaccounted sources of plasticity, (ii) the role of social environment on maturation and (iii) the significance of estimating PMRNs early and late in the maturation process (initiation and completion of maturation, respectively). We reared male guppies (Poecilia reticulata) under laboratory conditions, subjected to two food levels and three different social cues. We found that growth and social environment affected the maturation in a way that could not be accounted for by their effect on age and size. PMRNs estimated for the initiation stage were less plastic (growth differences and social cues influenced the PMRN shape only little) than those for completion. The initiation of maturation is probably closer to the maturation ‘decision’ and allows determining factors influencing maturation decision most accurately.acceptedVersio

What can selection experiments teach us about fisheries-induced evolution?

There is evidence that fisheries are altering the phenotypic composition of fish populations, often in ways that may reduce the value of fish stocks for the exploiters. Despite the increasing number of theoretical and field studies, there is still debate as to whether these changes are genetic, can be reversed, and are occurring rapidly enough to be considered in fisheries management. We review the contribution that selection experiments have already provided with respect to the study of the evolutionary effect of fisheries, identify issues that still require more study, and outline future directions for doing so. Selection experiments have already been crucial in showing that harvesting can lead to phenotypic and genetic evolution over relatively short time frames. Furthermore, the experiments have shown the changes involve many other traits than those under direct selection, and that these changes tend to have population-level consequences, including a decreasing fisheries yield. However, experiments focused on fisheries-induced evolution that fulfil all our requirements are still lacking. Future studies should have more controlled and realistic set-ups and assess genetic changes in maturation and growth (i.e. traits most often reported to change) to be more relevant to exploited populations in the wild.acceptedVersio

The importance of social dimension and maturation stage for the probabilistic maturation reaction norm in Poecilia reticulata

Maturation is an important event in an organism's life history, with important implications on dynamics of both wild and captive populations. The probabilistic maturation reaction norm (PMRN) has emerged as an important method to describe variation in maturation in wild fish. Because most PMRNs are based on age and size only, it is important to understand limitations of these variables in explaining maturation. We experimentally assessed (i) the sensitivity of age- and size-based PMRNs to unaccounted sources of plasticity, (ii) the role of social environment on maturation and (iii) the significance of estimating PMRNs early and late in the maturation process (initiation and completion of maturation, respectively). We reared male guppies (Poecilia reticulata) under laboratory conditions, subjected to two food levels and three different social cues. We found that growth and social environment affected the maturation in a way that could not be accounted for by their effect on age and size. PMRNs estimated for the initiation stage were less plastic (growth differences and social cues influenced the PMRN shape only little) than those for completion. The initiation of maturation is probably closer to the maturation ‘decision’ and allows determining factors influencing maturation decision most accurately