Abstract The usefulness and relevance of size-based indicators (SBIs) to an ecosystem approach fisheries (EAF) are assessed through a review empirical modelling studies. SBIs tabulated along with their definitions, data requirements, potential biases, availability time-series, expected directions change in response fishing pressure. They include mean length population, community, maximum the slope intercept size spectra. Most can be derived from fairly standard survey on frequencies, without...

Abstract The natural mortality of exploited fish populations is often assumed to be a species‐specific constant independent body size. This assumption has important implications for size‐based population models and predicting the outcome size‐dependent fisheries management measures such as mesh‐size regulations. To test assumption, we critically review empirical estimates mortality, M (year −1 ), marine brackish water stocks model them function von Bertalanffy growth parameters, L (cm) K...

By analysing data sets from different world regions we add evidence to documented changes in demersal fish community structure that may be related fishing. Changes are analysed by properties might expected capture relevant overall – size spectra slopes and intercepts, Shannon-Wiener diversity, dominance. Cross-system differences the shape of integrated appear ecosystem productivity. The slope appears respond a consistent way exploitation levels. In most areas studied, but particularly...

Abstract We investigate changes in the North Sea fish community with particular reference to possible indirect effects of fishing, mediated through ecosystem. In past, long-term slope size spectra research vessel catches have been related fishing effort, but such may simply reflect cumulative, direct selective removal large individuals. If there is resilience a towards we expect increases specific components, for instance as consequence an associated reduction predation and/or competition....

Following an introduction to the broader context of Symposium, scope oral presentations is summarized under three themes: a global synthesis fisheries impacts in different ecosystems; overview methods available for quantifying ecosystem impacts; and integration environmental management. The generated substantial evidence that marine ecosystems have been impacted by fishing. Also there appeared be broad consensus present approach achieving conservation objectives management does not...

Abstract The Baltic Sea is a large brackish semienclosed sea whose species‐poor fish community supports important commercial and recreational fisheries. Both the species fisheries are strongly affected by climate variations. These climatic effects underlying mechanisms briefly reviewed. We then use recent regional – scale ocean modelling results to consider how change during this century will affect of management. Expected changes in northern Europe likely both temperature salinity Baltic,...

Abstract We revisit the empirical equation of Gislason et al. (2010, Fish and Fisheries 11 :149–158) for predicting natural mortality ( M , year −1 ) marine fish. show it to be equivalent where L ∞ (cm) K (year are von Bertalanffy growth (VBGE) parameters, is fish length along trajectory within species. then interpret in terms VBGE mass that previous itself a −⅓ power function rule between at first reproduction W α ); this new emerges directly from life history maximizes Darwinian fitness...

Balanced harvesting, where species or individuals are exploited in accordance with their productivity, has been proposed as a way to minimize the effects of fishing on marine fish communities and ecosystems. This calls for thorough examination consequences balanced harvesting community structure yield. We use size- trait-based model that resolves individual interactions through competition predation compare traditional selective which protects juvenile from fishing. Four different...

Many marine fish stocks are overexploited and considerable overcapacity exists in fishing fleets worldwide. One of the reasons for imbalance between resource availability capacity is technological development, which continuously increases efficiency vessels—a mechanism referred to as "technological creep." We review how introduction new more efficient electronic equipment, gear design, engines, deck catch-handling procedures influences capture (catchability) commercial vessels. On average,...

The relationship between biodiversity and ecosystem functioning (BEF) is a topic of considerable interest to scientists managers because better understanding its underlying mechanisms may help us mitigate the consequences loss on ecosystems. Our current knowledge BEF relies heavily theoretical experimental studies, typically conducted narrow range spatio-temporal scales, environmental conditions, trophic levels. Hence, whether holds in natural environment poorly understood, especially...

Abstract To measure and predict the response of fish communities to exploitation, it is necessary understand how direct indirect effects fishing interact. Because predation are size-selective processes, potential can be explored with size-based models. We use a simulation approach describe relationship between size spectrum slope overall mortality try linear might maintained. The model uses 15 parameters 13-“species” community, where species defined by their maximum body general life-history...

Abstract Aim Higher temperatures increase the metabolic rate of ectothermic organisms up to a certain level and make them grow faster. This temperature‐sensitivity growth is frequently used predict long‐term effects climate warming on ectotherms. Yet, realized also depends ecological factors evolutionary adaptation. Here we study whether faster observed along temperature clines within between marine fish species from polar tropical regions. Location Global. Time period The sampling or...

Understanding the drivers of greenhouse gas emissions in food production systems is becoming urgent. For wild capture fisheries, fuel use during fishing phase generally dominates and highly variable between fisheries. Fuel also essential for economy but fuel-intensive fisheries can still be profitable due to subsidies, particular, if target species high value. Developing an innovative bottom-up approach based on detailed catch spatial effort data, absence direct we analysed intensity (fuel...

Biological reference points (BRPs) are widely used to define safe levels of harvesting for marine fish populations. Most BRPs either minimum acceptable biomass or maximum fishing mortality rates. The values determined from historical abundance data and the life-history parameters species. However, when change over time, become moving targets. In particular, natural rate prey species depends on predator levels; conversely, growth rates depend availability. We tested a suite their robustness...

The large variability in Baltic cod (Gadus morhua) recruitment has been attributed both to environmental factors dependent on the inflow of saline water (oxygen and salinity spawning deeps) size stock. Due complex interactions between hydrographic biological processes, future levels will remain highly uncertain increase uncertainties stock predictions management advice. We assessed effects exploitation level mesh used by a trawl fishery some variables interest under different conditions....

In this paper we investigate whether single and multispecies fisheries models can be used to predict the response of size diversity spectra fish assemblages changes in exploitation. Both types estimate that slope spectrum will steepen intercept increase when fishing intensity increases, while depend on model used. The are found proportional change intensity. proportionality is insensitive natural mortality, but sensitive growth relationship between stock recruitment. results agree well with...

Single and multispecies models are used to examine the effect of species interaction on biological reference points for cod, herring, sprat in Baltic. The results demonstrate that different single contexts. Reference fishing mortality based single-species yield SSB calculations difficult use when natural depends absolute abundance predators their alternative prey. maximizing total from system may lead impractical interact. Multispecies predictions suggest cod stock Baltic should be reduced a...

Understanding how human impacts have interacted with natural variability to affect populations and ecosystems is required for sustainable management conservation. The Baltic Sea one of the few large marine worldwide where relative contribution several key forcings changes in fish can be analyzed empirical data. In this study we investigate climate multiple (fishing, mammal hunting, eutrophication) affected multi-decadal scale dynamics cod during 20th century. We document significant...

Atlantic mackerel (Scomber scombrus) occurs on both sides of the north and has traditionally been grouped into 5 spawning components, some which were thought to be isolated natal homing stocks. Previous studies have provided no evidence for cross migration or weak support components within either side North Atlantic. We question de-facto accepted hypothesis isolation between basis age distribution data. The intensities, proxied by larval abundances, are negatively correlated Sea Celtic Sea,...