Camilla Novaglio

and 11 more

Climate-driven ecosystem changes are increasingly affecting the world’s ocean ecosystems, necessitating urgent guidance on adaptation strategies to limit or prevent catastrophic impacts. The Fisheries and Marine Ecosystem Model Intercomparison Project (FishMIP) is a network and framework that provides standardised ensemble projections of the impacts of climate change and fisheries on ocean life and the benefits that it provides to people through fisheries. Since its official launch in 2013 as a small, self-organised project within the larger Inter-Sectoral Impact Model Intercomparison Project, the FishMIP community has grown substantially and contributed to key international policy processes, such as the IPCC AR5 and AR6, and the IPBES Global Biodiversity Assessment. While not without challenges, particularly around comparing heterogeneous ecosystem models, integrating fisheries scenarios, and standardising regional-scale ecosystem models, FishMIP outputs are now being used across a variety of applications (e.g., climate change targets, fisheries management, marine conservation, Sustainable Development Goals). Over the next decade, FishMIP will focus on improving ecosystem model ensembles to provide more robust and policy-relevant projections for different regions of the world under multiple climate and societal change scenarios, and continue to be open to a broad spectrum of marine ecosystem models and modellers. FishMIP also intends to enhance leadership diversity and capacity-building to improve representation of early- and mid-career researchers from under-represented countries and ocean regions. As we look ahead, FishMIP aims to continue enhancing our understanding of how marine life and its contributions to people may change over the coming century at both global and regional scales.

Daniel van Denderen

and 6 more

Robust projections of future trends in global fish biomass, production and catches under different fishing scenarios are needed to inform fisheries policy in a changing climate. Trust in future projections, however, relies on establishing that the models used can accurately simulate past relationships between exploitation rates, catches and ecosystem states. Here we use fisheries catch and catch-only assessment models in combination with effort data to estimate regional fishing exploitation levels (defined as the fishing mortality relative to fishing mortality at maximum sustainable yield, F/FMSY). These estimates are given for large pelagic, forage and demersal fish types across all large marine ecosystems and the high seas between 1961 and 2004; and with a ‘ramp-up’ between 1841-1960. We find that global exploitation rates for both large pelagic and demersal fish are consistently higher than for forage fish and reached their peaks in the late 1980s. We use the exploitation rates to globally simulate historical fishing patterns in a mechanistic fish community model. We find a good match between model and reconstructed fisheries catch, both for total catch as well as catch distribution by functional type. Simulations show a clear deviation from an unfished model state, with a 25% reduction in fish biomass in large pelagic and demersal fish in shelf regions in the most recent years and a 50% increase in forage fish, primarily due to the release of predation pressure. These results can set a baseline from which the effect of climate change relative to fishing could be estimated.

Julia L. Blanchard

and 42 more

There is an urgent need for models that can robustly detect past and project future ecosystem changes and risks to the services that they provide to people. The Fisheries and Marine Ecosystem Model Intercomparison Project (FishMIP) was established to develop model ensembles for projecting long-term impacts of climate change on fisheries and marine ecosystems while informing policy at spatio-temporal scales relevant to the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) framework. While contributing FishMIP models have improved over time, large uncertainties in projections remain, particularly in coastal and shelf seas where most of the world’s fisheries occur. Furthermore, previous FishMIP climate impact projections have mostly ignored fishing activity due to a lack of standardized historical and scenario-based human activity forcing and uneven capabilities to dynamically model fisheries across the FishMIP community. This, in addition to underrepresentation of coastal processes, has limited the ability to evaluate the FishMIP ensemble’s ability to adequately capture past states - a crucial step for building confidence in future projections. To address these issues, we have developed two parallel simulation experiments (FishMIP 2.0) on: 1) model evaluation and detection of past changes and 2) future scenarios and projections. Key advances include historical climate forcing, that captures oceanographic features not previously resolved, and standardized fishing forcing to systematically test fishing effects across models. FishMIP 2.0 is a key step towards a detection and attribution framework for marine ecosystem change at regional and global scales, and towards enhanced policy relevance through increased confidence in future ensemble projections.

