Are we ready to track climate-driven shifts in marine species across international boundaries? - A global survey of scientific bottom trawl data

Marine biota are redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of data availability, and mismatch between data and real species distributions. To assess the extent of this challenge, we review the global status and accessibility of ongoing scientific bottom trawl surveys. In total, we gathered metadata for 283,925 samples from 95 surveys conducted regularly from 2001 to 2019. We identified that 59% of the metadata collected are not publicly available, highlighting that the availability of data is the most important challenge to assess species redistributions under global climate change. Given that the primary purpose of surveys is to provide independent data to inform stock assessment of commercially important populations, we further highlight that single surveys do not cover the full range of the main commercial demersal fish species. An average of 18 surveys is needed to cover at least 50% of species ranges, demonstrating the importance of combining multiple surveys to evaluate species range shifts. We assess the potential for combining surveys to track transboundary species redistributions and show that differences in sampling schemes and inconsistency in sampling can be overcome with spatio-temporal modeling to follow species density redistributions. In light of our global assessment, we establish a framework for improving the management and conservation of transboundary and migrating marine demersal species. We provide directions to improve data availability and encourage countries to share survey data, to assess species vulnerabilities, and to support management adaptation in a time of climate-driven ocean changes.En prensa6,86

Canada–U.S. Fisheries Management in the Gulf of Maine: Taking Stock and Charting Future Coordinates in the Face of Climate Change

Climate change and ocean acidification are the biggest non-fisheries threats to marine organisms across the global oceans. But where fish stocks are shared be- tween different countries, these oceanographic changes can have consequenc- es for governance regimes and extractive marine activities through changes in stock distribution, and the affording of fishing and access rights. The Gulf of Maine is considered a single ecosystem that is rapidly warming and undergoing ecosystem change. It is also bisected by an international maritime boundary, known as the Hague Line, separating the exclusive economic zones (EEZs) of Canada and the United States. Several fish species, such as cod, haddock, flounders, halibut, American eel, sandlance, cusk, pollock, herring, mackerel, and dogfish straddle the Line and although scientists suspect species’ distributional shifts in relation to the Line due to natural fluctuations and anthropogenic disturbances such as climate change, the full impact and extent of these shifts are not completely known and in some ways are unpredictable

Canada–U.S. Fisheries Management in the Gulf of Maine: Taking Stock and Charting Future Coordinates in the Face of Climate Change

Climate change and ocean acidification are the biggest non-fisheries threats to marine organisms across the global oceans. But where fish stocks are shared be- tween different countries, these oceanographic changes can have consequenc- es for governance regimes and extractive marine activities through changes in stock distribution, and the affording of fishing and access rights. The Gulf of Maine is considered a single ecosystem that is rapidly warming and undergoing ecosystem change. It is also bisected by an international maritime boundary, known as the Hague Line, separating the exclusive economic zones (EEZs) of Canada and the United States. Several fish species, such as cod, haddock, flounders, halibut, American eel, sandlance, cusk, pollock, herring, mackerel, and dogfish straddle the Line and although scientists suspect species’ distributional shifts in relation to the Line due to natural fluctuations and anthropogenic disturbances such as climate change, the full impact and extent of these shifts are not completely known and in some ways are unpredictable

Data from: The potential for spatial distribution indices to signal thresholds in marine fish biomass

The frequently observed positive relationship between fish population abundance and spatial distribution suggests that changes in distribution can be indicative of trends in abundance. If contractions in spatial distribution precede declines in spawning stock biomass (SSB), spatial distribution reference points could complement the SSB reference points that are commonly used in marine conservation biology and fisheries management. When relevant spatial distribution information is integrated into fisheries management and recovery plans, risks and uncertainties associated with a plan based solely on the SSB criterion would be reduced. To assess the added value of spatial distribution data, we examine the relationship between SSB and four metrics of spatial distribution intended to reflect changes in population range, concentration, and density for 10 demersal populations (9 species) inhabiting the Scotian Shelf, Northwest Atlantic. Our primary purpose is to assess their potential to serve as indices of SSB, using fisheries independent survey data. We find that metrics of density offer the best correlate of spawner biomass. A decline in the frequency of encountering high density areas is associated with, and in a few cases preceded by, rapid declines in SSB in 6 of 10 populations. Density-based indices have considerable potential to serve both as an indicator of SSB and as spatially based reference points in fisheries management

Data from: The potential for spatial distribution indices to signal thresholds in marine fish biomass

The frequently observed positive relationship between fish population abundance and spatial distribution suggests that changes in distribution can be indicative of trends in abundance. If contractions in spatial distribution precede declines in spawning stock biomass (SSB), spatial distribution reference points could complement the SSB reference points that are commonly used in marine conservation biology and fisheries management. When relevant spatial distribution information is integrated into fisheries management and recovery plans, risks and uncertainties associated with a plan based solely on the SSB criterion would be reduced. To assess the added value of spatial distribution data, we examine the relationship between SSB and four metrics of spatial distribution intended to reflect changes in population range, concentration, and density for 10 demersal populations (9 species) inhabiting the Scotian Shelf, Northwest Atlantic. Our primary purpose is to assess their potential to serve as indices of SSB, using fisheries independent survey data. We find that metrics of density offer the best correlate of spawner biomass. A decline in the frequency of encountering high density areas is associated with, and in a few cases preceded by, rapid declines in SSB in 6 of 10 populations. Density-based indices have considerable potential to serve both as an indicator of SSB and as spatially based reference points in fisheries management

Change in Realized Thermal Habitat Index of individual species for long-term (2060) and short-term (2030) scenarios

<p>. Each boxplot represents the distribution of net change calculated from 10 models fit to subsamples of each species. Dashed lines are at 10%. Net change is considered neutral if median net change among 10 subsamples is between dashed lines. Positive outliers >100 are not shown. Change in habitat under scenario 1 (Y2060) in Canada (A) and the USA (B) and under scenario 2 (Y2030) in Canada (C) and USA (D). Abbreviated species names are listed beside full common names in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090662#pone.0090662.s003" target="_blank">Table S2</a>.</p

Thermal Habitat Index of Many Northwest Atlantic Temperate Species Stays Neutral under Warming Projected for 2030 but Changes Radically by 2060

<div><p>Global scale forecasts of range shifts in response to global warming have provided vital insight into predicted species redistribution. We build on that insight by examining whether local warming will affect habitat on spatiotemporal scales relevant to regional agencies. We used generalized additive models to quantify the realized habitat of 46 temperate/boreal marine species using 41+ years of survey data from 35°N–48°N in the Northwest Atlantic. We then estimated change in a “realized thermal habitat index” under short-term (2030) and long-term (2060) warming scenarios. Under the 2030 scenario, ∼10% of species will lose realized thermal habitat at the national scale (USA and Canada) but planktivores are expected to lose significantly in both countries which may result in indirect changes in their predators’ distribution. In contrast, by 2060 in Canada, the realized habitat of 76% of species will change (55% will lose, 21% will gain) while in the USA, the realized habitat of 85% of species will change (65% will lose, 20% will gain). If all else were held constant, the ecosystem is projected to change radically based on thermal habitat alone. The magnitude of the 2060 warming projection (∼1.5–3°C) was observed in 2012 affirming that research is needed on effects of extreme “weather” in addition to increasing mean temperature. Our approach can be used to aggregate at smaller spatial scales where temperate/boreal species are hypothesized to have a greater loss at ∼40°N. The uncertainty associated with climate change forecasts is large, yet resource management agencies still have to address climate change. How? Since many fishery agencies do not plan beyond 5 years, a logical way forward is to incorporate a “realized thermal habitat index” into the stock assessment process. Over time, decisions would be influenced by the amount of suitable thermal habitat, in concert with gradual or extreme warming.</p></div

Area Under Receiving Operating Curve (AUC).

<p>Expected Accuracy (of classification) of GAM model fit for each species, compared to the observations. An AUC value of 1 would indicate that predicted values resulted in a completely accurate classification of observations. For all but one species, the model was able to accurately classify >80% probability of occurrence.</p

Change in Realized Thermal Habitat Index by functional group in Canada and USA.

<p>Panels depict results under the long-term (Y2060) (A) and short-term (Y2030) (B) scenarios. Functional group member species are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090662#pone.0090662.s002" target="_blank">Table S1</a>. Piscivore refers to piscivore. Zoopisciv refers to zoopiscivore, Lg.Benthi refers to large benthivores, Md.Benthi refers to Medium-sized benthivores, Sm.Benthi refers to small-sized benthivores. Decapod B refers to decapod benthivores, Planktivo refers to planktivores, FilterFee refers to filter feeders (scallop).</p