Alexandra Johne

and 6 more

Fed aquaculture is one of the fastest growing and most valuable food production industries. The efficiency with which farmed fish convert feed into biomass influences both environmental impact and economic revenue. Salmonid species, such as king salmon (Oncorhynchus tshawytscha), exhibit high levels of plasticity in vital rates such as feed intake and growth rates. Accurate estimations of individual variability in vital rates are important for production management. The use of mean trait values to evaluate feeding and growth performance can mask individual-level differences that potentially contribute to inefficiencies. Here, we apply an integral projection model (IPM) to investigate individual variation in growth performance of 1625 individually tagged king salmon fed one of three distinct rations and tracked over 276 days. To capture the observed sigmoidal growth, we compared a non-linear mixed-effects (logistic) model to a linear regression model used within the IPM framework. Ration significantly influenced several aspects of growth. Mean final body mass and mean growth rate increased with ration, however, variance in body mass and feed intake also increased significantly over time. Trends in body mass mean and variance were captured by both logistic and linear models, suggesting the linear model to be suitable for use in the IPM. Higher rations resulted in a decreasing proportion of individuals reaching the cohort’s mean size or larger by the end of the experiment. This suggests that, in our trial, feeding to satiation did not produce the desired effects of efficient and uniform growth in juvenile king salmon. While monitoring individuals through time is challenging in commercial aquaculture settings, recent technological advances combined with an IPM approach could provide new scope for tracking growth performance in experimental and farmed populations. The IPM framework also allows the exploration of other size-dependent processes affecting vital rate functions, such as competition and mortality.

Amy Coghlan

and 5 more

Climate change and fisheries exploitation are dramatically changing the species composition, abundances, and size spectra of fish communities. We explore whether variation in abundance-size spectra, a widely studied ecosystem feature, is influenced by a critical parameter thought to govern the shape of size-structured ecosystems—the relationship between the sizes of predators and their prey (predator-prey mass ratios, or PPMRs). PPMR estimates are lacking for vast numbers of fish species, including at the broader trophic guild scale. Using measurements of 8,128 prey items in gut contents of 97 reef fish species, we established PPMRs for four major trophic guilds (piscivores, invertivores, planktivores and herbivores) using linear mixed effects models. To assess theoretical predictions that higher mean community-level PPMR leads to shallower size spectrum slopes, we compared observations of mean community-level PPMR with size spectrum slopes for coastal reef sites distributed around Australia. PPMRs of individual fishes were remarkably high (median ~71,000), with significant variation between different trophic guilds (~890 for piscivores; ~83,000 for planktivores), and ~8,700 for whole communities. Community-level PPMRs were positively related to size spectrum slopes, broadly consistent with theory, however, this pattern was also influenced by the latitudinal temperature gradient. Tropical reefs showed a stronger relationship between community-level PPMRs and community size spectrum slopes than temperate reefs. The extent that these patterns apply outside Australia, and consequences for community structure and dynamics, are key areas for future investigation.

Romain Forestier

and 5 more

1. Fishing is a strong selective force and is supposed to select for earlier maturation at smaller body size. However, the extent to which fishing-induced evolution is shaping ecosystems remains debated. This is in part because it is challenging to disentangle fishing from other selective forces (e.g. size-structured predation and cannibalism) in complex ecosystems undergoing rapid change. 2. Changes in maturation size from fishing and predation have previously been explored with multi-species physiologically structured models but assumed separation of ecological and evolutionary timescales. To assess the eco-evolutionary impact of fishing and predation at the same timescale, we developed a stochastic physiologically size-structured food web model, where new phenotypes are introduced randomly through time enabling dynamic simulation of species’ relative maturation sizes under different types of selection pressures. 3. Using the model, we carried out a fully factorial in silico experiment to assess how maturation size would change in the absence and presence of both fishing and predation (including cannibalism). We carried out ten replicate stochastic simulations exposed to all combinations of fishing and predation in a model community of nine interacting fish species ranging in their maximum sizes from 10g to 100kg. We visualised and statistically analysed the results using linear models. 4. The effects of fishing on maturation size depended on whether or not predation was enabled and differed substantially across species. Fishing consistently reduced the maturation sizes of two largest species whether or not predation was enabled and this decrease was seen even at low fishing intensities (F = 0.2yr−1 ). In contrast, the maturation sizes of the three smallest species evolved to become smaller through time but this happened regardless 2 of the levels of predation or fishing. For the four medium-size species, the effect of fishing was highly variable with more species showing significant and larger fishing effects in the presence of predation. 5. Ultimately our results suggest that the interactive effects of predation and fishing can have marked effects on species’ maturation sizes, but that, at least for the largest species, predation does not counterbalance the evolutionary effect of fishing. Our model also produced relative maturation sizes that are broadly consistent with empirical estimates for many fish species.